Since the introduction of the concept of left bundle branch pacing (LBBP), extensive research has been done to define parameters for successful capture of conduction system [[1], [2], [3], [4]]. Soon after, a novel technique was used to achieve cardiac resynchronization in patients with heart failure and unfavorable coronary veins anatomy [5,6]. At the beginning of 2023, a consensus statement endorsed by several heart rhythm societies has been published in order to unify the implantation technique and the criteria for confirmation of conduction system pacing (CSP) [7]. However, most of the proposed electrocardiographic criteria pertain to patients with preserved left ventricular contractility and narrow QRS, and may not necessarily be suitable for patients with heart failure.

We present a case of cardiac resynchronization using left bundle branch pacing (LBBP) in a patient with heart failure and ischemic heart disease in whom electrocardiographic confirmation of CSP was hampered by an extremely long conduction latency.