Arrhythmic risk stratification in patients with dilated cardiomyopathy and intermediate left ventricular dysfunction.

Objective: Arrhythmic risk stratification is a challenging issue in patients with dilated cardiomyopathy (DCM), particularly when left ventricular ejection fraction (LVEF) is more than 35%. We studied the prevalence and predictors of sudden cardiac death or malignant ventricular arrhythmias (SCD/MVAs) in DCM patients categorized at low arrhythmic risk because of intermediate left ventricular dysfunction under optimal medical treatment (OMT).

Methods: DCM patients considered at low arrhythmic risk (LVEF >35% and New York Heart Association class I-III after 6 ± 3 months of OMT) were analysed. An arrhythmogenic profile was defined as the presence of at least one among a history of syncope, nonsustained ventricular tachycardia, at least 1000 premature ventricular contractions/24 h, at least 50 ventricular couplets/24 h at Holter ECG monitoring. SCD/MVAs was considered as the study end-point.

Results: During a median follow-up of 152 months (interquartile range 100-234), 30 out of 360 (8.3%) patients at low arrhythmic risk (LVEF 47 ± 7%) experienced the study end-point [14 (3.9%) SCD and 16 (4.4%) MVA]. Compared with survivors, patients who experienced SCD/MVAs had more frequently an arrhythmogenic profile and a larger left atrium. Their LVEF at the last available evaluation before the arrhythmic event was 36 ± 12%. At multivariable analysis, left atrial end-systolic area [hazard ratio 1.107; 95% confidence interval (95% CI) 1.039-1.179, P = 0.002 for 1 mm increase] and arrhythmogenic profile (hazard ratio 3.667; 95% CI 1.762-7.632, P = 0.001) emerged as predictors of SCD/MVAs during follow-up.

Conclusions: A consistent quota of DCM patients with intermediate left ventricular dysfunction receiving OMT experienced SCD/MVA during follow-up. Left atrial dilatation and arrhythmogenic pattern were associated with a higher risk of SCD/MVA.