Is 10-second electrocardiogram recording enough for accurately estimating heart rate in atrial fibrillation.
BACKGROUND
At present, the estimation of rest heart rate (HR) in atrial fibrillation (AF) is obtained by apical auscultation for 1min or on the surface electrocardiogram (ECG) by multiplying the number of RR intervals on the 10second recording by six. But the reasonability of 10second ECG recording is controversial.


METHODS
ECG was continuously recorded at rest for 60s to calculate the real rest HR (HR60s). Meanwhile, the first 10s and 30s ECG recordings were used for calculating HR10s (sixfold) and HR30s (twofold). The differences of HR10s or HR30s with the HR60s were compared. The patients were divided into three sub-groups on the HR60s <80, 80-100 and >100bpm.


RESULTS
No significant difference among the mean HR10s, HR30s and HR60s was found. A positive correlation existed between HR10s and HR60s or HR30s and HR60s. Bland-Altman plot showed that the 95% reference limits were high as -11.0 to 16.0bpm for HR10s, but for HR30s these values were only -4.5 to 5.2bpm. Among the three subgroups with HR60s <80, 80-100 and >100bpm, the 95% reference limits with HR60s were -8.9 to 10.6, -10.5 to 14.0 and -11.3 to 21.7bpm for HR10s, but these values were -3.9 to 4.3, -4.1 to 4.6 and -5.3 to 6.7bpm for HR30s.


CONCLUSIONS
As 10s ECG recording could not provide clinically accepted estimation HR, ECG should be recorded at least for 30s in the patients with AF. It is better to record ECG for 60s when the HR is rapid.
Department of Cardiology, Second Affiliated Hospital of Nanchang University, China. Electronic address: 1006640125@qq.com.
Wei
W
Shuai
Department of Cardiology, Second Affiliated Hospital of Nanchang University, China. Electronic address: 976463357@qq.com.
Xi-Xing
XX
Wang
Department of Cardiology, Second Affiliated Hospital of Nanchang University, China. Electronic address: hongkui88@163.com.
Kui
K
Hong
Department of Cardiology, Second Affiliated Hospital of Nanchang University, China. Electronic address: pengqiang2008@2008.sina.com.
Qiang
Q
Peng
Department of Cardiology, Second Affiliated Hospital of Nanchang University, China. Electronic address: ljx912@126.com.
Ju-Xiang
JX
Li
Department of Cardiology, Second Affiliated Hospital of Nanchang University, China. Electronic address: mailto@sohu.com.
Ping
P
Li
Department of Cardiology, Second Affiliated Hospital of Nanchang University, China. Electronic address: chenjing6011@163.com.
Jing
J
Chen
Department of Cardiology, Second Affiliated Hospital of Nanchang University, China. Electronic address: xiaoshumenfan@126.com.
Xiao-Shu
XS
Cheng
Department of Cardiology, Second Affiliated Hospital of Nanchang University, China. Electronic address: suyihappy@sohu.com.
Hai
H
Su
D000368:Aged; D000369:Aged, 80 and over; D001281:Atrial Fibrillation / Q000503:physiopathology*; D004562:Electrocardiography / Q000379:methods*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013997:Time Factors
Atrial fibrillation; Electrocardiogram; Heart rates; Variation