What Drug is Taken in Small Doses on a Continuing Basis to Reduce Platelet Adhesion

Interventional cardiology procedures directed against coronary artery obstructions inevitably produce damage to the endothelium and, to varying degrees, the underlying arterial wall. The exposed surfaces are highly thrombogenic and contribute to acute complications in the form of death, MI, or recurrent ischemia requiring repeat PTCA, stent placement, or CABG surgery. These events have multiple causes but commonly are mediated by a thrombotic event. Intra-arterial thrombosis in this setting is initiated by platelet adhesion, activation, and aggregation. The drug therapy commonly used to prevent thrombosis is a combination of heparin and aspirin.^{1 2} These agents, however, have not been completely effective, and several studies have shown that events associated with thrombotic closure during PTCA occur in 4% to 12.8% of patients.^{3 4 5}

Recently, more potent antiplatelet agents have been used to reduce platelet-mediated thrombotic complications.^{5 6 7 8 9 10 11 12 13 14} Abciximab, the c7E3 monoclonal antibody directed against the platelet GP integrin receptor IIb/IIIa, has significantly reduced thrombotic complications occurring after PTCA in a high-risk population.^{5 15 16 17} Abciximab reduced the composite incidence of death, MI, emergency repeat angioplasty, emergency CABG, or stent implantation by 35% at both 2 and 30 days.^{5 15} However, bleeding complications were increased. The purpose of the present study was to investigate the effectiveness of tirofiban, a synthetic, small-molecule nonpeptide GP IIb/IIIa receptor blocker, in patients undergoing high-risk coronary interventions.

Tirofiban, a tyrosine derivative with a molecular weight of 495 kD, is a novel, highly selective inhibitor of fibrinogen binding to platelet GP IIb/IIIa.^{18 19 20 21 22 23 24} Preclinical and clinical studies have confirmed that tirofiban inhibits ex vivo platelet aggregation in response to a variety of agonists, including ADP, collagen, epinephrine, and thrombin. Potential advantages of such a drug include immediate onset of action, rapid reversal of antiplatelet activity after drug discontinuation, suitability for multiple repeat administrations, and high specificity for the IIb/IIIa receptor.

Methods

Study Population

The RESTORE trial was a randomized, double-blind, placebo-controlled trial of tirofiban in patients who were undergoing coronary interventions (balloon angioplasty or DCA) within 72 hours of presentation with an acute coronary syndrome (unstable angina pectoris or acute MI). Unstable angina was defined as angina at rest or with minimal effort and either ECG changes, hemodynamic changes suggestive of ischemia, or angiographic evidence of coronary artery thrombus. Patients were also included if acute MI had occurred within the previous 72 hours. Infarction was defined as ischemic pain lasting >20 minutes with ST-T changes or pathological Q waves (ie, non–Q-wave or Q-wave infarction) and CK elevation more than twice the upper limit of normal or an elevated CK-MB value.

Patients were excluded from the study if they had received thrombolytic therapy within 24 hours, had a contraindication to anticoagulation, had a history of a platelet disorder or thrombocytopenia, had a history of stroke or other intracranial pathology likely to predispose to bleeding, or were scheduled for elective stent placement or if angioplasty using a rotablator or transluminal extraction catheter device was planned.

Procedures

The intervention was performed at the discretion of the operator by standard methods. Informed consent was obtained before the intervention, but randomization was to be delayed until a guidewire was successfully passed across the lesion intended for dilation or atherectomy.

Qualified patients received aspirin (325 mg) within 12 hours before the PTCA procedure and preprocedure heparin according to individual cardiac catheterization laboratory procedures. Investigators were provided with guidelines for heparin administration during PTCA that recommended a maximum heparin bolus of 10 000 U before the procedure (weight-adjusted to 150 μ/kg for patients weighing <70 kg) and heparin as required during the procedure to maintain an ACT of 300 to 400 seconds.

After randomization, a bolus of tirofiban (10 μg/kg) or placebo was administered intravenously over a 3-minute period once the angioplasty guidewire was across the lesion. After the bolus was administered, an intravenous infusion of tirofiban (0.15 μg · kg⁻¹ · min⁻¹) or placebo was started and maintained for 36 hours. This dosing regimen for tirofiban has been shown to achieve rapid and sustained inhibition of platelet aggregation.²³ It resulted in a mean inhibition of platelet aggregation (5 μmol/L ADP) of 96% at 5 minutes, 100% at 2 hours, and 95% at the end of the infusion. The angioplasty balloon catheter or atherectomy catheter was advanced across the lesion and inflated or activated after the tirofiban bolus. Investigators were instructed to limit intracoronary stent implantation to urgent "bailout" situations such as actual or threatened abrupt closure. The protocol guidelines advised investigators to discontinue heparin after the procedure and to remove arterial and venous sheaths when the ACT was <180 seconds. Investigators could modify these guidelines at their discretion to meet the medical needs of individual patients. Patients could be discharged after completion of the 36-hour study drug infusion.

Periprocedural clinical event monitoring was supplemented by periodic laboratory evaluations. Hematocrit and hemoglobin and platelet counts were checked 6, 24, and 48 hours after initiation of the study drug and more frequently as necessary if bleeding occurred.

A 12-lead ECG and a CK measurement with CK-MB isoenzyme levels were obtained at the end of the tirofiban/placebo infusion and as needed clinically to evaluate myocardial ischemia. A routine serum chemistry panel and urinalysis were also performed at the end of study drug infusion (36 hours after angioplasty).

End Points

The end points of the study were death from any cause, MI, CABG surgery owing to angioplasty failure or recurrent ischemia, repeat target-vessel angioplasty for recurrent ischemia, insertion of a stent owing to actual or threatened abrupt closure of the target artery, and a composite end point that represented the occurrence of any of these events. End points were evaluated on a per-patient basis so that each patient was counted only once in the composite end point. End points were evaluated at 2 days, 7 days, 30 days, and 6 months. In addition, a subset of patients underwent repeat angiography at 6 months to evaluate the angiographic incidence of restenosis. The present study reports the results ≤30 days after the initial procedure. The prespecified primary hypothesis of the study was that tirofiban would result in a reduction in the 30-day composite end point compared with placebo.

All end points were adjudicated by an independent, blinded end-point adjudication committee according to the following definitions:

1. Death (due to any cause).

2. MI.

a. In patients entering the study with unstable angina and normal CK/CK-MB values at screening, without a history of MI within 72 hours before randomization, the development of a new MI after PTCA/DCA and before hospital discharge was defined as follows: (1) typical chest pain with new ST-T changes or new pathological Q waves (≥0.04 seconds in duration or with a depth >25% of the corresponding R-wave amplitude in two or more contiguous leads) and an elevated CK-MB level (or a serum CK level more than twice the upper limit of normal if CK-MB level was not available) or (2) CK-MB level ≥3 times the upper limit of normal or CK level ≥3 times the upper limit of normal with an elevated CK-MB level, unaccompanied by chest pain and/or ECG changes.

b. In patients entering the study within 72 hours after an acute MI (including patients undergoing primary PTCA/DCA), the development of a new MI after PTCA/DCA and before hospital discharge was defined as follows: (1) a CK-MB level (or CK level if CK-MB level was not available) ≥3 times the upper limit of normal and representing an increase of ≥33% from the previous valley (defined as a decrease of ≥25% from a previous peak value but remaining at least twice the upper limit of normal) or (2) a CK-MB level (or CK level if CK-MB level was not available) ≥3 times the upper limit of normal and representing an increase of ≥100% from the previous value that was <50% of peak value and less than twice the upper limit of normal.

c. In all patients, the development of a new MI after PTCA/DCA and after hospital discharge was defined as follows: (1) typical chest pain with new ST-T changes or new pathological Q waves (≥0.04 seconds in duration or with a depth >25% of the corresponding R-wave amplitude in two or more contiguous leads) and an elevated CK-MB level (or a serum CK level more than twice the upper limit of normal if CK-MB level was not available); or (2) a CK-MB level ≥2 times the upper limit of normal or CK level ≥2 times the upper limit of normal with an elevated CK-MB level, unaccompanied by chest pain and/or ECG changes.

In the case of an MI that occurred in association with a CABG procedure, the development of a new Q wave was required for evidence of infarction.

3. CABG. CABG was considered an end point when performed owing to a complication (eg, large dissection or perforation) or failure of the initial PTCA/DCA attempt or owing to recurrent ischemia after completion of the initial PTCA/DCA. CABG end points were also categorized as to whether or not they were performed on an emergency basis. An emergency procedure was defined as one that could not be delayed for 24 hours but required a rush to the procedure (operating) room.

4. Repeat coronary angioplasty. Repeat percutaneous intervention was considered an end point when performed for recurrent ischemia (ie, after completion of the initial PTCA/DCA) on the same vessel that was dilated at the initial procedure. Revascularization end points were also categorized as to whether or not they were performed on an emergency basis. An emergency procedure was defined as above but also included non–target-vessel emergency PTCA procedures for consistency with the definition used in other trials.^{5 16}

5. Stent placement. Insertion of an intracoronary stent was considered an end point when performed because of procedure failure. Placement of a stent immediately after an unsuccessful initial PTCA/DCA attempt was considered an end point if there was imminent or complete abrupt closure before stent placement, as demonstrated by TIMI grade 0 or 1 flow in the target vessel or TIMI grade 2 flow in the target vessel associated with a large dissection or residual stenosis >50%. Angiographic assessment of stent placement for procedure failure was performed by an independent core laboratory in a blinded manner. Stent placement for suboptimal result, as opposed to true procedural failure, was not considered an end point.

Bleeding complications were defined as major if they were associated with a decrease in hemoglobin level >5 g/dL, a requirement for transfusion of >2 U, or corrective surgery or if the bleeding site was intracranial or retroperitoneal. Bleeding was also categorized by use of the TIMI criteria for major bleeding (decrease in hemoglobin level >5 g/dL or intracranial bleed).²⁵ Thrombocytopenia was defined as a confirmed platelet count <90 000/mm³.

Statistical Methods

The study sample size was chosen to detect a 35% reduction in a composite event rate of 12.8% in the placebo group⁵ with 90% power. This sample size of 1050 per group resulted in ≈80% power to detect a 30% reduction in the composite event rate. Statistical significance of the difference between treatment groups for the primary end point, the composite of events at 30 days, was assessed by use of a χ² test. To investigate the time course of end points during a 30 day-period, these results were corroborated with a log-rank test that truncated the analysis at days 2, 7, and 30. A similar analysis was performed for the composite end point that included only urgent or emergency procedures instead of all repeat revascularizations. This latter post hoc analysis was done to permit comparison with other published trials of GP IIb/IIIa inhibitors in patients undergoing PTCA.^{5 16 26} Individual end points were compared by use of a χ² test. Cumulative event rates over time were plotted with the use of Kaplan-Meier curves.

Treatment groups were also compared with respect to the frequency of patients experiencing protocol-defined major bleeding complications. A similar analysis that used the more restrictive TIMI definition for major bleeding was also performed. Statistical significance of the difference between groups with respect to the incidence of major bleeding was performed by use of Fisher's exact test. All tests were two-sided, and statistical significance was declared if P≤.05.

Results

Patient Population

A total of 2212 patients were randomized in the trial. Recruitment began on January 9, 1995, and ended on December 1, 1995. The goals of recruitment were met within the time frame specified in the protocol. Seventy-one patients were randomized but never received the study drug (tirofiban or placebo) for an administrative or technical reason (most often because the angioplasty procedure was not done or the indication for angioplasty changed). In the majority of these cases, randomization preceded guidewire placement across the lesion. Therefore, the 2141 patients for whom the study drug infusion was actually initiated were included in the efficacy and safety analyses according to the intention-to-treat principle specified in the protocol.

Baseline Characteristics

Table 1 identifies the baseline characteristics of the patients in the trial. The mean age was ≈60 years, and >70% of the patients were male. Baseline characteristics were similar in the placebo and tirofiban groups. Twenty percent of patients in both groups had a history of diabetes, and in the placebo and tirofiban groups, respectively, 56% and 54% of patients had hypertension, 49% and 50% had elevated serum cholesterol levels, 67% and 64% had a history of smoking, and 34% and 35% had a history of prior MI. Unstable angina pectoris was the most common diagnosis for inclusion in the placebo (68%) and tirofiban (67%) groups. The mean time from the qualifying episode of chest pain to the time of angioplasty was 30 hours. Intervention after the acute phase of MI was the reason for inclusion in 26% of patients. Thirty-two percent of these patients had received prior thrombolytic therapy. Angioplasty was performed during the acute phase of MI as a primary recanalization procedure (primary PTCA) in 6% and 7% of patients in the placebo and tirofiban groups, respectively. The initial procedure was most often balloon angioplasty (93% in the placebo group and 92% in the tirofiban group), with atherectomy used in the remaining patients. Single-lesion angioplasty was performed in 79% and 77% of patients in the placebo and tirofiban groups, respectively.

End Points

The primary analysis for the composite end point from randomization through 30 days is shown in Fig 1 (cumulative event rate), and individual event rates for components of the composite end point are tabulated in Table 2. At 30 days, the primary composite end point as defined in the protocol showed a reduction from 12.2% in the placebo group to 10.3% in the tirofiban group, a 16% relative reduction (P=.160). However, 2 days after the intervention, the tirofiban group had a 38% reduction in the composite end point (P=.005), with a reduction in nonfatal MI and repeat angioplasty. The incidence of the composite end point at 2 days was reduced from 8.7% to 5.4%, and at 7 days the tirofiban group had a 27% relative reduction in the composite end point (P=.022).

The end-point adjudication criteria in this trial included repeat angioplasty or surgery for any target-vessel ischemia. To interpret the present study with respect to other studies,^{5 16} an analysis was also performed that included CABG or repeat revascularization only for urgent or emergency indications. Accordingly, in a post hoc analysis, the RESTORE end-point adjudication committee evaluated all CABG and repeat PTCA end points (including non–target-vessel PTCA) for emergency indication, blinded to the treatment assignment. These results are shown in Fig 2 and Table 3. Sixty-six percent of the repeat PTCA procedures and 63% of the CABG procedures during the first 30 days after randomization were adjudicated as emergency procedures. Most of the nonemergency procedures occurred later than the emergency procedures, as evidenced by a change in the mean number of days from the initial procedure to occurrence of repeat angioplasty from 6.5 (all target-vessel revascularization owing to ischemia) to 3.6 days (emergency target- or non–target-vessel revascularization only) and of CABG from 6.4 to 1.6 days when only emergency procedures were included. Including only urgent or emergency angioplasty or bypass surgery as components of the end point, the composite 30-day event rates were 10.5% for the placebo group and 8.0% for the tirofiban group, a relative risk reduction of 24% (P=.052). Fig 3 shows the cumulative event rate during a 30-day period for acute MI. The tirofiban and placebo group incidences of MI were parallel after the 36-hour drug infusion and did not demonstrate a rebound phenomenon in the tirofiban group after drug discontinuation.

The 30-day end-point events were examined on the basis of inclusion criteria (unstable angina, post MI, or primary PTCA) and procedure performed (balloon angioplasty or atherectomy). The event rate trended lower in the tirofiban-treated patients in all groups when groups were based on inclusion diagnosis. There was a trend for atherectomy patients to have a greater benefit from tirofiban therapy than balloon angioplasty patients, although the number of patients was relatively small and the difference was not statistically significant.

Bleeding complications were not significantly different between the two treatment groups (see Table 4). Major bleeding, defined as a decrease in hemoglobin level >5 g/dL, transfusion of >2 U of blood, or corrective surgery or as a retroperitoneal or intracranial bleed, was not significantly higher in the tirofiban group (5.3%) than in the placebo group (3.7%) (P=.096). When the TIMI criteria for major bleeding were used (decrease in hemoglobin level >5 g/dL or intracranial bleed), the incidence was 2.4% in the tirofiban group compared with 2.1% in the placebo group (P=.662). Thrombocytopenia, a concern in this class of drug, was not significantly increased in the tirofiban group (1.17% versus 0.9% in the placebo group; P=.831). Severe thrombocytopenia (<50 000/mm³) was a rare occurrence in both groups (0.2% in the tirofiban group versus 0.1% in the placebo group; P=1.000).

Discussion

Drugs that block platelet GP IIb/IIIa receptors appear to have important beneficial effects on ischemic complications occurring after coronary angioplasty. This study showed a reduction in acute ischemic complications during the 36-hour infusion period of tirofiban, and this benefit persisted for several days thereafter. At 2 days, there was a 3.3% absolute or 38% relative reduction in the composite event rate of death, MI, CABG, repeat PTCA, or stent placement for abrupt closure (P<.005), and at 7 days there was a 2.8% absolute or 27% relative reduction (P=.022). By 30 days, the absolute difference had narrowed to 1.9%, with a relative reduction of 16% (P=.16), largely owing to nonemergency CABG and repeat PTCA procedures. Abciximab, the GP IIb/IIIa antibody, demonstrated a similar early efficacy but a greater late (30-day) reduction in adverse cardiovascular events in the EPIC trial.⁵ It may be that although both tirofiban and abciximab are equally effective in preventing early ischemic complications after angioplasty, the antibody might be more effective at 30 days. Differences between abciximab and tirofiban, including the longer duration of effect of the antibody²⁷ and possibly other non–GP IIb/IIIa receptor–blocking activities of the antibody, could account for what appears to be a more sustained clinical benefit with abciximab. Before ascribing differences in the 30-day results of EPIC and RESTORE to biological differences between abciximab and tirofiban, it is important to note that the end-point definitions differ between the trials. As indicated in Table 2 of the original report of the EPIC trial⁵ and as confirmed in a recent report on health economic aspects of EPIC,²⁸ the composite end point in that trial included only emergency CABG and emergency repeat PTCA procedures. In contrast, the present trial considered all target-vessel revascularizations owing to ischemia within 30 days as contributing to the composite end point. Accordingly, an attempt was made to analyze the RESTORE trial results using end-point definitions similar to those in the EPIC and IMPACT II studies.^{5 16 26} When a common definition of repeat intervention is used (ie, CABG or PTCA for urgent or emergency indications only), the difference in outcome between the studies narrows.

Another potentially important difference between RESTORE and previous trials concerns the use of stents. The use of stents for abrupt closure became more prevalent during the most recent trial (RESTORE) and increased from 0.6% in the EPIC trial to 1.4% in IMPACT II and 2.5% in RESTORE. Conversely, the use of CABG surgery decreased from 3.6% in EPIC to 2.8% in IMPACT II and 1.3% in RESTORE (using the similar definition of urgent or emergency surgery). These changes in practice patterns in the more recent study further compound the difficulty in understanding differences between drug effects on the basis of these separate clinical trials.

Serum CK sampling frequency was also different between the trials. In the EPIC trial, the serum CK value was measured at multiple time points after PTCA. In the RESTORE trial, serum CK was measured according to protocol only at the completion of infusion of the drug. Additional CK measurements were done at the discretion of the investigator and were most often prompted by clinical evidence of ischemia. Thus, the lower nonfatal MI rate in patients receiving placebo in RESTORE (5.7%) versus EPIC (8.6%) may reflect differences in the frequency of serum CK measurement rather than a true difference in event rates. However, another potential factor accounting for this difference could be the randomization of patients before PTCA in EPIC as opposed to after guidewire placement across the lesion in RESTORE. Because of these variations in study design and protocol, it is difficult to determine if these agents provide different levels of protection from adverse ischemic events after angioplasty or atherectomy in high-risk patients.

Thrombocytopenia and bleeding are potential side effects of GP IIb/IIIa receptor antagonists.^{5 11 12} In the present study, there was no statistically significant increase in thrombocytopenia or major bleeding associated with tirofiban, despite the concomitant use of aspirin and heparin. This result contrasts with the 1.6- to 2.0-fold increase in major bleeding due to abciximab in the EPIC trial.⁵ However, the bleeding incidence due to abciximab can be decreased by the use of lower doses of heparin, as shown in the EPILOG trial.¹⁶ The recommendation to discontinue heparin after the PTCA procedure and to remove the arterial sheath early (either once the ACT is <180 seconds or 4 hours after heparin cessation) probably contributed to the safety profile of tirofiban and has now become common practice in angioplasty trials.¹⁶

In summary, in patients undergoing coronary angioplasty for acute coronary syndromes, tirofiban was protective against adverse cardiac events during administration of the drug (38% reduction; P=.005) and 7 days thereafter (27% reduction; P=.027). This relative reduction was not statistically demonstrable in the primary end point at 30 days largely because of ongoing nonemergency revascularization that occurred over time. If only urgent revascularization was considered as contributing to the composite end point, there was a 24% reduction in the composite end point attributable to tirofiban (P=.052). The difference between the rates of nonurgent and urgent procedures may in part reflect a stabilization by the GP IIb/IIIa receptor blocker of suboptimally treated lesions that subsequently required elective reintervention for unresolved ischemia. The demonstrated reduction in early adverse cardiovascular events after angioplasty was achieved at a dose of tirofiban and heparin that did not result in any excess major bleeding. It is possible that longer GP IIb/IIIa inhibition, such as might be afforded by an oral agent, could prolong the early benefit achieved by intravenous tirofiban; alternatively, the early reduction in thrombotic events may salvage some patients who will still require future elective intervention. A study of extended GPIIb/IIIa inhibition could help resolve this issue.

Selected Abbreviations and Acronyms

ACT	=	activated clotting time
CABG	=	coronary artery bypass graft
CK	=	creatine kinase
CK-MB	=	creatine kinase–MB
DCA	=	directional coronary angioplasty
GP	=	glycoprotein
MI	=	myocardial infarction
PTCA	=	percutaneous transluminal coronary angioplasty
RESTORE	=	Randomized Efficacy Study of Tirofiban for Outcomes and REstenosis
TIMI	=	Thrombolysis In Myocardial Infarction

Appendix A1

The following are the principal investigators of the RESTORE Study Group, listed in alphabetical order by city:

Klinikum der Rhine–Westphalian Technical University Aachen, Aachen, Germany—P. Hanrath, J. vom Dahl; O.L.V. Ziekenhuis, Aalst, Belgium—W. Paulus, G. Heyndrickx; St. Peter's Hospital, Albany, NY—J.A. Sosa; University of Michigan Medical Center, Ann Arbor, Mich—D. Muller; Emory University Hospital, Atlanta, Ga—S.B. King III; The Johns Hopkins Hospital, Baltimore, Md—J.R. Resar; University of Maryland Hospital, Baltimore, Md—W. Herzog; Eastern Maine Medical Center, Bangor, Me—M.T. Silver; Swedish Hospital Medical Center, Bellevue, Wash—B. Green; Providence Medical Center, Bellevue, Wash—H.S. Lewis; Universitaets Klinikum Benjamin Franklin, Berlin, Germany—H.P. Schultheiss; Medizinische Universitaetsklinik Inselspital, Bern, Switzerland—B. Meier; Beth Israel Hospital, Boston, Mass—D. Cohen; Massachusetts General Hospital, Boston—I.-K. Jang; St. Elizabeth's Medical Center, Boston, Mass—D.W. Losordo; New England Medical Center, Boston, Mass—T. Palabrica; Brigham & Women's Hospital, Boston, Mass—R. Piana; Albert Einstein College of Medicine, Bronx, NY—E.S. Monrad; Maimonides Medical Center, Brooklyn, NY—J. Shani; Cliniques Universitaires Saint-Luc, Brussels, Belgium—M.F. Rousseau, J. Col; Millard Fillmore Hospital, Buffalo, NY—J.Corbelli; Medical Center Hospital of Vermont, Burlington, Vt—P.T. Vaitkus; Medical University of South Carolina, Charleston—M.J. Miller; University of Virginia Health Sciences Center, Charlottesville—E. Powers; University of Chicago Medical Center, Chicago, Ill—J.D. Carroll; Northwestern University Medical School, Chicago, Ill—C. Davidson; The Christ Hospital, Cincinnati, Ohio—D. Kereiakes; University of Cincinnati Medical Center, Cincinnati, Ohio—J.P. Runyon; The Cleveland Clinic Foundation, Cleveland, Ohio—C. Simpfendorfer; Ohio State University Medical Center, Columbus—R. Magorien; Riverside Methodist Hospitals, Columbus, Ohio—S. Yakubov; University of Texas Southwest Medical Center, Dallas—C. Landau; Baylor University Medical Center, Dallas, Tex—B. Leonard; Delray Community Hospital, Delray Beach, Fla—L.D. Snyder; Iowa Heart Center, Des Moines—M. Ghali; Broward General Medical Center, Fort Lauderdale, Fla—A. Niederman; Southwest Florida Regional Medical Center, Fort Myers—E. Toggart; University of Florida at Gainesville Medical College—C. Pepine; Lady Davis Carmel Hospital, Haifa, Israel—B. Lewis; Hartford Hospital, Hartford, Connecticut—M. Azrin; The Milton S. Hershey Medical Center, Hershey, Pa—M. Kozak; University of Texas Medical School, Houston—H.V. Anderson; The Methodist Hospital, Houston, Tex—N.S. Kleiman; Huntsville Hospital, Huntsville, Ala—D. Drenning; St. Vincent Hospital and Health Care Center, Indianapolis, Ind—E. Fry; University of Iowa Hospitals and Clinics, Iowa City—J. Rossen; Shaare Zedek Medical Centre, Jerusalem, Israel—D. Tzivioni; Green Hospital of Scripps Clinic, La Jolla, Calif—P. Teirstein; Lancaster General Hospital, Lancaster, Pa—P. Casale; Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland—L. Kappenberger; Saint Joseph Hospital, Lexington, Ky—B. Harris; Hôpital Cardiologique, Lille, France—M. Bertrand; Baptist Medical Center, Little Rock, Ark—R.F. Hundley; The Royal Brompton Hospital, London, UK—S. Davies; St. Mary's Hospital, London, UK—R.A. Foale; Kaiser Permanente Hospitals, Los Angeles, Calif—P. Mahrer; Good Samaritan Hospital, Los Angeles, Calif—T. Shook; Audubon Regional Medical Center, Louisville, Ky—W. Schmidt; Clinica Cardiovascular Santa Maria, Medellin, Colombia—J.E. Mesa; Jackson Memorial Hospital, Miami, Fla—R.F. Sequeira; Winthrop University Hospital, Mineola, NY—L. Heller; The University of Minnesota Hospital and Clinic, Minneapolis—C.W. White; Technical University of Munich, Munich, Germany—F.J. Neumann; Klinikum Grosshadern, Munich, Germany—G. Steinbeck, W. von Scheidt; Vanderbilt University Medical Center, Nashville, Tenn—D. Vaughan; Yale University School of Medicine, New Haven, Conn—M. Cleman; Ochsner Clinic, New Orleans, La—T. Collins; Medical Center of Delaware, Newark—M.E. Stillabower; Munroe Regional Medical Center, Ocala, Fla—R. Feldman; University of Oklahoma Health Sciences Center, Oklahoma City—A. Kugelmass; Oklahoma Foundation for Cardiovascular Research, Oklahoma City—D. Schmidt; Florida Hospital, Orlando—H.B. Whitworth, R. Ivanhoe; Allegheny University, Philadelphia, Pa—M. Cohen; Temple University Hospital, Philadelphia, Pa—E. Deutsch; Thomas Jefferson University Hospital, Philadelphia, Pa—S. Goldberg; Graduate Hospital, Philadelphia, Pa—R. Gottlieb; University of Pennsylvania Medical Center, Philadelphia—H. Herrmann; Pennsylvania Hospital, Philadelphia—G.J. Reis; University of Pittsburgh Medical Center, Pittsburgh, Pa—M. Feldman; The Western Pennsylvania Hospital, Pittsburgh—A. Gradman; Allegheny General Hospital, Pittsburgh, Pa—N. Reichek; Maine Medical Center, Portland—M.A. Kellett; Oregon Health Sciences University, Portland—M. Morton; Rhode Island Hospital, Providence—D.O. Williams; Wake Medical Center, Raleigh, NC—J.T. Mann III; Medical College of Virginia, Richmond—G.W. Vetrovec; Mayo Clinic, Rochester, Minn—M. Bell; Strong Memorial Hospital, Rochester, NY—M. Cunningham; William Beaumont Hospital, Royal Oak, Mich—R.D. Safian; University of California–Davis Medical Center, Sacramento—G. Gregoratos; Sharp Memorial Hospital, San Diego, Calif—J. Gordon; University of California–San Diego/San Diego VA Medical Center—W.F. Penny; Goleta Valley Community Hospital, Santa Barbara, Calif—J. Vogel; Santa Rosa Memorial Hospital, Santa Rosa, Calif—R. Miller; Sarasota Memorial Hospital, Sarasota, Fla—M. Frey; University of Washington Medical Center, Seattle—W.D. Weaver, J. Chambers; Jewish Hospital, St. Louis, Mo—P.L. Cole; Washington University School of Medicine, St. Louis, Mo—P.A. Ludbrook; Stanford University Medical Center, Stanford, Calif—A. Yeung; James A. Haley VA Hospital, Tampa, Fla—R.G. Zoble; University of Arizona Health Sciences Center, Tucson—S. Butman; Universitaetskilinik fuer Innere Medizin, Vienna, Austria—P. Probst; Georgetown University Medical Center, Washington, DC—D.J. Diver; Washington Hospital Center, Washington, DC—J.J. Popma; George Washington University Medical Center, Washington, DC—A.M. Ross; John F. Kennedy Medical Center, West Palm Beach, Fla—J. Midwall; West Roxbury VA Medical Center, West Roxbury, Mass—C.M. Gibson; Bowman Gray/Baptist Hospital, Winston-Salem, NC—M. Kutcher; St. Vincent Hospital, Worcester, Mass—J.R. Benotti; University of Massachusetts Medical Center, Worcester—B.H. Weiner.

Committee Members

Steering Committee: S.B. King III (chair), M. Bertrand, P.I. Chang (nonvoting), L.I. Deckelbaum (nonvoting), S. Goldberg, W. Grossman (nonvoting), D.R. Holmes, Jr, K.H. Lipschutz (Project Statistician), J.T. Mann III, A.M. Ross, F.L. Sax (ex officio), W.D. Weaver, and J.T. Willerson. Data and Safety Monitoring Committee: L.S. Cohen (Chairman), M. Cheitlin, L. Fisher, R.L. Frye, and J.W. Kennedy. End-point Committee: M. Cleman, H. Herrmann, G.W. Vetrovec, and D.O. Williams.

Angiographic Core Laboratory

C.M. Gibson.

Merck Research Laboratories

P.I. Chang, L.I. Deckelbaum, W. Grossman, K.H. Lipschutz, F.L. Sax, W.C. Shaw, and S.M. Snapinn. Medical Program Coordinators: R.L. Colamesta, R. Draper, P.A. Holmes, L.K. Kelly, C.J. Lis, G.A. Snyder, and V.L. Willison.

1The principal investigators of the RESTORE (Randomized Efficacy Study of Tirofiban for Outcomes and REstenosis) trial are listed in the "Appendix."

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Figure 1. Time to composite end point: primary analysis. The Kaplan-Meier curves show the proportion of patients treated with placebo and tirofiban who experienced an adverse event of the composite end point (death, MI, CABG, or repeat PTCA for ischemia or stent placement for abrupt closure) during the 30-day study period. The probability values (log-rank test) for the risk reduction attributable to tirofiban at days 2, 7, and 30 are shown. The majority of events occurred shortly after the angioplasty procedure.

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Figure 2. Time to composite end point including only revascularizations performed on an urgent or emergency basis. The Kaplan-Meier curves show the proportion of patients treated with placebo and tirofiban who experienced an adverse event of the composite end point during the 30-day study period. In this analysis, CABG due to angioplasty failure or recurrent ischemia and repeat target-vessel angioplasty for recurrent ischemia were considered as contributing to the composite end point only if they were performed on an urgent or emergency basis. The probability values (log-rank test) for the risk reduction attributable to tirofiban at days 2, 7, and 30 are shown.

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Figure 3. Time to MI. The Kaplan-Meier curves show the proportion of patients treated with placebo or tirofiban who experienced an MI during the 30-day study. Most infarctions occurred in the early postangioplasty period, and there was no evidence of any rebound phenomenon after discontinuation of the tirofiban infusion.

Table 1. Baseline Characteristics of Patients in the RESTORE Trial

	Placebo (n=1070)	Tirofiban (n=1071)
Baseline characteristics
Mean age, y	59.2	59.2
Male sex	72%	72%
Risk factors
Diabetes mellitus	20%	20%
Hypertension	56%	54%
Elevated cholesterol	49%	50%
History of smoking	67%	64%
Previous MI	34%	35%
Previous procedure
Angioplasty	20%	21%
CABG	8%	6%
Number of diseased vessels
1	58%	55%
2	28%	31%
3	14%	14%
Qualifying event
Unstable angina	68%	67%
Acute MI (nonprimary angioplasty)	26%	26%
Acute MI (primary angioplasty)	6%	7%
Initial procedure
Procedure performed
PTCA	93%	92%
Atherectomy	8%	7%
Number of lesions treated
1	79%	77%
2	17%	19%
3+	3%	5%
Vessels undergoing angioplasty
Coronary artery/graft	98%/2%	98%/2%
Single vessel/double vessel	91%/9%	91%/9%

Table 2. Outcome Events in the Treatment Group: Primary Analysis

	Placebo (n=1070), n (%)	Tirofiban (n=1071), n (%)	Risk Reduction, %	P
Results at 2 days
Composite end point	93 (8.7)	58 (5.4)	38	.005
Components of composite end point
Death	2 (0.2)	2 (0.2)	0	1.000
MI	47 (4.4)	29 (2.7)	39	.039
Repeat PTCA	34 (3.2)	12 (1.1)	66	.001
CABG	15 (1.4)	10 (0.9)	36	.315
Stent for abrupt closure	27 (2.5)	16 (1.5)	40	.093
Results at 7 days
Composite end point	111 (10.4)	81 (7.6)	27	.022
Components of composite end point
Death	4 (0.4)	4 (0.4)	0	.986
MI	57 (5.3)	39 (3.6)	32	.055
Repeat PTCA	47 (4.4)	29 (2.7)	39	.034
CABG	17 (1.6)	13 (1.2)	25	.462
Stent for abrupt closure	27 (2.5)	16 (1.5)	40	.093
Results at 30 days (primary end point)
Composite end point	130 (12.2)	110 (10.3)	16	.160
Components of composite end point
Death	8 (0.7)	9 (0.8)	…	.808
MI	61 (5.7)	45 (4.2)	26	.113
Repeat PTCA	58 (5.4)	45 (4.2)	22	.178
CABG	23 (2.2)	20 (1.9)	14	.641
Stent for abrupt closure	27 (2.5)	16 (1.5)	40	.093

Table 3. Outcome Events in the Treatment Groups: Analysis Including Only Emergency Revascularization Procedures

	Placebo (n=1070), n (%)	Tirofiban (n=1071), n (%)	Risk Reduction, %	P
Results at 2 days
Composite end point	93 (8.7)	56 (5.2)	40	.002
Components of composite end point
Death	2 (0.2)	2 (0.2)	0	1.000
MI	47 (4.4)	29 (2.7)	39	.039
Emergency PTCA	35 (3.3)	10 (0.9)	73	<.001
Emergency CABG	14 (1.3)	10 (0.9)	31	.422
Stent for abrupt closure	27 (2.5)	16 (1.5)	40	.093
Results at 7 days
Composite end point	105 (9.8)	74 (6.9)	30	.016
Components of composite end point
Death	4 (0.4)	4 (0.4)	0	.986
MI	57 (5.3)	39 (3.6)	32	.055
Emergency PTCA	42 (3.9)	22 (2.1)	46	.011
Emergency CABG	15 (1.4)	12 (1.1)	21	.569
Stent for abrupt closure	27 (2.5)	16 (1.5)	40	.093
Results at 30 days
Composite end point	112 (10.5)	86 (8.0)	24	.052
Components of composite end point
Death	8 (0.7)	9 (0.8)	…	.808
MI	61 (5.7)	45 (4.2)	26	.113
Emergency PTCA	43 (4.0)	25 (2.3)	43	.027
Emergency CABG	15 (1.4)	12 (1.1)	21	.569
Stent for abrupt closure	27 (2.5)	16 (1.5)	40	.093

Table 4. Incidence of Major Bleeding

	Placebo (n=1070), n (%)	Tirofiban (n=1071), n (%)	P
Major bleeding	40 (3.7)	57 (5.3)	.096
Decrease in hemoglobin >5 g/dL	19 (1.8)	25 (2.3)
Transfusion >2 U	24 (2.2)	38 (3.5)
Bleeding requiring corrective surgery	3 (0.3)	2 (0.2)
Intracranial hemorrhage	3 (0.3)	1 (0.1)
Retroperitoneal hemorrhage	3 (0.3)	6 (0.6)
Major bleeding (TIMI criteria)	22 (2.1)	26 (2.4)	.662
Thrombocytopenia <90 000/mm3	10 (0.9)	12 (1.1)
Thrombocytopenia <50 000/mm3	1 (0.1)	2 (0.2)

Footnotes

Correspondence to Spencer B. King III, MD, Emory University Hospital–F606, 1364 Clifton Rd, Atlanta, GA 30322-1104.

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Source: https://www.ahajournals.org/doi/full/10.1161/01.cir.96.5.1445

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