This patient had sick sinus
This patient had sick-sinus syndrome and also took sotalol for the prevention of VT related to ARVC. Therefore, constant atrial pacing was indispensable for maintaining a physiological atrial rhythm. Frequent right ventricular pacing is known to cause left ventricular dysfunction, myocardial perfusion defects, abnormal septal contractility, and heart failure in some patients [7,8]. Therefore, it appears possible that the semagacestat ventricular pacing that occurred after the dislodgement of the atrial lead caused exacerbation of her chronic heart failure.
ICD lead implantation through a PLSVC is often challenging and sometimes unsuccessful . A loop on the lead across the tricuspid valve can result in higher mechanical stress, making it prone to lead failure [10,11]. Furthermore, this patient may need an upgrade from an ICD to a cardiac resynchronization therapy device in the near future because of the presence of cardiomyopathy, but a left ventricular (LV) lead implantation via a PLSVC seems difficult. A recent paper has demonstrated both successful ICD  and LV [13,14] lead implantation through a small branch communicating between a PLSVC and the right-sided venous drainage. However, as in our case, the PLSVC and right superior vena cava are not connected by a communicating branch in 40% of cases (Fig. 2A) . Thus, before the implantation procedure, the PLSVC system should be carefully inspected for any communicating branches or appropriate lateral coronary veins using detailed venography.
The current generation of ICDs is also capable of achieving acceptable defibrillation thresholds when placed in the right pectoral region . However, the easier method of performing a right-sided ICD implantation in patients with both a PLSVC and dextral dominance may cause an unusual form of lead dislodgement. To prevent an iatrogenic complication after an unavoidable right-sided implantation, such as that reported here, tightening of the suture on the lead fixation sleeve should be recommended.
Conflict of interest
Disclosures and funding sources