Long-Term Prognosis in Early-Onset Atrial Fibrillation Without Overt Cardiovascular Disease.

Background: The prognostic implications of early-onset atrial fibrillation (AF) in patients without coexisting cardiovascular conditions are not clear.

Objective: To investigate the risk of long-term stroke, heart failure (HF), and mortality in patients with early-onset AF.

Methods: Using nationwide registers, we included adult patients with early-onset AF (18-45 years old) with a first-time AF diagnosis during 1999-2023 without co-existing cardiovascular conditions. All AF patients were matched with a control group from the background population without AF. The long-term absolute risks of stroke, HF, and death were estimated as well as standardized risk ratios (RR) comparing patients with and without AF.

Results: Among 7,632 patients with AF (median age: 39 years, 71% men, 1.9% cancer, 2.1% diabetes), clinically relevant crude risks of stroke (20-year risk: 6.89%, 95% CI 5.96%-7.82%), HF (20-year risk: 6.45%, 95% CI 5.60%-7.31%), and death (20-year risk: 7.10%, 95% CI 6.18%-8.02%) were observed. Comparing the AF cohort with a matched sample from the background population (median age: 38 years, 71% men, 1.1% cancer, 1.3% diabetes) revealed elevated standardized risks of stroke (RR: 2.00, 95% CI 1.67-2.33), HF (RR: 4.33, 95% CI 3.55-5.11), and death (RR: 1.37, 95% CI 1.17-1.57).

Conclusions: Early-onset AF in patients without concomitant cardiovascular conditions was associated with increased long-term risk of cardiovascular complications, most notably a four- to five-fold increased risk of HF. Hence, AF in otherwise healthy young patients should be considered an important marker of increased risks of a future cardiomyopathy and HF events.