Outcomes Of Minimally Invasive Myocardial Bridge Unroofing In Adults
Hanjay Wang, Camille E. Hironaka, Christian T. O'Donnell, Vedant S. Pargaonkar, Chad J. Abbot, Ian S. Rogers, Jennifer A. Tremmel, Michael P. Fischbein, Robert S. Mitchell, Ingela Schnittger, Jack H. Boyd.
Stanford University, Palo Alto, CA, USA.
Objective: Myocardial bridges (MBs) are a congenital coronary variant in which contractile myocardium overlies a coronary artery. Patients with hemodynamically significant MBs of the left anterior descending (LAD) coronary artery may present with debilitating angina despite optimal medical therapy. We previously demonstrated that surgical MB unroofing via sternotomy significantly improves symptoms and quality of life. We hypothesized that minimally invasive MB unroofing could achieve similar results. Methods: Adult patients (n=101) who underwent LAD MB unroofing at our institution between 11/2011-12/2018 were included. MBs were characterized by coronary angiography and intravascular ultrasonography. Hemodynamic significance was determined by diastolic fractional flow reserve (dFFR) measured distal to the MB. Surgical unroofing was performed via sternotomy (n=72, 2011-2018) or left anterior mini thoracotomy (n=29, 2016-2018). The primary outcome was symptom status assessed by Seattle Angina Questionnaire (SAQ) before and 6 months after surgery. Secondary outcomes included surgery duration, length of hospital stay, and incidence of postoperative complications. Results: There were no significant differences in baseline patient characteristics between the groups. Patients were young (sternotomy 45.5 [36.5-58.0] years, mini 54.0 [39.0-57.0] years) and mostly female (sternotomy 58.3%, mini 51.7%). All patients were symptomatic. MB lengths were comparable (sternotomy 2.87 [2.07-4.62] cm, mini 2.84 [2.16-3.60] cm), although dFFR was lower in the mini group (0.59 [0.53-0.68] vs 0.67 [0.57-0.73], p=0.036). 51.4% of sternotomy cases were performed with the heart arrested on cardiopulmonary bypass while all mini thoracotomy cases were performed off-pump. The mini group experienced a shorter surgery duration (134 [120-149] min vs 162 [134-216] min, p=0.001) and shorter hospital stay (3 [3-4] days vs 4 [4-5] days, p=0.001). There were no occurrences of death, myocardial infarction, or stroke in either group. The mini group experienced no blood transfusions or surgical wound infections, whereas these occurred in 4.2% and 2.8% of sternotomy cases, respectively. SAQ scores improved significantly after mini MB unroofing with regards to physical limitation, anginal stability and frequency, treatment satisfaction, and quality of life (Figure). Conclusions: In selected patients, minimally invasive MB unroofing is safe, expedites recovery compared to a sternotomy approach, and provides significant improvements in symptoms and quality of life. 
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