CLINICAL AND ANGIOGRAPHIC PROFILE OF MYOCARDIAL INFARCTION WITH NONOBSTRUCTIVE CORONARY ARTERIES ( MINOCA )

Routray S. N. 1 , Tripathy S. K. 2 , Satpathy C. 3 , Mohanty N.K. 3 and Dash B.K. 4 . 1. Professor , Dept. of Cardiology, S.C.B.Medical College. Cuttack, Odisha, India. 2. Senior Resident, Dept. of Cardiology, S.C.B.Medical College. Cuttack, Odisha, India. 3. Asso. Professor , Dept. of Cardiology, S.C.B.Medical College. Cuttack, Odisha, India. 4. Asst.Professor , Dept. of Cardiology, S.C.B.Medical College. Cuttack, Odisha, India. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History Received: 10 February 2019 Final Accepted: 12 March 2019 Published: April 2019


…………………………………………………………………………………………………….... Introduction:-
Although the occurrence of an acute myocardial infarction without significant coronary artery disease (CAD) was initially reported almost 80 years ago, 1 the term MINOCA (myocardial infarction with nonobstructive coronary arteries) has been used only recently to describe these patients. 2 In keeping with the definition of MINOCA outlined in the 2016 European Society of Cardiology position paper, 3 the term MINOCA should be reserved for those patients with an AMI (as defined by the "Third Universal Definition of Myocardial Infarction" 4 ) in the absence of obstructive coronary arteries and no other clinical findings to suggest alternative causes for the elevated cardiac biomarkers.
Coronary angiography may identify normal coronaries or minimal disease in patients with MINOCA. 'Significant' or " obstructive CAD" or "MICAD " is defined by lesion > 50% stenosis. There are various modifiable and non modifiable risk factors of acute myocardial infarction like diabetes, hypertension, dyslipidemia ,obesity, physical inactivity, age, family history of myocardial infarction, smoking and psychosocial stress.
This study has been designed to evaluate the prevalence, risk factors, clinical and angiographic profie in patients of acute myocardial infarction with non-obstructive coronary arteries (MINOCA).   Among the obstructive CAD group Single vessel disease dominated the picture by about 54.2% followed triple vessel disease 19% and double vessel disease 18.0% and left main disease was present in 9.5%.

Discussion:-
The diagnosis of MINOCA requires: (1) documentation of a acute myocardial infarct, (2) exclusion of obstructive CAD (3) no overt specific cause for the AMI presentation 5,6 . The diagnosis is made usually following invasive coronary angiography. Obstructive CAD is defined as an epicardial coronary artery stenosis of ≥50 % on angiography 7 . Hence, a stenosis < 50 % is required for the diagnosis of MINOCA 8,9 .
In our study, twenty-Five of 274 patients (9.1%) admitted for acute myocardial infarction (MI) were classified as MINOCA. It was 8% in study by Javier Lopez Pais et al 10  Compared to our study (4.0% vs 1.0%), study by Ramnath V S et al 13 (6.6% vs 11.9%) was associated with higher prevalence of peripheral arterial disease in patients with MINOCA and obstructive CAD respectively.
In our study among the MINOCA patients, 50.6% had recanalised vessel with non obstructive lesion, 24% had normal coronaries and 12% had slow flow. There is equal distribution of about 2.7% for Coronary anomalies, myocardial bridging and coronary thrombus each. In a study by Javier Lopez Pais et al 10 the most prevalent pathophysiological mechanisms of MINOCA were plaque disruption (25%) and stress myocardiopathy (25%). Other mechanisms were coronary spasm (13.6%), coronary embolus (9.1%) and coronary artery dissection (2.3%). In 11.4% of the patients they did not find the mechanism.

Limitation
The disparity in the value obtained in this study when compared to the other studies is mainly because of the ethnic and racial differences in various regions. The differences in values can be also attributed to the different methods and materials used in assessing the patients.
In addition to the conventional coronary angiogram, other imaging modalities like CMR, IVUS and OCT is needed to identify the potential pathological mechanism involved in this disorder. Due to financial constraint additional imaging modalities were not done in our study.

Conclusion:-
In our study, MINOCA was more common in younger age group, females and patients with NSTEMI. Cardiovascular risk factors like Diabetes , Hypertension and smoking were less prevalent in MINOCA group and risk factors like dyslipidemia, obesity, family history of CAD and presence of PAD were similar in both the groups. In coronary angiography Recanalised and minimally obstructive lesion was found to be the commonest one followed by normal coronaries in MINOCA patients.
However, it could be a chance finding due to small sample size, and it needs to be substantiated by a large ongitudinal study, so that it will help to reduce morbidity and improve quality of life.

Conflict of Interest -Nil
Financial support-Nil