Long-Term Recording of Cardiac Arrhythmias With an Implantable Cardiac Monitor in Patients With Reduced Ejection Fraction After Acute Myocardial Infarction: The Cardiac Arrhythmias and Risk Stratification After Acute Myocardial Infarction (CARISMA) Study

P. E. Bloch Thomsen, C. Jons, M. J. P. Raatikainen, R. Moerch Joergensen, J. Hartikainen, V. Virtanen, J. Boland, O. Anttonen, U. J. Gang, N. Hoest, L. V. A. Boersma, E. S. Platou (+3 others)
2010 Circulation  
for the Cardiac Arrhythmias and Risk Stratification After Acute Myocardial Infarction (CARISMA) Study Group Background-Knowledge about the incidence of cardiac arrhythmias after acute myocardial infarction has been limited by the lack of traditional ECG recording systems to document and confirm asymptomatic and symptomatic arrhythmias. The Cardiac Arrhythmias and Risk Stratification After Myocardial Infarction (CARISMA) trial was designed to study the incidence and prognostic significance of
more » ... hythmias documented by an implantable cardiac monitor among patients with acute myocardial infarction and reduced left ventricular ejection fraction. Methods and Results-A total of 1393 of 5869 patients (24%) screened in the acute phase (3 to 21 days) of an acute myocardial infarction had left ventricular ejection fraction Յ40%. After exclusions, 297 patients (21%) (meanϮSD age, 64.0Ϯ11.0 years; left ventricular ejection fraction, 31Ϯ7%) received an implantable cardiac monitor within 11Ϯ5 days of the acute myocardial infarction and were followed up every 3 months for an average of 1.9Ϯ0.5 years. Predefined bradyarrhythmias and tachyarrhythmias were recorded in 137 patients (46%); 86% of these were asymptomatic. The implantable cardiac monitor documented a 28% incidence of new-onset atrial fibrillation with fast ventricular response (Ն125 bpm), a 13% incidence of nonsustained ventricular tachycardia (Ն16 beats), a 10% incidence of high-degree atrioventricular block (Յ30 bpm lasting Ն8 seconds), a 7% incidence of sinus bradycardia (Յ30 bpm lasting Ն8 seconds), a 5% incidence of sinus arrest (Ն5 seconds), a 3% incidence of sustained ventricular tachycardia, and a 3% incidence of ventricular fibrillation. Cox regression analysis with time-dependent covariates revealed that high-degree atrioventricular block was the most powerful predictor of cardiac death (hazard ratio, 6.75; 95% confidence interval, 2.55 to 17.84; PϽ0.001). Conclusions-This is the first study to report on long-term cardiac arrhythmias recorded by an implantable loop recorder in patients with left ventricular ejection fraction Յ40% after myocardial infarction. Clinically significant bradyarrhythmias and tachyarrhythmias were documented in a substantial proportion of patients with depressed left ventricular ejection fraction after acute myocardial infarction. Intermittent high-degree atrioventricular block was associated with a very high risk of cardiac death. A pproximately 10% to 15% of acute myocardial infarction (AMI) survivors with depressed left ventricular function die within the first 2 years after the AMI. 1-5 About 80% of deaths in population are cardiac, half of which are sudden 6 and are often attributed to bradyarrhythmias or ventricular tachyarrhythmias, especially in patients with heart failure. [2] [3] [4] [5] 7 Previous studies among patients with implantable devices suggest, however, that a large proportion of deaths defined as
doi:10.1161/circulationaha.109.902148 pmid:20837897 fatcat:kerpea7s4zblpcuweuaynvxspe