The shorter the better? clinical outcomes of CRT-P/D-patients with a focus on stimulated QRS duration

Background The importance of the postoperative stimulated QRS duration in patients requiring CRT-Pacemaker (CRT-P) or –Defibrillator (CRT-D) implantation is a matter of debate. In clinical practice, a short stimulated QRS duration seems electrophysiologically intriguing; however, its impact on long term clinical outcomes in larger populations with heart failure is unknown. To evaluate this issue, in this retrospective single-center study with a thirteen-year clinical follow-up, CRT-P/D interrogations and available echocardiography findings in 487 consecutive patients (QRS short: age 70.3 ± 9.8 years, 25.4% female, n = 283; QRS long 71.2 ± 8.7 years, 19.6% female, n = 204, p = n.s.) scheduled for CRT-P/D implantation were analyzed. A stimulated QRS duration of ≤130ms for "QRS short" and >130ms for "QRS long" was chosen. We were able to achieve a follow-up time of up to 13 years. Results The baseline characteristics in both groups were evenly distributed. Intrinsic QRS duration was significantly shorter in QRS short patients vs. QRS long (QRS short: 145.7 ± 26.7, 150 ms (n = 268) vs. QRS long: 162.6 ± 31.5, 160ms (n = 179), p=<0.0001). During follow-up, left ventricular ejection fraction after 2 years (LV-EF after 2 years, QRS short: 37.2% ± 12.6%, 35 (n = 43), QRS long: 33% ± 11.8%, 29 (n = 54), p=0.047) was significantly increased in QRS short patients. The administration of concomitant heart failure medication or biventricular stimulation rate (Biventricular stimulation rate (4 years, %) QRS short: 96.1% ± 11.4%, 99 (n = 105), QRS long: 96.8% ± 5.8%, 99 (n = 79), p=0.731.) did not differ between groups. Interestingly, we found a robust and significant reduction of the atrial stimulation rate in QRS short vs. QRS long after 2- 4 years (QRS short: 30.1 ± 33.9, 9.3% (n = 82), QRS long: 47.7 ± 41.4, 34.5% (n = 60). Finally, we observed a significant benefit with regard to a combined endpoint of hospitalization and/or cardiac death in QRS short vs. QRS long patients (HR 1.3 CI 95% 1.06-1.61, p=0.012). Conclusions In patients with heart failure requiring CRT-P/D implantation, a shorter stimulated QRS complex led to a slightly increased LV-EF after 2 years and a reduced atrial stimulation rate in 2-4 years. There were no differences in the administration of concomitant heart failure medication or biventricular stimulation percentage between the two groups. Additionally, we detected a significant benefit with regard to a combined endpoint of hospitalization and/or cardiac death in QRS short vs. QRS long patients. Further multicentric studies should investigate the impact of a shorter QRS-complex on clinical outcomes in CRT-P/D patients.