Understanding the incidence of atrial fibrillation and stroke in hypertrophic cardiomyopathy patients: insights from Danish nationwide registries

Abstract

Background The treatment of atrial fibrillation (AF) in hypertrophic cardiomyopathy (HCM) can be challenging since AF aggravates symptoms and increases the risk of stroke. Which factors contribute to the development of AF and stroke in HCM remains unknown. Purpose Determine the incidence of AF and stroke in HCM patients and identify risk factors. Methods Using Danish National Registers all HCM patients from 2005-2018 were included. The association between HCM, incident AF and stroke was investigated using multivariable Cox proportional-hazard analysis. Cumulative incidences were calculated using the Aalen-Johansen estimator. Results Among 3,367 patients without prevalent AF, 24% reached the endpoint of incident AF with death as a competing risk. Median follow-up time was 4 years. AF incidence was equal between sexes and increased for patients with ischemic heart disease (HR 1.33, CI[1.08–1.63]), hypertension (HR 1.36, CI[1.14–1.67]) and obstructive HCM (HR 1.27, CI[1.05–1.52]). A total of 7% developed stroke, with no difference detected stratifying for presence of AF. Sub-analysis revealed that when AF was treated with oral anticoagulants (OAC) stroke was less likely (HR 0.4, CI[0.18-0.86], p = 0.02). However, 34% of patients were not receiving adequate anticoagulation following AF diagnosis. Conclusion Obstructive HCM, hypertension and ischemic heart disease was associated with increased risk of AF. Prevalent AF alone was not predictive of stroke, however AF patients treated with OAC were significantly less likely to develop stroke, suggesting that this development is driven by the protective effect of OAC. Despite this, 34% of patients did not receive OAC.