Usefulness and limitations of contractile reserve evaluation in patients with low‐flow, low‐gradient aortic stenosis eligible for cardiac resynchronization therapy

Aims In low‐flow, low‐gradient aortic stenosis ( LF / LG AS ), the assessment of contractile reserve ( CR ) by dobutamine stress echocardiography ( DSE ) is recommended for risk stratification and treatment strategy. However, DSE may show limitations in cases of left ventricular dyssynchrony ( LVD ). The impact of LVD in LF / LG AS , and the feasibility of CRT in this setting have never been evaluated. We aimed to assess: (i) the proportion of LF / LG AS patients with LVD ; (ii) the influence of LVD on CR at DSE ; and (iii) the effects of CRT in these patients. Methods and results Thirty consecutive patients with LF / LG AS underwent DSE with study of CR . The operative risk for aortic valve replacement ( AVR ) was assessed using the logistic EuroSCORE . Twenty‐one of the 30 patients had LVD . They were significantly older, more symptomatic, had a higher EuroSCORE , and a lower prevalence of CR than those with a narrow QRS (47% vs. 100%, P  = 0.009). A CRT pacemaker was implanted in 19 of the 21 patients with LVD . All 19 (except for one patient who died suddenly) experienced significant clinical and echocardiographic improvement. Fourteen CRT patients underwent subsequent AVR with a low event rate. Four CRT patients refused AVR ; two of them worsened again 1–2 years post‐ CRT . Conclusion LVD is common in LF / LG AS patients and may be a major mechanism of afterload mismatch, as well as a cause of underdetection of CR . CRT in this population is feasible and may be proposed as a bridge to surgery.