Reversible myocardial ischaemia caused by ectopic left circumflex coronary artery: a case report

Abstract

Background: Coronary artery anomalies (CAAs) are congenital disorders associated with variable manifestations and pathophysiological mechanisms. Anomalies can be asymptomatic or cause chest pain, myocardial infarction, or even sudden cardiac death.

Case summary: We describe a 34-year-old man with a history of a single episode of chest pain. An ectopic origin on the part of the left circumflex (LCX) coronary artery from the proximal right coronary artery (RCA) was evident upon coronary computed tomography angiography. A positron emission tomography perfusion study revealed a stress-induced perfusion defect in the anomalous LCX territory (infero-posterior wall). The patient experienced dyspnoea and ST-segment depression in electrocardiography, suggestive of myocardial ischaemia during the maximal bicycle ergometer stress test. No mechanical compression or stenosis was seen upon invasive coronary angiography. The left ventricular perfusion normalized after the initiation of beta-blocker medication.

Discussion: Patients with CAAs especially benefit from a multimodality assessment of the vascular territories. In our case, the myocardial perfusion of the infero-posterior wall normalized after treatment with beta-blockers. This may be due to increased coronary vasodilation capacity and myocardial flow reserve, as well as reduced oxygen consumption. Beta-blockers may represent a viable option in low-symptomatic CAA patients with perfusion defect and no ostial stenosis or compression.

Keywords: Case report; Coronary anomaly; Left circumflex coronary artery; Myocardial ischaemia; PET perfusion.

Figure 1

Computed tomography coronary angiography of the left circumflex artery (LCX) and related cardiac structures. (A): Multiplanar reconstruction of the left circumflex artery. The left circumflex artery originates from the right coronary artery (RCA) and is located between the aorta (AO) and right atrium (RA). (B) Three-dimensional reconstruction of the coronary anatomy. LAD, left anterior descending coronary artery.

Figure 2

¹⁵O-water perfusion maps with absolute segmental perfusion values (mL/kg/min). Red/orange areas (perfusion values 2.3 mL/min/kg or more) have normal perfusion, and those in green represent regions of decreased perfusion. On the left: The stress perfusion before beta-blocker medication. Ischaemic (<2.3 mL/min/kg) perfusion values are bolded. On the right: The stress perfusion after 3 weeks of beta-blocker treatment. Areas with over 10% improvement are underlined.

Figure 3

Hybrid-image (combined ¹⁵O-water perfusion map and computed tomography angiography) before the initiation of beta-blocker therapy. On the left, a posterior projection with decreased perfusion in the ectopic left circumflex territory (yellow–green). On the right, an anterior projection with normal perfusion in the left anterior descending territory. LCX, left circumflex; LAD, left anterior descending; RCA, right coronary artery.

Figure 4

The patient was referred to undergo a bicycle ergometer test with a ramp protocol (20 W/min). The electrocardiography sample is presented from all 12 leads. The first and fifth columns represent electrocardiography samples at baseline (in the sitting position). Maximum ST-depressions developed in Leads II, III, aVF, and V6 at peak exercise (Columns 2–3 and 6–7). Recovery electrocardiography samples are presented in Columns 4 and 8 at 6 min 50 s after stress, when the electrocardiography had normalized.

Figure 5

Invasive coronary angiography of the ectopic left circumflex coronary artery (LCX) with an origin in the right coronary artery (RCA). There was no mechanical compression or stenosis during its course.