Atrial cardiomyopathy: markers and outcomes

Background and Aims Atrial cardiomyopathy (AtCM) is increasingly recognized as an important substrate for atrial fibrillation (AF). This study aimed to examine potential markers and risk factors of AtCM, and associations with incident AF, heart failure (HF), and stroke. Methods Individuals from the UK Biobank with cardiac magnetic resonance imaging and electrocardiographic information were included. Atrial cardiomyopathy markers included left atrial dilation, left atrial mechanical dysfunction, P-wave prolongation, and abnormal P-wave terminal force. Risk factors for AtCM were assessed using logistic regressions. Incident AF, HF, and stroke according to AtCM markers were assessed in multivariable Cox-regression and cumulative incidence models. AF risk according to AtCM markers, clinical and genetic risk factors was evaluated by integrating the HARMS2-AF score and a polygenic risk score for AF. We used net reclassification improvement (NRI) to evaluate reclassification of risk when considering AtCM markers. Results Among 26 467 individuals, 4145 (15.7%) had ≥1 marker and 619 (2.3%) had ≥2 markers of AtCM. Age, coronary artery disease, and hypertension were consistently associated with AtCM. Having one AtCM marker conferred a hazard ratio (HR) for AF of 1.88 [95% confidence interval (CI): 1.54–2.31; P < .001], with higher rates observed in individuals with ≥2 markers (HR: 4.59; 95% CI: 3.52–5.99; P < .001). Addition of AtCM markers was associated with an NRI of 13.7% (95% CI: 9.2%–18.3%). Integration of clinical and genetic risk factors indicated an additive effect on AF rates. Having ≥2 markers associated with HF (HR: 3.08, 95% CI: 2.03–4.66, P < .001), and stroke (HR: 3.07, 95% CI: 1.78–5.28, P < .001). Conclusions One in seven individuals had at least one marker of AtCM. Atrial cardiomyopathy markers were associated with AF, HF, and stroke, supporting AtCM as a common substrate for all three outcomes.