Background: The prognostic value of an isolated J-point depression, or rapidly upsloping ST-segment, on an exercise ECG has long been assumed to be a benign variant. However, little or no data supporting this assumption may be found in the literature. Our task was to examine if a rapidly upsloping ST-segment on an exercise ECG is associated with changes in risk of dying from CHD in 2014 healthy middle-aged men followed for 35 years.
Methods: A group of healthy middle-aged men (n = 2014) participated in a cardiovascular survey. They underwent an examination programme including a symptom-limited ECG bicycle exercise test. Exercise induced ST-segments were categorised in three groups: normal ST-segment (n = 1383), rapidly upsloping (n = 401), and ST-depression (n = 230). Survival analyses were adjusted for smoking status, total cholesterol, systolic blood pressure, maximal heart rate, and physical fitness. The mean follow-up time was 35 years.
Results: The rapidly upsloping group had a 30% decreased risk of CHD death (hazard ratio, HR, 0.70, 95% CI 0.51-0.95) compared to the normal ST-segment group. The risk of CVD-death was numerically lower in the rapidly upsloping group (HR 0.82, 95% CI 0.65-1.04) compared to the normal ST-segment group. The ST-depression group had a 1.45-fold (HR 1.45, 95% CI 1.09-1.90) increased risk of CHD death compared to the normal ST-segment group.
Conclusions: The rapidly upsloping ST-segment was a common finding (20%) on exercise ECG among healthy middle-aged men and was associated with a 30% reduced risk of dying from CHD compared to individuals with normal ST-segment. A rapidly upsloping ST-segment on exercise ECG may represent the true healthy state.
Keywords: Autonomic nervous system; CHD mortality; exercise ECG; rapidly upsloping ST-segment.