Serial intravascular ultrasound analysis of the impact of myocardial bridge on neointimal proliferation after coronary stenting in patients with acute myocardial infarction.

BACKGROUND

Mechanisms underlying the association between myocardial bridge (MB)-stenting and in-stent restenosis (ISR) are still unclear.

OBJECTIVE

To assess the impact of MB on ISR using intravascular ultrasound (IVUS).

METHODS

In the Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial, 100 left anterior descending artery (LAD) culprit lesions (79 treated with paclitaxel-eluting stents [PES] and 21 treated with bare metal stents) were imaged with serial IVUS immediately postprocedure and at 13 months.

RESULTS

At baseline the LAD stent extended into the MB segment beyond the culprit lesion in seven patients (MB-stent group). In the remaining 93 patients the LAD stent was implanted only in the culprit lesion without extending into the MB segment (non-MB-stent group). In PES-treated lesions intimal hyperplasia (IH) was greater in MB-stent group than in non-MB-stent group (1.0 [0.9, 1.3] mm(2) vs. 0.4 [0.2, 0.7] mm(2), P = 0.007). When comparing the MB-stent segment with the non-MB-stent segment in the MB-stent group treated with PES, a significant reduction in lumen area was observed in only the MB-stent segment, owing to an augmented IH within the MB-stent segment (1.56 [1.40, 1.91] mm(2) vs. 0.77 [0.55, 1.23] mm(2) for non-MB-stent segment, P = 0.08), not significant stent recoil (Deltastent area). At follow-up, the minimum lumen area was smaller in the MB-stent group than in the non-MB-stent group (2.9 [2.5, 4.2] mm(2) vs. 5.2 [4.1, 6.7] mm(2), P = 0.02).

CONCLUSIONS

Increased incidence of ISR associated with MB-stenting may be attributable to enhanced IH, specific to stented MB segment, not to chronic stent recoil.