The incidence of HAVB in STEMI patients treated with pPCI has been reduced compared with reports from the thrombolytic era. However, despite this improvement high-degree AV block remains a severe prognostic marker in the pPCI era. The mortality rate was only increased within the first 30 days. High-degree atrioventricular block patients who survived beyond this time-point thus had a prognosis equal to patients without HAVB.

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 arrhythmias 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. Clinical Trial Registration-URL: http://www.ClinicalTrials.gov, Unique identifier: NCT00145119.

We appreciate the very relevant comments by Ravensbergen and colleagues, and agree that the Cardiac Arrhythmias and Risk Stratification After Acute Myocardial Infarction (CARISMA) Study 1 had several limitations. As we also pointed out, the main limitation, regarding the definition and diagnosis of tachyarrhythmias, was that the rate had to be Ն125 beats per minute for every beat of at least 16 consecutive beats. Thus, tachyarrhythmias of 16 consecutive beats, and with varying R-R intervals longer than 480 ms, could not be recorded by the implantable cardiac monitor (ICM). Another important limitation was the time delay (mean: 11 days) from the acute myocardial infarction to the implantation of the ICM, which may contribute to underreporting of arrhythmias.Despite the limitations, CARISMA was the first study using long-term ECG monitoring in patients surviving an acute myocardial infarction with depressed left ventricular function. The study was only observational, but the results were encouraging. Therefore, we are planning a multinational prospective study in which patients similar to those in the CARISMA Study, but with a few additional risk factors, will be randomized to receive the next generation ICM with 256 Hz resolution before discharge from the hospital versus best medical treatment, to study the possible diagnostic and therapeutical value of the ICM.Hopefully, the newer ICM models will be able to diagnose and store nonsustained irregular ventricular tachycardia lasting less than 16 beats and atrial fibrillation irrespective of ventricular rate, and allow risk assessment by using spectral analysis as well as analysis of heart rate turbulence from the ICM-ECG. Disclosures