Purpose <p>Quantify the long-term mechanical durability of Abbott stylet-driven leads for left bundle branch area pacing (LBBAP) using a combination of computational modeling and fatigue bench test.</p> Methods <p>Intracardiac lead curvatures were simulated in a 3D computational heart model across a range of lead implant scenarios and cardiac electro-mechanical scenarios over a complete cardiac cycle to determine the range of induced stresses. Safety factor was determined using the bending curvature and mechanical properties of the conductor. A benchtop fatigue physical test was implemented at higher stress levels, thus lower safety factors, than the computational modeling cohort.</p> Results <p>Computer simulation modeling showed that maximum curvature and safety factor (SF) were comparable for LBBA implants (0.06 ± 0.02&#xa0;mm⁻¹ and 4.7 ± 1.6) vs. other traditional implant locations (0.05 ± 0.03&#xa0;mm⁻¹ and 5.0 ± 0.7). Lead durability was verified through successful fatigue bench testing at max curvatures of 0.12 ± 0.01&#xa0;mm^-1 and safety factor of 2.2 ± 0.2. These test conditions represented approximately a twofold increase in maximum curvature and a 2.1-fold reduction in safety factor relative to simulated cases, over a test duration representative of 10&#xa0;years of service.</p> Conclusion <p>Abbott stylet-driven leads were demonstrated to be safe for LBBAP, even at stresses far exceeding those which may be clinically observed for 400 million cardiac cycles. No differences in long-term safety were observed between LBBAP and traditional pacing locations.</p>