We thank Dr. Hoşoğlu for his thoughtful letter in response to our recent report describing implantable cardioverter-defibrillator (ICD) lead placement via the left inferior phrenic vein (LIPV). In patients with prior tricuspid valve repair or replacement, conventional ICD lead placement in the RV is less desirable. In such cases, anatomically guided alternative routes deserve consideration.1

Catheter ablation for atrial fibrillation (AF) is superior to pharmacological rhythm control in certain patient populations, and there is evidence that early rhythm control improves patient outcomes and results in decreased disease progression [1]. The safety of AF ablation should be the priority with advances proposed in recent years ranging from refining the method and energy delivery of ablation to various device-related strategies to improve esophageal protection.

Radiation therapy can cause a malfunction of cardiac implantable electronic devices (CIEDs) due to electromagnetic interference (EMI) or an overcurrent. Although rare, such malfunctions may lead to life-threatening outcomes. One reported case described inappropriate ventricular pacing caused by software errors in an implantable cardioverter defibrillator (ICD), which led to ventricular tachycardia1. Another case reported rapid atrial pacing due to pacemaker software errors, resulting in hypotension2.

Inappropriate sinus tachycardia (IST) is a diagnosis of exclusion, characterized by debilitating symptoms such as a markedly elevated heart rate at rest or with minimal exertion, along with exercise intolerance. The condition is defined by a resting heart rate exceeding 100 bpm and a mean ambulatory heart rate over 90 bpm without a clear secondary cause. (1) Although the exact pathophysiology remains unclear, IST is believed to be multifactorial, involving abnormal neurohumoral modulation, antibody-mediated processes, and various receptor hyper- or hyposensitivity mechanisms.