Noninvasive electrocardiographic risk factors for sudden cardiac death in dilated ca rdiomyopathy: is ambulatory electrocardiography still relevant?

Arrhythmias and cardiac MRI associations in patients with established cardiac dystrophinopathy

AIMS

Some patients with cardiac dystrophinopathy die suddenly. Whether such deaths are preventable by specific antiarrhythmic management or simply indicate heart failure overwhelming medical therapies is uncertain. The aim of this prospective, cohort study was to describe the occurrence and nature of cardiac arrhythmias recorded during prolonged continuous ECG rhythm surveillance in patients with established cardiac dystrophinopathy and relate them to abnormalities on cardiac MRI.

METHODS AND RESULTS

A cohort of 10 patients (36.3 years; 3 female) with LVEF<40% due to Duchenne (3) or Becker muscular (4) dystrophy or Duchenne muscular dystrophy-gene carrying effects in females (3) were recruited, had cardiac MRI, ECG signal-averaging and ECG loop-recorder implants. All were on standard of care heart medications and none had prior history of arrhythmias.No deaths or brady arrhythmias occurred during median follow-up 30 months (range 13-35). Self-limiting episodes of asymptomatic tachyarrhythmia (range 1-29) were confirmed in 8 (80%) patients (ventricular only 2; ventricular and atrial 6). Higher ventricular arrhythmia burden correlated with extent of myocardial fibrosis (extracellular volume%, p=0.029; native T1, p=0.49; late gadolinium enhancement, p=0.49), but not with LVEF% (p=1.0) on MRI and atrial arrhythmias with left atrial dilatation. Features of VT episodes suggested various underlying arrhythmia mechanisms.

CONCLUSIONS

The overall prevalence of arrhythmias was low. Even in such a small sample size, higher arrhythmia counts occurred in those with larger scar burden and greater ventricular volume, suggesting key roles for myocardial stretch as well as disease progression in arrhythmogenesis. These features overlap with the stage of left ventricular dysfunction when heart failure also becomes overt. The findings of this pilot study should help inform the design of a definitive study of specific antiarrhythmic management in dystrophinopathy.

TRIAL REGISTRATION NUMBER

ISRCTN15622536.

Ischemia testing and revascularization in patients with monomorphic ventricular tachycardia: A relic of the past?

Testing for myocardial ischemia in patients presenting with sustained monomorphic Ventricular Tachycardia(VT) even without evidence of acute myocardial infarction is a tempting strategy that is frequently utilized in clinical practice. Monomorphic VT is mainly caused by re-entry around chronic myocardial scar and active ischemia has no role in its pathogenesis, thus making testing for ischemia futile, at least in theory. This systematic literature review sought to address the usefulness of ischemia testing (mainly coronary angiography) in patients presenting with monomorphic VT through 8 selected studies after evaluating a total of 130 published manuscripts. Particularly, we sought to unveil whether coronary angiography and possibly concomitant revascularization leads to lesser tachycardia recurrence. Our conclusion can be summarized as follows: this approach whether combined with revascularization or not, does not seem to reduce VT recurrence nor does it affect mortality in such patients. Even though most of the published literature points at this direction, validation from randomized controlled trials is imperative.