Impact of Myocardial Bridge on Clinical Outcome After Coronary Stent Placement

Abstract

Most intravascular ultrasound (IVUS)-identifiable myocardial bridges (MBs) were not appreciated angiographically, especially when they occurred adjacent to fixed proximal obstructive disease. The impact of MB stent placement on clinical outcome was determined in 317 consecutive patients with obstructive left anterior descending coronary artery lesions undergoing coronary stent placement. In these patients, IVUS identified 70 MBs, defined as a segment of coronary artery with both systolic compression and perivascular echolucent muscle. IVUS showed that the stent extended into the MB segment beyond the obstructive lesion in 24 patients (34%; MB stent group), although significant plaque was not observed within any MB segment. In the remaining 46 patients, the left anterior descending artery stent was implanted in only the obstructive lesion, avoiding the distal MB segment (non-MB stent group). Minimum stent area was significantly smaller in the MB stent group than non-MB stent group (4.8 +/- 1.1 vs 5.8 +/- 1.8 mm(2); p = 0.02). Rates of target-lesion revascularization, target-vessel revascularization, and composite end point (death/myocardial infarction/target-lesion revascularization/target-vessel revascularization, evaluated at a mean follow-up of 358 +/- 252 days) were more common in patients with versus without MB stent placement. Specifically, target-lesion revascularization rates were 24% versus 3%, respectively (log-rank p = 0.003). In-stent restenosis occurred within the stented MB segment in 3 of 5 MB stent group patients who required target-lesion revascularization (60%). In conclusion, inadvertent MB stent placement in left anterior descending artery lesions occurred commonly and may have been associated with an increased incidence of late events.