The Interplay of PR Interval and AV Pacing Delays Used for Cardiac Resynchronization Therapy in Heart Failure Patients: Association with Clinical Response in a Retrospective Analysis of a Large Observational Study.

Background. Cardiac resynchronization therapy (CRT) is a treatment for heart failure (HF) patients with prolonged QRS and impaired left ventricular (LV) systolic function. We aim to evaluate how the baseline PR interval is associated with outcomes (all-cause death or HF hospitalizations) and LV reverse remodeling (>15% relative reduction in LV end-systolic volume). Methods. Among 2224 patients with CRT defibrillators, 1718 (77.2%) had a device programmed at out-of-the-box settings (sensed AV delay: 100 ms and paced AV delay: 130 ms). Results. In this cohort of 1718 patients (78.7% men, mean age 66 years, 71.6% in NYHA class III/IV, LVEF = 27 ± 6%), echocardiographic assessment at 6-month follow-up showed that LV reverse remodeling was not constant as a function of the PR interval; in detail, it occurred in 56.4% of all patients but was more frequent (76.6%) in patients with a PR interval of 160 ms. In a median follow-up of 20 months, the endpoint of death or HF hospitalizations occurred in 304/1718 (17.7%) patients; in the multivariable regression analysis it was significantly less frequent when the PR interval was between 150 and 170 ms (hazard ratio = 0.79, 95% confidence interval (CI): 0.63−0.99, p = 0.046). The same PR range was associated with higher probability of CRT response (odds ratio = 2.51, 95% CI: 1.41−4.47, p = 0.002). Conclusions. In a large population of CRT patients, with fixed AV pacing delays, specific PR intervals are associated with significant benefits in terms of LV reverse remodeling and lower morbidity. These observational data suggest the importance of optimizing pacing programming as a function of the PR interval to maximize CRT response and patient outcome.

Determinants of worse prognosis in patients with cardiac resynchronization therapy defibrillators. Are ventricular arrhythmias an adjunctive risk factor?

AIMS: Cardiac resynchronization therapy (CRT) is indicated in patients with systolic heart failure (HF), severe left ventricle (LV) dysfunction and interventricular dyssynchrony.In prospective observational research, we aimed to evaluate whether CRT-induced LV reverse remodelling and occurrence of ventricular arrhythmias (VT/VF) independently contribute to prognosis in patients with CRT defibrillators (CRT-D). METHODS: In 95 Italian cardiological centres, after a screening period of 6 months, patients were categorized according to VT/VF occurrence and CRT response, defined as LV end-systolic volume relative reduction >15% or LV ejection fraction absolute increase >5%. The main endpoint was death or HF hospitalizations. RESULTS: Among 1308 CRT-D patients (80% male, mean age 66 years), at 6 months, follow-up 71% were identified as CRT responders and 12% experienced appropriate VT/VF detections. The main endpoint was significantly and independently associated with previous myocardial infarction, New York Heart Association Class, VT/VF occurrence and with CRT response. CRT nonresponder patients who suffered VT/VF in the screening period had a risk of death or HF hospitalizations [HR = 7.82, 95% confidence interval (CI) = 3.95-15.48] significantly (P < 0.001) higher than CRT responders without VT/VF occurrence. This risk is mitigated without VT/VF occurrence (HR = 3.47, 95% CI = 2.03-5.91, P < 0.001) or in case of CRT response (HR = 3.11, 95% CI = 1.44-6.72, P = 0.004). CONCLUSION: Our data show that both CRT response and occurrence of VT/VF independently contribute to the risk of death or HF-related hospitalizations in CRT-D patients. Early VT/VF occurrence may be identified as a marker of disease severity than can be mitigated by CRT response both in terms of all-cause mortality and long-term VT/VF onset. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT00147290 and NCT00617175.

Prevention of long-lasting atrial fibrillation through antitachycardia pacing in DDDR pacemakers.

OBJECTIVE: The MINERVA trial showed that in pacemaker patients with atrial fibrillation (AF) history, DDDRP pacing combining three algorithms - (a) atrial antitachycardia pacing with Reactive ATP enabled, (b) atrial preventive pacing and (c) managed ventricular pacing (MVP)-may effectively delay progression to persistent/permanent AF compared with standard DDDR pacing. We performed a comparative non-randomised evaluation to evaluate if Reactive ATP can be the main driver of persistent/permanent AF reduction independently on preventive pacing. METHODS: Thirty-one centres included consecutive dual-chamber pacemaker patients with AF history. Reactive ATP was programmed in all patients while preventive atrial pacing was not enabled. These patients were compared with the three groups of MINERVA randomised trial (Control DDDR, MVP, and DDDRP). The main endpoint was the incidence of AF longer than 7 consecutive days. RESULTS: A total of 146 patients (73 years old, 54% male) were included and followed for a median observation period of 31 months. The 2-year incidence of AF > 7 days was 12% in the Reactive ATP group, very similar to that found in the DDDRP arm of the MINERVA trial (13.8%, P = .732) and significantly lower than AF incidence found in the MINERVA Control DDDR arm (25.8%, P = .012) and in the MINERVA MVP arm (25.9%, P = .025). CONCLUSIONS: In a real-world population of dual-chamber pacemaker patients with AF history, the use of Reactive ATP is associated with a low incidence of persistent AF, highlighting that the positive results of the MINERVA trial were related to the effectiveness of Reactive ATP rather than to preventive pacing.