In a recent study published in the Circulation: Arrhythmia and Electrophysiology, a group of researchers investigated the risk factor (RF) burden, clinical outcomes, and long-term survival among patients with atrial fibrillation (AF) under 65 years of age.
Study: Mortality, Hospitalization, and Cardiac Interventions in Patients With Atrial Fibrillation Aged <65 Years. Image Credit: Nakharin T/Shutterstock.com
Background
AF, the most prevalent heart rhythm disorder in the United States (U.S.), affected an estimated 5.2 million people in 2010, with projections rising to 12.1 million by 2030.
While AF is typically seen in older adults, a growing number of patients are under 65 at diagnosis, representing 10%-15% of cases. This age group faces increasing rates of RFs, such as hypertension, diabetes, and obesity.
Despite their prevalence, the impact of AF on mortality and major clinical events in younger patients remains poorly defined. Further research is needed to clarify the unique clinical outcomes and effective management strategies for younger patients with AF.
About the study
The present study was a retrospective observational cohort analysis at the University of Pittsburgh Medical Center involving patients over 18 years diagnosed with AF.
The diagnosis was confirmed using the International Classification of Diseases (ICD), Ninth and Tenth Revision codes. Patients evaluated between January 2010 and December 2019, were included if they had at least two outpatient visits in internal medicine, family medicine, or cardiology.
Data were extracted from an extensive electronic health record system combined with administrative and other data sources.
This study assessed a range of cardiovascular risk factors and comorbidities, including obesity, smoking history, hypertension, diabetes, and various heart conditions. Detailed information on patient characteristics such as age, gender, and race was gathered, along with data on previous cardiovascular interventions and medication usage at baseline.
The primary outcome measured was all-cause mortality, verified through the Social Security Death Index and supplemented by electronic health record data. The study also looked at secondary outcomes like hospitalizations for cardiovascular events and cardiac interventions that occurred during follow-up.
Statistical analyses involved various tests to compare continuous and categorical variables and utilized Kaplan-Meier survival analysis and Cox proportional hazards models to explore the impact of AF on mortality in patients under 65, adjusting for multiple confounders.
Sensitivity analyses were conducted to consider the effects of various exclusions on the study results.
Study results
The study included 67,221 patients diagnosed with AF, reflecting an average CHA2DS2-VASc score of 3.1±1.6. The cohort's average age was 72.4±12.3 years, with 45% female and 95% white participants. Notably, a significant portion, 26%, were under 65 years at their initial evaluation.
Within the subgroup of patients younger than 65, males were more prevalent, especially in those under 50 (73%) and those between 50 to 65 years (66.3%). This group displayed substantial cardiovascular RFs, including hypertension (55%), diabetes (21%), heart failure (HF) (21%), and dyslipidemia (47%).
Lifestyle RFs such as obesity (over 20% affected) and current smoking (16%) were also significant. Among these younger patients, 4% had a history of stroke, and peripheral vascular disease was present in 1.35%.
Cardiac interventions were common: 3% had an implantable cardioverter-defibrillator, 2% had a pacemaker, 5.5% underwent percutaneous coronary intervention, and 2.5% had prior mitral valve surgery.
Additional comorbidities included obstructive sleep apnea (18%), chronic obstructive pulmonary disease (11%), and chronic kidney disease (1.3%).
At baseline, over half of the patients under 65 were taking anticoagulants, with similar rates for aspirin and significant use of class 1 (6%) and class 3 (17%) antiarrhythmic drugs.
Mortality and hospitalization rates varied by age, with the younger cohort experiencing notably lower mortality rates compared to their older counterparts. In the under-50 age group, the 5-year and 10-year mortality rates were 5.6% and 10.3%, respectively, which approximately doubled in the 50 to 65 age group to 11.5% and 20.8%.
Hospitalization for AF, HF, and myocardial infarction was reported in 31%, 12%, and 2.7% of those under 50, while those figures increased to 38%, 19%, and 4.7% in the 50 to 65 group.
Further analysis revealed multiple cardiovascular RFs and comorbidities independently associated with all-cause mortality among those under 65. HF, peripheral vascular disease, diabetes, coronary artery disease, smoking, and obesity significantly impacted mortality rates.
Notably, chronic kidney disease and chronic obstructive pulmonary disease were also linked to poorer outcomes. Interaction analyses indicated a significant correlation between age and the impact of hypertension and HF on mortality rates.
Comparing the AF cohort with national mortality estimates highlighted a considerably higher all-cause mortality rate among the AF patients, particularly notable in younger males and females. Furthermore, adjusting for cardiac and noncardiac risk factors, AF significantly increased the mortality hazard in patients under 65 compared to a control group without AF.
This population also showed a heightened risk of hospitalization for myocardial infarction, HF, and stroke, underscoring the severe impact of AF in younger patients.
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