Pathophysiology of Chronic Left Ventricular Dysfunction New Insights From the Measurement of Absolute Myocardial Blood Flow and Glucose Utilization

Background Chronically dysfunctional myocardium may improve after coronary revascularization. This condition was thought to be due to a chronically reduced myocardial blood flow (MBF). Recently, however, it has been shown that in patients without previous infarction but with chronic left ventricular dysfunction, baseline MBF was normal. Methods and Results To study the pathophysiology of chronic left ventricular dysfunction in patients with previous infarction, regional MBF (milliliter per minute per gram of water-perfusable tissue) and glucose utilization (MRG; micromoles per minute per gram) during hyperinsulinemic euglycemic clamp were measured with positron emission tomography in 30 patients before bypass. At baseline, 133 myocardial segments were normal, and 107 were dysfunctional. After revascularization, 59 of 107 segments improved, while 48 of 107 were unchanged. MBF was 0.92±0.25 mL · min−1 · g−1 in normal segments, 0.87±0.31 mL · min−1 · g−1 in improved segments (P=NS versus normal), and 0.82±0....