HealthDay News – For patients with advanced systolic heart failure, the effect of cardiac resynchronization therapy with defibrillation (CRT-D) varies according to PR interval, according to research published in the February issue of the Journal of Cardiovascular Electrophysiology.

Jeffrey Lin, MD, from the University of Wisconsin School of Medicine and Public Health in Madison, and colleagues stratified 308 patients enrolled in the optimal pharmacologic therapy and 595 patients in the CRT-D arms of the Comparison of Medical Therapy, Pacing, and Defibrillation in Heart Failure trial according to normal (≤230 ms) or prolonged (>230 ms) PR interval.

The researchers found that, compared with optimal pharmacologic therapy, CRT-D treatment correlated with reduced hospitalization or all-cause mortality and all-cause mortality (P =.002 and .003, respectively). In patients with longer baseline PR intervals, CRT-D was increasingly more effective in reducing all-cause mortality hazard (P =.002), irrespective of left bundle branch block (LBBB) status. All-cause mortality was reduced with CRT-D vs optimal pharmacologic therapy (P =.001) in the prolonged baseline PR interval subgroup, with little evidence of a reduction in all-cause mortality in the normal PR subgroup (P =.07).

“In patients with advanced systolic heart failure, wide QRS complexes, and prolonged PR intervals, restoration of atrioventricular mechanical coupling with CRT-D may improve survival regardless of LBBB status,” the authors wrote.

Related Articles


Lin J, Buhr KA, Kipp R. Effect of PR interval on outcomes following cardiac resynchronization therapy: a secondary analysis of the COMPANION trial [published online January 5, 2017]. J Cardiovasc Electrophysiol. doi: 10.1111/jce.13131