Non-dilated Left Ventricular Cardiomyopathy Vs. Dilated Cardiomyopathy: Clinical Background and Outcomes.

Aims Non-dilated left ventricular cardiomyopathy (NDLVC) was proposed as a new category of cardiomyopathy that included patients with non-left ventricular (LV) dilatation, LV wall motion abnormality, or LV scar. However, the clinical background and event rates of NDLVC were unclear. The aim of this study was to examine the characteristics and event rates of patients with NDLVC and reduced LV ejection fraction (NDLVC-REF) in comparison with those with dilated cardiomyopathy (DCM). Methods and results We retrospectively included 363 patients with newly diagnosed non-ischaemic cardiomyopathy and reduced LV ejection fraction (<50%) between December 2004 and January 2018. Patients who did not have LV dilatation (LV dimension index of 31 mm/m(2) in men and 34 mm/m(2) in women) were categorized as NDLVC-REF (n = 80, 22.2%), and the remaining patients were categorized as DCM. Cardiac events were defined as sudden cardiac death and rehospitalization for heart failure. Patients with NDLVC-REF had a higher prevalence of atrial fibrillation and a higher LV ejection fraction than those with DCM at baseline. LV ejection fraction was higher and LV end-diastolic diameter was smaller in patients with NDLVC-REF than in those with DCM at all time points after diagnosis. During the median follow-up period of 68.8 months (interquartile range: 33.0-93.7 months), 44 patients experienced cardiac events. The Kaplan-Meier curves showed no significant differences in the probability of cardiac events among NDLVC-REF and DCM patients (P = 0.349). However, patients with NDLVC-REF and LV dilatation after diagnosis (14%) had a higher risk of cardiac events than those with NDLVC-REF without LV dilatation (P = 0.049). Conclusions There was no significant difference in the incidence of cardiac events between NDLVC-REF and DCM. Among NDLVC-REF patients, 18% of patients who showed LV dilatation after diagnosis had poor outcomes. Therefore, both NDLVC-REF and DCM patients may require equivalent attention to follow-up and regular assessment of LV function.