Causes of errors in the electrocardiographic diagnosis of atrial fibrillation by physicians.

BACKGROUND

The emphasis of most large studies has been placed on the treatment and prevention of atrial fibrillation (AF) and its complications. Little is known about the accuracy of physicians in the electrocardiographic (ECG) diagnosis of AF and the possible causes of the diagnostic errors.

METHODS

Over a period of 10 months, a total of 35508 ECGs (28356 patients) were overread in a 385-bed community hospital within 24 hours of the initial reading. Corrected ECGs were returned to the patient file. The gold standard for the final diagnosis was based on the consensus by the cardiologist readers.

RESULTS

In all, 35508 ECGs were reviewed. A total of 2809 cases of AF were studied. Incorrect diagnoses related to AF were found in 219 cases. Type I errors (overdiagnosis) occurred in 137 cases. Rhythms with irregular R-R intervals (sinus rhythm with premature atrial contractions and atrial tachycardia or flutter with variable atrioventricular conduction) were misdiagnosed as AF. The presence of low-amplitude atrial activity and/or baseline artifact significantly increased the likelihood of the erroneous diagnosis, whereas ventricular rates of 130 beats/min did not influence the rate of error. Type II errors (missed AF) occurred in 82 cases where AF was either missed or confused with atrial tachycardia/flutter. Finally, ventricular pacing significantly increased the likelihood of type II errors.

CONCLUSIONS

In our institution, about 900 ECGs are read each week and 5 of them carry a wrong interpretation related to AF. More attention to common sources of errors as reinforced by an ongoing quality improvement program may reduce the rate of mistakes and thus prevent serious consequences.