[Assessing the physiologic significance of intermediate coronary lesions: comparison of coronary flow measurements with exercise electrocardiography]

Abstract

Angiography may provide limited assessment of intermediate coronary stenoses. Doppler coronary flow reserve has been applied to determine the physiologic significance of such lesions. This study compared coronary flow reserve derived from intracoronary Doppler flow wire with the results of the exercise tolerance test to evaluate the validity of intracoronary flow measurements in the assessment of intermediate stenoses. Sixty eight patients with 91 vessels harboring angiographically mild-to-severe coronary stenoses in the left anterior descending or right coronary artery were studied. All patients had single-vessel disease, and angiography showed the target vessel. Distal coronary flow reserve was measured with the Doppler guide wire during cardiac catheterization. Exercise tolerance tests by bicycle ergometer were performed the day before catheterization. Quantitative coronary angiography showed a mean percentage diameter stenosis of 44 +/- 21%(range 0-90%). Forty seven of 91 vessels combined intermediate lesions(40% to 70%). Percentage diameter stenosis and coronary flow reserve were linearly correlated in both overall and intermediate lesions(r = -0.52 vs -0.42; both p < 0.0001). Percentage diameter stenosis of overall lesions was significantly higher in the positive exercise test group than the negative group(59.8 +/- 17.2% vs 37.7 +/- 18.1%, p < 0.0001), but not significantly different in intermediate lesions(49.1 +/- 7.8% vs 54.7 +/- 6.6%, p = 0.03). The positive exercise test group showed significantly lower coronary flow reserve compared to the negative group in both overall and intermediate lesions(overall: 1.6 +/- 0.5 vs 2.6 +/- 0.9, p < 0.0001; intermediate: 1.6 +/- 0.5 vs 2.5 +/- 0.7, p < 0.0001). Coronary flow reserve < 2.0 and positive exercise test agreed in 38 of 46 intermediate lesions(83%), and percentage diameter stenosis > or = 50% and positive exercise test agreed in 34 of these 46 lesions(74%). Coronary flow reserve, more than percentage diameter stenosis, correlated with the results of the exercise tolerance test, and is considered to be useful to evaluate the functional severity of intermediate stenosis.