Induction of atrial fibrillation with rapid high voltage ventricular pacing for ventricular fibrillation conversion testing. The Ventak AV II DR Study

Induction of atrial fibrillation by implantable cardioverter-defibrillator shock: a forgotten entity

A 65-year-old patient received an implantable cardioverter-defibrillator shock that resulted in ventricular tachycardia termination but induction of atrial fibrillation. The possible consequences of this rarely reported event are discussed.

Does P-Wave Dispersion Predict the Atrial Fibrillation Occurrence After Direct-Current Shock Therapy?

Supraventricular tachycardia attacks, including atrial fibrillation (AF), occur after both external and internal cardioversions. These attacks of atrial fibrillation after direct-current (DC) shock may be related to hemodynamic impairment, thromboembolic events, or enhanced electrical instability of the ventricular and atrial myocardium, especially in predisposed patients. In this study, the authors aimed to show the importance of P-wave dispersion (PWD), which lead the atrium to fibrillate, in predicting post-DC shock AF after external cardioversion. Thus physicians may be able to choose the patients with high risk for AF occurrence and apply some other therapeutic modalities to those patients. The authors identified 18 patients in whom an AF attack was induced by urgent or elective cardioversion for a ventricular tachycardia attack and compared these patients with a control group composed of 40 patients without AF in regard to some clinical, echocardiographic, and electrocardiographic parameters. Left atrial diameters were greater (4.3 ±0.3 vs 3.5 ±0.5 cm, p=0.001), left ventricular ejection fractions (LVEF) were lower (45.2 ±8.2 vs 54.9 ±7.5, p=0.001), the energy needed for successful cardioversion was higher (166.6 ±59.4 vs 80.8 ±51.6 J, p=0.001), and P max (135.2 ±7.4 vs 118.7 ±10.5 ms, p=0.001) and PWD (53.8 ±12.2 vs 23.8 ±9.5 ms, p=0.001) values were higher in patients with AF when compared to those without AF. Thus, the patients with higher PWD values had a greater risk for development of AF after a DC shock.