Acute Cardiac Complications of COVID-19: What We Know Now

GE Healthcare

After 18 months and millions of infections worldwide, troves of patient data have uncovered new answers about the links between COVID-19 and cardiac complications.

New information regarding COVID-19 continues to emerge daily. This content was based on the sources available at the time of writing.

When SARS-CoV-2 first emerged, it created many questions about how the virus would impact the cardiac care continuum. Now, after many months and millions of infections worldwide, troves of patient data have revealed new answers about the acute cardiac complications of COVID-19.

These new insights have confirmed some prior beliefs, such as the hypothesis that preexisting cardiovascular disease is a major risk factor for COVID-19 severity and mortality. But the data has also raised new concerns about issues such as the risk of false MI diagnosis and the potential for rare effects in otherwise healthy patients.

While more research is still needed, here's what we know about the acute cardiac complications of COVID-19.

A Fundamental Shift in Understanding

One of the most significant changes in cardiologists' understanding of COVID-19 relates to how the virus affects the heart muscle. Previously, experts posited that SARS-CoV-2 damaged cardiac tissue directly, and this notion was supported by the fact that patients had high troponin values.

But additional insights have challenged those beliefs, given the propensity for COVID-19 patients to have elevated troponin. Instead of the virus causing direct damage to the heart, it's now believed that the heart is—as the American College of Cardiology (ACC) puts it—a "bystander of injury."1

While some concerns about issues such as myocarditis and stress cardiomyopathy may still exist, most of the heart damage that was once credited to COVID-19 directly is now viewed as a secondary consequence of the systemic inflammation caused by the virus.

Importantly, this revised understanding does not undermine the value of troponin, which may still be a predictor for MI. However, providers shouldn't assume that high troponin indicates a viral cause of cardiac injury without corroborating through other diagnostic means. As the European Heart Journal: Acute Cardiovascular Care notes, these additional diagnostic measures may include ECG and echocardiogram.2 Accordingly, the ACC advises that troponin only be evaluated if the clinician suspects MI based on clinical factors.3

Acute Cardiac Complications of COVID-19

Early in the pandemic, cardiologists began to report that arrhythmia and conduction disorders were among the most prevalent cardiac complications of COVID-19. Now that more data has emerged, these conditions are still the most commonly seen, although their prevalence appears to have dropped slightly from earlier estimates.

As more becomes known about the heart's role as a bystander of inflammation rather than a direct target, experts predict that these adverse acute effects are likely due to cardiac inflammation, rather than the impact of the virus itself.

According to the study published in the European Heart Journal, out of an international patient registry of more than 3,000 hospitalized patients, arrhythmia (particularly Afib) and conduction disorders occurred in 8.6% of patients, down from 16.7%, which was the rate given by a February 2020 study in JAMA.4 However, the ACC adds that, unlike cardiac arrest, Afib is not necessarily tied to higher mortality.5

A few other problems identified by the research are also worth noting. For instance, it was found that 0.5% of hospitalized patients had ACS, with MI still being a possibility as well. Myocarditis was very rare at 0.1%, and another study in JAMA showed zero incidence of myocarditis.6

While preexisting cardiovascular disease (CVD) has been found to roughly double the risk of fatality among hospitalized patients according to research in PLoS ONE, people without known underlying heart conditions may still be susceptible to acute cardiac complications.7 The European Heart Journal found that 57.8% of hospitalized patients with cardiac complications had no known preexisting cardiac disease. However, very often these complications involve Afib, which doesn't drive mortality.

Additionally, other complications may arise in patients who have recovered from an infection—such as postural orthostatic tachycardia syndrome (POTS) and myocarditis (ACC).8

How Complications May Present on ECG

Whether a patient has COVID-19 or not, a range of factors can warrant a 12-lead ECG, including chest pain and heart rate concerns, as the American Heart Association notes.9 Cases involving high troponin will also benefit from corroboration with ECG, as the infection can drive abnormalities in lab values.

If an ECG is conducted, look for the following waveform characteristics:


Afib is the significant ECG-related pathology which can occur even without preexisting cardiac disease. Look for these findings:

  • Heart Rate: Slow-to-rapid (V); can be too low or too high depending upon ventricular response to chaotic atrial arrhythmia
  • Rhythm: Irregular
  • P Wave: Absent fibrillatory (F) waves
  • QRS: < 0.12 seconds

Acute Cardiac Injury

As the American Journal of Emergency Medicine Notes, it can be challenging to differentiate myocardial injury from STEMI and myocarditis because they can have similar ST and T-wave changes.10 In particular, providers should look for these signs of acute cardiac injury:

  • ST deviations (up or down)
  • T-wave inversion
  • Pathologic Q waves

Myocardial Infarction

Graphs on Healio provide a comprehensive overview of the waveforms to watch for MI, though researchers have noted that it can be difficult to distinguish these indications from those of other acute injuries.11 Other factors that may help inform a STEMI diagnosis include:

  • Focal ST elevations (However, differentiating between STEMI, myocarditis, and myocardial injury may be difficult when using ECG for ST segment elevation. Corroborating with other factors such as chest pain may be helpful.)
  • Chest pain presentation
  • Focal wall motion abnormalities with depressed LV function on echocardiogram

Stay on top of cardiology trends and best practices by browsing our Diagnostic ECG Clinical Insights Center.

Looking Toward the Future

While we've learned a great deal in 2020 and 2021, there are still more insights to uncover, particularly as new variants and vaccines exert a push and pull effect.12 Given the remaining unknowns in the areas of reinfection, immunity, and long-term heart impacts, clinicians should continue to consider potential COVID-19 complications and diligently utilize essential tools such as ECG as they provide cardiac care.



  1. Chilazi M, Duffy E, Thakkar A, Michos ED. Intermediate and long-term impact of covid-19 on cardiovascular disease. American College of Cardiology. Accessed October 28, 2021.

  2. Linschoten M, Peters S, van Smeden M, et al. Cardiac complications in patients hospitalised with COVID-19. European Heart Journal: Acute Cardiovascular Care. 2020;9(8):817–823.
  3. Key questions on covid-19 and cardiovascular disease. American College of Cardiology. Accessed October 28, 2021.

  4. Wang D, Hu B, Hu C, et al. Clinical Characteristics of 138 Hospitalized Patients With 2019 Novel Coronavirus–Infected Pneumonia in Wuhan, China. JAMA. 2020;323(11):1061–1069.
  5. Crawford TC. Covid-19 and cardiac arrhythmias. American College of Cardiology. Accessed October 28, 2021.

  6. Lindner D, Fitzek A, Bräuninger H, et al. Association of Cardiac Infection With SARS-CoV-2 in Confirmed COVID-19 Autopsy Cases. JAMA Cardiol. 2020;5(11):1281–1285.
  7. Ssentongo P, Ssentongo AE, Heilbrunn ES, et al. Association of cardiovascular disease and 10 other pre-existing comorbidities with COVID-19 mortality: A systematic review and meta-analysis. PLOS ONE. August 2020;15(8). Accessed October 28, 2021.
  8. Mukherjee D. Prevalence of myocarditis in competitive athletes with SARS-COV-2. American College of Cardiology. Accessed October 28, 2021.

  9. When to perform an ECG? American Heart Association. Accessed October 28, 2021.

  10. Long B, Brady WJ, Bridwell RE, et al. Electrocardiographic manifestations of COVID-19. Am J Emerg Med. 2021;41:96-103.
  11. Lome S. Top 5 mi ECG patterns you must know. Healio. Accessed October 28, 2021.

  12. Rauseo AM, O'Halloran JA. What Are the Clinical Implications of the SARS-CoV-2 Variants: 5 Things Every Cardiologist Should Know. JACC: Basic to Translational Science. 2021;6(3):305-308.