Coronary artery distensibility in diabetic patients with simultaneous measurements of luminal area and intracoronary pressure: evidence of impaired reactivity to nitroglycerin.

OBJECTIVES: This study investigated whether noninsulin dependent diabetes mellitus (NIDDM) adversely affects the elastic properties of the coronary arteries in patients with coronary artery disease (CAD) and NIDDM.
BACKGROUND: Attenuated vascular smooth muscle dilation to exogenous donors of 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 with only CAD (nondiabetics) were evaluated. Intracoronary ultrasound (ICUS) imaging with simultaneous intracoronary pressure (P2) recordings were performed at the imaging site with 0.014 in fiber-optic high fidelity pressure monitoring 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 microg of intracoronary nitroglycerin (IC-NTG). Electrocardiographic tracings recorded simultaneously with ICUS images were used for timing. Systolic and diastolic cross-sectional lumen area (CSLA) and coronary artery distensibility (C-DIST) were measured, C-DIST = [(systolic CSLA-diastolic CSLA)/[(intracoronary pulse pressure) x (diastolic CSLA)]] x 1,000.
RESULTS: Diabetics had smaller CSLA (diabetics = 8.6 +/- 0.6 mm2, nondiabetics = 11.5 +/- 0.5 mm2, 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.