Adaptive CRT associated with decreased risk of AF compared to standard biventricular pacing

First author Jonathan C Hsu

In a large, real-world population of cardiac resynchronisation therapy recipients followed by remote monitoring, use of the adaptive cardiac resynchronisation therapy biventricular and left ventricular algorithm compared to standard biventricular pacing was associated with a “significantly reduced risk” of developing atrial fibrillation. This was the conclusion reached by Jonathan C Hsu (University of California, San Diego, USA) and colleagues in an article recently published in HeartRhythm.

In addition, the investigators found that a higher percentage of left ventricular (LV)-only pacing during adaptive cardiac resynchronisation therapy was associated with a lower incidence of atrial fibrillation (AF).

The investigators describe how the AdaptivCRT algorithm (aCRT) automatically adjusts atrioventricular delays each minute to achieve ventricular fusion through left ventricular or biventricular (BiV) pacing. “While this algorithm is associated with superior clinical outcomes compared to standard BiV pacing,” write Hsu and colleagues, “the association of aCRT and subsequent AF in a real-world population has not been fully evaluated.”

A total of 37,450 patients, followed for a mean of 15.5±9.1 months, were included in the study, of which 9.7% (n=3,647) developed ≥48 hours of AF. In a univariate analysis, compared with standard biventricular pacing (BiV), the aCRT BiV and LV mode was associated with a 54% lower risk of ≥48 hours of AF at two years, which persisted after multivariate adjustment, even when stratified by a sensed PR interval of ≤200ms and >200ms. Furthermore, higher percentages of LV-only pacing with aCRT were associated with a lower incidence of AF.

Patients implanted with a CRT device between 2013 and 2016 were studied via the de-identified Medtronic CareLink database. For the univariate and multivariate analysis, the investigators used Kaplan-Meier and Cox proportional hazards, respectively.

Hsu and colleagues note some limitations of the present study. For example, the de-identified Medtronic CareLink database only contains limited patient demographic information and no information regarding comorbidities, risk factors for AF, or other therapeutic interventions. “This may confound the associations evaluated and prohibits adjustments in multivariable modelling,” they comment, “however, the size of the database suggests that this is a real-world population with representative demographics.”

Secondly, they mention that because this was a retrospective observational study, there was no protocolled assignment of aCRT versus standard BiV pacing programming, and it is not possible to evaluate the reasons why patients with aCRT-enabled devices were initially programmed with a aCRT off instead of utilising the aCRT pacing algorithm. Additionally, 8.2% of patients switched aCRT modes before 48 hours of AF for unknown reasons.

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