Current issues of ACP Journal Club are published in Annals of Internal Medicine


Prognosis

Ventricular arrhythmias predicted total mortality and sudden death after myocardial infarction

ACP J Club. 1993 July-Aug;119:26. doi:10.7326/ACPJC-1993-119-1-026


Source Citation

Maggioni AP, Zuanetti G, Franzosi MG, et al. Prevalence and prognostic significance of ventricular arrhythmias after acute myocardial infarction in the fibrinolytic era.GISSI-2 results. Circulation. 1993 Feb;87:312-22.


Abstract

Objective

To establish the prognostic value of ventricular arrhythmias after myocardial infarction in patients who had been treated with fibrinolytic agents during their acute infarction.

Design

Inception cohort followed for 6 months.

Setting

Multicenter trial in Italy.

Patients

8676 patients (81% aged ≤ 70 years, 82% men) who were enrolled in the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico (GISSI-2) study. Entry criteria were chest pain with ST-segment elevation of ≥ 1 mm in a limb lead of the electrocardiogram (ECG) or ≥ 2 mm in any precordial lead, admission to the cardiac care unit within 6 hours of the onset of symptoms, and no contraindication to fibrinolytic treatment or heparin. All patients were treated with fibrinolytic agents during the acute infarction phase. 6-month mortality data were available for 8552 patients (99%).

Assessment of prognostic factors

24-hour ambulatory ECG monitoring obtained before hospital discharge was analyzed for the presence of ventricular arrhythmias (premature ventricular beats [PVBs] and ventricular tachycardia). β-blockers and other antiarrhythmic drugs were withdrawn before monitoring.

Main outcome measures

Total and sudden cardiovascular mortality.

Main results

5564 patients (64%) had ventricular arrhythmias. More than 10 PVBs per hour were recorded in 1712 patients (20%); 2892 patients (33%) had complex ventricular arrhythmias; and 586 patients (7%) had nonsustained ventricular tachycardia. 256 deaths (3%) occurred; 84 were defined as sudden cardiac deaths. Mortality rates were 2% among patients without ventricular arrhythmias, 3% in patients with 1 to 10 PVBs per hour, 6% in patients with > 10 PVBs per hour, and 5% in patients with complex PVBs. After adjustment for several risk factors (e.g., age, sex, history of diabetes, or treated hypertension), frequent ventricular arrhythmias (> 10 PVB/h) were an independent predictor of total mortality (relative risk [RR] 1.62, 95% CI 1.16 to 2.26) and sudden death (RR 2.24, CI 1.22 to 4.08). Complex ventricular arrhythmias were also an independent predictor of total mortality (RR 1.64, CI 1.27 to 2.12) and sudden death (RR 2.11, CI 1.34 to 3.17).

Conclusion

Frequent and complex ventricular arrhythmias in the first 6 months after an acute myocardial infarction were independent predictors of total mortality and sudden death in patients initially treated with fibrinolytic agents.

Sources of funding: Boehringer Ingelheim Italy SpA; ICI-Pharma Italy and Italfarmaco SpA; Italian National Council of Research.

For article reprint: Dr. A.P. Maggioni, GISSI-2 Coordinating Center, Via Eritrea 62, 20157 Milano, Italy. FAX 39-2-332-00049.


Commentary

These results from GISSI-2 add to our understanding of the clinical significance of ventricular arrhythmias after myocardial infarction. The sample size, homogeneity of baseline Holter data (all patients off antiarrhythmic agents), and completeness of follow-up allow a reliable, current estimate of the prevalence and prognosis of ventricular ectopy after infarction. As expected, the prevalence of ventricular arrhythmias was lower (64%) than in prethrombolytic trials (84% to 86%); however, frequent and complex ventricular arrhythmias remain 2 independent predictors of mortality.

Other studies support the hypothesis that electrical stability after myocardial infarction is improved through either the preservation of left ventricular function (thrombolytics, angiotensin-converting enzyme inhibitors) or through direct antiarrhythmic effect (β-blockers). Newer data suggest that successful percutaneous transluminal coronary angioplasty that restores flow to the infarcted vessel reduces the frequency of late potentials (a predictor of arrhythmias) (1).

These studies direct the reader to consider 2 important questions that should now be addressed in protocols: 1) How do these interventions compare (alone or in combination) in the prophylaxis of arrhythmias and subsequent cardiovascular events; and 2) in the post-CAST study (2) era, should we be treating complex ventricular arrhythmias after myocardial infarction and, if so, with what agent(s)?

The take-home message from this trial is that ventricular arrhythmias after myocardial infarction are still a common problem, that complex ventricular arrhythmias may predict adverse outcomes, and that optimal management of these patients awaits further randomized clinical trials.

Olivia Vynn-Adair, MD
University of Colorado Health Science CenterDenver, Colorado, USA


References

1. Boehrer JD, Glumann DB, Lange RA, et al. Effect of coronary angioplasty on late potentials one to two weeks after acute myocardial infarction. Am J Cardiol. 1992;70:1515-9.

2. Echt DS, Liebson PR, Mitchell LB, et al. Mortality and morbidity in patients receiving encainide, flecainide, or placebo: the Cardiac Arrhythmia Suppression Trials. N Engl J Med. 1991;324:781-8


Editor's Comments

Recent randomized clinical trials' data suggest a role for amiodarone in the prevention of sudden death after myocardial infarction particularly in high-risk patient groups (1-3). The use of automated implantable defibrillators has also been shown to reduce total mortality and sudden death in patients after myocardial infarction who are at high risk for ventricular arrhythmias (4, 5).

1. Cairns JA, Connolly SJ, Roberts R, Gent M, for the Canadian Amiodarone Myocardial Infarction Arrhythmia Trial Investigators. Randomised trial of outcome after myocardial infarction in patients with frequent or repetitive ventricular premature depolarisations: CAMIAT. Lancet. 1997;349:675-82.

2. Julian DG, Camm AJ, Frangin G, et al., for the European Myocardial Infarct Amiodarone Trial Investigators. Randomised trial of effect of amiodarone on mortality in patients with left-ventricular dysfunction after recent myocardial infarction: EMIAT. Lancet. 1997;349:667-74.

3. Amiodarone Trials Meta-Analysis Investigators. Effect of prophylactic amiodarone on mortality after acute myocardial infarction and in congestive heart failure: meta-analysis of individual data from 6500 patients in randomised trials. Lancet. 1997;350:1417-24.

4. The Antiarrhythmics Versus Implantable Defibrillators (AVID) Invetigators. A comparison of antiarrhythmic-drug therapy with implantable defibrillators in patients resuscitated from near-fatal ventricular arrhythmias.N Engl J Med. 1997;337:1576-83.

5. Moss AJ, Hall WJ, Cannom DS, et al., for the Multicenter Automated Defibrillator Implantation Trial Investigators. Improved survival with an implanted defibrillator in patients with coronary disease at high risk for ventricular arrhythmia. N Engl J Med. 1996;335:1933-40.