Distribution of Ventricular Fibrosis Associated With Life-Threatening Ventricular Tachyarrhythmias in Patients With Nonischemic Dilated Cardiomyopathy.

BACKGROUND: Current guidelines recommend the implantation of an implantable cardioverter-defibrillator (ICD) for primary prevention of sudden cardiac death (SCD) in a subgroup of patients with nonischemic cardiomyopathy (NICM) who have a left ventricular ejection fraction (LVEF) ≤ 30-35%, and are NYHA functional class II or III. However, the majority of patients with an ICD implantation for primary prevention did not receive appropriate ICD therapy. The purpose of this study was to evaluate the association between myocardial fibrosis detected by cardiovascular magnetic resonance (CMR) imaging and life-threatening ventricular arrhythmic events in NICM patients.

METHODS: One hundred and seventy-five NICM patients with an LVEF ≦ 35 % and NYHA functional class II or III, (60 ± 15 years, LVEF 29 ± 5.4%) were studied. Myocardial fibrosis was identified with a late gadolinium enhancement (LGE) on CMR. Clinical events were defined as SCD or life-threatening ventricular arrhythmic events and were followed up for 5.1 ± 3.3 years.

RESULTS: The presence of an LGE was detected in 122 patients (70%). No life-threatening ventricular arrhythmia events occurred in patients with the absence of an LGE. A total of 18 ventricular tachycardia and 8 ventricular fibrillation events were found in patients with the presence of an LGE (P < 0.01). Sensitivity, specificity, and positive and negative predictive value of LGE in predicting life-threatening ventricular arrhythmia events were 100%, 34%, and 15% and 100%, respectively. Multivariate analysis showed that the presence of both septal and lateral mid-wall LGE was associated with life-threatening ventricular arrhythmic events (hazard ratio 23.1 CI; 2.88-184.9, P = 0.003).

CONCLUSIONS: The absence of an LGE predicts a low potential risk of SCD and life-threatening ventricular arrhythmia events in the near future. CMR may be a useful tool for selecting suitable patients for primary ICD implantations in NICM patients.