Coronary flow reserve early and late after minimally invasive coronary artery bypass grafting in patients with totally occluded left anterior descending coronary artery

Background: The impairment of flow reserve of the left anterior descending coronary artery in the early postoperative period in patients receiving a l eft internal thoracic artery graft has been related to the effects of cardi opulmonary bypass. Indeed, the late improvement in flow has been attributed to a late increase in left internal thoracic artery diameter. Methods: We evaluated 12 patients who underwent minimally invasive direct coronary arte ry bypass surgery with the internal thoracic artery used to graft an occlud ed left anterior descending artery without extracorporeal circulation. Earl y and 6 months after the operation, patients underwent a second angiogram o f the left internal thoracic artery graft and assessment of coronary flow r eserve by use of an intracoronary 0.014-inch Doppler guide wire. Results: A t the late study, coronary flow reserve had increased compared with the ear ly postoperative data from 1.8 +/- 0.4 (standard deviation) to 2.5 +/- 0.6 (P = .002) because of a significant decrease in baseline averaged peak velo city (32.4 +/- 6.2 vs 21.3 +/- 6.4 cm/s, P = .002), whereas the hyperemic v alues were similar (51 +/- 6 vs 53.7 +/- 21.9 cm/s, P =,6), The diameters o f the thoracic artery (2.1 +/- 0.3 vs 2.2 +/- 0.3 mm, P = .7) and the left anterior descending coronary artery (1.8 +/- 0.1 vs 1.8 +/- 0.2 mm, P = .5) , as well as myocardial oxygen consumption (106 +/- 14 vs 101 +/- 16 mm Hg . beats/min . 10(-2), P = .5), were unchanged. Conclusions: Our findings su ggest that the late improvement in coronary flow reserve is independent of the diameter of the graft and probably reflects an early distal coronary ve ssel dysfunction, which normalizes with time.