Abstract
The evidence that conventional right ventricular pacing can result in the development of cardiomyopathy and heart failure over time has prompted the search for alternative pacing sites. Conduction system pacing (CSP) represents an attempt to overcome the limitations of conventional pacing and to provide an alternative for patients with reduced EF and various degrees of dyssynchrony for whom resynchronization therapy is not feasible for technical or anatomical reasons. In particular, His bundle pacing and left bundle branch area pacing (LBBAP), with their advantages and disadvantages, have been shown to meet the criteria of physiological pacing. The former, although technically more challenging and less satisfactory in terms of electrical parameters, allows to obtain a QRS complex that is identical to the spontaneous one. The latter produces a wider paced QRS and although the technical complexity at the time of implantation is significantly reduced, is subject to a series of mechanical complications related to the trans-septal positioning of the lead. Careful patient selection along with an adequate learning curve for the operators make CSP a safe and effective procedure, although burdened by a higher complication rate compared with conventional pacing. Future studies will clarify its role, which is currently limited by current ESC guidelines to His Pacing only as an alternative procedure in case of failure of resynchronization therapy (class of recommendation IIa), after the 'ablate and pace' procedure or as an alternative to right ventricular pacing in patients with AV block, left ventricular ejection fraction <40% and an expected right ventricular pacing percentage >20% (class of recommendation IIb).