Between fire and flood. Drug-induced QT prolongation causes torsades de pointes and electrical storm

Electrocardiography (ECG) is recommended for all patients undergoing anti-cancer therapy before and during treatment [1]. However, the problem of drug-induced QT interval prolongation is often underestimated, sometimes leading to severe consequences including life-threatening torsades de pointes (TdP). We describe here a case of a 50-year-old woman with no previous cardiac history and no chronic diseases requiring drug therapy, hospitalized at the Hematology Unit with a diagnosis of acute lymphoblastic leukemia. The patient received 2 rounds of initial chemotherapy – doxorubicin, vincristine and prednisolone. Unfortunately, further hospitalisation was complicated by severe atypical pneumonia and fungal infection. The patient’s condition was critical, requiring a week stay at the Intensive Care Unit. Chemotherapy was suspended and antibiotics (clarithromycin) and antifungal treatment (voriconazole) were introduced. After 2 weeks of therapy, the patient had a sudden cardiac arrest but was successfully reanimated. Her laboratory tests showed potassium 3.4 mmol/l (below normal), hemoglobin 8.0 g/dl (below normal), C-reactive protein 90 mg/l (above normal), D-dimer 12 µg/ml (above normal), and troponin T 0.058 ng/ml (normal). As frequent ventricular extrasystoles were observed, an amiodarone bolus of 300 mg was administered, and a cardiologist was consulted, who obtained an ECG. A sinus rhythm of 85/min with significant QT prolongation (QTc 580 ms) was observed (Figure 1 A), while in ECG performed at the patient’s admission to the hospital, QTc was normal, 456 ms. The patient was recommended to stop the QT-prolonging therapy and continue ECG monitoring. On echocardiography, the left ventricle ejection fraction was moderately decreased to 40%. Due to the clinical suspicion of pulmonary embolism, suggested by active cancer treated by chemotherapy, inverted T waves in leads V4–V6 on ECG (Figure 1 A) and an elevated D-dimer level, the patient underwent computed tomographic pulmonary angiography, which failed to detect any pulmonary embolisms. The patient’s clarithromycin and voriconazole were stopped, and the electrolyte depletion was corrected. However, due to the observed ventricular arrhythmia, amiodarone infusion was continued during the night shift.
The next morning, she experienced an electrical storm that recurred for several hours with multiple episodes of TdP (Figure 1 B) and cardiac arrests requiring defibrillation. The patient was transferred to...


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