Coronary artery distensibility in diabetic patients with simultaneous measurements of luminal area and intracoronary pressure - Evidence of impaired reactivity to nitroglycerin

OBJECTIVE This study investigated whether noninsulin dependent diabetes mel litus (NIDDM) adversely affects the elastic properties of the coronary arte ries in patients with coronary artery disease (CAD) and NIDDM. BACKGROUND Attenuated vascular smooth muscle dilation to exogenous donors o f nitric oxide, such as nitroglycerin, has been observed with forearm blood flow studies in patients with NIDDM. METHODS Twenty patients with CAD and NIDDM (diabetics), and 20 patients wit h only CAD (nondiabetics) were evaluated. Intracoronary ultrasound (ICUS) i maging with simultaneous intracoronary pressure (P-2) recordings were perfo rmed at the imaging site with 0.014 in fiber-optic high fidelity pressure m onitoring wire. The same wire was used as guide wire for the ICUS catheter. Sites with less than 50% luminal stenosis by ICUS were studied. Recordings were done before and after 300 mu g of intracoronary nitroglycerin (IC-NTG ). Electrocardiographic tracings recorded simultaneously with ICUS images w ere used for timing. Systolic and diastolic cross-sectional lumen area (CSL A) and coronary artery distensibility (C-DIST) were measured, C-DIST = {(sy stolic CSLA-diastolic CSLA)/[(intracoronary pulse pressure) x (diastolic CS LA)]} x 1,000. RESULTS Diabetics had smaller CSLA (diabetics = 8.6 +/- 0.6 mm(2), nondiabe tics = 11.5 +/- 0.5 mm(2), p < 0.01). Although C-DIST was similar before IC -NTG in the two groups, it became significantly lower in diabetics after IC -NTG (diabetics C-DIST = 3.02 +/- 0.14 mm Hg-1 nondiabetics C-DIST = 4.21 /- 0.15 mm Hg-1, p < 0.01). Degrees of circumference involved, total plaque burden and composition were similar in both groups. CONCLUSIONS Noninsulin dependent diabetes mellitus reduces C-DIST after IC- NTG administration. (J Am Coll Cardiol 1999;34:1 075-81) (C) 1999 by the Am erican College of Cardiology.