Dobutamine stress echocardiography in low-flow, low-gradient aortic stenosis with concomitant severe functional mitral regurgitation: a case report

BACKGROUND: Dobutamine stress echocardiography (DSE) in classical low-flow, low-gradient (LFLG) aortic stenosis (AS) is recommended in recent guidelines to differentiate true-severe AS from pseudo-severe AS. However, DSE for patients with concomitant significant mitral regurgitation (MR) is often inaccurate or inconclusive. CASE SUMMARY: A 73-year-old man with a history of coronary artery bypass grafting was referred to our institution with congestive heart failure. Transthoracic echocardiogram showed severe functional MR and LFLG AS. The results of DSE to determine the severity of AS were inconclusive owing to the absence of flow reserve, usually defined as stroke volume increase of ≥20%. In addition, calcium score by computed tomography scan was also inconclusive. Our heart team decided to reassess the severity of AS after percutaneous edge-to-edge mitral valve repair (PMVR), considering the patient's high surgical risk. Percutaneous edge-to-edge mitral valve repair was uneventful, resulting in marked reduction of MR from severe to trivial. Dobutamine stress echocardiography after PMVR revealed true-severe AS with the presence of flow reserve. Transcatheter aortic valve implantation (TAVI) was performed, and the patient ambulatorily discharged. DISCUSSION: The coexistence of significant AS may lead to overestimation of the severity of MR, and reportedly, concomitant MR improves in the majority of patients after TAVI, especially MR of functional aetiology. However, the coexistence of significant MR often leads to inconclusive DSE results because dobutamine stress may worsen MR and fail to increase the stroke volume. In our case, DSE after PMVR was useful to diagnose the true-severe AS for the patient with LFLG AS and severe functional MR.