Reduction Of Myocardial Perfusion During Acute Hyperglycemia Is More Marked In The Presence Of Insulin Resistance: A Noninvasive Bedside Evaluation Using Vasodilator Myocardial Contrast Echocardiography

Background: The effect of insulin resistance (IR) on coronary perfusion in humans is poorly studied. We evaluated the association of IR during acute hyperglycemia on myocardial blood flow (MBF) and coronary flow reserve (CFR) as measured by myocardial contrast echocardiography (MCE) in nondiabetic volunteers Methods: We prospectively enrolled 19 [5 males] nondiabetics. IR status was based on glucose infusion rate (GIR, mg/kg/min) during euglycemic hormone clamp [somatostatin, replacement glucagon, growth hormone, and insulin]. Glucose was infused for total of 4 hrs (arterialized blood glucose (BG) monitored every 10 min) to achieve euglycemic (BG 95± 6.8mg/dl) and hyperglycemic (BG 233 ± 18 mg/dl) states. For each glycemic state, MCE was done (Definity: 1.3 ml in 60 cc 0.9% saline at 200 ml/hr;) at rest and during stress (regadenoson 400 ug IV bolus) to measure myocardial blood volume (A dB); microbubble velocity (β sec -1 ); MBF (dB/sec); and CFR Results: Stress MBF, CFR and β reserve were significantly reduced during acute hyperglycemia vs. euglycemia [stress MBF 4.5± 2.1 vs. 5.5± 2.5, P=0.040, CFR 2.07 ± 0.89 vs. 3.2 ± 1.3, P Figure . Using a threshold GIR of 5.5 ± 3.3 mg/kg/min (median 5 mg/kg/min), MBF and CFR were significantly differentiated, although, clinical characteristics were not , Table Conclusions: During acute hyperglycemia, the degree of underlying insulin resistance correlates with the magnitude of reduction in myocardial blood flow and coronary flow reserve as determined noninvasively by vasodilator MCE in nondiabetics.