Reposting a thread by Frank Han MD Pediatric/ACHD/GUCH Cardiologist @han_francis on the Thai study, “Cardiovascular Effects of the BNT162b2 mRNA COVID-19 Vaccine in Adolescents (Preprint)”, in response to the comments of Tracy Hoeg, MD, Phd @TracyBethHoeg


OK, lets analyze this study properly. This study out of Thailand used the prospective cohort method to attempt to characterize the rate of myocarditis and its clinical/ lab/ EKG/ echo findings in a group of > 300 students 1/9

The findings as presented in the tweet are a distortion by someone who did not take into account what normal pediatric EKG findings are; the study listed above did not take pre-vaccination EKGs. (2/9)

The structure of the study was essentially, enroll some students, give informed consent for vaccination, and see what lab/ imaging/ EKG findings exist after COVID vaccination #2. They also calculated an estimated rate of myocarditis based upon this cohort. (3/9)

The overall conclusions mirror what has been produced by several health departments, but I push back the strongest on what readers consider to be abnormal EKG findings: (4/9)

I can make the strongest pushback on sinus arrhythmia – this is not a matter of opinion, this is a fundamental pediatric cardiology fellow learning point. Sinus arrhythmia is the natural variation in respiratory rate in kids. It is grossly misleading to call this abnormal. (5/9)

Sinus tachycardia just means the heart rate is faster than normal for age. By itself, this is insufficient to diagnose myocarditis but is one of the most sensitive findings on EKG for myocarditis. (6/9)

Ectopic atrial rhythm is highly likely to be normal in the absence of other cardiac abnormalities. Junctional escape rhythm is known to occur in well trained athletes especially during sleep but must be measured formally. (7/9)

PACs and PVCs are also quite common in kids; it is their quantity that is one of the determining factor of how much cardiologists worry. In the absence of baseline EKGs, it is harder to call the above EKGs not normal (especially when lots of kids already have this). (8/9)

Conclusion: this article supports the prior work and A tweet associated with

@HealthyFla doesn’t necessarily mean the writer knows how to deal with pediatric EKGs. (9/9) There’s really nothing stunning to the trained observer.



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