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The effect of atrial fibrillation and the ventricular rate control on exercise capacity
R H Ostermaier1, S Lampert, L Dalla Vecchia
1Lown Cardiovascular Center, Brookline, MA 02146, USA.
Insights
Atrial fibrillation (AF) minimally impacts exercise endurance, with faster heart rates compensating for lost synchrony in patients with preserved left ventricular function. The decrease in performance is linked to synchrony loss, not heart disease or rate control.
Area of Science:
- Cardiology
- Electrophysiology
- Exercise Physiology
Background:
- Atrial fibrillation (AF) is a prevalent cardiac arrhythmia in the US, impacting millions.
- Understanding AF's effects on cardiovascular performance is crucial for patient management.
Purpose of the Study:
- To evaluate the impact of AF on exercise endurance.
- To determine if ventricular rate control during AF influences cardiovascular performance.
Main Methods:
- Exercise stress tests were conducted on 63 patients with AF during both sinus rhythm and AF.
- Key metrics included heart rate, blood pressure, exercise duration, and left ventricular systolic function.
Main Results:
- Atrial fibrillation led to a statistically significant, albeit small, decrease in exercise endurance.
- This reduction in exercise tolerance was observed irrespective of underlying heart conditions or ventricular rate control.
- Heart rate was consistently higher at rest and during peak exercise in AF compared to sinus rhythm.
Conclusions:
- Loss of atrioventricular synchrony minimally affected cardiovascular performance in patients with preserved left ventricular function.
- Reduced cardiovascular performance was primarily attributed to the loss of synchrony, not the underlying heart disease or ventricular rate.
- A faster heart rate during AF compensated for the diminished atrial contribution to cardiac output.
Background:
Atrial fibrillation (AF) is a common cardiac arrhythmia, affecting approximately 1.5 million patients in the United States.
Hypothesis:
This study was designed to determine the effect of AF and the ventricular rate control during AF on cardiovascular performance as measured by exercise endurance on a standard Bruce protocol.
Methods:
Sixty-three patients with AF who underwent exercise stress testing during both sinus rhythm and AF were analyzed. Heart rate, blood pressure, heart rate acceleration, exercise duration, and left ventricular (LV) systolic function were measured.
Results:
Atrial fibrillation resulted in a small but statistically significant decrease in exercise endurance (426 +/- 180 vs. 402 +/- 168 s, p < 0.05). The drop in exercise tolerance was consistent regardless of the underlying heart condition or adequate ventricular rate control during AF. Heart rate in AF was consistently faster than in sinus rhythm, at rest, and at peak exercise (63 vs. 79 beats/min and 125 vs. 149 beats/min, respectively, p < 0.001).
Conclusion:
Our analyses indicated that (1) the loss of atrioventricular synchrony had minimal effect on cardiovascular performance in patients with preserved LV function, (2) the decrease in cardiovascular performance was related to loss of atrioventricular synchrony but not to underlying heart disease or ventricular rate control, and (3) compensation for the loss of the atrial contribution was provided by consistently faster heart rate during AF.