**6.4 Myocardial bridging**

 Myocardial bridging (MB) is a challenging problem in the presence of HCM. It can cause significant symptoms (chest pain) after an initial septal myectomy and at the same time not all patients with MB requires unroofing of their MB. A challenging task is to identify those who will benefit from concomitant unroofing of MB and septal myectomy. Currently no guidelines or recommendations regarding the optimal management of these patients.

 Wang and colleagues reported their midterm results of different treatment methods for MB in patients with HCM after their septal myectomy [ 14 ]. A total of 823 patients were included, where the authors identified 31 events with mortality in 24 patients and nonfatal myocardial infarction (MI) in 7. The three-year cumulative event-free survival of all cause-death was 100% for both those who underwent coronary artery bypass grafting, and unroofing, however, the 3-year cumulative event-free survival of non-fatal MI and the combined endpoints were significantly lower in the un-treated group. The authors concluded that surgical treatment of MB at the time of septal myectomy is beneficial.

 We do perform coronary angiography in the majority of these patients especially when the presentation is of a chest pain. If a MB is identified, a hemodynamic evaluation of the bridge is performed to determine its significance and help making the decision for concomitant unroofing.

 We have described the technique previously [ 15 ] and we prefer performing the unroofing procedure on the arrested heart to avoid inadvertent injury of the coronary artery. A combination of sharp and electrocautery dissection is used to unroof the entire bridged segment ( **Figure 13** ). It is critical to remember that the bridged segment of the coronary artery is always fragile and the unroofing process has to be done with extreme caution.

#### **Figure 13.**

 *Intraoperative photo of a patient with hypertrophic cardiomyopathy who underwent repeat operation with unroofing of a long segment of the left anterior descending coronary artery due to missed diagnosis of myocardial bridge after his initial septal myectomy. LAD: Left anterior descending coronary artery.* 
