Abstract
BACKGROUND: The aim was to evaluate the effect of beta-blockers (BB) on the response of heart rate (HR) to 6-min walk test (6MWT) in atrial fibrillation (AF) and whether the AF patients treated with BB have a similar HR response to 6MWT as the AF and sinus rhythm (SR) patients without BB treatment at the same resting HR level. METHODS: The before-after study involving 74 AF patients was to evaluate the effect of BB treatment (pre-BB and with BB). The comparison study included 74 BB-treated AF patients (with BB), 74 matched AF patients without BB (no BB), and 74 SR patients. The percentage increase amplitude of HR (HR-PIA) in 6MWT was calculated: [(the exercise HR - the resting HR)/(the resting HR)] × 100%. RESULTS: The before-after study showed that BB treatment decreased the resting and mean exercise HR (98.6 ± 15.2 vs. 85.5 ± 11.2 bpm and 121.3 ± 17.3 vs. 109.0 ± 16.7 bpm) during 6MWT. The comparison study demonstrated that against the SR, the AF with BB and no BB groups have higher mean exercise HR-PIA (28.2 ± 17.1% and 22.0 ± 9.6%, vs. 6.9 ± 3.7%) when their resting HR is similar. Moreover, the mean exercise HR-PIA was also significantly higher in the with BB group than in the no BB group. CONCLUSION: In AF patients with relatively higher resting HR, BB treatment could decrease the resting and exercise HR during 6MWT. However, BB treatment could not effectively attenuate the exercise HR rise as compared with AF without BB treatment, even with similar resting HR levels.