A patient-level pooled analysis of the Disrupt CAD I-IV Studies including 628 patients reported no arrhythmias [
1]. One case of self-limiting atrial fibrillation caused by capture beats during S-IVL to the proximal RCA has been reported [
3]. Furthermore, one case of atrial flutter during S-IVL to the proximal left anterior descending artery has been reported [
4]. The Disrupt CAD III Study included 431 patients treated with S-IVL [
2]. Heart rhythm assessment was evaluable in 416 patients. IVL-induced capture beats were seen during S-IVL in 41.1% of cases. S-IVL-induced capture beats did not result in sustained ventricular tachycardia or VF during or immediately after the procedure in any patient and were not associated with adverse events. Cox regression analysis identified heart rate ≤ 60 bpm, male sex, and total number of S-IVL pulses delivered as independent predictors of S-IVL-induced capture beats. To the best of our knowledge, VF caused by S-IVL has only been reported once previously [
5]. In that case report, a spontaneous ventricular ectopic beat was followed by a compensatory pause before the next sinus beat and then a S-IVL capture beat during repolarization causing VF. The patient’s spontaneous ventricular ectopic beat caused a short–long–short sequence which may act as one susceptibility-substrate for the S-IVL triggered VF. The patient in the present case had sinus bradycardia during the procedure which, according to the data presented above, increases the risk of capture beats. Furthermore, the patient's ECG showed a long QT interval, especially in the ECG taken immediately after the procedure. The long QT interval makes the heart more vulnerable to VF which is frequently preceded by one or more premature ventricular beats coupled to the prolonged QT segment of the preceding basic beat [
7]. The combination of S-IVL, sinus bradycardia and long QT interval might explain the episodes with VF. The R-on-T phenomenon occurs when a ventricular premature (spontaneous or paced) complex falls during a vulnerable period of repolarization. If the R-on-T phenomenon is caused by a pacemaker, or as in this case S-IVL, it is often related to ventricular under sensing problems or asynchronous pacing [
8]. The S-IVL causes asynchronous pacing when the S-IVL results in capture beats. Thus, the potential life threatening complication described in the present case could potentially be avoided by electrocardiography synchronized S-IVL to avoid causing capture beats in the vulnerable period of the cardiac cycle. The most common cause of arrhythmias, including VF, during coronary intervention procedures is ischemia. Also in this case, ischemia is a potential alternative trigger of VF.