1Universitätsklinikum Regensburg Klinik und Poliklinik für Innere Med. II, Kardiologie Regensburg, Deutschland; 2Krankenhaus Barmherzige Brüder Regensburg Klinik für Kardiologie Regensburg, Deutschland; 3Klinikum St. Marien Klinik für Innere Medizin I Amberg, Deutschland; 4Universitätsklinikum Gießen und Marburg GmbH Medizinische Klinik I - Kardiologie und Angiologie Gießen, Deutschland
Introduction
Fluid overload and congestion are a common symptom in patients with mitral regurgitation. However, assessment for subclinical congestion is difficult and a clear risk stratification for patients under evaluation for transcatheter mitral valve replacement (TMVR) does not yet exist. The estimated plasma volume status (ePVS) has already been demonstrated as a predictor of poorer outcomes in patients with acute and chronic heart failure and in patients undergoing transcatheter aortic valve implantation (TAVI). This study aimed to evaluate the impact of preprocedural increased ePVS on outcome and mortality in patients undergoing transcatheter mitral valve repair.
Methods
As part of the ongoing, prospective Regensburg Trial on TMVR Techniques in Mitral Regurgitation (RETORT-MR) 286 patients were prospectively enrolled prior to TMVR. The ePVS as the difference between the actual and ideal plasma volume [%] was calculated based on Hakim's formula using hematocrit, body weight after complete recompensation and two sex dependent constants. After initial assessment prior to TMVR, follow-up data were collected at regular intervals. Based on 1-year mortality, cut-off values for ePVS and NT-proBNP were calculated using receiver operating characteristic curves.
Results
Among the 286 patients (mean age 77±8 years, 61% men) with a mean ePVS of -3.3±10.7%, 102 (35.7%) presented an ePVS above the calculated cut-off value of 0.4%. Median NT-proBNP was 2203pg/ml (IQR 1064/4571) with a calculated cut-off-value of 2794 pg/ml. Patients with an ePVS above the cut-off presented significantly higher all-cause (p<0.001, HR 3.2, 95%CI 1.8-5.6) and cardiovascular mortality (p<0.026, HR 2.5, 95%CI 1.1-5.6). 1-year mortality was also significantly worse (14.1% vs. 5.6%; Chi²(1)=4.6, p=0.044, n=220, Cramer’s V=0.144, p=0.044) in those patients. Patients with both ePVS and NT-proBNP above the calculated cut-off showed a further deterioration in outcome regarding all-cause (p<0.001, HR 13.0, 95%CI 4. 5-37.6) and cardiovascular mortality (p=0.003, HR 10.4, 95%CI 2.3-47.3), as well as heart-failure-related rehospitalizations (p<0.001, HR 3.0, 95%CI 1.6-5.7) and 1-year mortality (17.0%). In contrast, the patients in whom neither NT-proBNP nor ePVS exceeded the cut-off showed a much more favorable outcome regarding 1-year mortality (2.2%)
Conclusion
In this study, an increased ePVS before TMVR was associated with significantly worsened outcome and increased mortality. When considered together with NT-proBNP, the significance of this prediction model could be further increased. The easy-to-assess ePVS can therefore be a useful addition to clinical assessment and established laboratory parameters in the evaluation of patients with mitral regurgitation regarding fluid overload and congestion.
Attachment: Kaplan–Meier survival estimates (all-cause mortality) depending on preprocedural ePVS and NT-proBNP.