Multimorbidity is common in Atrial Fibrillation (AF), yet the impact of comorbidity type and burden on outcomes remains incompletely defined. This cohort study published in the Journal of the American Heart Association examined associations between cardiometabolic, other somatic, and mental health conditions and adverse outcomes in patients with new-onset AF.

The analysis included 16,509 patients diagnosed with AF between 2013 and 2017 in a Midwest US region (mean age 74 years; 43% women). Eighteen chronic conditions present at AF diagnosis were categorized as cardiometabolic, other somatic, or mental health. Cox regression models assessed associations between the number of each condition type and outcomes, including death, ischemic stroke/transient ischemic attack (TIA), and congestive heart failure (CHF), stratified by age.

On average, patients had 2.7 cardiometabolic, 1.4 other somatic, and 0.5 mental health conditions. A higher number of cardiometabolic conditions was associated with increased 90-day mortality only among patients aged ≥85 years (≥4 vs 0 conditions: hazard ratio [HR] 1.74; 95% confidence interval [CI] 1.05–2.87). For mortality beyond 90 days, associations were strongest in younger patients (<65 years: HR 1.83; 95% CI 1.35–2.46), with attenuation across older age groups. Other somatic conditions showed strongest associations in younger patients, while patterns for mental health conditions were less consistent.

Comorbidity burden and type were associated with outcomes in AF, with age-specific variations. These findings highlight the importance of considering multimorbidity profiles in AF management.