Implications of myocardial bridging on heart rhythm in patients with hypertrophic cardiomyopathy

Myocardial bridging has a prevalence ranging from 1% to 3% in the general population. Previous studies have shown that it is significantly more prevalent in patients with Hypertrophic Cardiomyopathy (HCM), reaching about 25% in some cohorts. The clinical relevance of myocardial bridging in patients with HCM is still mostly unknown, with some studies suggesting that this condition may have a role in arrhythmic events related to sudden cardiac death whilst other propose it is mostly benign.

We aimed to study the influence of myocardial bridging on 24-hour Holter monitoring studies, particularly regarding ventricular events, in a population of patients with HCM.

Patients with HCM accompanied at our center who had coronary anatomy studied by either cardiac catheterization (CAT) or Coronary computed tomography angiography (CCTA) were included. We retrospectively analyzed the prevalence of myocardial bridging in our population and correlated the phenomenon to the characteristics of Holter studies. We also registered the occurrence of ventricular tachycardia (VT) events during follow-up.

Sixty-four patients with HCM (mean age 66.7±11.6, 50% male sex) were included. Fifteen (23%) patients (age 60.73±8.5, 73.3% male sex) had myocardial bridging. The groups had similar baseline characteristics, and no significant differences were registered when comparing clinical aspects. There were no significant differences in medication, particularly in anti-arrhythmic drugs. No significant differences were seen regarding the findings on Holter monitoring. The patients with myocardial bridging did not have more ventricular ectopies, either in absolute number (p=0.53) or percentage during the 24 hours (p=0.57). There were no differences in the occurrence of non-sustained ventricular tachycardia between the groups (p=1.0). Additionally, there was no significant difference in ST segment elevation or depression during the monitoring between the studied groups. There was no record of VT in neither of the groups during the follow-up time.

Our cohort of HCM patients had a prevalence of myocardial bridging similar to that described in previous studies. This condition seems to have no overall impact on arrhythmic events in our population.