Is There an Association Between External Cardioversions and Long-Term Mortality and Morbidity? Insights From the Atrial Fibrillation Follow-Up Investigation of Rhythm Management Study

Study Questions:

Do external cardioversions (ECVs) for atrial fibrillation (AF) affect prognosis?

Methods:

In this post hoc analysis of 4,060 patients with AF in the AFFIRM study, the relationship between the number of ECVs and mortality was investigated.

Results:

The patients were categorized as having zero ECVs (n = 2,460), 1 ECV (n = 1,186), 2 ECVs (n = 289), or ≥3 ECVs (n = 125). All-cause mortality at a mean follow-up of 3.5 years was 10.4-16.7% among these groups, with no association between the number of ECVs and mortality. Cardiovascular mortality was 5.6-8.4% and also was not associated with the number of ECVs. ECVs were an independent predictor of cardiac hospitalizations (odds ratio 1.39 for any ECV vs. no ECV in the interval between follow-up visits). The strongest significant independent predictors of all-cause mortality were prior myocardial infarction (hazard ratio [HR], 1.65) and digoxin use (HR, 1.62).

Conclusions:

The authors concluded that ECVs for AF are not associated with either all-cause or cardiovascular mortality.

Perspective:

Both appropriate and inappropriate shocks are associated with a higher risk of mortality in patients with an implantable cardioverter-defibrillator (ICD). It is unclear whether this is because of electrical injury to cardiac myocytes or because ICD shocks are a marker of patient characteristics that portend a poor prognosis. The present study demonstrates that ECVs are not associated with mortality. This may be because of less potential for injury from external versus internal shocks, or because patients in the ICD trials had more severe heart disease than the patients in the AFFIRM study.

Clinical Topics: Arrhythmias and Clinical EP, Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias

Keywords: Odds Ratio, Myocardial Infarction, Defibrillators, Follow-Up Studies, Morbidity, Shock, Digoxin, Electric Countershock, Electrocardiography, Prognosis, Electric Injuries, Cardiovascular Diseases


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