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Cardiorespiratory Fitness and AF Recurrence | Journal Scan
Study Questions:
What is the effect of cardiorespiratory fitness on atrial fibrillation (AF) recurrence?
Methods:
The study was comprised of patients referred for management of symptomatic paroxysmal or persistent AF to the Centre for Heart Rhythm Disorders at the University of Adelaide, Adelaide, Australia. Of 1,415 consecutive patients with AF, 825 had body mass index (BMI) ≥27 kg/m2 and were offered risk factor management and participation in a tailored exercise program. After exclusions, 308 patients were included in the analysis. Patients underwent exercise stress testing to determine peak metabolic equivalents (METs). To determine a dose-response, cardiorespiratory fitness was categorized as: low (<85%), adequate (86-100%), and high (>100%). Impact of cardiorespiratory fitness gain was ascertained by the objective gain in fitness at final follow-up (≥2 METs vs. <2 METs). AF rhythm control was determined using 7-day Holter monitoring and AF severity scale questionnaire.
Results:
There were no differences in baseline characteristics or follow-up duration between the groups defined by cardiorespiratory fitness. Arrhythmia-free survival with and without rhythm control strategies was greatest in patients with high cardiorespiratory fitness compared to adequate or low cardiorespiratory fitness (p < 0.001 for both). AF burden and symptom severity decreased significantly in the group with cardiorespiratory fitness gain ≥2 METs as compared to <2 METs group (p < 0.001 for all). Arrhythmia-free survival with and without rhythm control strategies was greatest in those with METs gain ≥2 compared to those with METs gain <2 in cardiorespiratory fitness (p < 0.001 for both). In multivariable analyses, baseline cardiorespiratory fitness (p < 0.001), cardiorespiratory fitness gain (p < 0.001), and weight loss (p = 0.008) were independent predictors of outcomes. METs gain ≥2 in cardiorespiratory fitness resulted in a twofold (95% confidence interval, 3.4-10.3; p < 0.001) greater probability of arrhythmia-free survival.
Conclusions:
The authors concluded that cardiorespiratory fitness predicts arrhythmia recurrence in obese individuals with symptomatic AF.
Perspective:
This study reports that in overweight and obese individuals with symptomatic AF, preserved baseline cardiorespiratory fitness predicts long-term freedom from AF. There was a significant dose-response relationship between baseline cardiorespiratory fitness with a 20% reduction in the risk of AF recurrence for each MET increase in baseline cardiorespiratory fitness. These data highlight the role for exercise testing in predicting AF outcomes and the importance of measures to improve physical activity and cardiorespiratory fitness in overweight and/or obese symptomatic AF patients.
Keywords: Arrhythmias, Cardiac, Atrial Fibrillation, Body Mass Index, Electrocardiography, Ambulatory, Exercise, Follow-Up Studies, Metabolic Equivalent, Obesity, Overweight, Primary Prevention, Physical Fitness, Risk, Risk Factors, Weight Loss
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