VF was observed in four patients (group A) with preexcited AF presenting to the emergency department who had been given 12 mg of adenosine. These patients were resuscitated and underwent electrophysiological study and catheter ablation of the accessory pathway (AP). In a control (group B) of five patients with manifest AP, sustained AF was induced by rapid atrial pacing during electrophysiological study and 12 mg of adenosine was administered. The ECG and electrophysiologic features in the two groups were compared. All patients had a single manifest AP. In group A, three patients had a left free-wall AP and one patient had a posteroseptal AP, while in the control group all had left free-wall APs. The antegrade AP effective refractory period (ERP) in groups A and B was 227 +/- 29 and 289 +/- 37 ms, respectively (P < 0.05). The atrial ERP was 210 +/- 17 versus 219 +/- 21 ms, respectively, in groups A and B (P > 0.05). The shortest R-R interval during AF in group A was 246 +/- 51 ms and 301 +/- 60 ms in group B (P value < 0.05). After adenosine, no patient in group B developed VF. Adenosine may cause VF when administered during preexcited AF. This phenomenon is seen in patients having APs with short refractory periods.

WT may be detected by its attenuated ultrasound pattern versus a non-attenuated pattern for RT by IVUS. This technique has potential for characterizing WT and RT.

Patients undergoing ICD implantation for NICM and NS-VT receive appropriate ICD therapy at a greater rate than those implanted for ICM, NS-VT, and a positive EPS. Although these data do not prove survival benefit in NICM, they suggest a beneficial effect.

No abstract