Abstract Body (Do not enter title and authors here): Background: Obesity and HFpEF are associated with sudden cardiac death (SCD), independent of underlying coronary disease. Noninvasive markers of SCD risk for these patients are needed. Increased mechanical dispersion (MD), defined as the variability in time from depolarization to force formation, has been suggested as a marker of arrhythmic death. In support of this observation, mouse models for metabolic syndrome in our laboratory demonstrated that increased MD predicts development of HFpEF and inducibility of ventricular tachycardia. Abnormalities of MD for patients with obesity and HFpEF are not yet defined.
Hypothesis: Obesity, metabolic syndrome, and HFpEF are associated with abnormalities of MD.
Methods: This is a retrospective study of patients with preserved LVEF referred for TTE. Patients were categorized by BMI (18-24.9 (normal), 25-29.9 (overweight), or ≥30 (obese)). Strain analysis was performed using Philips aCMQ software (QLAB; Philips Medical System, Andover, MA). MD was measured in standard fashion as the standard deviation of time from Q/R on the ECG, to peak longitudinal strain in 6 LV segments on an apical 4-chamber view. MD was measured for each of the three cardiac layers and reported as mean values. MD gradient was measured as the difference between epicardial MD and endocardial MD. A correlation heat map was generated to analyze the relationship between these markers.
Results: Sixty-eight patients were included with a median age of 63.5 (IQR 22.2), and 42% were female. Global longitudinal strain was similar between the BMI groups, but epicardial MD was significantly increased in obese patients (obese 99.2 [SEM 7.86] vs. normal 69.15 [SEM 6.31], p=0.005) and patients with high HFA-PEFF score (HFA-PEEF ≥ 4 vs. <4, p<0.001). Further, the MD gradient was also significantly increased in these patients (obese 60.52 [SEM 9.53] vs. normal 33.8 [SEM 6.93]; p=0.026). A correlation heat map revealed a significant (p< 0.05) relationship between elevated epicardial MD, MD gradient, and BMI, high HFA-PEFF score, and multiple risk factors associated with metabolic syndrome.
Conclusion: Abnormalities of MD that are associated with SCD risk in mouse models for metabolic syndrome are also associated with obesity, higher HFA-PEFF score and metabolic syndrome for patients with preserved LVEF. These findings highlight the potential of MD as a non-invasive marker of SCD risk and HFpEF development for patients with obesity and metabolic syndrome.