Risk Stratification and Serious Ventricular Arrhythmias: The Importance of Left Ventricular Hypertrophic Remodeling in Patients with Depressed Ejection Fraction

Abstract

Previous studies indicate an association between ventricular arrhythmias and left ventricular (LV) structural and functional remodeling. There has been emphasis on LV systolic dysfunction, yet little is known about LV structural remodeling and arrhythmias. Accordingly, we studied the extent of LV hypertrophy (LVH) as well as the patterns of hypertrophic remodeling and their relation to ventricular tachycardia/fibrillation (VT/VF) in patients with depressed ejection fraction (EF) and an implantable cardioverter-defibrillator (ICD). Of 565 patients who underwent implantation of a single or dual chamber ICD between 2006 and 2009, 127 had echocardiographic evidence of LV dysfunction and were followed in our device clinic. Standard echocardiographic Methods were used. LVH was defined as mass > 95 g/m2 in women and > 115 g/m2 in men. A relative wall thickness partition value of 0.42 was used to differentiate concentric vs. eccentric geometry. Serious ventricular arrhythmias were defined as VT/VF requiring anti-tachycardia pacing and/or ICD discharge. This diagnosis was made and confirmed by ICD interrogation and medical record review. Data are mean +/- SD. In the 127 patients, VT/VF occurred in 29 (23%). The average EF was 29 +/- 9%, LV mass was 115 +/- 33 g/m2, and LV end-diastolic dimension was 58 +/- 8 mm. The average age was 66 +/- 13 years; 78% were male. Clinical characteristics: hypertension: 69%, NYHA functional class I/II: 87%, diabetes: 31%, atrial fibrillation: 34%. VT/VF was significantly more prevalent in the 60 patients with LVH vs. 67 patients with normal LV mass (37% vs. 10%; p=0.0006). There was a trend towards more VT/VF in patients with LV enlargement vs. those with normal LV size (30% vs. 17%; p=ns), and in patients with eccentric hypertrophy vs. those with concentric remodeling/hypertrophy (38% vs. 20%; p=ns). There was no significant difference in clinical characteristics, indication for ICD, ischemic etiology, cardiac medications, and EF in patients with and without VT/VF. In patients with LV systolic dysfunction, we found a significant relationship between serious ventricular arrhythmias requiring device therapy and LVH. There was a trend towards more VT/VF in patients with LV enlargement and/or eccentric hypertrophy vs. those with concentric remodeling/hypertrophy. These data provide a rationale for improving risk stratification of patients with LV systolic dysfunction.