PReventive Effect Of Left Bundle Branch Area Pacing Versus righT vEntricular paCing on All Cause deaTh, Heart Failure Progression, and Ventricular dysSYNChrony in Patients With Substantial Ventricular Pacing (PROTECT-SYNC): Multicenter Prospective Randomized Controlled Trial

"LBBAP success is defined if ventricular lead is successfully placed at interventricular septum and RBB configuration observed during unipolar tip pacing.~LBB capture is defined if fulfilling criterion 1 and at least one in criteria 2.~1. RBBB configuration observed during unipolar tip pacing~2. One of the following should be met:~ 1. Abrupt shortening of Stim-LVAT (stimulus to peak of the R wave in V6 \[LV activation time\]) of \>10ms during increasing output~ 2. Short and constant stim-LVAT and the shortest stim-LVAT \<75ms in non-LBBB and \<85ms in LBBB~ 3. Programmed stimulation by pacing lead changes QRS morphology from nonselective LBB to LV septal capture~ 4. LBB potential (LBB-V interval of 15 to 35ms)~ 5. Transition from nonselective LBB capture to selective LBB capture at near threshold outputs~If criterion 1 is fulfilled but none in criteria 2 is met, the procedure is considered to be deep septal pacing (DSP)."

Right ventricular pacing is the traditional pacing modality for ventricular pacing. Implantation of a RV pacing lead (apex or septum of right ventricle) will be attempted using the standard-of-care technique first