Utility and futility of MitraClip implantation in secondary mitral regurgitation in a real-world population: the role of 3D transthoracic echocardiography

Abstract Introduction Two recent prospective trials have been published, reporting opposite results on the efficacy and utility of the MitraClip (MC) procedure in patients with secondary mitral regurgitation (SMR). A ratio between the effective regurgitant orifice area (EROA) and left ventricular end-diastolic volume (LVEDV) ≥0.150 by two-dimensional (2D) transthoracic echocardiography (TTE) has been proposed to identify patients with disproportionate SMR, who would benefit from MC. Purpose To assess the prognostic role of clinical and echocardiographic parameters in a real-world population of SMR patients undergoing the MC procedure at our Institute. Methods Ninety-two patients underwent MC implantation. We retrospectively reviewed their clinical, and laboratory data, as well as 2D and three-dimensional (3D) TTE, and intraoperative transoesophageal echocardiography (Figure 1). The primary endpoint was a composite of cardiovascular death and/or hospitalisation for heart failure within 12-months follow-up. Results Thirty-one patients reached the endpoint (EP+), 61 did not (EP−). Demographics and anti-remodelling drugs were similar in EP+ and EP. Among comorbidities and laboratory data, EP+ significantly differed from EP− in smoking history, and extracardiac artery disease prevalence (65% vs. 39%, and 39% vs. 16%, respectively); EuroScoreII (12.2% vs. 5.2%); NYHA class ≥3 (94% vs. 69%); haemoglobin (12±2 vs. 13±2 g/dL), and brain natriuretic peptide levels (855 [426–1500] vs. 357 [170–902] pg/mL). At 2D TTE no significant difference emerged, including the SMR grade, except for the tricuspid annular plane systolic excursion (Figure 2). Biventricular 3D ejection fraction was significantly lower in EP+ vs. EP− (Figure 2). Residual intraoperative SMR grade after MC deployment was 1.9±0.6 in EP+ vs. 1.3±0.5 in EP− (p<0.001). Conclusion The proposed cut-off for EROA/LVEDV ratio may be suboptimal for predicting the MC utility in real-world populations. Rather, prognosis may be more influenced by the patient's pre-operative clinical status, right ventricular systolic function, 3D left ventricular ejection fraction, and by the success of the procedure. Funding Acknowledgement Type of funding sources: None.