Cardiac arrhythmias and risk stratification after myocardial infarction: results of the CARISMA pilot study

Abstract

CARISMA is a multicenter study enrolling patients with a left ventricular ejection fraction < or = 40% after acute myocardial infarction (AMI), in whom an electrocardiogram (ECG) loop recorder (ILR) is implanted to measure the incidence of tachyarrhythmia and bradyarrhythmia episodes. The value of 24 hour ambulatory ECG, signal-averaged ECG late potentials, QT dispersion, T wave alternans, and electrophysiologic testing as predictors of life-threatening arrhythmias is examined. The study tested the automatic documentation of arrhythmias by the ILR in 30 post-AMI patients.

Results: At a mean follow-up of 47 days, the ILR had detected atrial tachyarrhythmias in 8 of 28 patients, nonsustained ventricular tachycardias in 2, and transient third degree atrioventricular block in 3. An indication for implantation of an implantable cardioverter defibrillator (ICD) or permanent pacemaker (PM) was observed in 9 out of 29 patients (31%). An average of 2.3 events stored by the ILR were due to inappropriate triggering. Because its memory size is limited to a maximum of 14 episodes, the ILR was unable to store arrhythmias 28% of the follow-up time. False events rate and monitoring time were improved by suturing the device within its pocket.

Conclusions: The ILR allowed the automatic detection of brady- and tachyarrhythmias in post-AMI patients, though a high incidence of false activations were observed. Clinically significant arrhythmias were recorded in a large number of patients with depressed left ventricular function early after AMI. This prompted the implantation of ICD or PM in nearly one third of patients.