Poor Clinical Outcomes Reported in Patients With COVID-19 and Myocarditis

Myocarditis secondary to COVID-19 infection increases risk for poor clinical outcomes in patients who are hospitalized.

Among patients with COVID-19-associated myocarditis, poor clinical outcomes have been reported, including significantly higher in-hospital mortality and major adverse cardiovascular events, according to findings from a Nationwide Inpatient Sample (NIS) Database study published in The American Journal of Cardiology.

Since the onset of the COVID-19 pandemic in March 2020, most related deaths have been linked to cardiovascular complications, such as myocarditis, pericarditis, acute coronary syndrome, thromboembolic events, arrhythmias, and sudden cardiac death.

Data in the NIS database from 2020 were analyzed. The primary study outcome was in-hospital mortality. Secondary outcomes were heart failure (HF), acute kidney injury (AKI), stroke, cardiogenic shock (CS), sudden cardiac arrest (SCA), and mechanical circulatory support (MCS), along with major adverse cardiovascular and cerebrovascular events (MACCEs). MACCEs comprise a composite of in-hospital death, cardiogenic stroke, myocardial infarction (MI), and stroke. The use of percutaneous coronary intervention and percutaneous coronary angiography (PCA) was evaluated as well.

In 2020, a total of 1,678,995 weighted hospitalizations for COVID-19 were identified, with only 3565 of them linked to myocarditis. Patients with COVID-19 infection and myocarditis were younger than individuals with COVID-19 without myocarditis (59.6±21.6 years vs 62.6±18.4 years). Moreover, patients with COVID-19 and myocarditis were predominantly men (59.9% vs 52.0%) and were not White patients (54.3% vs 47.0%).

The most common comorbidities reported in the group with COVID-19 and myocarditis compared with the group with COVID-19 without myocarditis included fluid and electrolyte imbalance (67.0% vs 50.0%), cardiac arrhythmias (43.9% vs 24.5%), hyperlipidemia (38.6% vs 39.2%), and complicated diabetes (29.9% vs 26.1%). 

Large prospective trials are necessary to validate these findings with diagnostic measures, including biopsy and cardiac magnetic resonance imaging for the extent of myocardial involvement.

According to an unadjusted analysis, a higher likelihood of in-hospital mortality, HF, MI, stroke, CS, SCA, AKI, temporary use of MCS, and MACCEs was reported among participants with COVID-19 with myocarditis than in individuals with COVID-19 without myocarditis.

Following adjustment for baseline demographics and comorbidities, per propensity-matched analysis, a matched sample of 630 patients was obtained for each of the groups. Results of the propensity score matching  analysis closely reflected those of the crude analysis, with the adjusted outcomes of in-hospital mortality, MI, HF, CS, use of MCS, MACCE, and AKI remaining significantly higher in those with COVID-19 and myocarditis compared with patients with COVID-19 without myocarditis. No significant difference in SCA and stroke was observed between the 2 groups, however.

Per multivariate regression analysis, patients with COVID-19 with myocarditis compared with those with COVID-19 without myocarditis had a higher adjusted likelihood of the following:

  • In-hospital mortality (odds ratio [OR], 1.59; 95% CI, 1.27-1.90)
  • CS (OR, 10.20; 95% CI, 7.90-1.30)
  • SCA (OR, 1.43; 95% CI, 1.04-1.97)
  • MCS use (OR, 2.81; 95% CI, 1.60-4.90)
  • HF (OR, 2.77; 95% CI, 2.30-3.40)
  • MACCE (OR, 3.54; 95% CI, 2.80-4.40)
  • AKI (OR, 1.29; 95% CI, 1.27-1.90)

Further, the presence of myocarditis among patients hospitalized for COVID-19 infection was associated with a longer length of stay (12.2±13.0 days vs 8.0±9.5 days) and higher adjusted total hospitalization-related charges ($223,992±$335,201 vs $101,398±$194,987).

The use of PCA and percutaneous coronary intervention in patients with COVID-19 and myocarditis was 6.45% and 0.42%, respectively. Use of invasive PCA was significantly higher among patients with myocarditis that was complicated by CS compared with patients without any such complication (13.9% vs 5.3%, respectively;
P <.001).

A key limitation of the study is the intrinsic nature of the cross-sectional NIS database, because the diagnosis of myocarditis is based on International Classification of Disease, Tenth Edition, Clinical Modification (ICD-10-CM) code, thus, selection bias regarding the cohort may exist. Additionally, longitudinal follow-up data are unavailable since NIS data are “snapshot in-hospital outcomes only.” Further, the potential exists for several selection and observational biases.

“Large prospective trials are necessary to validate these findings with diagnostic measures, including biopsy and cardiac magnetic resonance imaging for the extent of myocardial involvement,” the researchers wrote.


Sattar Y, Sandhyavenu H, Patel N, et al. In-hospital outcomes of COVID-19 associated myocarditis (from a Nationwide Inpatient Sample Database study). Am J Cardiol. Published online January 29, 2023. doi:10.1016/j.amjcard.2023.01.004