'A bridge over troubled water': a case report

Abstract

Background: Myocardial bridge (MB) is the most common inborn coronary artery variant, in which a portion of myocardium overlies a major epicardial coronary artery segment. Myocardial bridge has been for long considered a benign condition, although it has been shown to cause effort-related ischaemia.

Case summary: We present the case of a 17-year-old female patient experiencing chest pain during physical activity. Since her symptoms became unbearable, electrocardiogram and echocardiography were performed together with a coronary computed tomography scan, revealing an MB on proximal-mid left anterior descending artery. In order to unequivocally unmask the ischaemic burden lent by MB, the patient underwent coronary angiography and physiological invasive test: instantaneous wave-free ratio (iFR) and fractional flow reserve (FFR) were calculated, both at baseline and after dobutamine infusion (5 µg/kg/min). At baseline, iFR value was borderline (= 0.89), whereas after dobutamine infusion and increase in the heart rate, the patient suffered chest pain. This symptom was associated with a decrease in the iFR value up to 0.77. Consistently, when FFR was performed, a value of 0.92 was observed at baseline, while after inotrope infusion the FFR reached the haemodynamic significance (= 0.79). Therefore, a medical treatment with bisoprolol was started.

Discussion: Our clinical case shows the importance of a comprehensive non-invasive and invasive assessment of MB in young patients experiencing chest pain, with significant limitation in the daily life. The coronary functional indexes allow to detect the presence of MB-derived ischaemia, thus guiding the decision to undertake a medical/surgical therapy.

Keywords: Case report; Chest pain; Functional intracoronary assessment; Ischaemic heart disease; Myocardial bridge.

Figure 1

Baseline electrocardiogram.

Figure 2

Twenty-four-hour electrocardiogram monitoring.

Figure 3

Transthoracic echocardiogram: normal origins of coronary arteries (A), normal size of atrial and ventricular chambers (B), normal systolic and diastolic functions (C).

Figure 4

Cardiopulmonary exercise test: baseline electrocardiogram recording (A), peak event electrocardiogram recording (B) and VO₂ trend (C).

Figure 5

Coronary computed tomography scan showing the tunnelled arterial segment (A and B), compared with coronary angiography documenting the milking effect (C and D).

Figure 6

Functional intracoronary evaluation: At baseline, instantaneous wave-free ratio value was 0.89 (A), reaching 0.82 after 5 min of dobutamine infusion (B) and 0.77 after 9 min at hyperaemic flow (C). Similarly, fractional flow reserve after dobutamine and atropine infusion acquired haemodynamic significance (= 0.79) (D). At the end, an instantaneous wave-free ratio pullback was performed and instantaneous wave-free ratio value was 0.53 (E).