Ablation is Associated With Decreased Mortality and Stroke

From www.practiceupdate.com

This study finds that ablation for atrial fibrillation (AF) produces a hazard ratio of 0.59 with a statistical significance of less than 0.0001, i.e., reduces the annual mortality rate by an estimated 31% versus no ablation.  That sounds fantastic.  However, it corresponds to a reduction in estimated annual mortality only from 1.9% to 0.9%, which is important but not fantastic.  Sometimes, hazard ratios make thing sound better than they are.

Nevertheless, the long term implication is important.

To put this in perspective, the controls have a 98.1% probability of surviving for a year versus 99.1% for the ablation group.  Suppose these probabilities do not change over time (they do) and that you come down with AF at age 60.  With ablation, your survival probability over the next 20 years is 0.991^20=0.835=83.5%.  Without ablation it is 0.981^20=0.681=68.1%.  While the difference of 15.4 percentage points is important, it doesn't sound nearly as great as the hazard ratio.
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BACKGROUND

Ablation for atrial fibrillation (AF) is superior to medical therapy for rhythm control. We compared stroke and mortality among patients undergoing ablation for AF to matched controls in a large multiethnic population.

METHODS

Using discharge and surgical records from California nonfederal hospitals, we identified patients who had ablation and principal diagnosis of AF with at least 1 prior hospitalization for AF. We excluded cases with valve disease, open maze, other arrhythmias, or implantable devices. Matched controls were selected based on years of AF diagnosis, age, sex, and being alive the same number of days from the initial AF encounter to the ablation date. Clinical outcomes, including mortality, ischemic stroke, or hemorrhagic stroke, were assessed using a weighted proportional hazard model, adjusting for demographics, prior admissions with AF before the ablation, calendar year, and presence of chronic comorbidities.

RESULTS

There were 4169 ablation cases and 4169 weighted-matched controls; 39% percent of the ablation group was >65 years, 72% men, 84% white; mean follow-up was up to 3.6±0.9 years. In adjusted models, ablation was associated with significantly lower mortality (per patient-years) 0.9% versus 1.9%, hazard ratio=0.59 (P<0.0001; confidence interval: 0.45-0.77); ischemic stroke (>30 days post-ablation ≤5 years), 0.37% versus 0.59%, hazard ratio=0.68 (P=0.04; confidence interval: 0.47-0.97); hemorrhagic stroke 0.11% versus 0.35%, hazard ratio=0.36 (P=0.001; confidence interval: 0.20-0.64) compared with controls.

CONCLUSIONS

In this large population-based study of hospitalized patients with nonvalvular AF, ablation was associated with lower mortality, ischemic stroke, and hemorrhagic stroke compared with controls.