Influence of the location of left anterior descending coronary artery stenosis on left ventricular function during exercise
The purpose of this investigation was to determine if a stenosis of a coronary artery located proximally caused greater deterioration of left ventricular function than a stenosis of a similar magnitude located more distally in the artery. Twenty-six patients with isolated left anterior descending coronary artery (LAD) lesions documented by cardiac catheterization were studied by radionuclide angiocardiography (RNA) at rest and during exercise on a bicycle ergometer. Thirteen patients (9 males and 4 females) had a proximal lesion of the LAD averaging 91 ± 11% of the diameter of the lumen (group 1) and 13 patients (8 males and 5 females) had a distal lesion averaging 88 ± 12% of the lumen (group 2). The mean age of group 1 was 49 ± 9 years and the mean age of group 2 was 48 ± 9 years. In group 1, the ejection fraction decreased from 63 ± 8% to 55 ± 11% (p = 0.02), left ventricular end-diastolic volume (EDV) increased from 130 ± 32 ml to 174 ± 34 ml (p = 0.001) and left ventricular end-systolic volume (ESV) increased from 49 ± 16 ml to 80 ± 26 ml (p = 0.001) during exercise. In group 2, the ejection fraction and ESV showed no significant change during exercise. In this group, the left ventricular EDV increased from 117 ± 28 ml to 140 ± 37 ml (p = 0.04) during exercise. The 2 groups showed no significant hemodynamic differences during the rest studies, but group 1 showed significantly lower ejection fraction and higher EDV and ESV during exercise. These findings indicate that a stenotic lesion located at a more proximal level of the coronary arterial system reduces blood flow in a larger area of myocardium, resulting in a more pronounced ischemic response to exercise than a similar lesion located more distally.
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