Left Ventricular Relaxation Half-Time as a Predictor of Cardiac Events in Idiopathic Dilated Cardiomyopathy and Hypertrophic Cardiomyopathy With Left Ventricular Systolic and/or Diastolic Dysfunction

Purpose: Diastolic dysfunction preceding systolic dysfunction is considered an important interaction in cardiomyopathy with poor prognosis. The aim of this study was to compare left ventricular (LV) isovolumic relaxation with the other parameters as a potential prognostic marker for patients with idiopathic dilated cardiomyopathy (IDC) and hypertrophic cardiomyopathy (HC). Methods: A total of 145 patients with IDC and 116 with HC were evaluated for hemodynamic parameters; LV pressure was directly measured by a micromanometer catheter, and relaxation half-time (T_1/2) was used to determine LV isovolumic relaxation. The median follow-up period was 4.7 years. Results: The mean ages of the patients with IDC and HC were 52.0 ± 12.0 and 57.1 ± 12.4 years, respectively. Each patient group was further divided into 2 groups based on the median value of T_1/2: (1) <41.0 ms (D-L group) and ≥41.0 ms (D-H group) (2) <38.5 ms (H-L group) and ≥38.5 ms (H-H group). Kaplan-Meier analysis showed a significantly higher probability of cardiac events in the D-H group than in the D-L group (p = 0.001) and in the H-H group than in the H-L group (p = 0.028). Further, Cox proportional hazard regression analysis revealed that T_1/2 was an independent predictor of cardiac events for patients with IDC (hazard ratio 1.109; p = 0.007) and HC (hazard ratio 1.062; p = 0.041). In conclusion, regardless of the type of cardiomyopathy, T_1/2 as a measure of LV isovolumic relaxation function was found to be associated with the occurrence of cardiac events.