Secondary AF: Risk of Recurrence Found in Framingham

Atrial fibrillation (AF) may occur spontaneously or as a result of an acute, secondary, precipitant. Data addressing follow-up of long-term AF outcomes after diagnosis during a secondary precipitant is limited. Current guidelines assign lower risk of recurrence to AF with acute precipitant, which can influence follow-up, including thromboembolism prophylaxis. Study goal: To characterize long-term risks of AF recurrence and morbidity in the Framingham Heart Study according to the presence or absence of secondary AF precipitants.

Participants from Framingham Heart Study original and offspring cohorts (first-detected AF btw 1949-2012).Excluded: Individuals who died within 30 days of first-detected AF (n=215). Individuals with incomplete baseline covariate data (n=158). Total of 1409 remained eligible for analysis.

Initial AF event defined as “secondary” if potentially reversible factor was present: Surgery (within 30 days, which we subdivided into cardiothoracic and noncardiothoracic), acute MI (within 30 days), infection, alcohol consumption, thyrotoxicosis, pericardial disease, acute PE, or other acute pulmonary pathology (e.g., pneumothorax and bronchoscopy related). If ≥1 precipitant, used hierarchical fashion using the following sequence: cardiothoracic surgery, noncardiothoracic surgery, acute MI, acute infection, and other precipitants.

Results: 439 patients (31%) with AF diagnosed with a secondary precipitant: cardiothoracic surgery (n=131 [30%]), infection (n=102 [23%]), noncardiothoracic surgery (n=87 [20%]) acute myocardial infarction (n=78 [18%]).

AF recurred in 544 of 846 eligible individuals without permanent AF (5-, 10-, and 15-year recurrences of 42%, 56%, and 62% with vs. 59%, 69%, and 71% without secondary precipitants) Multivariable-adjusted hazard ratio: 0.65 [95% confidence interval, 0.54–0.78]). Stroke risk (n=209/1262 at risk; hazard ratio, 1.13 [95% confidence interval, 0.82–1.57]) no different. Mortality (n=1098/1409 at risk; hazard ratio, 1.00 [95% confidence interval, 0.87–1.15]) no different. Heart failure risk was reduced (n=294/1107 at risk; hazard ratio, 0.74 [95% confidence interval, 0.56–0.97]).

Summary: 31% of all incident AF cases were associated with a secondary, or potentially reversible, AF precipitant. AF recurs in most individuals, thus “lone” AF probably doesn't exist. 62% in whom initial AF was attributed to a secondary precipitant had recurrent AF within 15 years

Long-term AF-related stroke and mortality risks were similar between individuals with and without secondary AF precipitants. HF reduced by ≈25% among individuals with a secondary AF precipitant after multivariable adjustment. Future studies may determine whether increased arrhythmia surveillance or adherence to general AF management principles in patients with reversible AF precipitants and single occurrence will reduce morbidity.