Diltiazem in acute myocardial infarction treated with thrombolytic agents: a randomised placebo-controlled trial. Incomplete Infarction Trial of European Research Collaborators Evaluating Prognosis post-Thrombolysis (INTERCEPT)

BACKGROUND: Diltiazem reduces non-fatal reinfarction and refractory ischaemia after non-Q-wave myocardial infarction, an acute coronary syndrome similar to the incomplete infarction that occurs after successful reperfusion. We postulated that this agent would reduce cardiac events in patients after acute myocardial infarction treated initially with thrombolytic agents-a clinical application previously unexplored with heart-rate-lowering calcium antagonists. METHODS: A prospective, randomised, double-blind, sequential trial was done in 874 patients with acute myocardial infarction, but without congestive heart failure, who first received thrombolytic agents. Patients received either 300 mg oral diltiazem once daily, or placebo, initiated within 36-96 h of infarct onset, and given for up to 6 months. The trial primary endpoint was the cumulative first event rate of cardiac death, non-fatal reinfarction, or refractory ischaemia. Additional prespecified endpoints included several composites of non-fatal cardiac events (non-fatal reinfarction combined with refractory ischaemia, all recurrent ischaemia, or the need for myocardial revascularisation). The diagnosis of ischaemia, whether refractory or recurrent, and the need for myocardial revascularisation, was always based on objective electrocardiographical evidence of ischaemia, either at rest or on exertion. RESULTS: For the trial primary endpoint, 131 events occurred in the 444 placebo patients and 97 events in the 430 diltiazem patients (hazard ratio 0.79; 95% CI, 0.61-1.02; p=0.07). For non-fatal cardiac events, diltiazem treatment was associated with a relative decrease (0.76; 0.58-1.00) in the combined event rate of non-fatal reinfarction and refractory ischaemia. There was a similar decrease in the composite non-fatal endpoints of non-fatal reinfarction combined with all recurrent ischaemia (0.80; 0.64-1.00) and non-fatal reinfarction combined with the need for myocardial revascularisation (0.67; 0.46-0.96). The need for myocardial revascularisation alone was significantly reduced by 42% (0.61; 0.39-0.96). No major safety issues were encountered. CONCLUSIONS: Diltiazem did not reduce the cumulative occurrence of cardiac death, non-fatal reinfarction, or refractory ischaemia during a 6-month follow-up, but did reduce all composite endpoints of non-fatal cardiac events, especially the need for myocardial revascularisation.

Overview of randomized trials of intravenous heparin in patients with acute myocardial infarction treated with thrombolytic therapy.

Intravenous heparin is routinely given after thrombolytic therapy for patients with acute myocardial infarction in the United States and in some, but by no means all, other countries. Several trials have documented improved infarct-artery patency in patients treated with heparin; however, none was large enough individually to assess the effect of heparin on clinical outcomes. We performed a systematic overview of the 6 randomized controlled trials (1,735 patients) to summarize the available data concerning the risks and benefits of intravenous heparin versus no heparin after thrombolytic therapy. Mortality before hospital discharge was 5.1% for patients allocated to intravenous heparin compared with 5.6% for controls (relative risk reduction of 9%, odds ratio 0.91, 95% confidence interval 0.59 to 1.39). Similar rates of recurrent ischemia and reinfarction were observed among those allocated to heparin therapy or control. The rates of total stroke, intracranial hemorrhage, and severe bleeding were similar in patients allocated to heparin; however, the risk of any severity of bleeding was significantly higher (22.7% vs 16.2%; odds ratio 1.55, 95% confidence interval 1.21 to 1.98). There was no significant difference in the observed effects of heparin between patients receiving tissue-type plasminogen activator and those receiving streptokinase or anisoylated plasminogen streptokinase activator complex, or between patients who did and did not receive aspirin. The findings of this overview demonstrate that insufficient clinical outcome data are available to support or to refute the routine use of intravenous heparin therapy after thrombolysis. It is not known if these findings are due to lack of statistical power, inappropriate levels of anticoagulation, or lack of benefit of intravenous heparin. Large randomized studies of heparin (and of new antithrombotic regimens) are needed to establish the role of such therapy.

[Acute myocardial infarction: thrombolytic efficacy of 500.000 UI of streptokinase combined with heparin]. / Infarto agudo del miocardio: eficacia trombolítica de 500.000 UI de estreptokinasa asociada a heparina.

Most reports concerning the use of streptokinase (SK) for thrombolysis in myocardial infarction (MI) have employed doses over 1,000,000 units. We evaluated the efficacy of a dose of 500,000 U in 40 patients with acute MI who received full heparin dose before, during and after SK. Thrombolytic effect, as measured by the protamine neutralized thrombin time was shown to be strong in 60% of cases, moderate in 17% and weak in 22%, and this was not modified by larger SK doses. A patent culprit artery was demonstrated at coronary arteriography performed 3 days after SK in 90% of patients. Only one instance of severe bleeding was observed. Thus, a reduced SK dose in association to heparin provides adequate lytic effect and artery patency rate in patients with MI.

Pharmacokinetics, thrombolytic efficacy and hemorrhagic risk of different streptokinase regimens in heparin-treated acute myocardial infarction.

The systemic activator activity of 4 streptokinase (SK) regimens (250,000 IU intracoronary, group A; 500,000 IU, group B; 1.5 X 10(6) IU, group C; and 30 U anisoylated plasminogen streptokinase activator complex (APSAC) intravenously, group D) was tested with the fibrin plate technique. One hour after initiation of treatment, the activator activity was highest after APSAC (3.6 +/- 0.9 U), slightly but not significantly less after SK 1.5 X 10(6) IU (3.0 +/- 0.7), and significantly less after SK 500,000 IU (1.6 +/- 0.5) and 250,000 IU (0.6 +/- 0.5), p less than 0.001. After SK, activator activity half-lives were 184 minutes (group B) and 169 minutes (group C), and after APSAC 188 minutes (group D). These were all in agreement with greater than 12 hour duration of changes in other markers of systemic fibrinolysis (euglobulin lysis time) and substrates depletion (fibrinogen, plasminogen, alpha 2 antiplasmin). In extended pilot clinical groups given identical thrombolytic regimens during full anticoagulation with heparin, angiographic coronary patency was found in 83% (35 of 42) after intracoronary SK (group 1), in 73 and 75%, respectively, after 500,000 IU (31 of 43) and 1.5 X 10(6) IU (30 of 40) (group 2 and 3, difference not significant) and 80% (8 of 10) after the 30-U bolus of APSAC (group 4). The overall hemorrhagic risk was 24%, equally distributed among the 4 regimens and mostly (91%) related to catheters. The incidence of bleeding unrelated to vessel puncture was 4%; no deaths occurred. It is concluded that APSAC is the most fibrinolytic regimen but its potential thrombolytic superiority over SK remains to be demonstrated.(ABSTRACT TRUNCATED AT 250 WORDS)