Coronary flow reserve improves after aortic valve replacement for aortic stenosis: an adenosine transthoracic echocardiography study

OBJECTIVES The goal of this study was to assess coronary flow reserve (CFR) before and after aortic valve replacement (AVR). BACKGROUND Coronary flow reserve is impaired under conditions of left ventricular (LV) hypertrophy. It is not known whether CFR improves with regression of LV hypertrophy in humans. METHODS We investigated 35 patients with pure aortic stenosis, LV hypertrophy and normal coronary arteriograms. Patients underwent adenosine transthoracic echocardiography on two occasions—immediately before AVR and six months postoperatively. Left ventricular mass, distal left anterior descending coronary artery (LAD) diameter, flow and CFR were assessed on each occasion. RESULTS Distal LAD diameter was successfully imaged in 30 patients (86%), and blood flow was successfully imaged in 27 (77%). Paired data were subsequently available in 24 patients, of whom 14 were men, mean age 68.1 ± 12.5 years, body mass index 24.5 ± 2.0 kg/m2, aortic valve gradient 93 ± 32 mm Hg. Pre- to post-AVR a significant decrease was seen in LV mass (271 ± 38 vs. 236 ± 32g, p < 0.01) and LV mass index (154 ± 21 vs. 134 ± 21g/m2, p < 0.01). Distal LAD diameter fell from 2.27 ± 0.37 to 2.23 ± 0.35 mm, p = 0.08). Pre- to post-AVR there was no significant change in resting parameters of peak diastolic velocity (0.43 ± 0.16 vs. 0.41 ± 0.11 m/s), distal LAD flow 23.3 ± 10.1 vs. 20.9 ± 5.2 ml/min or distal LAD flow scaled for LV mass (8.7 ± 3.8 vs. 9.0 ± 2.5 ml/min/100 g LV mass), but there was significant increase in hyperemic peak diastolic velocity (0.71 ± 0.26 vs. 1.08 ± 0.24 m/s; p < 0.01), distal LAD flow (37.8 ± 11.3 vs. 53.5 ± 16.1 ml/min; p < 0.01) and distal LAD flow scaled for LV mass (14.3 ± 5.0 vs. 23.3 ± 8.5 ml/min/100 g LV mass; p < 0.01). Coronary flow reserve, therefore, increased from 1.76 ± 0.5 to 2.61 ± 0.7. CONCLUSIONS Coronary flow reserve increases after AVR for aortic stenosis. This increase occurs in tandem with regression of LV hypertrophy.