Coronary artery perforation in a patient with STEMI and a myocardial bridge: an increased risk for coronary artery perforation? Cardiovasc Revasc Med. 2015;16:246-248. [PMID: 25842348 DOI: 10.1016/j.carrev.2015.03.004]

Plaque herniation after stenting the culprit lesion with myocardial bridging in ST elevation myocardial infarction: A case report

BACKGROUND

Myocardial bridging (MB) is increasingly recognized to stimulate atherogenesis, which may contribute to an acute coronary syndrome. Stenting the coronary segment with MB has been recognized to have an increased risk of in-stent restenosis, stent fracture and coronary perforation. The safety and efficacy of stenting the culprit lesion with overlaying MB in ST elevation myocardial infarction (STEMI) as primary reperfusion therapy has not been established.

CASE SUMMARY

We reported a patient who presented with inferior STEMI with a culprit lesion of an acute thrombotic occlusion in the right coronary artery and thrombolysis and thrombin inhibition in myocardial infarction 0 flow. After the stent placement during primary percutaneous coronary intervention, intravascular ultrasound revealed MB overlying the stented segment where heavy atherosclerotic plaque were present. Likely due to the combination of plaque herniation or prolapse caused by MB, as well as local increased inflammation and thrombogenicity, acute stent thrombosis occurred at this region, which led to acute stent failure. The patient required an emergent repeated cardiac catheterization and placing a second layer of stent to enhance the radial strength and reduce the inter-strut space.

CONCLUSION

Plaque herniation or prolapse after stenting a MB segment in STEMI is a potential etiology for acute stent failure.

The Outcome of Percutaneous Coronary Intervention for Significant Atherosclerotic Lesions in Segment Proximal to Myocardial Bridge at Left Anterior Descending Coronary Artery

This study aimed to evaluate the efficacy of percutaneous coronary intervention (PCI) for significant atherosclerosis lesions proximal to myocardial bridge (MB) at left anterior descending coronary artery (LAD).A total of 330 consecutive patients with LAD significant stenosis, diagnosed as acute coronary syndrome (ACS), were included. Based on whether combined with MB, the patients were divided into the MB group (MB, n = 48) and non-MB group (NMB, n = 282). Drug eluting stents (DES) were successfully implanted in the stenostic segments prior to MB. All patients were followed up during the hospital stay, 30 days and 12 months after PCI, to evaluate the major adverse cardiac events (MACEs).There was no difference in the incidence of MACEs between the two groups (6.2% versus 2.1%, P = 0.254) when in the hospital. During the follow-up of 30 days and 12 months after PCI, the rate of MACEs was significantly higher in the MB group than in the NMB group (18.2% versus 6.4% and 43.8% versus 17.0%, respectively, P < 0.001). Stent restenosis occurred in four patients in the MB group; whereas, in five patients in the NMB group, the rate of stent restenosis was higher in the MB group than in the NMB group (8.3% versus 1.8%, P = 0.036). Cox proportional hazards regression analysis revealed that the presence of MB was an independent predictor of MACEs (hazard ratio (HR) = 1.781, 95% confidence intervals (95% CI) = 1.108-2.863, P = 0.017).DES implantation for significant atherosclerosis stenosis in the segments proximal to MB have higher incidence of MACEs. MB appears to be associated with a higher incidence of stent restenosis after PCI and is a significant factor in the occurrence of MACEs.

Increased risk of coronary perforation during percutaneous intervention of myocardial bridge: What histopathology says

Introduction: Myocardial bridge (MB) is a segment of a major epicardial coronary artery that goes intramurally under a bridge of overlying myocardium. Complications have been reported during or after stent implantation particularly coronary perforation. The aim of this study was to determine histological differences between proximal left anterior descending artery (LAD) and the tunneled segment that may have a possible role in increased risk of coronary artery perforation during percutaneous coronary intervention.

Methods: Twenty specimens of MB were obtained from dissection of 45 cadavers. Sections were stained using hematoxylin and eosin (H&E), and trichrome methods. The proximal section and the tunneled artery were compared with a normal sample in terms of the characteristics of a muscle artery.

Results: The findings of this study showed an MB prevalence of 51%, as 23 out of the 45 examined cadavers were discovered to be afflicted by the MB. The intima layer in the suffering artery had gone through significant hypertrophy, while it had remained thin in the tunneled artery section. The epithelial cells under the bridge were spindle-shaped, while they were polygonal in the proximal section. In the myocardium the nuclei of the muscle fibers in the MB section were smaller than the normal section. Adventitial layer was almost normal.

Conclusion: The histopathological differences between MB and proximal part of vessel combined with small vessel diameter in the tunneled segment can explain the high incidence of the LAD rupture and perforation in the section under the bridge.