Prodromal ventricular premature beats preceded by a diastolic wave

Area of Science:

• Cardiology
• Electrophysiology
• Pharmacology

Background:

• Quinidine is an antiarrhythmic drug used for atrial fibrillation/flutter.
• Quinidine can cause potentially fatal ventricular tachyarrhythmias like ventricular tachycardia (VT) and ventricular fibrillation (VF).
• Predictive markers for quinidine-induced VT/VF are crucial for patient safety.

Purpose of the Study:

• To identify novel electrocardiographic (ECG) predictors of quinidine-induced ventricular tachyarrhythmias (VT/VF).
• To investigate the diagnostic significance of a specific ECG pattern, the diastolic wave (DW) followed by a ventricular premature beat (VPB), in patients on quinidine therapy.

Main Methods:

• Prospective ECG monitoring of 71 patients with atrial fibrillation/flutter starting quinidine therapy for four days.
• Analysis of ECG recordings for Q-T prolongation, diastolic waves (DWs), and ventricular premature beats (VPBs).
• Comparison of findings in patients who developed VT/VF with those who did not, and with cases of long Q-T syndrome and myocardial infarction.

Main Results:

• Six out of 71 patients developed VT/VF within 48 hours of starting quinidine.
• Q-T prolongation was common but not predictive of VT/VF.
• A diastolic wave (DW) preceding a ventricular premature beat (VPB) was observed in 5 of 6 patients with VT/VF, and in none of the 63 patients without VT/VF.
• DW-VPBs were present in patients with idiopathic long Q-T/Brugada syndrome but absent in myocardial infarction patients with VT/VF.

Conclusions:

• The diastolic wave (DW) preceding a ventricular premature beat (VPB) is a highly specific potential predictor of quinidine-induced ventricular tachyarrhythmias.
• The amplitude of the DW may correlate with the risk of developing VT/VF.
• Further research is warranted to determine if the DW initiates ventricular tachyarrhythmias.