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CRT benefited HF patients with, without intermittent atrial tachyarrhythmias
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Patients with HF and left bundle branch block experienced similar clinical benefits from cardiac resynchronization therapy regardless of a history for, or in-trial development of, intermittent atrial tachyarrhythmias in a recent substudy of the MADIT-CRT trial.
Researchers evaluated data from 1,264 patients with mildly symptomatic HF with left bundle branch block. Participants received either CRT with defibrillator (CRT-D; n=757) or an implantable cardioverter defibrillator (n=507), with a mean follow-up of 3.4 ± 1.1 years. The primary endpoint of the substudy was a composite of all-cause mortality and nonfatal HF events, with reverse remodeling as indicated by reduced left atrial volume within 1 year as a secondary endpoint.
Death or HF occurred in 24.2% of the cohort during the course of follow-up. Patients had a history of intermittent atrial tachyarrhythmias in 11.3% of cases; these participants were not at increased risk for HF or death compared with those without a history of tachyarrhythmias (HR=1.04; 95% CI, 0.75-1.45).
Patients experienced significantly reduced risk for HF or death regardless of whether they had a history of intermittent atrial tachyarrhythmias (HR=0.5, P=.028) or did not (HR=0.46, P<.001; P=.79 for interaction). The benefit was most pronounced for HF events (HR=0.36; 95% CI, 0.18-0.75 for those without tachyarrhythmia history and HR=0.4; 95% CI, 0.3-0.53 among those with a history).
Patients in both groups experienced a significant reduction in left atrial volume, regardless of intermittent atrial tachyarrhythmia history (P<.001 for all), but the reduction was more pronounced among those in the CRT-D group than in the ICD group.
Researchers calculated a cumulative probability of developing tachyarrhythmias during the study of 4% at 1 year, 6% at 2 years, 8% at 3 years and 10% at 4 years, with no significant difference in probability between the groups (P=.67). Patients who developed tachyarrhythmias were at significantly increased risk for HF and death (HR=1.63; 95% CI, 1.06-2.5). However, those in the CRT-D group who developed tachyarrhythmias during the study were significantly less likely to experience HF or death compared with those who developed in-trial tachyarrhythmias in the ICD group (HR=0.43; P=.047).
Among 632 evaluable patients in the CRT-D group, a similar number of patients with and without a history of intermittent atrial tachyarrhythmias had biventricular pacing of 92% or higher (95% of those with prior history vs. 89.6% of those without; P=.43). Similar results were observed among patients who did (87.5%) and did not (90.2%) develop in-trial tachyarrhythmias (P=.43).
“In patients with mild HF and left bundle branch block, the overall beneficial echocardiographic and clinical benefits of CRT are not attenuated among patients who have a prior history of intermittent atrial tachyarrhythmia and among those who develop intermittent atrial tachyarrhythmia following device implantation,” the researchers wrote. “These findings further stress the pronounced beneficial effects of CRT in patients with mild HF symptoms, regardless of associated intermittent atrial arrhythmias.”
Disclosure: See the full study for a list of relevant financial disclosures.
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