Abstract 16240: Abnormal Basal Longitudinal Left Ventricular Strain and Left Ventricular Dyssynchrony in Patients with Idiopathic Out of Hospital Cardiac Arrest

Abstract

Introduction: Many patients with unexplained out of hospital cardiac arrest (OHCA) have normal left ventricular (LV) systolic function. Strain imaging via 2D speckle-tracing echocardiography is a new technique that can detect changes in mechanical function before changes in ejection fraction (EF) occur. Subtle cardiomyopathic changes may be detectable by LV strain in these patients.

Hypothesis: LV strain is reduced and LV dyssynchrony is present in patients with idiopathic OHCA compared to a matched control population.

Methods: Between July 2000 and December 2009, 1200 patients were evaluated in our Genetic Heart Rhythm Clinic. We reviewed records for all patients with channelopathy/cardiomyopathy/ischemia-negative OHCA and a normal LV EF on echocardiography. LV longitudinal (L) and circumferential (C) strain (S) and strain rate (SR, LVLS, LVLSR, LVCS and LVCSR) were analyzed off-line in the study population using Syngo VVI software (Siemens Medical Solutions Malvern, PA) and compared against an age/sex-matched normal population. To assess mechanical synchrony, the mean plus 2 standard deviations (SD) of the global longitudinal time to peak (TTP) S SD was computed for each subject in the control group. A value above the 95^th percentile was considered abnormal.

Results: There were 22 OHCA patients that met selection criteria (mean age 38.5±14.7 years, 14 women, EF 62 ± 6%). There were no statistically significant differences in age, sex, or EF between the study and control populations. Patients with idiopathic OHCA compared with controls had a reduced basal LVLS (-15.9% vs. -17.8%, p=0.009) and LV dyssynchrony (SD of TTP LVLS was 59 ms vs. 30 ms, p= 0.0001, 41% vs. 5% with LV dyssynchrony). The basal inferoseptal, anteroseptal, and anterior segments all had a reduced LVLS as compared with controls. Area under the curve for the basal LVLS and SD of TTP LVLS was 0.89 (sensitivity 86%, 1-specificity 0.18). No differences were detected in global LVLS, global LVLSR, LVCS, or LVCSR.

Conclusions: Patients with idiopathic OHCA and a normal EF have reduced basal LVLS and LV dyssynchrony compared with an age/sex-matched normal population. Whether or not this suggests the presence of a sudden death predisposing yet pre-clinical cardiomyopathy warrants further study.