Can a little heat (or cold) really mend a broken heart? Patients with atrial fibrillation were found to have a better mortality rate when sinus rhythm was maintained through radiofrequency ablation (RFA) according to a study published in the September issue of Heart Rhythm.
Researchers from Ann Arbor, Mich. performed a retrospective analysis on 3,058 patients who underwent RFA and followed their outcomes over a 10-year span.
Lead author Hamid Ghanbari, MD, MPH, of the Division of Cardiovascular Medicine at the University of Michigan, and colleagues intended to understand the effects of sinus rhythm on patients’ mortality risks and risk of cerebrovascular events.
They found that while there was no reduction in risk of cerebrovascular events for patients when sinus rhythm was maintained through ablation, RFA and, in some cases, repeat RFA reduced the risk of mortality once sinus rhythm was achieved.
In multivariable analysis, the predictors of recurrence of arrhythmia in this study were persistent atrial fibrillation, larger left atrium size and old age, with persistent atrial fibrillation having the most risk after RFA.
Mortality predictors included age, diabetes and coronary artery disease, however death occurred in 3.6 percent of patients during the time monitored and the majority of those deaths were non-cardiac. Looking at the cardiac deaths as part of all-cause mortality, 12 percent were due to arrhythmia. Non-arrhythmic cardiac deaths comprised 20 percent. Major cardiac death predictors were coronary artery disease, Lower left ventricle ejection fraction, and obstructive sleep apnea.
Ghanbari et al determined that 60 percent lower risk of cardiac mortality occurred in the absence of symptomatic or documented recurrences of atrial fibrillation, regardless of blanking period or drug use.
The research team determined that the highest predictors of cerebrovascular events in atrial fibrillation patients following RFA were a history of cerebrovascular events and coronary artery disease. However, RFA sinus rhythm control did not have an effect on risk for these events, irrespective of blanking period, antiarrhythmic or anticoagulant drug use.
Ghanbari et al found that arrhythmia burden after RFA was split; patients either had an atrial fibrillation burden of less than 20 percent or greater than 80 percent. They also found that patients with paroximal or persistent atrial fibrillation had a proportionally similar rate of cerebrovascular events, approximately 2 percent. Of those, approximately 20 percent are hemorrhagic.
To some degree, the mortality findings contradict those from previous studies that used antiarrhythmic drugs to achieve sinus rhythm, however Ghanbari et al stressed that these studies lacked the ablation component and sinus rhythm was difficult to maintain on drugs alone. While repeated RFA procedures may have been needed to achieve sinus rhythm in some patients, the overall effect was better, prolonged outcomes.
They recommended further study to determine long term outcomes in these repeated ablation patients.
Jason G. Andrade, MD, of the University of Montreal, and colleagues wrote in an editorial that this study pointed out the need for more effective strategies to improve outcomes in atrial fibrillation patients to impact clinical outcomes. They were on the fence about what sinus rhythm achieved in these patients, however.
“Patients who can maintain SR [sinus rhythm], irrespective of the therapy, are likely to represent a healthier cohort than those who experience treatment failure,” they wrote. “Thus, it remains entirely conceivable that AF is simply a marker of enhanced cardiovascular risk whose modification may not improve hard cardiovascular outcomes.”
Regardless, Ghanbari et al recommended further review of sinus rhythm as a means of increasing patient longevity.
“SR remained as a significant and strong predictor of improved cardiac survival after correcting for baseline covariates on multivariable analysis,” they wrote. “This finding challenges the notion that AF is simply another surrogate for underlying disease and other comorbidities. Rather, it suggests that elimination of AF by RFA is likely to improve survival.”
Ghanbari et al suggested others should reassess the significance of atrial fibrillation and sinus rhythm through ablation in future trials.
For more on this issue see: Ablation & Afib: Zapping Barriers to Success.