Natural history of the electrocardiographic pattern of early repolarization in ambulatory patients.

Although it is known that the electrocardiographic pattern of early repolarization (ER) occurs most commonly in healthy young bradycardic men, its natural history is uncertain. We considered initial electrocardiograms (ECGs) at rest from 29,281 ambulatory patients recorded from 1987 through 1999 at Veterans Affairs Palo Alto Hospital. With PR interval as the isoelectric line and amplitude criterion as >0.1 mV ER was identified when any of the following fulfilled the amplitude criterion: ST-segment elevation at the end of the QRS duration, J waves as an upward deflection, and slurs as delay on the R wave downstroke. The first 250 ECGs with the greatest ER increase were selected and the database was searched for an ECG >5 months later. Of the 250 patients selected with the greatest amplitude of ER 6 were excluded for electrocardiographic abnormalities, leaving 244 subjects, of whom 122 had another ECG ≥5 months later. Their average age was 42 ± 10 years and average time from the first to second ECG was 10 years. Of the 122 patients 47 (38%) retained ER, whereas most (62%) no longer fulfilled the amplitude criterion. There were no significant differences in heart rate or time interval between ECGs. In conclusion, the electrocardiographic pattern of ER was lost over 10 years in more than half of this young clinical cohort and the loss was not caused by higher heart rate, longer time between ECGs, decrease in R-wave amplitude, death, acute disease, or alterations in electrocardiographic diagnostic characteristics.