ST-SEGMENT DEPRESSION DURING ADENOSINE INFUSION AS A PREDICTOR OF MYOCARDIAL-ISCHEMIA

The incidence and hemodynamic changes associated with ST-segment depre ssion during adenosine stress testing are poorly defined. To examine t his, 550 consecutive patients who underwent adenosine perfusion testin g were evaluated for the development of ST-segment depression. At leas t 1 mm of horizontal or downsloping depression developed in 82 patient s (15.9%) and was observed with similar frequency in patients with nor mal scans and those with only fixed defects. ST depression developed i n 58 of 242 patients with reversible defects (sensitivity = 24%) and i n only 24 of 275 patients without reversible defects (specificity = 91 %). Its presence was highly predictive of reversible perfusion defects (predictive accuracy = 71%). Similar findings were observed in patien ts with and without ECG evidence of left ventricular hypertrophy. Pati ents with ST depression had perfusion defects in more vessel distribut ions, had more severe defects, and had a greater increase in heart rat e during adenosine infusion. Thus ST-segment depression occurs infrequ ently during adenosine infusion but is specific for and predictive of myocardial ischemia, as evidenced by reversible perfusion scan defects . Patients with ST depression have more severe disease and develop fas ter heart rates during infusion, which could result in decreased coron ary perfusion during diastole allowing for the development of myocardi al ischemia.