Background information 

The SARS CoV2 (COVID-19) pandemic, which is now entering its 3rd year, has wreaked unprecedented morbidity and mortality, the world over. Initially characterized as a severe and rapidly progressive respiratory distress syndrome, it quickly became apparent that COVID-19 infection also encompasses a variety of cardiac and vascular manifestations, including hypercoagulability with extensive formation of venous and arterial thrombus, acute coronary syndromes (ACS), ST-segment elevation myocardial infarction (STEMI) and sudden cardiac death. The risk for STEMI is now known to persist for several weeks after the onset of clinical COVID-19 infection.

The North American COVID-19 STEMI (NACMI) registry represents a collaboration between the Society for Cardiovascular Angiography and Interventions (SCAI), the American College of Cardiology (ACC) Interventional Council, and the Canadian Association of Interventional Cardiology (CAIC).

NACMI was established in 2020 to characterize the presentation profiles, treatment and outcomes for patients who were hospitalized with STEMI in the context of confirmed COVID-19 infection. A total of 64 North American centers contributed data to the NACMI Registry.

Dr. Garcia, on behalf of the NACMI Investigators, reported important differences in mortality as well as composite MACE outcomes occurring in these patients between 2020 and 2021, the latter timeframe corresponding to the availability of vaccines in North America.   

Why is this study important?

• The NACMI Investigators analyzed data from 586 patients: n=227 in the 2020 cohort and n=359 in the 2021 cohort. 
• In April 2021, Garcia et al. reported that the primary endpoint of in-hospital mortality for COVID-19 infection complicated by STEMI was 33% (75/227) in 2020, a figure which dropped to 23% (83/359) in 2021. 
• The notable reduction in COVID-19 STEMI mortality was likely related to the lower incidence of cardiogenic shock and concomitant pulmonary manifestations in 2021, both of which significantly increased mortality when present. 
• Vaccination data was available for 54% (193/359) of the 2021 cohort and found that 0% of vaccinated patients suffered in-hospital mortality while 22% of unvaccinated patients died in 2021, a value which is significantly higher than historical (pre-COVID-19) estimates of in-hospital STEMI mortality. 

What question was this study supposed to answer?  

• Wide global fluctuations in the incidence of STEMI were noted early in the pandemic (2020) with previously unseen drops in STEMI and ACS case volumes across the world.  This was also accompanied by data suggesting rising rates of out of hospital cardiac arrest and numerous anecdotal reports detailing that when STEMI patients did present, they often manifested a greater presentation acuity and more frequently had cardiogenic shock and larger thrombus burden in the culprit vessel, than historical correlates. 
• There were also published reports of “STEMI mimic” cases perhaps resulting from localized myocarditis in the absence of epicardial coronary occlusion. 
• The NACMI Registry sought to understand clinical trends and in-hospital outcomes of STEMI in patients with COVID-19 infection across the 2 years of the pandemic to date. 

What did the study show?

• Approximately 75% of patients were > 55 years of age, 70% were male, 70% had hypertension and roughly 45% had diabetes.  Average BMI in this study was 28 which falls into the overweight category. 
• As noted, a significant drop in in-hospital mortality (primary endpoint) was observed in the 2021 cohort as compared with the 2020 cohort. 
• The investigators also found a significant drop in the secondary composite endpoint of death, stroke, or a repeat myocardial infarction from 35% in 2020 to 25% in 2021. 
• The relative risk for in-hospital mortality was highest for patients with shock pre-PCI (relative risk, RR 2.762), those > 66 years of age (RR 1.802) and patients with infiltrates on chest Xray (RR 1.721). 
• STEMI mortality for unvaccinated COVID-19 patients remained unacceptably high in 2021 despite a better understanding of the underlying disease and advances in the management of these patients.   

All editors: Sandeep Nathan, MD, MSc, FSCAI