PMC7418230_01
Electrocardiogram on admission demonstrates atrial fibrillation with premature ventricular complexes, a ventricular rate of 95 beats per minute, and corrected QT of 473 ms. Bazett formula is used to correct the QT interval (QTc) for heart rate. There is no consensus regarding the measurement of QT interval in patients with atrial fibrillation. Some suggest averaging the measured QT interval over 10 beats or averaging the QT intervals with the shortest and longest preceding RR intervals. In the above electrocardiogram, it is difficult to discern the QT interval for 10 successive beats. Hence the QT interval is calculated by averaging the shortest and longest QT interval.
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Initial electrocardiogram (ECG) demonstrated AF with premature ventricular complexes and a corrected QT (QTc) interval of 473 ms (Figure 1).
Electrocardiogram obtained during the previous hospitalization 6 months ago while on sinus rhythm demonstrates sinus bradycardia with a heart rate of 55 beats per minute and corrected QT (QTc) of 498 ms as per Bazett formula.
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The patient was found to have prolonged QTc at baseline ranging from 460 to 510 ms on reviewing several ECGs from previous admissions (Figure 2).
Chest X-ray on admission shows patchy bilateral opacities.
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Chest X-ray showed diffuse bilateral patchy opacities (Figure 3).
Computed tomography of the thorax shows diffuse bilateral ground-glass opacities.
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Computed tomography scan of the thorax demonstrated worsening diffuse bilateral ground-glass opacities (Figure 4).
Electrocardiogram on hospital day 2 demonstrates sinus bradycardia with a ventricular rate of 54 beats per minute, inferolateral deep T-wave inversions, and corrected QT of 718 ms per Bazett formula. Notably, the heart rate decreased significantly compared with day 1, and rhythm reverted to sinus likely related to intubation, mechanical ventilation, and usage of sedative agents such as propofol.
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Repeat ECG showed sinus bradycardia with first-degree heart block, deep T-wave inversions in the inferolateral leads, and markedly prolonged QTc of 718 ms (Figure 5).
The telemetry strip on day 5 demonstrates a self-terminating episode of polymorphic ventricular tachycardia. Note the varying amplitude, axis, and duration of QRS complexes suggestive of torsade de pointes (TdP). At the beginning of the strip, there are 2 runs of bigeminy (narrow complex QRS followed by a premature ventricular complex [PVC] at the end of the T-wave). The PVC rising in the third beat initiates TdP.
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On hospital day 5, the patient developed recurrent self-terminating episodes of TdP without hemodynamic collapse (Figure 6).
Electrocardiogram on day 20 demonstrates atrial fibrillation with prolonged QTc of 622 ms. The QT intervals are corrected for preceding RR intervals using Bazett formula and averaged over 9 successive beats in lead V4.
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Unfortunately, on hospital day 20, the patient had several runs of ventricular tachycardia/ventricular fibrillation with underlying prolonged QTc of >600 ms, culminating in cardiac arrest and death (Figures 7 and 8).
The telemetry strip on day 20 demonstrates ventricular tachycardia associated with hemodynamic collapse.
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Unfortunately, on hospital day 20, the patient had several runs of ventricular tachycardia/ventricular fibrillation with underlying prolonged QTc of >600 ms, culminating in cardiac arrest and death (Figures 7 and 8).