An electrocardiogram (ECG) records the electrical activity as it travels through the heart. The QT interval refers to the electrical signal from the moment the ventricles of the heart contract until the resting ventricles cease and are measured in milliseconds.
A new study examined the association between QT prolongation and long-term mortality in patients hospitalized with COVID-19. In addition, it assessed the link between prolonged QT interval and myocardial injury, a condition in which cells in the heart die.
Scientists found that a simple ECG can pinpoint hospitalized COVID-19 patients at high risk of mortality which might need intensive management. In particular, a prolonged QT interval on the ECG was an independent risk factor for myocardial injury and one-year mortality.
Lead author Dr. Ariel Banai of Tel Aviv Sourasky Medical Center, Israel, said, “An ECG is an inexpensive, non-invasive, easily attainable and widely available test applied in nearly all hospitalized patients. Our study suggests that a simple ECG tracing performed upon admission may help healthcare professionals triage patients with COVID-19 and identify those in need of intensive care.”
For this study, scientists studied 335 consecutive hospitalized patients. All the patients had an ECG done upon admission.
If patients showed reduced function on echocardiogram, they were considered a myocardial injury. An echocardiogram is an ultrasound of the heart and/or had troponin in the bloodstream. Troponin is a protein found only in heart cells. When the heart is damaged, for example, troponin is released into the bloodstream in myocardial injury.
Based on the duration of the QT interval, patients were divided into two groups:
- 109 patients (32.5%) had a prolonged QT interval.
- 226 patients (67.5%) had a normal QT interval.
Compared to those with a normal QT interval, patients with a prolonged QT interval were older (70 years on average versus 63 years), more often had co-existing conditions such as hypertension, diabetes, and congestive heart failure, and presented more frequently with severe (as opposed to mild) COVID-19.
71.6% of people with QT prolongation had myocardial injury compared to 110 (48.7%) with a normal QT interval. Prolonged QT poses two times increased risk of myocardial injury after adjusting for age, co-existing conditions, and severity of COVID-19.
Dr. Banai said: “Interestingly, among patients with myocardial injury, half had no troponin in the blood, suggesting blood tests alone may miss many patients with this heart problem.”
At one year, 41% of patients in the prolonged QT group had died, contrasted with 17% in the normal QT group. QT prolongation was related to a 1.85 times increased risk of mortality within a year after adjusting for age, co-existing conditions, and severity of COVID-19.
When scientists classified patients into four groups based on myocardial injury (yes/no) and QT prolongation (yes/no), those with both conditions had a 6.6-fold higher likelihood of one-year mortality than patients without QT prolongation and no myocardial injury.
Dr. Banai said: “In our study, one-third of hospitalized COVID-19 patients had a prolonged QT interval. These patients were generally older and sicker, but prolonged QT interval was independently associated with worse survival even after adjusting for these factors. More studies are needed to confirm our observations, but the results indicate that ECG assessment could play a role in the risk stratification of patients admitted with COVID-19 infection.”
The abstract “QT interval prolongation is a novel predictor of one-year mortality in patients with coronavirus disease-19 infection” will be presented during the session “Moderated ePosters – Diagnostic methods to improve arrhythmia therapy,” which takes place on 4 April at 13:10 CEST.