Early Arrhythmic Events in Idiopathic Dilated Cardiomyopathy

Study Questions:

What are the characteristics and the prevalence of idiopathic dilated cardiomyopathy (DCM) patients with early sudden cardiac death/major ventricular arrhythmias (SCD/MVAs), and what are possible baseline indicators of early major arrhythmic events?

Methods:

This was a report from the Heart Muscle Disease Registry of Trieste for patients enrolled between 1988 and 2014.

Results:

From among a total of 952 patients, 20 (2.1%) experienced SCD/MVAs within the first 6 months. At baseline, they showed a worse functional class (New York Heart Association class III-IV 42% vs. 22%, p = 0.04), a longer QRS complex duration (127 ms vs. 108 ms, p = 0.013), and a larger indexed left ventricular end-systolic volume (LVESVI) (82 ml/m2 vs. 67 ml/m2; p = 0.05). Beta-blockers were less tolerated (59% vs. 83%, p = 0.008), mostly due to hemodynamic intolerance. At multivariate analysis, LVESVI (odds ratio [OR], 1.012; p = 0.04) and QRS complex duration (OR, 1.017; p = 0.015) were independently associated with SCD/MVAs, whereas beta-blockers had a protective effect (OR, 0.169; p = 0.006).

Conclusions:

Patients with DCM present a significant risk of major arrhythmic events in the first phase of the disease. Baseline LVESVI, QRS duration, and intolerance to beta-blocker therapy might be useful tools in the arrhythmic early risk assessment.

Perspective:

A large proportion of patients diagnosed with idiopathic dilated cardiomyopathy show an improvement in the LV function after appropriate medical therapy. The American Heart Association Science Advisory on wearable cardioverter-defibrillator therapy gives a Class IIb indication for patients with decreased LV function who are being optimized on medical therapy and who are at elevated risk for SCD. A recent implantable cardioverter-defibrillator (ICD) trial (DANISH; N Engl J Med 2016;375:1221-30) in patients with nonischemic cardiomyopathy has highlighted the need to better risk stratify patients likely to benefit from an ICD. Late gadolinium enhancement on magnetic resonance imaging (MRI) has been proposed as an additional risk stratification marker. Unfortunately, the authors do not report any MRI data in this study. The optimal timing of ICD placement in patients with DCM has yet to be determined.

Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Prevention, Implantable Devices, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure, Magnetic Resonance Imaging

Keywords: Adrenergic beta-Antagonists, Arrhythmias, Cardiac, Cardiomyopathies, Cardiomyopathy, Dilated, Death, Sudden, Cardiac, Defibrillators, Implantable, Gadolinium, Heart Conduction System, Heart Failure, Magnetic Resonance Imaging, Myocardium, Secondary Prevention, Stroke Volume, Ventricular Function, Left


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