Lessons Learnt from Case Series of Out-of-hospital Cardiac Arrest and Unexpected Death after COVID-19 Vaccination

Figures

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  Figure 1.. Several types of early repolarization patterns are encountered in electrocardiographic (ECG) health screening. The J point is defined as a junction of the QRS complex and ST segment (arrows). This point elevation by ≥0.1 mV above baseline is considered a normal variant of early repolarization (A). A hump is observed immediately after the QRS complex with its amplitude by ≥0.1 mV above baseline and defined as one of the patterns of early repolarization (B). A slurry is observed at the end of the QRD complex with its inflection amplitude by ≥0.1 mV above baseline as one of the early repolarization patterns (C). All of these patterns are called J waves and are sometimes observed in the same young healthy male athlete and included in early repolarization syndrome as a normal variant [cited from ref. (14) with permission].

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  Figure 2.. Actual recording of an ECG showing J waves in the consecutive left precordial leads (V4-V6) in the case described in the text (21). J waves are so prominent that the QRS complex is combined with the ST-T segment (A), forming triangular waves, sometimes known as lambda (Λ) waves (B), lean-tower-like waves (C), or shark-fin-like waves (D).

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  Figure 3.. A schematic illustration of the genesis of a prominent J wave. The intrinsic physiological transmural voltage gradient across the ventricular free wall causes a small J wave immediately after the QRS complex as a normal variant. The endocardial action potential configuration differs from that of the epicardial action potential, which shows a clear phase 1 notch and shorter action potential duration (A). Myocarditis causes infiltration of inflammatory cells, tissue edema, and loss of myocytes. Although these pathological changes are transmural in COVID-19 vaccine-related myocarditis, the location and severity of inflammatory damage depend on the specific case. When depression of electrical activity is predominant in the epicardium relative to the endocardium, the transmural voltage gradient is augmented, yielding the prominent J wave in myocarditis (B).

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  Figure 4.. An ECG stored in the automated external defibrillator (AED) showed ventricular fibrillation (VF) before the DC shock (arrow in the upper panel) and ventricular tachycardia (VT) after the shock delivery, which transformed spontaneously to the idioventricular rhythm (middle panel) in the case described in the text (23). A prominent J wave was observed (arrowheads) in the middle and lower panels. The vertical and horizontal bars indicating 1.0 mV and 500 millisecond (lower panel), respectively, apply to all panels.

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  Figure 5.. Twelve-lead ECG of a 26-year-old Japanese man with out-of-hospital cardiac arrest recorded immediately (A) and several minutes (B) after arrival at the emergency room. The ECG data in this case (23) had been obtained at a school health checkup when he was 15 years old (C). The dynamicity of the J wave lasting several minutes is evident. A: The J wave is so prominent that the QRS complex is combined with the ST-T segment, forming a triangular wave. B: Residual J waves with upward polarity are observed in I, II, aVF, V5, and V6 (notch), while those with inverse polarity are recorded in aVR (notch) and V1-V2 (slur). The AED-stored ECG generally resembles the II lead ECG, as external pads are placed on the right upper and left lower chest wall. Therefore, the ventricular wave observed in the AED after successful defibrillation (middle and lower panels of Fig. 4) is concluded to contain the prominent J wave (arrowheads) by comparison with the II lead ECG (A) as a reference. The vertical and horizontal bars indicating 1.0 mV and 500 millisecond, respectively, in panel B apply to all the panels.

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  Figure 6.. Screening algorithm of idiopathic ventricular fibrillation (VF) triggered by J wave augmentation in teenagers, due to cardiac condition (health and disease, hypertrophy, fibrosis, aging, intrinsic transmural electromechanical gradient), autonomic nervous system (tonic and phasic sympathovagal interaction), electrolyte balance (Na+, K+, Ca2+, and Mg2+), etc., for human idea but due to deep-learning large amount of historical ECG datasets and other health records for artificial intelligence (AI). Deep-learning convolutional neural networks consist of three layers: an input-learning phase, self-training phase, and output-modeling phase, including binary determination concerning the occurrence of VF. *Personal health records may include COVID-19 vaccination data, although this vaccination is voluntary for teenagers in Japan.