Background Clear epidemiological data regarding rhythm disturbances in 12-lead ECGs is lacking. Rhythm disturbances in the Holter recordings of healthy subjects are well described. This study analyses 12-lead ECGs of patients who present to their General Practitioner complaining of palpitation to determine the frequency of rhythm disturbances. The presence of multifocal atrial rhythm and its distinction from sinus arrhythmia was a particular area of investigation.

Methods 500 ECGs were studied. Rhythms were categorised as supraventricular rhythm disturbances, ventricular rhythm disturbances, multifocal atrial rhythm, sinus arrhythmia, and sinus rhythm. Multifocal atrial rhythm was diagnosed either if there were a minimum of 2 complexes of each of 3 or more distinct P wave shapes, none of which were obvious atrial ectopics, or if an ectopic atrial rhythm morphed into an ectopic atrial rhythm from another atrial focus.

Results Supraventricular rhythm disturbances (8.6%) were more common than ventricular rhythm disturbances (5.2%). Multifocal atrial rhythm was found in 12.7% of ECGs and sinus arrhythmia in 4.0%. The relative frequency of the rhythms varied significantly with age, but not by gender or by ethnicity.

Conclusions Approximately a quarter of the subjects with palpitation had a rhythm disturbance on a 10 s 12-lead ECG. Multifocal atrial rhythm was found in many subjects with palpitation and so should be considered as potential cause of palpitation.