Relation Between Flow Reserve Capacity of Penetrating Intramyocardial Coronary Arteries and Myocardial Fibrosis in Hypertension: Study Using Transthoracic Doppler Echocardiography

Objective: The purpose of this study was to compare coronary flow reserve (CFR) capacity of penetrating intramyocardial coronary artery (PICA) using transthoracic Doppler echocardiography and biochemical marker of myocardial fibrosis in hypertension (HTN). Methods: In 58 patients (male:female ratio = 31:27; mean age 47 ± 9 years) with chest pain and normal coronary angiogram findings, the width of color Doppler signal and peak diastolic velocity of PICA flow were measured in the myocardium just beneath the apical impulse window using transthoracic Doppler echocardiography. PICA-CFR and PICA-width ratio were calculated as the ratio of hyperemic to baseline peak diastolic velocity and as the ratio of hyperemic to baseline width after the adenosine infusion (140 μg/kg/min), respectively. Serum carboxy-terminal propeptide of procollagen type I, as a biochemical marker, was measured and patients were divided into 3 groups: 19 with HTN and PICA-CFR less than 2.0 (group A); 23 with HTN and PICA-CFR of 2.0 or more (group B); and 16 who were normotensive with PICA-CFR of 2.0 or more (group C). Results: Baseline peak diastolic velocity for group A was higher than the other two groups (P < .005 vs groups B and C). PICA-width ratio was higher than the other two groups (P < .005 vs groups B and C). Serum propeptide of type I was 137.1 ± 16.6 ng/mL in group A, 96.2 ± 13.7 ng/mL in group B, and 78.8 ± 11.2 ng/mL in group C (P < .0001 vs group B and group C). PICA-CFR was closely related to serum propeptide of type I (P < .001, r = -0.723). Conclusion: The impaired PICA-CFR is related to myocardial fibrosis in patients with HTN, chest pain, and normal coronary angiogram results.