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Obesity and Sleep Apnea Are Independently Associated With Adverse Left Ventricular Remodeling and Clinical Outcome in Patients With Atrial Fibrillation and Preserved Ventricular Function
Study Questions:
Among patients with atrial fibrillation (AF) and heart failure with preserved ejection fraction (HFpEF), does sleep apnea (SA) affect left ventricular (LV) remodeling and clinical outcomes?
Methods:
Patients undergoing ablation for AF at a single institution were referred for cardiac magnetic resonance (CMR) between September 2005 and June 2011. Patients were excluded for LV dysfunction or prior infarction. SA was diagnosed by sleep study. Treatment of SA was defined as continuous positive airway pressure >4 hours per night. CMR was used to measure LV mass, volumes, and EF. Patients were followed post-ablation at 3- to 6-month intervals. The primary endpoint was a composite of all-cause mortality and HF admissions.
Results:
A total of 403 patients were identified and followed for 3.3 ± 1.5 years. Overall, 290 (72%) patients were male, with a median age 57 years. Patients had either paroxysmal AF (n = 138, 34%) or persistent AF (n = 267, 66%). Cardiovascular risks were prevalent including hypertension (47%) and diabetes (14%). Obesity was present in 148 patients (37%) and SA (19%). Both LVEF and right ventricular EF were similar between obese and nonobese subjects (p = 0.62 and 0.85, respectively). LV mass and LV mass-to-volume ratio were higher in patients with SA and obesity (p < 0.0001 for all). Body mass index (BMI) (p < 0.0001) and SA (p = 0.045) were independently associated with LV mass index. Patients with treated SA had a lower LV mass index (but not LV mass-to-volume ratio) compared to untreated patients (p = 0.002). SA (hazard ratio [HR], 2.94; p = 0.0004) and BMI (HR per 1 kg/m2, 1.08; p = 0.004) were associated with clinical outcome in unadjusted analysis. Only SA was associated with clinical outcome in a best-overall multivariable model (HR, 2.14; p = 0.02).
Conclusions:
In this prospective observational cohort study of patients with HFpEF referred for CMR prior to AF ablation, the authors concluded that both obesity and SA are associated with indices of LV remodeling, independent of traditional risk factors for LV remodeling.
Perspective:
SA remains underdiagnosed and may be as frequent as 50% of AF patients undergoing ablation. Since sleep studies were not performed in all patients, the prevalence in this report is likely an under-representation of the problem. Abnormalities in LV structure in this study translated into a higher rate of all-cause mortality or HF hospitalization for AF patients with either obesity or SA. After 3 years of follow-up, SA was independently associated with a twofold increase of all-cause mortality or HF hospitalization, even after adjustment for previous HF, age, or diabetes. Whether targeting SA treatment in addition to weight reduction could reverse LV remodeling and improve clinical outcomes has yet to be tested and proven.
Keywords: Heart Diseases, Ventricular Function, Right, Follow-Up Studies, Body Mass Index, Polysomnography, Weight Loss, Cardiovascular Diseases, Risk Factors, Obesity, Magnetic Resonance Spectroscopy, Diabetes Mellitus, Sleep Apnea Syndromes
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