METABOLIC AND FUNCTIONAL RECOVERY OF ISCHEMIC HUMAN MYOCARDIUM AFTER CORONARY ANGIOPLASTY

Although revascularization of hypoperfused but metabolically active human myocardium improves segmental function, the temporal relations among restoration of blood flow, normalization of tissue metabolism and recovery of segmental function have not been determined. To examine the effects of coronary angioplasty on 13 asynergic vascular territories in 12 patients, positron emission tomography and two-dimensional echocardiography were performed before and within 72 h of revascularization. Ten patients underwent late echocardiography (67 +/- 19 days) and eight underwent a late positron emission tomographic study (68 +/- 19 days). The extent and severity of abnormalities of wall motion, perfusion and glucose metabolism were expressed as wall motion scores, perfusion defect scores and perfusion-metabolism mismatch scores. Angioplasty significantly increased mean stenosis cross-sectional area (from 0.95 +/- 0.9 to 2.7 +/- 1.4 mm2) and mean cross-sectional luminal diameter (from 0.9 +/- 0.6 to 1.9 +/- 0.5 mm) (both p < 0.001). Perfusion defect scores in dependent vascular territories improved early after angioplasty (from 116 +/- 166 to 31 +/- 51, p < 0.002) with no further improvement on the late follow-up study. The mean perfusion-metabolism mismatch score decreased from 159 +/- 175 to 65 +/- 117 early after angioplasty (p < 0.01) and to 26 +/- 29 at late follow-up (p < 0.001 vs. before angioplasty; p = NS vs. early after angioplasty). However, absolute rates of glucose utilization remained elevated early after revascularization, normalizing only at late follow-up. The average wall motion score did not improve significantly early after angioplasty (from 111 +/- 76 to 81 +/- 72), but a highly significant improvement was observed at late follow-up (43 +/- 46, p < 0.005). Perfusion-metabolism mismatch scores before angioplasty were linearly related to late improvement in wall motion scores (change in wall motion score = 23 + (0.29 x mismatch score); r = 0.87, p < 0.001). Thus, restoration of blood flow to ischemic human myocardium by coronary angioplasty is followed by an early improvement in perfusion and by the initial persistence of an abnormal metabolic and functional state. Assessment of both myocardial perfusion and glucose metabolism with positron emission tomography in patients with ischemic wall motion abnormalities before revascularization may quantitatively predict the amount of late recovery of contractile function.