A randomized controlled trial of cardiac resynchronization therapy in patients with prolonged atrioventricular interval: the REAL-CRT pilot study

Aims A prolonged PR interval is known to be associated with increased mortality and a higher risk of developing atrial fibrillation (AF). We tested the hypothesis that cardiac resynchronization therapy (CRT) is superior to conventional dual-chamber pacing with algorithms for right ventricular pacing avoidance (DDD-VPA) in preserving systolic and diastolic function and in preventing new-onset AF in patients with normal systolic function, indication for pacing and prolonged atrioventricular conduction (PR interval >= 220ms). Methods and results We randomly assigned 82 patients with ejection fraction >35%, indication for pacing and PR interval >= 220ms to CRT or to DDD-VPA. On 12-month follow-up examination, the study and control arms did not differ in terms of left ventricular end-systolic volume (4417mL vs. 4716mL, P=0.511) or ejection fraction (55 +/- 6% vs. 57 +/- 8%, P=0.291). The E to A mitral wave amplitude ratio was higher in the CRT arm (1.3 +/- 1.3 vs. 0.8 +/- 0.4, P=0.046) and the E wave deceleration time was longer (262 +/- 83ms vs. 205 +/- 51ms, P=0.027). Left atrial volume was smaller in the CRT arm (64 +/- 17mL vs. 84 +/- 25mL, P=0.035). Moreover, the functional class was lower in CRT patients (1.4 +/- 0.6 vs. 1.8 +/- 0.5, P=0.010). During follow-up, CRT was associated with a lower risk of new-onset AF [hazard ratio=0.37 (0.13-0.98), P=0.046]. Conclusion Cardiac resynchronization therapy proved superior to DDD-VPA in terms of better diastolic function, less left atrial enlargement and lower risk of new-onset AF, at 12months. These data need to be confirmed in a larger trial with longer follow-up. Clinical trial registration URL: http://clinicaltrials.gov/ Identifier: NCT02150538