Abstract 2182: Left Ventricular Dyssynchrony in Acute Onset Cardiomyopathy
Background: Left ventricular (LV) dyssynchrony has typically been studied in patients with chronic heart failure and wide QRS. Our objective was to test the hypothesis that patients with acute onset cardiomyopathy have significant mechanical dyssynchrony with narrow QRS and that it’s resolution is related to improvements in LV function.
Methods: We studied 51 patients, aged 44±15 yrs with acute onset cardiomyopathy, defined as recent onset nonischemic cardiomyopathy < 6 months, as part of the IMAC multi-center study. Their ejection fraction (EF) was 25± 9% and 33% were female. Echocardiograms were done at presentation and at 6 mo. follow-up. EF was calculated by biplane Simpson’s rule. Dyssynchrony was assessed by Velocity Vector Imaging (Siemens Corp.) using B-mode pixel tracking algorithms to track the myocardial motion on routine grey scale images. Time to peak longitudinal velocities were recorded in 12 segments from apical 4, 2 and 3 chamber views, with dyssynchrony calculated as the opposing wall delay. A normal control group of 10 subjects was similarly studied.
Results: Although QRS was narrow (107±24 ms), acute onset cardiomyopathy was associated with dyssynchony; 92±48ms vs. 32±24ms in controls (*p<0.001). At 6 mo. follow-up, group mean EF improved from 25±9 % to 39±11%* and dyssynchrony improved from 92±48ms to 54±37ms*, (*p <.001 vs. baseline). Prevalence of dyssynchrony ≥75ms was reduced from 61% of patients at baseline to 14%* at 6 mo. follow up (*p<0.001).
Conclusion: LV dyssynchrony is present in a significant proportion of patients with acute onset cardiomyopathy. Dyssynchrony appears to resolve as EF improves. These observations may have clinical implications.