Abstract 253: Effect of First-Degree Heart Block on Left Ventricular Filling and Hemodynamics

Abstract

Background: First degree heart block (FHB) is considered a benign electrographic finding. However, recent studies have suggested that FHB is associated with excess mortality. In another study PR interval greater than 220msec was associated with increased rate of heart failure hospitalizations. So far, very little is known about the effect of FHB on left ventricular (LV) filling and hemodynamic. Objective: To evaluate the hemodynamic effects and LV filling in patients with FHB Methods: This was retrospective chart review of 133 patients with and without FHB. The patients were identified from our electrocardiography (EKG) database. All the patients that had both echocardiogram and EKG in 2010 were included for the study. FHB was confirmed with the ekg tracing on the echocardiogram. For LV filling we calculated mitral inflow velocity time integral (MV VTI), by tracing the mitral inflow pulse wave doppler tracing using the standard software. The data was analyzed using the R version 2.12 statistical package. Linear regression analysis was preformed to study the effect of FHB on LV filling. Several linear models were fitted to the data using the PR interval and HR as predictor variables. Results: The patients were divided in two groups, PR interval less than and greater than 220. In the patients with PR interval less than 220msec (n=65), LV filling (MV VTI) was noticed to progressively decrease with increase in PR interval (P<0.02) and was unaffected by heart rate (P=0.4). However, in patients with PR interval greater than 220 msec (n=66), LV filling progressively decreased with increase PR interval (P<0.03) and increase in heart rate (P<0.02). Interestingly, it appears that for lower heart rates HR-50 beats per minute ( BPM), increase in PR interval resulted a greater reduction in LV filling as compared to higher heart rate (HR-70 BPM) Conclusion: LV filling is adversely affected with increase in PR interval and heart rate. In addition, it appears that lower heart (<50 BPM) in patients with PR interval >260 msec results in more pronounced reduction of LV filling. Patients with PR intervals >220msec might benefit from higher heart rates which needs to be further evaluated.