#10. COVID and ECG: Clinical Evidence

Hi, I am Dr. Nicola Cosentino. Welcome to this podcast series on COVID-19 and ECG, sponsored by GE Healthcare. Today’s topic will be on clinical evidence on COVID and ECG.

After two and half years of facing cardiovascular patients with COVID-19, we have more and more appreciated the close association between COVID-19 and ECG. I would start from two points.

Thus far, the medical evidence show that cardiovascular patients have not an increased risk of SARS-CoV2 infection but, when they have the SARS-Cov2 infection, they have a significantly higher risk of complications as compared to those patients without a history of cardiovascular disease. So, the next question is: does COVID-19 affect the myocardium? And the answer is yes: COVID-19 can cause myocardial injury through several mechanisms both ischemic and non-ischemic, including cytokine storm effects and direct myocardial injury. When myocardial injury occurs, as assessed by the increase in high-sensitivity troponin levels in these patients, early mortality increases up to 10 times. The mechanisms underlying the association between COVID-19 and acute myocardial injury are the same responsible for ECG alterations. Indeed, thus far no specific ECG changes have been described in COVID-19 patients so that we might assume the infection does not translate into characteristics ECG manifestations in the majority of patients; however, in severe COVID-19 patients, ECG acute changes may occur and they reflect the mechanisms underlying the ongoing acute cardiac injury.

Several studies have been published focusing on ECG manifestations during SARS-CoV2 infection. Indeed, the QRS complex is wider in COVID-19 patients with elevated troponin or brain-natriuretic peptide values and this is the same for the QTc interval which has been shown to be longer in patients with elevated troponin or brain-natriuretic peptide values. So that when myocardial injury occurs during SARS-CoV2 infection, the QRS complex becomes wider and the QTc interval longer. Importantly, the more severe is the clinical picture in terms of respiratory and hemodynamic impairment, the longer is the QTc. Not only the QTc correct is associated with the clinical picture and with the ongoing acute myocardial injury, but also QTc dispersion does. QTc dispersion is the difference between the longest and shortest QTc interval in the 12-lead ECG.

In COVID-19 patients, the more severe is the clinical picture and the longer is the QTc dispersion; moreover, QTc dispersion is greater in non-surviving patients and this ECG parameter is a critical prognostic marker especially in younger patients (<65 years) hospitalized with COVID-19. QTc dispersion mainly depends on the difference in T wave morphology across the 12 leads. Interestingly, about 5% of hospitalized COVID-19 patients show a new T wave inversion in the ECG. If T wave inversion occurs, mortality is about 25%, while the need of invasive mechanical ventilation is 30%. In addition, when ECG alterations occur with simultaneous increase in troponin value, overall survival may be only 50% in COVID-19 hospitalized patients, so that ECG and troponin have a synergist prognostic effect. In particular, if new T wave inversion occurs in all leads and troponin levels are increased, in-hospital mortality may rise up to 80%.

Finally, it is important to repeat ECG along hospitalization: in particular, ECG at 7 day is critical as the cytokine storm occurring during COVID-19 usually is present between day 5 to day 15. If ECG at 7 days is abnormal, especially if it shows an increase in heart rate > 20% or a new acquired wide QRS complex, the rate of in-hospital mortality and the need of oro-tracheal intubation is very high. Similar data have been observed when investigating the prognostic impact of new ST-segment alterations. Of note, the presence of ST-segment deviation is associated with higher troponin values and with a worse prognosis, particularly if this occurs later during hospitalization (again at 7 days since hospital admission), as it reflects the ongoing oxygen supply/demand imbalance due to arterial hypotension, hypoxemia, sepsis, and anemia, or less frequently, due to coronary plaque activation, disruption, and thrombosis

Not only ECG may be acutely abnormal but also the risk of arrhythmia is common among COVID-19 patients. Indeed, 20% of hospitalized COVID-19 patients have cardiac arrhythmias (atrial or ventricular) and a higher incidence has been observed among those requiring ICU admission (nearly 50%) with malignant ventricular arrhythmias (ie, ventricular tachycardia/fibrillation) occurring in 6% of COVID-19 patients requiring ICU admission. All spectrum of arrhythmias has been observed in hospitalized COVID-19 patients (ICU and non-ICU wards), but the most frequent ones are sinus tachycardia (about 40% of patients), premature ventricular complex (about 25%), atrial fibrillation (about 12%, new-onset Atrial fibrillation about 6%), and non-sustained VT (nearly 15%). However, the most dangerous arrhythmias, most closely associated with a worse prognosis, are: new onset high-degree AV block, new-onset atrial fibrillation with rapid ventricular rate; polymorphic VT, and sinus tachycardia with new LBBB. If these arrhythmias are encountered, the risk of invasive mechanical ventilation and the risk of needing ECMO or even dying during hospitalization may be high.

Regardless of the underlying arrhythmia, faster heart rates are always an ominous sign as they reflect the ongoing respiratory and hemodynamic impairment. Therefore, ECG is very useful when managing COVID-19 patients as any ECG alterations, by reflecting the ongoing acute cardiac injury, identify those patients at higher risk of complications who need to be closely monitored and urgently treated.

Thank you for listening to this podcast on clinical evidence in ECG and COVID. The next podcast of this series will be on who to ECG monitor in COVID patients.

References:

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Kang Y, Chen T, Mui D, Ferrari V, Jagasia D, Scherrer-Crosbie M, Chen Y, Han Y. Cardiovascular manifestations and treatment considerations in COVID-19. Heart. 2020 Aug;106(15):1132-1141.

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