The SARS-CoV-2 pandemic infection has been reported in 223 countries, with about 136 million cases and almost 3 million deaths since December 2019.1 Although the real mortality associated with COVID-19 remains unknown, the current global case fatality reported across countries ranges from 0.2% (in Germany) to 7.7% (in Italy).2 Cardiovascular disease, diabetes and age have been outlined as risk factors for poorer outcomes in COVID-19 patients.3

The clinical presentation varies widely, from asymptomatic or mild flu-like symptoms to acute severe respiratory distress syndrome and systemic complications impacting several organs. Cardiovascular complications from COVID-19 infection are being reported more frequently, ranging from silent myocardial injury to thromboembolic events, acute coronary syndromes, cardiogenic shock and arrhythmias.4

Arrhythmias have been described in 17% of the hospitalized cases and in almost 50% of patients in the intensive care units (ICU), probably with a potential contribution to a higher risk of adverse outcomes, with an increased risk of in-hospital death.5 There are various reported series of different types of arrhythmias, including bradycardia (less common), sinus tachycardia and atrial arrhythmias (atrial fibrillation [AF] and atrial flutter) and ventricular dysrhythmias, including cardiac arrest.4,6

In the study “Cardiac arrhythmias in patients presenting with COVID-19 treated in Portuguese hospitals. A national registry from Portuguese Association of Arrhythmology, Pacing and Electrophysiology”, published in this issue of the Journal, Dinis Mesquita et al. present the results of a survey conducted by the Portuguese Association of Arrhythmology, Pacing and Electrophysiology to assess the occurrence of arrhythmias in COVID-19 patients in 20 Portuguese hospitals.7 They report data from 692 hospitalized patients, with arrhythmic episodes in 11.7% of the cases, including paroxysmal supraventricular tachycardia, atrial flutter and AF (the most common, being recurrence of previously existing arrhythmia in 35.9%), bradycardia and ventricular tachycardia. Surprisingly, none had arrhythmia-related complications nor arrhythmic death despite their elderly age (mean 73.5 years; minimum 61, maximum 80.3), associated comorbidities in a large majority of the reported arrhythmias (79.7%), and more severe COVID-19 disease, with mechanical ventilation, hemodynamic instability and multiple organ failure (in those patients with supraventricular arrhythmias) and high mortality rate (31.3%).

Although continuous cardiac rhythm monitoring was obtained only in the subgroup of 393 patients admitted to the ICU or with continuous cardiac monitoring, with detailed information available limited to 79% of the cases with documented arrhythmias, these are useful real clinical data for our understanding of the severity and impact of arrhythmias in COVID-19 infection.

The survey also reports the assessment of QT interval during hospital admission in 443 patients under therapy with ritonavir/lopinavir, hydroxychloroquine or azithromycin. Interestingly, despite medication capable of QT prolongation in 76.6% of the cases with arrhythmias, only seven patients (10.9%) had an increased QTc interval (ranging between 480 ms and 596 ms).

As pointed out by the authors, the availability of continuous cardiac monitoring in only 56.8% of the population poses strong limitations to the conclusions of the registry. Of course, it seems that the occurrence of arrhythmias (mostly supraventricular) is a common finding, particularly in patients with co-morbidities and more severe COVID-19 manifestations, but data from the whole population could identify clinical variables associated with higher risk of new onset (or reappearance) of arrhythmias, and contribute to a better approach to this specific group of patients.

According to the most recent literature, risk factors for the appearance of arrhythmias are: respiratory insufficiency, myocardial strain and ischemia or myocarditis, cardiogenic shock, sepsis or systemic inflammation, hyperactivity of the sympathetic nervous system, hypercoagulability status, electrolyte disturbances, and proarrhythmic drug side effects.4,6,8 Therefore, the incidence of arrhythmias in patients with COVID-19 is a likely consequence of systemic illness and not solely the direct cardiac effect of the infection.