Case Presentation: A 23-year-old male college student with no PMH or significant FH presented to the ER with a 12hr history of recurrent substernal chest pain associated with diaphoresis, dyspnea, nausea and vomiting. Initial vitals were BP 129/82mmHg, HR 94 bpm, RR 18 breaths/min, SpO2 100% on RA and afebrile. No significant findings on examination. Initial investigations revealed total CK 1320 U/L, CKMB 47 ng/ml, troponin I 18 ng/ml (peaking at 32) and EKG with ST elevations in the inferolateral leads, atrial fibrillation and RBBB. CBC, BMP, TFTs and urine toxicology screen were WNL. Echocardiogram showed no regional wall motion abnormality, pericardial effusion or valvulopathy. Cardiac catheterization showed normal angiographic coronaries. Patient received aspirin 325mg and started a β-blocker and statin. Post cardiac catheterization pt had persistent ST elevations in V3-V6 and inferior leads however the Afib had converted to NSR. Work up for hypercoaguable states was negative. TEE was done and ruled out PFO and left atrial appendage thrombus. Patient was discharged on Xarelto, atorvastatin and metoprolol. Echocardiogram done two months later was normal.
Discussion: Myocardial infarction with non-obstructive coronary arteries (MINOCA) is an important clinical entity with increasing recognition since the advent of cardiac catheterization. Overall prevalence is estimated at 6% of MIs with a mean age of 55 years [1], younger than those with established coronary artery disease. Only 33% of patients present with STEMI. MINOCA is diagnosed by clinical features of acute MI and coronary angiography reveals <50% lesions and there is no other apparent cause. Traditional risk factors like HTN, DM, smoking and FH of premature CAD are similar in these patients except they are less likely to have hyperlipidemia. Causes include myocarditis in one third of patients, subendocardial infarct in less than one third and majority have no identifiable cause. When compared to pts with MI and CAD, MINOCA pts have significantly reduced all-cause mortality at 12 months, however it is the same as pts with MI with single or double vessel CAD (3.2%) [2]. These patients therefore should not be ignored. Medical therapies were analyzed in one study and showed a 23%, 18% and 14% reduction with statins, ACEi/ARB and β-blockers respectively, for major adverse cardiovascular events in at 1 year follow up [4]. Dual antiplatelet therapy did not meet statistical significance. In this case of an unusually young patient coronary embolism secondary to atrial fibrillation was the postulated mechanism. Chronic Afib is a known cause of MINOCA however there is no statistical data attached to this. Anticoagulation was commenced for possible paroxysmal Afib which may be discontinued later pending follow up.
Conclusions: Myocardial infarction with nonobstructive coronary arteries is a rare condition with increasing recognition in a younger population. These patients carry an increased risk of morbidity and mortality and therefore should not be ignored.