A 27-year-old man from Cape Verde with rheumatic mitral stenosis had undergone mitral valve repair (MVR) in childhood. Two months prior to admission, he underwent mechanical MVR and tricuspid annuloplasty. Postoperative echocardiography showed mildly reduced systolic function (left ventricular ejection fraction (LVEF) 40–50%), interpreted in the context of abnormal interventricular septal motion, commonly observed after cardiac surgery. Additionally, the patient was in atrial fibrillation at that time. Although the conditions were suboptimal for precise regional wall motion assessment, no abnormalities were identified. Immediately after surgery, the patient developed transient complete atrioventricular block and exhibited a junctional rhythm at approximately 50 bpm, requiring VVI pacing (80 bpm) for hemodynamic optimization, which limited electrocardiogram (ECG) monitoring.

The patient presented with malaise, palpitations, dyspnea, and nausea starting five days prior to hospital admission. ECG showed atrial flutter with 1:2 transmission. Echocardiography demonstrated severe biventricular dysfunction (LVEF ∼10%) with preserved prosthetic function. Cardiogenic shock ensued, progressing to pulseless electrical activity. After resuscitation and prolonged CPR, venoarterial extracorporeal membrane oxygenation (VA-ECMO) was instituted. ECMO was removed after five days, with LVEF improvement to 15–20%.

Coronary angiography was performed at this time to exclude an ischemic etiology. It revealed left dominance and complete occlusion of the mid-left circumflex (LCx) with distal reperfusion and no other lesions (Figure 1). Percutaneous coronary intervention was attempted: a hydrophilic wire achieved distal re-entry after subintimal tracking, but aspiration thrombectomy was ineffective. Stepwise predilation with noncompliant balloons up to 3 mm/26 atm failed to achieve adequate expansion (Figure 2), precluding safe stent implantation. Final angiography confirmed persistent LCx occlusion.

Figure 1.

Complete occlusion of the mid-left circumflex.

Figure 2.

NC balloon 3 mm/26 atm failed to achieve adequate expansion.

Cardiac magnetic resonance imaging showed subendocardial late gadolinium enhancement in the inferior and inferolateral walls (LCx territory) with viable myocardium. Computed tomography coronary angiography demonstrated close proximity of the LCx to the mechanical mitral valve, supporting mechanical distortion as the occlusion mechanism (Figure 3).

Figure 3.

CT coronary angiography: close proximity of the LCx to the mechanical mitral valve.

Surgical correction or bypass was considered inappropriate by the heart team. Referral for heart transplantation evaluation was considered; however, given the presence of potentially reversible factors, including uncontrolled atrial arrhythmia, and the absence of guideline-directed medical therapy for heart failure with reduced ejection fraction, this option was deferred. The agreed strategy was close follow-up within a specialized heart failure clinic, allowing for timely reassessment should clinical deterioration occur. The patient underwent cavotricuspid isthmus ablation for recurrent flutter. At discharge, he was asymptomatic with optimized heart failure therapy.

Circumflex (LCx) artery injury is a rare but serious complication of mitral valve surgery, particularly in left-dominant circulation due to the close anatomical relation between the LCx and mitral annulus.1,2 Most cases present acutely.3 In this case, delayed diagnosis was likely related to echocardiographic imaging challenges and masked ischemic ECG changes due to junctional rhythm and ventricular pacing. PCI was unsuccessful due to fixed vessel kinking. While extended intraoperative imaging may not always be feasible, earlier routine postoperative transthoracic echocardiography could help detect new regional wall motion abnormalities. Furthermore, serial cardiac biomarker assessment and heightened awareness in high-risk anatomies may facilitate earlier recognition of this complication. Awareness of this complication is crucial, as management options are limited and outcomes remain challenging.1–3