Diagnosis and prognosis of myocardial infarction in a patient without obstructive coronary artery disease during bronchoscopy: a case study and literature review

BACKGROUND: It is increasingly recognized that a significant proportion of patients suffered from acute myocardial infraction (AMI) who did not have obstructive coronary artery disease (≥50% diameter stenosis). The term “MINOCA (myocardial infarction with nonobstructive coronary arteries)” was coined for such entity, however, the exact mechanism of MINOCA is still unclear. Herein, we report a patient with MINOCA during bronchoscopy and further review the recent literature. CASE PRESENTATION: A 65-year-old woman was hospitalized with the main complaint of chest tightness, nausea and vomiting for 30 min during bronchoscopy under local anesthesia. Immediate electrocardiogram (ECG) showed ST-segments elevation in leads V2–6 compared with those at admission, and the further evolvement of leads V2–3 into pathological Q wave. Serum cardiac biomarkers revealed high-sensitive cardiac troponin T (hs-cTnT) levels of 20.12 ng/L and 674.6 ng/L at the peak (normal range 0-14 ng/L). Emergency coronary angiography (CAG) showed only approximate 30% stenosis in the left anterior descending (LAD) ostium and 40% stenosis in the first diagonal branch (D1), with quantitative flow ratio (QFR) value for LAD of 0.96. Moreover, her echocardiographic examination presented new significant abnormal wall motion (anterior ventricular wall) with an estimated left ventricular ejection fraction (LVEF) of 62.1% after the cardiac attack. Thoracic enhanced CT scanning indicated no obvious sign of pulmonary embolism. Therefore, with confirmed AMI and the absence of significant coronary stenosis simultaneously, MINOCA was diagnosed with the prescription of dual-antiplatelet, statins, beta-blocker, angiotensin receptors antagonist, calcium channel blocker and nitrate. This patient had a good prognosis during a follow-up of 14 months. CONCLUSION: In this case, bronchoscopy might have caused extremely tense and anxious which led to a sympathetic hyperfunction and acute coronary thrombosis induced by plaque disruption and coronary artery spasm. QFR value is a feasible technique to evaluate the functional coronary stenosis and assist the diagnose of MINOCA. Also, the diagnosis of MINOCA deems an exploration of underlying causes for proper management and prognostic evaluation.