Letter by Loardi and Zanobini Regarding Article, “Echocardiographic Results of Transcatheter Versus Surgical Aortic Valve Replacement in Low-Risk Patients: The PARTNER 3 Trial”
Authors: Claudia Loardi, Marco Zanobini
Journal: Circulation (2020)

We read with interest the article by Pibarot et al 1 concerning an echocardiographic analysis of patients from the PARTNER 3 trial (Placement of Aortic Transcatheter Valves; transcatheter aortic valve replacement versus surgical aortic valve replacement in a low surgical risk cohort).Their main findings are that, despite a higher percentage of mild aortic regurgitation in the percutaneous group with no impact on 1-year outcome, patients undergoing surgical aortic valve replacement show a persisting impairment of right ventricular function and higher valvulo-arterial impedance (Z va ), correlating with a worse composite mortality, stroke, and rehospitalization end point.Such results are worthy of interest because of the progressive expansion of transcatheter aortic valve replacement in low-risk patients.To begin, we would like to discuss the well-known phenomenon of postoperative tricuspid annulus plane systolic excursion fall: because it is common after cardiac surgery, a 16-mm threshold (exactly corresponding to the present trial average 1-year measure) may be recognized as pseudonormal and not interpreted simply as right ventricular dysfunction, 2 especially in case of 3-dimensional contractility parameters preservation.Nevertheless, its negative prognostic impact is quite disturbing.What theory may justify such short-term influence?Moreover, because right ventricular longitudinal function impairment is a multifactorial and not a unanimously explicated process related to intraoperative variables, 3 including myocardial protection protocol, surgical approach (thoracothomy versus partial/full sternotomy), cardiopulmonary bypass conduction and deairing modalities, pericardial incision and suture type, and temporary interventricular septum injury, it would be interesting to know if diverse practices were used with a subsequent possible different tricuspid annulus plane systolic excursion trend.Another issue that we would like to better understand is Z va behavior, an index reflecting left ventricular hemodynamic burden.Because it depends on the mean valvular gradient and indexed stroke volume, we can argue that, in surgical aortic valve replacement, the postoperative decrease of the latter parameter weighs more on Z va augmentation than transprosthethic gradients reduction.Do the authors agree with this interpretation?Furthermore, how do they explain that indexed stroke volume trend (and consequently Z va ) is not symmetrical to the left ventricular ejection fraction one, which remains stable in both populations?Such a finding has been pointed out in previous studies, but no comprehensive clarification has been proposed. 4In our opinion, following a down-to-earth reasoning, the explication may be a major or simply different remodeling effect exercised by surgery on the left ventricle, in particular, on diastolic/ systolic volumes ratio.Moreover, is it conceivable that the more subtle parameters, Z va , indexed stroke volume, and perhaps tricuspid annulus plane systolic excursion, also require a longer normalization time in surgical patients, thus possibly limiting their negative long-term impact?The amount of basal myocardial fibrosis