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MI With Nonobstructive Coronary Arteries vs. AMI With Obstructive CAD
Study Questions:
What is the prognosis after myocardial infarction (MI) with nonobstructive coronary arteries (MINOCA) among patients ages ≥65 years? And how do the outcomes compare with patients with acute myocardial infarction with obstructive coronary artery disease (MICAD)?
Methods:
Data from patients undergoing coronary angiogram for acute MI (AMI) from the National Cardiovascular Data Registry CathPCI Registry (July 2009-December 2013) were linked with claims data from the Centers for Medicare and Medicaid. MICAD was diagnosed in patients with ≥50% stenosis in an epicardial vessel. The primary endpoint was major adverse cardiac events (MACE) at 12 months, defined as all-cause mortality, re-hospitalization for AMI, heart failure (HF), or stroke. The secondary endpoints were MACE over 12 months.
Results:
Among 286,780 admissions for AMI, 276,522 unique patients were admitted for AMI; of these, 18,849 (5.9%) had MINOCA. MACE at 12 months were lower for MINOCA vs. MICAD patients (18.7% vs. 27.6%, p < 0.001). Similarly, mortality (12.3% vs. 16.7%), re-hospitalization for AMI (1.3% vs. 6.1%), and HF (5.9% vs. 9.3%) were lower in MINOCA patients (p < 0.001), but similar for stroke (1.6% for MINOCA vs. 1.4% in MICAD, p = 0.128). In comparison to MICAD, patients with MINOCA had a 43% lower adjusted risk of MACE over 12 months (hazard ratio, 0.57; 95% confidence interval, 0.55-0.59).
Conclusions:
Patients ages ≥65 years with MINOCA undergoing coronary angiography have an unfavorable prognosis, with one in five suffering MACE over 12 months.
Perspective:
Although major adverse outcomes are statistically lower among patients with MINOCA compared to those with MICAD, this study underscores the high rates of complications and adverse events in this population. Approximately 5% of patients with MINOCA die within 30 days of diagnosis and almost 40% are re-hospitalized within a year. In this study, MINOCA patients were slightly younger, more likely to be female (77.0% vs. 41.5%; p < 0.001), and more likely to be black (10.2% vs. 6.4%; p < 0.001). In addition to demographic differences, more attention to the heterogeneous underlying etiologies for MINOCA require further attention. Microvascular dysfunction, coronary plaque disruption, epicardial vasospasm, thrombosis, and embolism have been proposed mechanisms, but more granular data and attention to each patient’s underlying etiology is needed to make recommendations about optimal medical therapy for MINOCA. This study also reported that dual antiplatelet therapy did not impact outcomes in MINOCA, thus highlighting the need for more research into the underlying mechanisms in this diverse and understudied population.
Keywords: Acute Coronary Syndrome, CathPCI Registry, Constriction, Pathologic, Coronary Angiography, Coronary Artery Disease, Coronary Thrombosis, Coronary Vasospasm, Embolism, Geriatrics, Heart Failure, Myocardial Infarction, National Cardiovascular Data Registries, Stroke, Women
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