No difference in thrombotic profile of patients with ACS with obstructive CAD and MINOCA
Authors: Kanji R , Gue Y.X , Dinarvand D , Gorog D.A 
Published: November 2020

Abstract

Introduction
Acute coronary syndrome (ACS) is caused by disruption of an atherosclerotic plaque with initiation of thrombosis, and outcome determined by the balance between prothrombotic drivers and the efficacy of endogenous fibrinolysis. Most patients have obstructive coronary artery disease (CAD), with high shear forces and turbulent flow across severe stenoses enhancing platelet activation. Recognition that some ACS patients have myocardial infarction (MI) with non-obstructive coronary arteries (MINOCA) has led to a search to identify drivers behind such presentations.

Purpose
To assess and compare the thrombotic status of patients with MINOCA and those with ACS due to obstructive CAD.

Methods
In a prospective observational study in patients with ACS, thrombotic and thrombolytic status was assessed from venous blood using the point-of-care Global Thrombosis Test, assessing time to in vitro occlusive thrombus formation under high shear (occlusion time,OT) and time taken for spontaneous lysis of the thrombus (lysis time,LT). Blood was taken after dual antiplatelet therapy loading, but before fondaparinux or heparin administration. Those with renal or hepatic impairment, bleeding diathesis, thrombocytopenia or on anticoagulation were excluded. MINOCA diagnosis was made according to the Fourth Universal Definition of MI, in the absence of obstructive CAD (no lesion ≥50%) and excluding patients with 1) other overt causes for elevated troponin, 2) overlooked obstructive CAD, and 3) nonischaemic causes for myocyte injury, according to the American Heart Association 2019 recommendation. Patients with Type 2, 4 and 5 MI were excluded.

Results
We assessed 746 patients, of whom 621 (83%) had ST-segment elevation MI (STEMI) and the rest non-STEMI. Of these, 706 (95%) had obstructive CAD and 40 (5%) had MINOCA. Apart from sex (78% obstructive CAD patients were male vs 50% MINOCA patients), cardiovascular risk factors were similar in MINOCA and obstructive CAD patients (smoking 28 vs 31%, p=0.615; hypertension 35 vs 47%, p=0.153; diabetes 20 vs 20%, p=0.948; hyperlipidaemia 30 vs 36%, p=0.475 and family history of premature CAD 35 vs 35%, p=1.000). There was no difference in time to form occlusive thrombus (OT 424 [371–471] vs 395 [287–512] s, p=0.093) or in endogenous fibrinolysis (LT 1450 [1082–2099] vs 1582 [1252–2130] s, p=0.178) between MINOCA and obstructive CAD patients. Even after propensity score matching with a ratio of 3:1 for clinical characteristics, there was no difference between patients with MINOCA and those with obstructive CAD, with respect to thrombus formation (OT 424 [371–471] vs 430 [300–538] s, p=0.602) or endogenous fibrinolysis (LT 1470 [1082- 2099] vs 1494 [1140–2074] s, p=0.625).

Conclusion
Amongst patients with ACS, those with MINOCA exhibit similar thrombotic profiles to patients with obstructive CAD with ACS. This represents a potential therapeutic target to modulate risk post myocardial infarction in patients with MINOCA and requires further research.

Funding Acknowledgement
Type of funding source: None