Comparison of high risk stress myocardial perfusion imaging findings in men with rapid versus prolonged recovery of ST-segment depression after exercise stress testing.

ST-segment depression during stress testing predicts future risk for adverse cardiovascular events and routinely prompts further noninvasive imaging or invasive evaluation for coronary artery disease (CAD). A subset of patients develop ST depression at peak exercise that rapidly resolves early in the recovery period (ST-rapid). The goal of this study was to compare the prevalence of single-photon emission computed tomographic myocardial perfusion imaging (MPI) findings in patients with ST-rapid to those with prolonged ST depression (ST-prolonged) and those without ST depression (ST-normal). A total of 637 men without previous CAD and with interpretable rest electrocardiograms referred for exercise stress MPI were included in this study. ST depression was defined as > or =1-mm ST depression occurring 80 ms after the J point at peak exercise. ST-rapid was defined as ST depression with recovery of the ST depression by 1 minute into recovery. Men with ST-rapid were younger (55.4 +/- 7.6 vs 62.6 +/- 9.6 years, p <0.001) and had better exercise capacity (11.2 +/- 2.8 vs 9.4 +/- 3.0 METs, p <0.001) than men with ST-prolonged. Compared to ST-prolonged, ST-rapid was associated with significantly less mild CAD (summed stress score > or =4; 27% vs 47%, p = 0.02), severe CAD (summed stress score >8; 9% vs 29%, p = 0.004), and a composite of high-risk MPI findings (summed stress score >8 or ejection fraction <40%; 11% vs 32%, p = 0.003). There were no significant differences in exercise capacity, the presence of CAD, or the composite of high-risk MPI findings between men with ST-rapid and those with ST-normal. In conclusion, men who developed ST-rapid during exercise stress testing had markedly fewer abnormal and high-risk MPI findings compared to those with prolonged ST depression. In fact, the prevalence of MPI abnormalities in men with ST-rapid was similar to that in men with normal electrocardiographic responses to exercise.