COVID-19 vaccination in patients with long QT syndrome

Inherited long QT syndrome (LQTS) is a genetic heart disease characterized by a prolongation of QT interval on the electrocardiogram (ECG) and an increased risk for sudden cardiac arrest and sudden cardiac death. The QT interval is the measure of the time the electrical excitation and recovery process of the heart takes. Because of COVID-19 pandemic, COVID-19 vaccination has become unavoidable management for most populations. In such a new era of the pandemic, the potential threats from COVID-19 vaccines that patients with inherited arrhythmia syndromes start to face have also evoked a lot of awareness. Current worldwide COVID-19 vaccines are composed of two major categories: messenger ribonucleic acid(mRNA)-based vaccines and viral vectored vaccines. These vaccines help defend against the virus, but people also stand a potential risk of adverse reactions mediated by the immune response. Fever is one of the potential issues. Attention to body temperatures is necessary because febrile status could make patients with electrical heart diseases vulnerable to life-threatening arrhythmic events (LAEs). Although the effect of fever has potentially much less impact in patients with LQTS, type 2 LQTS (LQT2) patients with particular genetic defects might be a possible exception. At higher temperature, fever-triggered arrhythmias probably happened. Hence, adequate precautions for fever after COVID-19 vaccination may be prudent for patients with LQT2.

Myocarditis, an inflammation of the heart muscle, is a rare, severe complication following COVID-19 vaccination (prevalence, 0.0013-0.003%1), particularly associated with mRNA-based vaccines, especially second dose, in males aged 16-29. All these patients had chest pain, and symptoms began around 2.4 days (1–16 days). The vaccine-related myocarditis also contributes to QT prolongation, which will further put patients at risk of arrhythmogenic events. Therefore, if an LQTS patient experiences myocarditis, monitoring the QT interval seems a reasonable precaution.

Postural orthostatic tachycardia syndrome (POTS) is another rare condition that may result from COVID-19 vaccination (prevalence, 0.27%2). It is characterized by a noticeable increase in heart rate with symptoms after standing (e.g., light-headedness, weakness, palpitations, blurred vision, breathing difficulties, nausea, or headache). The majority of cases with POTS were females at a young age, and the underlying mechanism of POTS after COVID-19 vaccines is still unclear. During tachycardia, the QT interval normally should be shortened. However, the genetic deficit related to LQT1 would make the QT interval fail to shorten adequately after tachycardia. Therefore, if these patients have any sign of POTS after COVID-19 vaccination, monitoring the ECG may also be reasonable in the initial phase and no medicine is currently specific in this situation. We know that β-blocker plays an important role in LQTS, and adherence to this medicine has been emphasized. However, it is also an agent to worsen POTS. Whether this condition leads to a change in medication in LQTS patients need additional attention. Taken together, COVID-19 vaccines could be an LQTS agitator, and these simple preventative measures seem prudent. To be sure, the risk-benefit calculus favors that patients with LQTS or any other genetic heart disease get vaccinated if age-eligible and then get boosted when time-eligible.


  1. Wong HL, Hu M, Zhou CK, et al. Risk of myocarditis and pericarditis after the COVID-19 mRNA vaccination in the USA: a cohort study in claims databases. Lancet. 2022 Jun 11;399(10342):2191-2199.
  2. Blitshteyn, S., Fedorowski, A. The risks of POTS after COVID-19 vaccination and SARS-CoV-2 infection: it’s worth a shot. Nat Cardiovasc Res1, 1119–1120 (2022).


Link to full article.

Translated by Cheng-I Wu, Taipei Veterans General Hospital, Taipei, Taiwan.

Wu CI, Schwartz PJ, Ackerman MJ, Wilde AAM. COVID-19 vaccination in patients with long QT syndrome. Heart Rhythm O2. 2022 Aug 3. doi: 10.1016/j.hroo.2022.07.011. Epub ahead of print. PMID: 35937046; PMCID: PMC9345651.