Myocardial bridging (MB) is a congenital anomaly in which a segment of a coronary artery, usually the mid left anterior descending (LAD), courses through the myocardium for a portion of its length and may have more or less severe dynamic compression (“milking effect”) during left ventricular systole [[1], [2], [3], [4], [5]]. The prevalence of MB varies widely in the general population, ranging from 5% to 86% depending on the detection method used [3,6]. For many years, MB has been considered a benign condition because most of the coronary blood flow occurs during diastole. Indeed, approximately 15% only of coronary blood flow is at risk of compromise by significant MB, a seemingly clinically irrelevant fraction. However, the potential effects on coronary flow may be more complex being influenced by the interplay between anatomical, clinical and physiology factors that may condition each other dynamically, leading to myocardial ischemia. In fact, case reports and series showed a possible correlation between MB and several adverse events, including sudden cardiac death, increasing concern about the anomaly [[7], [8], [9]].

Considering the high prevalence of MB and the absence of recommendations from the guidelines of major cardiovascular societies for its diagnosis and management, noninvasive imaging evaluation could help clinicians in this regard. In particular, coronary CT angiography (CCTA) emerged in the last decade as an accurate and reliable first-line noninvasive tool for assessing coronary arteries in patients with suspected coronary artery disease (CAD) in stable or acute chest pain settings [[10], [11], [12]]. The noninvasive imaging technique has been also proposed as the gold standard for detecting and evaluating congenital coronary anomalies, including MB [3,13]. The advantage of CCTA compared to invasive coronary angiography lies in the high spatial resolution and the ability to easily visualizing not only the coronary artery lumen but also the vessel wall and the surrounding myocardium in three dimensions [6]. The gradual increase in CCTA use has made it possible to demonstrate that the true incidence of MB can be as high as 58% [6]. Moreover, CCTA plays an instrumental role for classifying the course of the artery as normal (within the epicardial fat), superficial or deep within the myocardium, an anatomy grading that plays a role in the therapeutic strategy [14]. Superficial and short-length encasement is usually benign and eventual symptoms require only drug therapy. On the other hand, deep (>5 mm) and long (>25 mm) MB particularly if associated with symptoms and signs of myocardial ischemia may need a surgical approach. However, there is paucity of data regarding the prognosis and best treatment strategy of MB [4]. Therefore, aim of the present study was to assess the prevalence and the anatomical features of MB in a large population of patients who underwent CCTA for suspected CAD and to identify potential anatomical and clinical predictors of adverse events at long-term follow-up.