A, TOLB blunts workload‐induced APD shortening in LANG hearts when pacing at CLs of 220 ms and 170 ms (P = 0.025 and P = 0.006). B, APDs are longer in LWHs with TOLB during sinus rhythm and at all pacing CLs. C, LVDP is higher in LWHs with TOLB at pacing CLs of 330 and 220 ms. Values are the mean ± SE; LANG, n = 6; LWH, n = 7; LANG + TOLB, n = 3; LWH + TOLB, n = 4. *Significant difference with and without TOLB.