1336074 - Diagnostic value of cardiac MRI in patients with Myocardial Infarction with Non Obstructive Coronary Arteries (MINOCA)

Acute coronary syndrome is a leading cause of mortality and morbidity in the world¹. Hence, definitive diagnosis is crucial for ensuring appropriate medical management. In patients with acute Myocardial Infarction (MI), coronary angiography is performed with an aim to identify and treat the culprit coronary artery lesion². In up to 14% of these patients, no significant coronary obstruction is identified and thus these cases are classified as myocardial infarction with non-obstructive coronary arteries (MINOCA)³.

 


Patients with MINOCA are thought to have a better prognosis ; however, recent studies suggest that all-cause mortality may be as high as 4.7% at 12 months⁴. Confirmation or exclusion of MI by CMR facilitates tailoring of medical therapy, ensuring appropriate long-term secondary prevention and minimizing exposure to antiplatelet therapy for those with a non-coronary etiology for the MINOCA presentation³. Previous studies have shown that cardiac MRI (CMR) can identify the underlying diagnosis, most commonly acute myocarditis, acute MI with spontaneous recanalization, Takotsubo cardiomyopathy or other cardiomyopathies⁵.


Methods:

Inclusion criteria:

Patients satisfying the definition of acute MI according to modified 4^th universal criteria with non-obstructive coronary arteries (< 50% stenosis) by coronary angiogram presenting within 1 week of onset of symptoms for CMR.

Exclusion criteria:

Patients with alternate explanation for troponin elevation, eGFR < 30 ml/min, fibrinolytic therapy for qualifying MI event, prior history of obstructive coronary artery disease/cardiomyopathy/myocarditis or any other standard contraindication for MRI were excluded from the study.

50 consecutive patients fulfilling the study criteria were enrolled for the study after prior informed consent.

CMR Protocol: CMR was performed in a Philips Ingenia 1.5T MRI scanner. A comprehensive CMR protocol was carried out including cine sequences, STIR, T1/T2 mapping and late gadolinium enhancement (LGE) imaging. Intravenous gadolinium-chelate contrast agent (gadoterate meglumine) was administered at a dose of 0.1 mmol/kg body weight.  LGE images were acquired 15 min after contrast injection using a standard inversion recovery gradient echo sequence.

 


All CMR studies were analysed and reported by a trained cardiovascular radiologist.


Results:

Between August 2021 and August 2022, 50 patients (27 men and 23 women) with a working diagnosis of MINOCA were included in the study (Age range: 18 to 70 years). A definite diagnosis was made after CMR in 35 cases (70%). Diagnosis of acute MI was made in 16 cases (32%), acute myocarditis in 16 cases (32%) and hypertrophic cardiomyopathy in 3 cases (6%). CMR was normal in 15 cases (30%).



Conclusion: Data from this on-going registry from India will shed light on prevalence of the etiology of MINOCA in a hitherto unstudied heterogenous population from India and also provide data to support incorporation of CMR more widely into diagnostic algorithms in India