[Exercise-induced precordial ST depression in patients with prior inferior myocardial infarction with single vessel disease]

We investigated the mechanisms of exercise-induced precordial ST depression in prior inferior myocardial infarction in single vessel disease, and attempted to differentiate ST depression in single vessel from multivessel disease. Subjects were categorized as; Group I (n = 18), with inferior myocardial infarction and single vessel disease without (n = 11; Ia) and with (n = 7; Ib) exercise-induced precordial ST depression and group II (n = 10), inferior myocardial infarction with multivessel disease. The subjects were examined using 12-lead exercise ECG, stress T1-201 myocardial imaging and stress radionuclide ventriculography. Compared to group Ia, exercise-induced precordial ST depression in group Ib was associated with extensive infarction extending into the inferoseptal left ventricular wall by T1-201 myocardial imaging. Worsening of septal wall motion was also more frequently observed on stress radionuclide ventriculography. For detecting multivessel disease in prior inferior myocardial infarction, exercise ECG and radionuclide ventriculography had poor specificity and predictive value compared to stress T1-201 myocardial imaging. We conclude that exercise-induced precordial ST depression observed in patients with prior inferior myocardial infarction due to single vessel disease reflects a peri-infarction ischemia in the inferoseptal wall of the left ventricle. Great caution is necessary when predicting multivessel disease in prior inferior myocardial infarction using exercise ECG. Stress T1-201 myocardial imaging is the most accurate diagnostic means for this purpose.