Two cardiologists review an ECG demonstrating ST-segment elevation on a tablet.


Differentiating ST-Segment Elevation Myocardial Infarction from Myocarditis in COVID-19 Patients

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

Related Articles: Diagnostic ECG

While COVID-19's most devastating effects tend to target the lungs, cardiovascular complications are frequent and portend a poor prognosis. A study of 416 patients in Wuhan, China published in the Journal of the American Medical Association (JAMA) found that 19.7% of patients had cardiac injury defined by an elevated high-sensitivity troponin level. Mortality was 51.2% in those with cardiac injury versus 4.5% in those without (p< .001).

Myocardial injury as determined by troponin elevation is common in the sickest COVID-19 patients, and ECG plays a crucial role in differentiating thrombotic coronary occlusion (ST-segment elevation MI) from other causes. In turn, this will help ensure patients get the most effective treatment plans and avoid unnecessary cath lab activations.

COVID-19-Associated Myocarditis and Myopericarditis

Emerging evidence suggests myocarditis specific to SARS-CoV-2 may be playing a role in the cardiac injuries and ECG changes associated with COVID-19. A brief report from Italy published in JAMA Cardiology in late March described a 53-year-old, otherwise healthy woman with COVID-19 who presented with fatigue, fever, and cough. A 12-lead ECG showed diffuse T-wave inversion. Echocardiographic and MRI imaging were consistent with myopericarditis with severe LV dysfunction.

Another case report published in the Lancet in late April described a 69-year-old man from Italy with ARDS due to COVID-19. The ECG on admission to the ICU showed voltage criteria for LVH in the precordial leads, with diffuse inverted T waves, which were a change from prior ECGs. Due to elevated troponin levels, there was concern about acute type 1 myocardial infarction, and the patient was taken to coronary angiography, which demonstrated normal coronaries. Cardiac MRI was suggestive of myocarditis.

Four cases published in Circulation in April focused on the variety of cardiovascular manifestations in severe COVID-19 disease. Two of these cases had ECGs showing T-wave inversions (one inferior and one inferolateral) and had clinical presentations consistent with COVID-19-associated myocarditis.

An initial ECG for a 64-year-old woman presenting with chest pressure and troponin elevation, however, showed sinus tachycardia and ST elevation in leads I, II, aVL, and V2-V6, as well as PR elevation and ST depression in aVR. She was taken for urgent coronary angiography, which demonstrated nonobstructive coronary artery disease. Her subsequent evaluation and course were consistent with myopericarditis.

These cases demonstrate that patients with severe COVID-19 and nonspecific myocardial injury present with a variety of ECG changes, ranging from diffuse T-wave inversions to ST-segment elevation. Cardiologists should not rely solely on elevated troponin levels, but exercise caution when reading patient ECGs and consider reciprocal depression.

STEMI in Patients with COVID-19

A case series published in the New England Journal of Medicine (NEJM) brings home the point that COVID-19 patients can have standard STEMI, which must be quickly differentiated from ECG changes due to myocarditis.

Cardiologists at six New York hospitals identified eighteen patients with COVID-19 who presented with ECG features suggesting STEMI. Nine of these patients underwent coronary angiography, and two-thirds of those who were studied invasively were presumed to have obstructive disease. The 12-lead ECG on all eighteen patients can be viewed in the supplementary appendix, along with still frames of the coronary angiograms. Five patients underwent percutaneous coronary intervention.

After review of all clinical information, 8/18 were presumed to have MI, and 10/18 were presumed to have noncoronary myocardial injury.

ST-segment elevation was diffuse in 4/10 noncoronary cases and none of the acute MI cases, whereas focal ST-segment elevation was present in 6/10 noncoronary cases, versus all of the coronary cases.

All eight patients with coronary obstruction had lateral ST-segment elevation, versus only 1/10 without obstruction. The ECG below was from a patient with thrombotic coronary occlusion. It shows lateral ST-segment elevation with reciprocal ST depression in leads V1 and V2.

Differentiating-ST-Elevation - Image 1.png

Peak troponin I (normal <.06 ng/ml) levels ranged from 4.4 to 853 ng/ml in the patients diagnosed with true STEMI, and from 0.024 up to 80 in those presumed to have noncoronary myocardial injury.

The authors speculated that "Myocardial injury in patients with COVID-19 could be due to plaque rupture, cytokine storm, hypoxic injury, coronary spasm, microthrombi, or direct endothelial or vascular injury."

The NEJM series suggests that true STEMI ECG changes are more likely to be focal and to involve the lateral precordial leads than noncoronary ST-segment elevation. Reciprocal ST depression was also much more common in the true STEMI group.

Differentiating STEMI from COVID-19 Myocardial Injury

As these cases demonstrate, it can be a daunting task differentiating ST-segment elevation due to STEMI from elevation due to COVID-19-associated myopericarditis. More data on the specific ECG changes associated with COVID-19 disease is needed.

The most common findings in myocarditis, according to a November 2019 review in the Annals of Noninvasive Electrocardiology, are sinus tachycardia and nonspecific ST/T-wave changes.

PR-segment depression, a marker for pericarditis associated with myocarditis—whether it is due to COVID-19 or some other etiology—is the most useful finding. PR-segment depression in both precordial and limb leads, or in leads with ST-elevation, favors the diagnosis of myopericarditis rather than myocardial infarction.

As one of the COVID-19 cases from the NEJM series illustrated, PR-segment elevation in aVR also favors pericarditis rather than acute MI. The ECG below from a noncoronary case in the series exhibits PR-segment depression in the lateral precordial leads along with diffuse ST-segment elevation consistent with myopericarditis.

Differentiating-ST-Elevation - Image 2.png

Ultimately, as these case reports demonstrate, front-line physicians will need to use all the tools at their disposal to diagnose cardiac conditions in patients with COVID-19 accurately, including biomarkers, echocardiography, MRI, and coronary angiography. Given its ubiquity, inexpensiveness, and noninvasiveness, ECG remains the cornerstone of clinical care and early diagnosis of both myocarditis and STEMI.