Intracoronary thrombus and platelet glycoprotein IIb/IIIa receptor blockade with tirofiban in unstable angina or non-Q-wave myocardial infarction. Angiographic results from the PRISM-PLUS trial (Platelet receptor inhibition for ischemic syndrome management in patients limited by unstable signs and symptoms). PRISM-PLUS Investigators

ST deviation pattern and infarct related artery in acute myocardial infarction

BACKGROUND

Myocardial infarction (MI) may be classified as ST-elevation MI (STEMI) or non-ST-elevation MI (NSTEMI). There is little data regarding the relationship between the infarct related artery (IRA), clinical characteristics of the patients, and the ST deviation pattern (ie, STEMI or NSTEMI).

HYPOTHESIS

There is a predilection of any coronary artery to a particular ST deviation pattern of acute MI.

METHODS

We reviewed our institutional database and selected patients who presented with an acute MI and underwent coronary angiography within 7 days of admission. The analysis included 830 patients of whom 563 had STEMI and 267 had NSTEMI. The culprit lesion was defined by reviewing each patient's angiographic report, electrocardiogram, and echocardiogram. TIMI flow rate was determined.

RESULTS

The IRA in STEMI was most frequently the left anterior descending coronary artery (LAD) followed by the right coronary artery (RCA) and then the left circumflex coronary artery (LCX), a statistically significant difference. In patients with NSTEMI there were no significant differences in IRA. Patients with STEMI and LCX as the IRA were significantly younger and had a higher percentage of TIMI grade 3 flow then patients with STEMI and LAD or RCA as IRAs. These differences were not noted in patients with NSTEMI regardless of IRA.

CONCLUSIONS

In STEMI there were significant differences in age and TIMI flow depending on the IRA. These findings were not demonstrated in patients with NSTEMI.

The incidence and clinical predictors of early stent thrombosis in patients with acute coronary syndrome

BACKGROUND

Acute coronary syndrome (ACS) is associated with activation of platelets and the coagulation system which could influence the incidence of early stent thrombosis (EST). We aimed to determine the incidence and predictors of EST in patients undergoing coronary stenting during ACS.

METHODS

The study comprised 1202 consecutive patients, drawn from a nationwide ACS survey, who underwent coronary stenting during ACS and were followed up for 30 days. Early stent thrombosis was based on the Academic Research Consortium definition.

RESULTS

Thirty patients (2.5%) sustained EST. The occurrence of EST in patients with unstable angina/non-ST-elevation myocardial infarction and ST-elevation myocardial infarction (STEMI) was 0.9% and 3.9%, respectively (P < .05), and was even higher (5.2%) in STEMI patients who underwent primary percutaneous coronary intervention. On multivariate analysis, STEMI (OR 6.3, 95% CI 2.1-18, P = .0008), multivessel disease (OR 5.9, 95% CI 1.9-21, P = .003) and Killip class >/=2 (OR 2.9, 95% CI 1.3-6.6, P = .008) were independent correlates of EST. The use of bare versus drug-eluting stents was not associated with any significant difference in EST.

CONCLUSIONS

Patients presenting with STEMI who are hemodynamically unstable and have multivessel coronary disease undergoing coronary stenting during ACS, are at increased risk of EST.

Magnitude and consequences of missing the acute infarct-related circumflex artery

Emergent reperfusion strategies are integral to providing optimal patient outcomes in the setting of acute coronary artery occlusion. ST-segment elevation on the surface 12-lead electrocardiogram, although specific as a surrogate marker, is insensitive to acute posterior circulation coronary artery occlusion. Studies of non-ST-segment elevation acute coronary syndrome consistently identify patients who have epicardial vessel occlusion at the time of initial angiography, which is usually delayed for hours or days after the initial presentation. In addition, studies of ST-segment elevation myocardial infarction often divulge a disparity in identification of the infarct-related artery, with an underrepresentation of the left circumflex artery. Taken together, it is likely that many patients with left circumflex artery occlusion are "missed" during the early phases of myocardial infarction due to the electrocardiographically silent nature of the posterior territory, resulting in delayed myocardial salvage and worse cardiovascular outcomes. In this review, we report on the magnitude of missed left circumflex infarction and the consequences of this delay in diagnosis. We review the electrocardiographic findings of left circumflex occlusion and discuss strategies to enhance early identification. Heightened awareness of this clinical scenario and the available methods to avoid missing this elusive diagnosis are imperative in our quest to further improve the outcomes of patients with acute myocardial infarction.

Impact of an audit program and other factors on door-to-balloon times in acute ST-elevation myocardial infarction patients destined for primary coronary intervention

OBJECTIVES

This before-after study investigated the association between an audit program and door-to-balloon times in patients with acute ST-elevation myocardial infarction (STEMI) and explored other factors associated with the door-to-balloon time.

METHODS

An audit program that collected time data for essential time intervals in acute STEMI was developed with data feedback to both the Department of Emergency Medicine and the Department of Cardiology. The door-to-balloon times for 76 consecutive acute STEMI patients were collected from February 16, 2007, through October 31, 2007, after the implementation of the audit program, as the intervention group. The control group was defined by 104 consecutive acute STEMI patients presenting from April 1, 2006, through February 15, 2007, before the audit was applied. A multivariate linear regression model was used for analysis of factors associated with the door-to-balloon time.

RESULTS

The geometric mean 95% CI of the door-to-balloon time decreased from 164.9 (150.3, 180.9) minutes to 141.9 (127.4, 158.2) minutes (p = 0.039) in the intervention phase. The median door-to-balloon time was 147.5 minutes in the control group and 136.0 minutes in the intervention group (p = 0.09). In the multivariate regression model, the audit program was associated with a shortening of the door-to-balloon time by 35.5 minutes (160.4 minutes vs. 195.9 minutes, p = 0.004); female gender was associated with a mean delay of 58.4 minutes (208.9 minutes vs. 150.5 minutes; p = 0.001); posterolateral wall infarction was associated with a mean delay of 70.5 minutes compared to anterior wall infarction (215.4 minutes vs. 144.9 minutes; p = 0.037) and a mean delay of 69.5 minutes compared to inferior wall infarction (215.4 minutes vs. 145.9 minutes; p = 0.044). The use of a glycoprotein IIb/IIIa inhibitor was associated with a 46.1 minutes mean shortening of door-to-balloon time (155.7 minutes vs. 201.8 minutes; p < 0.001).

CONCLUSIONS

The implementation of an audit program was associated with a significant reduction in door-to-balloon times among patients with acute STEMI. In addition, female patients, posterolateral wall infarction territory, and nonuse of glycoprotein IIb/IIIa inhibitor were associated with longer door-to-balloon times.

Is it possible to predict which patients need distal protection during primary angioplasty?

BACKGROUND

Although the benefit of distal protection (DP) during primary percutaneous coronary intervention (PCI) remains questionable, there appears to be efficacy in some clinical situations. We sought to identify in patients with ST-segment elevation acute myocardial infarction (STEMI) which clinical and angiographic characteristics might indicate the patient who will benefit from the use of a DP device.

METHODS

A series of 103 consecutive patients with STEMI undergoing primary PCI using DP were compared with 98 consecutive patients treated by primary PCI alone.

RESULTS

The overall rates of thromboembolic complications and achievement of optimal reperfusion (myocardial blush grade >/=2 and ST-segment resolution >/=70%), and infarct size, were similar between the 2 groups. However, DP use was associated with higher rates of optimal reperfusion in patients with right coronary artery (RCA) lesions (OR 2.45; 95% CI, 1.07 to 5.59; P=0.034), thrombus score >/=4 (OR 2.64; 95% CI, 1.07 to 6.50; P=0.034) or infarct-related artery (IRA) of >/=3.5 mm in diameter (OR 4.09; 95% CI, 1.02 to 16.40; P=0.047). In this population (RCA location, thrombus score >/=4, or IRA >/=3.5 mm), DP use reduced the risk of thromboembolic complications (64%, P=0.012, 45%, P=0.035 and 54%, P=0.050, respectively), resulting in a smaller infarct size (8.0+/-5.1 vs. 11.7+/-7.5, P=0.028, 13.1+/-8.8 vs. 17.4+/-10.0, P=0.026 and 15.5+/-10.8 vs. 22.1+/-10.1, P=0.042, respectively).

CONCLUSIONS

The use of a DP during primary PCI may lead to a reduction of thromboembolic complications, subsequent higher rates of optimal reperfusion and reduced infarct size in patients with RCA culprit lesions, a large thrombus, or large IRA.

GP IIb-IIIa inhibitors administered upstream: evidence for improved outcomes with conventional and newer antithrombotic agents?

Glycoprotein IIb-IIIa inhibitors provide the most benefit in patients with non-ST-elevation acute coronary syndromes and high-risk features and in those who undergo early invasive treatment. Current guidelines recommend glycoprotein IIb-IIIa inhibition in these patients but offer little guidance as to timing of initiation. Preliminary data suggest superior outcomes with upstream initiation (upon admission to a medical facility) compared with delayed initiation (in the catheterization laboratory, just before percutaneous coronary intervention). The availability of new antiplatelet and antithrombotic drugs renders even more complex the question of the best strategy.

Smoking cessation does not alter ST deviation pattern of recurrent myocardial infarctions

BACKGROUND

Myocardial infarction (MI) may be classified as ST elevation MI (STEMI) or non ST elevation MI (NSTEMI). We used the term recurrent MI (RMI's) to denote repeated MI episodes, in a particular patient, in which a different coronary site is responsible for each episode. Recently we reported that most patients with recurrent MI episodes will have either STEMI's or NSTEMI's but not both. A history of smoking was associated with recurrent STEMI's.

OBJECTIVE

To determine whether smoking cessation will alter the type of RMI in patients with an index MI of STE type.

METHODS

The analysis included 128 patients who underwent at least 2 MI episodes. We attempted to include only MI's of native vessels, without the presence of extra cardiac conditions that intensify myocardial ischemia. All 128 patients were active smokers who presented with an index MI of the STE type. Of these patients 94 had recurrent STEMI and 34 had recurrent NSTEMI (STE/NSTE group).

RESULTS

We identified all patients who were no longer active smokers at the time of the recurrent MI: there were 31 (33%) such patients in the STEMI group and 13 (38%) in the STE/NSTE group (p=NS).

CONCLUSION

Smoking cessation did not influence the type of recurrent MI in these patients.

Antithrombotic strategies in non-ST elevation acute coronary syndromes: focus on bivalirudin

Acute coronary syndromes (ACS) are a common presentation of coronary artery disease, accounting for more than one million hospital admissions in the US annually. Owing to high rates of mortality and reinfarction, ACS represent a major public health concern. The following review discusses the pathogenesis of ACS and optimal approaches for the management of patients with ACS, with special focus on new antithrombotic strategies, including the direct thrombin inhibitor bivalirudin. Bivalirudin has several notable mechanistic advantages compared with unfractionated heparin, including activity against clot-bound thrombin, inhibition of thrombin-induced platelet activation, short plasma half-life in patients with normal or mildly impaired renal function (25 minutes), and linear pharmacokinetics less affected by plasma proteins and renal insufficiency. These properties provide a more predictable inhibition of coagulant activity than unfractionated heparin, with less degree of inter-patient variability in anticoagulation response. The findings from the several clinical trials assessing safety and efficacy of bivalirudin are analyzed in detail, including the recent randomized controlled Acute Catheterization and Urgent Intervention Triage Strategy (ACUITY) trial. Based on the results of the ACUITY trial, a newer streamlined strategy for the invasive treatment of moderate- and high-risk patients with ACS is discussed.

The evolving role of glycoprotein IIb/IIIa inhibitor therapy in contemporary care of acute coronary syndrome patients

Results from clinical trials of glycoprotein IIb/IIIa(GPIIb/IIIa) inhibitors during the past decade have established their current role in the treatment of non-ST-segment elevation acute coronary syndrome and in percutaneous coronary interventions. However, there are still unanswered questions on optimal use of GPIIb/IIIa inhibitors. Moreover, as new concomitant or alternative medications become available, the role of GPIIb/IIIa inhibitors must be reconsidered. This review discusses, in the light of clinical trials recently presented, what we know, what we are learning, and what we still need to learn.

Timing of glycoprotein IIb/IIIa inhibitor use and outcomes among patients with non-ST-segment elevation myocardial infarction undergoing percutaneous coronary intervention (results from CRUSADE)

Although glycoprotein (GP) IIb/IIIa inhibitors are recommended for patients with unstable angina and non-ST-segment elevation myocardial infarction who undergo percutaneous coronary intervention (PCI), the American College of Cardiology/American Heart Association guidelines do not specify optimal timing for their initiation. We compared patient characteristics and clinical outcomes in 30,830 patients with non-ST-segment elevation myocardial infarction included in the CRUSADE initiative (January 2001 to December 2004) who underwent PCI with upstream (>1 hour before PCI) or periprocedural use of GP IIb/IIIa inhibitors. GP IIb/IIIa inhibitors were administered upstream in 43% of patients versus periprocedurally in 57%. Time from arrival to PCI was longer for patients who received GP IIb/IIIa inhibitors upstream (median 25.6 hours) compared with periprocedurally (18.2 hours). Unadjusted incidence of in-hospital death or reinfarction was lower with upstream GP IIb/IIIa inhibitor use (3.8% vs 4.3%, p = 0.046), but after adjusting for patient and hospital characteristics, this difference was not statistically significant. Treatment with upstream GP IIb/IIIa inhibitors was associated with a lower incidence of unadjusted death or reinfarction in patients who underwent PCI <12 hours from hospital arrival. In conclusion, in this observational analysis, overall ischemic outcomes were similar between the 2 groups, but clinical trials are needed to solve the controversy over optional timing of GP IIb/IIIa inhibitor use.

Routine upstream versus selective down stream use of tirofiban in non-ST elevation myocardial infarction patients scheduled for early invasive therapy; a randomized comparison

BACKGROUND

Despite their proven beneficial effects and inclusion in the guidelines, glycoprotein (GP) IIb/IIIA blockers are underused in daily practice in patients with non ST-segment elevation acute coronary syndrome (NSTE ACS). This study combines the data from two randomized controlled trials, comparing routine upstream versus selective down stream use of tirofiban in patients with NSTE ACS.

METHODS

Inclusion criteria for both studies (ELISA-1 and 2) were angina pectoris, with ST depression >1 mm and or a positive cardiac biomarkers. All patients were scheduled for coronary angiography. The primary and secondary end points for both studies were enzymatic infarct size (LDHQ48) and initial TIMI flow of the culprit lesion respectively.

RESULTS

From August 2000 to January 2005, 273 patients were randomized to routine upstream tirofiban and 275 patients to selective down stream use of tirofiban. Selective down stream tirofiban was used in 55 patients (20%). Patients in the upstream group more often had a patent culprit lesion (65% vs. 50%, P=0.003) and a significantly smaller enzymatic infarct size, LDHQ48 median (25-75%): 125 (55-309) vs. 189 (68-504) IU/l, P=0.006 as compared to the selective down stream group. Subgroup analysis showed that routine upstream tirofiban was particularly effective in males, patients with a positive troponin on admission and in those not pretreated with clopidogrel.

CONCLUSION

Routine upstream GP IIb/IIIa is mainly effective in patients with elevated troponin on admission and those not pretreated with clopidogrel. Large scale randomized trials are needed to evaluate the effect of GP IIb/IIIa blockers on top of clopidogrel pretreatment on major adverse cardiac events.

Angiographic and clinical outcomes of bivalirudin versus heparin in patients with acute coronary syndrome undergoing percutaneous coronary intervention

BACKGROUND

Heparin with adjunctive glycoprotein IIb/IIIa platelet receptor (GP IIb/IIIa) inhibitors has demonstrated its effectiveness in patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI). Bivalirudin, a direct thrombin inhibitor, has recently been shown to be an effective alternative for patients undergoing elective PCI.

OBJECTIVES

To assess the angiographic and clinical outcomes of adjunctive pharmacological strategies in a high-risk population presenting with ACS.

METHODS

Of 891 consecutive PCI patients with ACS, 304 received bivalirudin (60.5% male, 68+/-11 years) and were compared with 283 who received heparin (58.7% male, 66+/-12 years). A 30-day major adverse cardiac event was defined as the occurrence of cardiac death, nonfatal myocardial infarction, urgent revascularization or major hemorrhage.

RESULTS

Adjunctive GP IIb/IIIa inhibitors were used in 14.1% of the bivalirudin group and in 72.4% of the heparin group (P<0.010). The occurrence of Thrombolysis In Myocardial Infarction (TIMI) flow less than grade 3 was lower and the achievement of angiographic success was higher in the bivalirudin group than in the heparin group (5.2% versus 8.2%, 94.7% versus 89.7%, P=0.039 and P<0.010, respectively). There was no difference between groups in the incidence of bleeding events (bivalirudin 2.0% versus heparin 3.5%, P not significant) and in 30-day major adverse cardiac events (bivalirudin 8.3% versus heparin 5.7%, P=0.223).

CONCLUSIONS

In the high-risk cohort undergoing PCI, bivalirudin with provisional GP IIb/IIIa inhibitors achieved better angiographic results. Although not powered to show a difference, and while acknowledging that a selection bias could have affected the data, the present study showed that bivalirudin may be as clinically effective and safe as heparin with adjunctive GP IIb/IIIa inhibitors.

Progressive epicardial coronary blood flow reduction fails to produce ST-segment depression at normal heart rates

ST-segment depression is commonly seen in patients with acute coronary syndromes. Most authors have attributed it to transient reductions in coronary blood flow due to nonocclusive thrombus formation on a disrupted atherosclerotic plaque and dynamic focal vasospasm at the site of coronary artery stenosis. However, ST-segment depression was never reproduced in classic animal models of coronary stenosis without the presence of tachycardia. We hypothesized that ST-segment depression occurring during acute coronary syndromes is not entirely explained by changes in epicardial coronary artery resistance and thus evaluated the effect of a slow, progressive epicardial coronary artery occlusion on the ECG and regional myocardial blood flow in anesthetized pigs. Slow, progressive occlusion over 72 min (SD 27) of the left anterior descending coronary artery in 20 anesthetized pigs led to a 90% decrease in coronary blood flow and the development of ST-segment elevation associated with homogeneous and transmural myocardial blood flow reductions, confirmed by microspheres and myocardial contrast echocardiography. ST-segment depression was not observed in any ECG lead before the development of ST-segment elevation. At normal heart rates, progressive epicardial stenosis of a coronary artery results in myocardial ischemia associated with homogeneous, transmural reduction in regional myocardial blood flow and ST-segment elevation, without preceding ST-segment depression. Thus, in coronary syndromes with ST-segment depression and predominant subendocardial ischemia, factors other than mere increases in epicardial coronary resistance must be invoked to explain the heterogeneous parietal distribution of flow and associated ECG changes.

Serial angiography in patients with acute coronary syndromes: effect of antithrombotic therapy on angiographic lesion severity

BACKGROUND

Patients presenting with acute coronary syndromes (ACS) commonly have a responsible culprit coronary lesion. There is limited data on the natural history of this culprit lesion in the short term and whether there is a change in morphology of this lesion in the days following presentation. Furthermore, the effect of antithrombotic therapy on this process is unknown.

METHODS

Sixty-eight patients presenting with ACS had their diagnostic study performed at our institution and had coronary angioplasty performed a few days later at a different hospital. Culprit lesion characteristics including minimum luminal diameter (MLD) and percentage diameter stenosis were determined on each occasion.

RESULTS

Acute myocardial infarction patients (n=14) had improved culprit lesion characteristics at angioplasty compared to baseline (diameter stenosis 78.9% versus 62.4%, p<0.01). Similarly, patients presenting with unstable angina (UA) or non-ST elevation myocardial infarction (non-STEMI) (n=54) had improved diameter stenosis (78.0% versus 72.7%, p<0.001). The change in MLD was greater in MI patients than UAP/non-STEMI patients (0.6mm versus 0.16mm, p<0.01).

CONCLUSION

Treatment of ACS patients with aspirin with anticoagulant therapy followed by delayed intervention results in angiographic improvement in lesion severity which may provide a more favourable environment in which to undertake percutaneous coronary intervention.

Coronary interventional devices: balloon, atherectomy, thrombectomy and distal protection devices

With increased operator experience and improved device technology, there has been a constant growth in the number of complex lesions (ie, thrombotic lesions, diffuse lesions,calcified lesions, nondilatable rigid lesions, ostial lesions, bifurcations, and chronic total occlusions) attempted by interventionalists with the use of drug-eluting stents. Although coronary stent implantation remains the mainstay and ultimate step for the treatment of most coronary lesions, adjunctive devices may be essential for lesion preparation in some cases (5%-10%) to allow stent deployment and expansion and prevent distal embolization. Thrombectomy and distal protection devices have shown to be effective in the interventions of saphenous vein graft lesions, although their use remains unproven in acute myocardial infarctions.

ST-deviation patterns in recurrent myocardial infarctions

Myocardial infarction (MI) may be classified as ST-elevation MI (STEMI) or non-STEMI (NSTEMI). We used the term "recurrent MI" (RMI) to denote repeat MI episodes in a particular patient in which a different coronary site is responsible for each episode. We investigated whether the type of RMI is more likely to be of the same type as the index MI or whether patients may have the 2 types of MI at random. The analysis included 305 patients who had >or=2 MI episodes. Acute MIs were classified as STEMI or NSTEMI. We attempted to include only MIs of native vessels, without the presence of extracardiac conditions that intensify myocardial ischemia. Most patients (76%) had repeat episodes of the same MI type, i.e., STEMI or NSTEMI. Recurrent STEMI occurred in 44% of patients, recurrent NSTEMI in 32%, and STEMI and NSTEMI in 24%. Thus, most patients with RMI episodes will have STEMIs or NSTEMIs but not the 2 types, suggesting a predilection of some patients to repeat episodes of occlusive thrombi and others to repeat episodes of nonocclusive thrombi.

Human complement receptor type 1-directed loading of tissue plasminogen activator on circulating erythrocytes for prophylactic fibrinolysis

Plasminogen activators (PAs) are not used for thromboprophylaxis due to rapid clearance, bleeding, and extravascular toxicity. We describe a novel strategy that overcomes these limitations. We conjugated tissue-type PA (tPA) to a monoclonal antibody (mAb) against complement receptor type 1 (CR1) expressed primarily on human RBCs. Anti-CR1/tPA conjugate, but not control conjugate (mIgG/tPA), bound to human RBCs (1.2 x 10(3) tPA molecules/cell at saturation), endowing them with fibrinolytic activity. In vitro, RBC-bound anti-CR1/tPA caused 90% clot lysis versus 20% by naive RBCs. In vivo, more than 40% of anti-CR1/(125)I-tPA remained within the circulation ( approximately 90% bound to RBCs) 3 hours after injection in transgenic mice expressing human CR1 (TgN-hCR1) versus less than 10% in wild-type (WT) mice, without RBC damage; approximately 90% of mIgG/(125)I-tPA was cleared from the circulation within 30 minutes in both WT and TgN-hCR1 mice. Anti-CR1/tPA accelerated lysis of pulmonary emboli and prevented stable occlusive carotid arterial thrombi from forming after injection in TgN-hCR1 mice, but not in WT mice, whereas soluble tPA and mIgG/tPA were ineffective. Anti-CR1/tPA caused 20-fold less rebleeding in TgN-hCR1 mice than the same dose of tPA. CR1-directed immunotargeting of PAs to circulating RBCs provides a safe and practical means to deliver fibrinolytics for thromboprophylaxis in settings characterized by a high imminent risk of thrombosis.

Angiographic and clinical outcome in ST-segment elevation myocardial infarction patients receiving an adjunctive double bolus regimen of tirofiban for primary percutaneous coronary intervention

BACKGROUND

Because of different dosages, the efficacy of adjunctive tirofiban therapy for primary percutaneous coronary intervention (PCI) is currently unclear. The hypothesis that a double bolus regimen of tirofiban will improve angiographic and clinical outcomes in patients with ST-segment elevation acute myocardial infarction (STEMI) undergoing PCI was tested in the present study.

METHODS AND RESULTS

Primary PCI was performed in 217 STEMI patients: 80 received standard PCI (control group) and 137 received tirofiban (tirofiban group). Tirofiban was given as a bolus (10 mg/kg) in the emergency room and again upon arrival at the cardiac catheterization laboratory, followed by infusion of 0.15 mg . kg(-1) . min (-1) until the total dose reached 12.5 mg. The primary endpoint was emergency target vessel revascularization, recurrent myocardial infarction, or cardiovascular mortality at 30 days and 1 year. Baseline clinical and angiographic variables of the 2 groups were similar, as were angiographic results after PCI and bleeding complications at 30 days. The primary 30-day and 1-year endpoints were 5.1% and 11.7% in the tirofiban group, respectively, vs 10.0% (p = 0.171) and 18.8% (p = 0.151) in the control group.

CONCLUSION

Although angiographic and clinical benefits were not demonstrated, the results suggest that research into an effective and uniform dosing regimen of adjunctive tirofiban therapy for PCI is warranted.

Effect of Tirofiban Therapy on ST Segment Resolution and Clinical Outcomes in Patients with ST Segment Elevated Acute Myocardial Infarction Undergoing Primary Angioplasty

BACKGROUND

In our study, we assessed the effect of glycoprotein (GP) IIb/IIIa receptor inhibition on microvascular flow after acute coronary occlusion using the early sum of ST segment resolution in electrocardiography. Platelets may play a major role in the dissociation of epicardial artery recanalization and tissue level reperfusion, referred to as the 'no-reflow phenomenon'. Therefore, GP IIb/IIIa receptor inhibition might improve myocardial reperfusion, distinct from its effects on epicardial patency.

METHODS AND RESULTS

One hundred and fifteen patients (mean age 57.7 +/- 12.2 years, 96 males, 19 females) with < or = 12-hour acute ST segment elevation myocardial infarction who underwent successful primary percutaneous coronary intervention were retrospectively enrolled into the study. Patients were grouped according to whether they received tirofiban therapy or not. Clinical and electrocardiographic parameters were evaluated. The first sum of ST segment elevation amounts in millimeters was obtained immediately before angioplasty and the second 60 min after restoration of thrombolysis in myocardial infarction III flow. The difference between the two measurements was accepted as resolution of the sum of ST segment elevation and expressed as SigmaSTR. There were no significant differences between the groups regarding age, gender, cardiovascular risk factors, and laboratory parameters, duration from angina onset to the emergency unit, and from door to angioplasty. SigmaSTR was higher in patients who received tirofiban than in those who did not (7.2 +/- 2.8 and 4.2 +/- 2.6 mm, respectively; p < 0.001). There was a significant and positive correlation between GP IIb/IIIa inhibition and SigmaSTR (r = 0.336, p < 0.001), as well as between ejection fraction and SigmaSTR (r = 0.310, p < 0.001). GP IIb/IIIa inhibition was the only independent determinant of SigmaSTR in a multivariate linear regression model which contains 10 variables (p < 0.001). The incidence of in-hospital post-myocardial infarction refractory angina, reinfarction, and heart failure was significantly lower in the tirofiban group (p < 0.05, p < 0.05, and p < 0.05, respectively). Additionally, after 30 days, reinfarction and heart failure were lower in the tirofiban group (p < 0.05 and p < 0.05, respectively).

CONCLUSIONS

It is well known that SigmaSTR determines microvascular perfusion. This study shows that GP IIb/IIIa inhibition with tirofiban is of value in preserving microvascular perfusion after restoring coronary thrombolysis in myocardial infarction III flow.

Imaging in the evaluation of the patient with suspected acute coronary syndrome

Over the last decade, major advances have been made in the treatment of acute coronary syndromes (ACSs). However, effective implementation of these treatments requires timely and accurate identification of the high-risk patient among all those presenting to the emergency department (ED) with symptoms suggestive of ACS. The opportunity for improving outcomes is time-dependent, so that early identification of the patient who has true ACS is essential. This necessity further increases the need for rapid triage tools, especially in the current setting of ED and hospital overcrowding that has become the norm in large urban centers.

Mechanical thrombectomy options in complex percutaneous coronary interventions

Percutaneous coronary interventions (PCI) of thrombus-containing lesions are associated with an increased risk of acute complications and poorer long term vessel patency. Dealing with these vessels provides many technical challenges, especially with the significant risk of coronary no reflow and distal embolization. Pharmacological strategies, including intravenous and intracoronary glycoprotein IIbIIIa inhibitors reduce intracoronary thrombus propagation, improve TIMI flow and are associated with a reduction in adverse event rates. Mechanical strategies (particularly embolic protection and thrombectomy catheters) help to improve coronary blood flow and myocardial perfusion. However, their impact on clinical outcomes is less clear. The use of embolic protection devices is associated with better perfusion, blood flow, and clinical outcomes among patients undergoing saphenous vein graft (SVG) PCI. However, the role for these devices in primary PCI and native coronary artery interventions is uncertain. This study examines the current approaches to manage thrombotic lesions during PCI and reviews the evidence in support of the different mechanical thrombectomy options that are available to the interventional cardiologist.

Administration of intracoronary eptifibatide during ST-elevation myocardial infarction

Distal embolization of atherothrombotic material during primary percutaneous coronary intervention (PCI) is associated with impaired myocardial perfusion, abnormal left ventricular function, and higher mortality. At high local concentrations, glycoprotein IIb/IIIa receptor antagonists have been demonstrated to promote clot disaggregation in vitro. Intracoronary administration of eptifibatide in vivo may increase local drug concentration by several orders of magnitude and promote clot disaggregation with a minimal increase in systemic drug concentrations. We hypothesized that intracoronary administration of eptifibatide before primary PCI for ST-elevation myocardial infarction would be safe and would be associated with high rates of normal myocardial perfusion. Clinical and angiographic data were pooled from patients who underwent primary PCI and received intracoronary eptifibatide as part of clinical practice. In-hospital adverse events were collected retrospectively. No deaths, urgent revascularizations, or reinfarctions were observed among the 59 patients who were treated with intracoronary eptifibatide. There were no Thrombolysis In Myocardial Infarction (TIMI) major bleeding events. Two TIMI minor bleeding events were noted. Normal TIMI myocardial perfusion grade 3 flow after PCI was noted in 54.4% of patients. No adverse events. including arrhythmias, were noted during intracoronary eptifibatide administration. In conclusion, intracoronary eptifibatide can be administered safely during primary PCI and is associated with few adverse events. Relatively high rates of normal myocardial perfusion were observed after primary PCI with adjunctive intracoronary eptifibatide. Further prospective randomized trials are warranted to evaluate the efficacy and safety of intracoronary eptifibatide.

Association between cardiac troponin T elevation and angioscopic morphology of culprit lesion in patients with non-ST-segment elevation acute coronary syndrome

BACKGROUND

It is well known that cardiac troponin T (TnT) elevation on admission indicates a high-risk subgroup among patients with non-ST-segment elevation acute coronary syndrome (NSEACS). Although the mechanism of TnT elevation is speculated to be the microthromboembolism from unstable plaques, it has not been clarified. The aim of this study is to clarify the association between the serum TnT elevation and the angioscopically evaluated morphology of culprit lesion in the patients with NSEACS.

METHODS

Among 113 patients with NSEACS who had significant coronary stenosis, 62 patients with successful angioscopic examination were prospectively and consecutively enrolled from October 2001 to August 2002. Patients were divided into 2 groups according to the serum TnT level measured before percutaneous coronary intervention: TnT-positive or TnT-negative group. Thrombus and plaque color at culprit lesion were evaluated by angioscopy and were compared between the groups. Plaque color was determined as yellow or white, and thrombus as none, small, or large. Three different definitions for TnT-positive (> or =0.1, > or =0.03, and > or =0.01 ng/mL) were used and the sensitivity and specificity for detecting thrombus was compared.

RESULTS

Prevalence of thrombus, large thrombus, and yellow plaque were all higher in TnT-positive than in TnT-negative group for 3 different cutoff values of TnT. Angiographic slow-flow occurred more frequently after percutaneous coronary intervention in TnT-positive than in TnT-negative group for 3 different cutoff values of TnT. Sensitivity/specificity of detecting large thrombus were 33%/100%, 44%/91%, and 56%/83% when TnT-positive was defined as TnT > or = 0.1, > or =0.03, and > or =0.01 ng/mL, respectively.

CONCLUSIONS

Serum TnT level was significantly associated with the prevalence of thrombus and yellow plaque at the culprit lesions of NSEACS. Troponin T, when positive was defined as > or =0.01 ng/mL, still have a high specificity for detecting intracoronary thrombus.

Correlation between the TIMI risk score and high-risk angiographic findings in non-ST-elevation acute coronary syndromes: observations from the Platelet Receptor Inhibition in Ischemic Syndrome Management in Patients Limited by Unstable Signs and Symptoms (PRISM-PLUS) trial

BACKGROUND

The TIMI risk score for unstable angina and non-ST elevation myocardial infarction is an effective tool for predicting the risk of death and ischemic events among patients with non-ST elevation acute coronary syndromes, as well as for identifying those who are likely to benefit most from low-molecular-weight heparin and glycoprotein IIb/IIIa inhibition.

METHODS

To explore the pathobiologic basis for this interaction, we evaluated the relationship between the risk score, assessed at presentation, and angiographic findings among patients with non-ST elevation acute coronary syndromes. Angiographic data regarding thrombus, epicardial flow, and lesion severity were available for 1491 patients from the angiographic substudy of PRISM-PLUS.

RESULTS

Patients with risk scores of 5 to 7 (N = 435) were more likely to have a severe culprit stenosis (81% vs 58%, P < .001) and multivessel disease (80% vs 43%, P < .001) compared to those with scores of 0 to 2 (N = 220). The probability of left main disease (P = .01), visible thrombus, and impaired flow in the culprit lesion also increased progressively with rising risk scores (P < .001). Of the risk indicators that comprise the score, history of coronary disease, advanced age, and ST changes showed the strongest association with severe epicardial disease. Positive biomarkers of necrosis, ST changes, and prior aspirin use emerged as stronger correlates of visible thrombus and/or impaired culprit artery flow.

CONCLUSIONS

The TIMI risk score identifies patients who are more likely to have intracoronary thrombus, impaired flow, and increased burden of coronary atherosclerosis. These findings likely explain in part the particular benefit of potent antithrombin and antiplatelet agents among patients with higher risk scores.

Thrombolytic Therapy: Current Clinical Practice

Thrombolytic therapy is an essential tool in the array of therapies designed to reopen arteries and veins occluded with thrombus. As the use of thrombolytic agents has entered mainstream practice, their application has expanded to include a wide variety of indications and settings. Thrombolytic agents are used in patients who have thrombosis of coronary arteries, precerebral and cerebral arteries, the aorta, iliac and mesenteric arteries, and peripheral arteries. The use of thrombolysis in venous thrombosis has included deep venous thrombosis of the upper and lower extremities and vena cava, mesenteric veins, cerebral veins, and central access catheters. Guidelines are available from the American College of Cardiology/American Heart Association regarding thrombolysis in myocardial infarction and from the American Stroke Association regarding thrombolysis in acute ischemic stroke.

Long-Term Clinical Outcomes of Platelet Glycoprotein IIb/IIIa Inhibitor Combined With Low Molecular Weight Heparin in Patients With Acute Coronary Syndrome

BACKGROUND

Platelet activation and aggregation with resultant arterial thrombus formation play a pivotal role in the pathophysiology of acute coronary syndrome (ACS). In the present study the efficacy of tirofiban, a specific inhibitor of the platelet glycoprotein IIb/IIIa receptor, combined with heparin or low-molecular-weight heparin (dalteparin), was evaluated for the management of ACS.

METHODS AND RESULTS

One hundred and sixty patients (60.9+/-11.1 years, 104 male) with unstable angina or non-ST elevation myocardial infarction and who had ST-T changes and elevated troponin were randomly assigned to 4 groups: group I (n=40: heparin alone), group II (n=40: dalteparin alone), group III (n=40: tirofiban + heparin) and group IV (n=40: tirofiban + dalteparin). The occurrence of major adverse cardiac events (MACE) was compared prospectively during a 6-month clinical follow-up. Percutaneous coronary intervention or coronary artery bypass graft was performed in 32 cases in group I, 29 in group II, 28 in group III and 31 in group IV (p=0.72). Minor bleeding complication developed in 2 patients (5.0%) in group I, 2 (5.0%) in group II, 4 (10.0%) in group III and 3 (7.5%) in group IV (p=0.78). During the follow-up MACE occurred in 10 patients (31.3%) in group I, 9 (31.0%) in group II, 4 (14.3%) in group III and 4 (12.9%) in group IV (p=0.02: Group I and II vs Group III and IV).

CONCLUSIONS

Tirofiban combined with dalteparin was associated with relatively more bleeding complications in the short term, but was effective in reducing the incidence of MACE during long-term clinical follow-up in patients with ACS.

Usefulness of tirofiban among patients treated without percutaneous coronary intervention (TIMI high risk patients in PRISM-PLUS)

Although the efficacy of glycoprotein IIb/IIIa inhibition in non-ST-elevation acute coronary syndromes is greatest in patients who undergo percutaneous coronary intervention (PCI), it was hypothesized that high-risk patients managed without PCI also benefit. The TIMI risk score was calculated for 1,570 patients randomized to tirofiban plus heparin versus heparin in the Platelet Receptor Inhibition in Ischemic Syndrome Management in Patients Limited by Unstable Signs and Symptoms trial. In high-risk patients (score > or =4) treated without PCI, tirofiban reduced the risk for death, myocardial infarction, and refractory ischemia at 30 days (28.8% vs 21.9%; odds ratio [OR] 0.69, p = 0.04). This benefit was similar in magnitude as that for patients who underwent PCI (32.4% vs 22.2%; OR 0.60, p = 0.06). No benefit was evident in low-risk patients.

Association between duration of tirofiban therapy before percutaneous intervention and tissue level perfusion (a TACTICS-TIMI 18 substudy)

In the setting of acute coronary syndromes, thrombotic embolization and activation of platelets with release of vasoconstrictors into the downstream microvasculature may occur before cardiac catheterization. In the Treat Angina with tirofiban and determine Cost of Therapy with an Invasive or Conservative Strategy-Thrombolysis In Myocardial Infarction 18 (TACTICS-TIMI 18) trial angiographic substudy, a shorter duration of tirofiban infusion before percutaneous coronary intervention was associated with impaired myocardial perfusion before and after intervention.

Angiographic aspects of ruptured plaque in patients with acute myocardial infarction: correlation with clinical and laboratory variables

In patients with acute myocardial infarction (AMI), little is known about the correlation between prognostic variables and aspects of ruptured plaque at the coronary angiography. Five hundred patients with acute myocardial infarction were studied in a consecutive and prospective manner; of these, 264 patients were excluded mainly because of the presence of an occluded culprit coronary artery. The remaining 236 patients were divided according to the presence (113, 52%) or absence (126, 48%) of angiographic aspects suggestive of ruptured plaque, and correlated with 49 clinical, electrocardiographic, in-hospital complications, procedures, and other angiographic prognostic variables. The variables that correlated significantly and independently with angiographic aspects of ruptured plaque were: presence of thrombi and higher degree of residual stenosis at the culprit coronary artery, as well as white ethnic group.

Treatment of intracoronary thrombus using tirofiban in a patient with normal coronary arteries

We report a 64-year-old Turkish man who presented with unstable angina pectoris. Coronary angiography revealed massive intracoronary thrombus, which completely occluded the distal part of the left circumflex coronary artery. The thrombotic segment and the rest of the coronary tree were free of atherosclerosis. The patient was treated with intravenous tirofiban, a glycoprotein IIb/IIIa inhibitor. A control angiography was performed one week later and showed total dissolution of the thrombus with tirofiban therapy.

Glycoprotein IIb-IIIa antagonists in non-ST elevation acute coronary syndromes and percutaneous interventions: from pharmacology to individual patient's therapy: part 1: the evidence of benefit

Antagonists of platelet glycoprotein IIb/IIIa (abciximab, tirofiban, eptifibatide) have now an approved role in reducing the extent of thrombotic complications leading to myocardial damage during percutaneous coronary interventions (PCI). This effect likely here translates into a long-term survival benefit. However, the question of their usefulness in different clinical scenarios (stable or unstable coronary disease, without PCI) has not been fully answered on the basis of considerations of dosing and cost-effectiveness. These agents seem most useful in high-risk patients with unstable coronary syndromes especially in the presence of co-morbidities such as diabetes or renal insufficiency. This article summarizes reasons for the ongoing debate on their efficacy and highlights areas of uncertainty.

Tirofiban therapy for patients with acute coronary syndromes and prior coronary artery bypass grafting in the PRISM-PLUS trial

The role of glycoprotein IIb/IIIa platelet receptor antagonist therapy for patients with an acute coronary syndrome (ACS) and a history of coronary artery bypass grafting (CABG) remains incompletely defined. We examined the outcomes of patients with an ACS and prior CABG who were treated with tirofiban versus placebo among subjects with prior CABG in the Platelet Receptor Inhibition in Ischemic Syndrome Management in Patients Limited by Unstable Signs and Symptoms (PRISM-PLUS) trial. Of 1,570 patients treated with tirofiban plus heparin (n = 773) or heparin alone (n = 797), 231 had prior CABG. Compared with patients without prior CABG, those with prior CABG were more likely to have risk factors for a complicated ACS course, including severe coronary artery disease and heart failure (all p <0.0001), typically had clinical predictors of benefit from tirofiban, such as ST-segment depression (p = 0.01) or a TIMI risk score >or=4 (p <0.001), and were more likely to die or have a myocardial infarction or refractory ischemia at all time points examined (p <0.0001). Among patients with prior CABG, decreases in the incidence of death, myocardial infarction, or refractory ischemia with tirofiban and heparin versus heparin alone were noted at 7 and 30 days (7 days: 16.9% vs 29.0%, p = 0.035; 30 days: 25.0% vs 40.2%, p = 0.015). Trends toward a decrease in death, myocardial infarction, and refractory ischemia with tirofiban and heparin versus heparin alone in the prior CABG subgroup were noted at 48 hours and 180 days (48 hours: 6.5% vs 14.0%, p = 0.09; 180 days: 37.1% vs 48.6%, p = 0.057). Bleeding rates were similar in patients with and without prior CABG. Tirofiban was well tolerated and tended to decrease the considerable risk for ischemic ACS complications in patients with prior CABG.

Relevance of multivessel disease in the development of in-hospital refractory angina and myocardial infarction in patients with unstable angina

We investigated the relationship between clinical, electrocardiographic and angiographic characteristics with development of refractory angina and acute myocardial infarction (AMI) in 976 consecutive patients with unstable angina (UA). AMI occurred in 63 (6%) and recurrent angina in 384 (39%), 201 of whom had >2 episodes (refractory, 21%). Patients with AMI were older (P<0.001) and had a higher rate of smoking (P<0.02), previous cerebrovascular accident (P<0.02), abnormal ST segment on admission (P<0.002), refractory angina (P<0.001) and multivessel disease (P<0.005) than those without AMI. Patients with refractory angina were older (P<0.001) and showed a higher incidence of abnormal ST segment on admission (P<0.001) and multivessel disease (P<0.001) than those without. A multivariate analysis, however, showed that refractory angina (P<0.0001), and multivessel disease (P<0.001) were the strongest predictors of AMI while age and multivessel disease were the strongest predictors of refractory angina (P<0.003). Thus, multivessel disease was the most frequent substrate of refractory angina and AMI in patients with UA. These findings may suggest that significant coronary stenosis in non-culprit arteries may facilitate recurrence of ischemia/AMI perhaps by reacting in concert with the culprit lesion and causing a further reduction of the ischemic threshold.

Effects of glycoprotein IIb/IIIa inhibition on microvascular flow after coronary reperfusion. A quantitative myocardial contrast echocardiography study

OBJECTIVES

We assessed the effect of glycoprotein IIb/IIIa inhibition (GPI) on microvascular flow after coronary occlusion/reperfusion using quantitative myocardial contrast echocardiography (QMCE).

BACKGROUND

Platelets may play a major role in the dissociation of epicardial artery recanalization and tissue-level reperfusion, referred to as the "no-reflow phenomenon." Therefore, GPI might improve myocardial reperfusion, distinct from its effects on epicardial patency.T METHOD: hree-hour occlusion of the left anterior descending coronary artery (LAD) was followed by 3-h reperfusion in 16 open-chest dogs: 8 controls and 8 given a continuous infusion of the GPI tirofiban, starting 45 min before LAD reopening. Perfusion of the LAD bed was quantified by the rate of intensity rise (b) by QMCE; myocardial blood flow (MBF) was assessed by fluorescent microspheres.

RESULTS

No differences in b or MBF were observed within the risk area between the control and GPI groups at baseline or occlusion. However, b and MBF were higher in GPI dogs than in controls during reperfusion, despite similar epicardial flow (p < 0.05 at 30, 60, and 90 min; p = NS at 180 min). Infarct area size was significantly reduced in GPI dogs compared with non-treated dogs (26.9 +/- 10.5% vs. 49.0 +/- 11.1% of at-risk area, respectively).

CONCLUSIONS

As demonstrated by QMCE, GPI improves microvascular flow and reduces the infarct area after coronary occlusion/reperfusion, independent of epicardial flow. These data demonstrate the usefulness of QMCE in assessing microvascular flow, provide novel evidence for the role of platelets in the early phase of reperfusion injury, and show that GPI is of value in preserving microvascular perfusion after coronary reperfusion.

A randomized, placebo-controlled trial of early eptifibatide for non-ST-segment elevation acute coronary syndromes

BACKGROUND

The acute benefits of platelet glycoprotein IIb/IIIa inhibitors for non-ST-segment elevation acute coronary syndromes (NSTE ACS) remain unclear.

METHODS

In this pilot trial, 311 patients with NSTE ACS were randomly assigned in the emergency department to double-blinded therapy with eptifibatide or placebo for 12 to 24 hours before crossover to open-label eptifibatide. Serial creatine-kinase MB (CK-MB) and quantitative cardiac troponin T levels were collected during the first 24 hours to assess the impact of early platelet glycoprotein IIb/IIIa blockade on infarct size as measured by cardiac markers.

RESULTS

Median peak CK-MB (10.3 vs 11.8 ng/mL; P =.71) and peak quantitative cardiac troponin T levels (0.2 vs 0.3 ng/mL; P =.95) were similar between treatment groups, respectively. Median calculated peak CK-MB values (41 vs 40 ng/mL; P =.72) and area under the CK-MB curve measurements (980 vs 764 microg/min/L; P =.68) from curve-fitting analyses that could be performed in 106 of 311 patients were also similar.

CONCLUSIONS

In this pilot trial, early administration of eptifibatide in the emergency department did not modulate serologic measurements of infarct size in patients with NSTE ACS.

Optimizing glycoprotein IIb/IIIa receptor antagonist use for the non-ST–segment elevation acute coronary syndromes: risk stratification and therapeutic intervention

Despite extensive data supporting their use for non-ST-segment elevation acute coronary syndromes, glycoprotein (GP) IIb/IIIa antagonists are underutilized. This is likely the consequence of confusion as to which patients should receive these agents, as well as to the most appropriate timing and venue for their initiation. We will review the advances in the understanding of GP IIb/IIIa antagonist therapy, emphasizing methods of identifying those most likely to benefit from the use of GP IIb/IIIa receptor blockade. In addition, we will consider appropriate methods/venues for use of GP IIb/IIIa receptor antagonism, including its role in an "early invasive" catheterization strategy.

Imaging in the evaluation of the patient with suspected acute coronary syndrome

Patients presenting to the emergency department with chest pain have a common problem. Definitive diagnosis at presentation is difficult due to limitations of the initial evaluation, and, thus, the majority of patients are admitted. Recognition of these limitations has driven the investigation of alternative evaluation techniques and protocols to attempt to improve diagnostic sensitivity without increasing overall costs. Acute myocardial perfusion imaging has been a highly valuable technique for risk stratification of intermediate to low-risk patients with chest pain. However, for a variety of reasons, it has not been widely embraced. In the past few years, alternative techniques have been investigated for use in the diagnosis of acute coronary syndromes in the acute setting. Coronary calcium scoring and cardiac magnetic resonance imaging show promise as new tools in the armamentarium for acute coronary syndromes. The challenge now lays in developing a strategy that uses these and future techniques most appropriately to support optimal medical decision making.

Effect of platelet glycoprotein IIb/IIIa receptor blockade with tirofiban on adverse cardiac events in women with unstable angina/non-ST–elevation myocardial infarction (PRISM-PLUS study)

BACKGROUND

Previous trials demonstrated the efficacy of platelet glycoprotein IIb/IIIa receptors blockade with tirofiban in reducing acute ischemic events in patients with unstable angina/non-ST-elevation myocardial infarction. Little is known about the effect of tirofiban among women with acute coronary syndromes.

OBJECTIVE

We aimed to determine the benefit and safety of tirofiban plus heparin versus heparin alone on cardiac ischemic events among women with unstable angina/non-ST-elevation myocardial infarction.

METHODS AND RESULTS

We performed a post hoc analysis of all women enrolled in the PRISM-PLUS trial. At early time points, there appeared to be a reduction of the primary composite end point of death, myocardial infarction, or refractory ischemia among women treated with tirofiban plus heparin (RR, 0.78 and 0.67) compared with women treated with heparin alone. However, at 30 and 180 days, there was no significant reduction of events with the combination therapy of tirofiban plus heparin (treatment-by-sex interaction, P =.05). Death or myocardial infarction was not significantly reduced by the combination therapy among women at all time points.

CONCLUSIONS

Although the effects of tirofiban in reducing the primary composite outcome were similar among men and women early in the study, there appeared to be a difference at the later time points. In particular, tirofiban was effective among men, but there was no clear effect among women at 30 and 180 days.