PR interval prognostic of cardiac resynchronization Tx outcome
Jeffrey Lin, M.D., from the University of Wisconsin School of Medicine and Public Health in Madison, and colleagues stratified 308 patients enrolled in the optimal pharmacologic therapy (OPT) 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 OPT, CRT-D treatment correlated with reduced hospitalization or all-cause mortality (ACM) and ACM (P = 0.002 and 0.003, respectively). In patients with longer baseline PR intervals, CRT-D was increasingly more effective in reducing ACM hazard (P = 0.002), irrespective of left bundle branch block (LBBB) status. ACM was reduced with CRT-D versus OPT (P = 0.001) in the prolonged baseline PR interval subgroup, with little evidence of a reduction in ACM in the normal PR subgroup (P = 0.07).
"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 write.
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