Mitral TEER: Preoperative Anemia, a Major Risk of Death

Pre-procedural anemia and TEER: a prognostic marker under the microscope

Mitral regurgitation (MR) affects nearly 10% of individuals aged 75 and older. For these patients, who are often ineligible for conventional surgery due to their frailty, transcatheter edge-to-edge repair (TEER) has emerged as a major therapeutic alternative. However, this elderly and polymorbid patient profile frequently presents with pre-existing anemia, with a prevalence reaching 53.9% in certain cohorts. While anemia is already correlated with increased morbidity and mortality in conventional cardiac surgery, its precise impact on outcomes following TEER remained to be rigorously synthesized.

This systematic review and meta-analysis, structured according to the PRISMA 2020 recommendations, explored seven databases (including PubMed, Embase, and the Cochrane Library) up to March 18, 2026. The objective was to evaluate the association between preprocedural anemia and clinical outcomes after TEER. The authors tested the hypothesis that a low hemoglobin level constitutes an unfavorable prognostic marker, significantly impacting post-interventional mortality and morbidity, thus addressing the limitations of isolated observational studies with diverging follow-up durations and analytical methods.

Methodology of the meta-analysis

This systematic review and meta-analysis, structured according to the PRISMA 2020 guidelines, compiles data from 6 observational studies (3 prospective and 3 retrospective) published between 2015 and 2024. The analysis focuses on a massive sample of 34,812 adult patients who underwent transcatheter edge-to-edge repair (TEER) in Germany and the United States.

The experimental protocol is based on the following parameters:

• Compared groups: Patients with documented pre-procedural anemia versus non-anemic patients at baseline.
• Population: Cohorts vary from 80 (Hellhammer et al.) to 28,995 patients (Al Yami et al.).
• Clinical follow-up: The duration extends from the intra-hospital period to a long-term follow-up reaching 12.3 years (median of 5.5 years in Khurrami et al.).
• Outcome measures: The primary endpoint is all-cause mortality. Secondary endpoints include acute kidney injury (AKI), cardiovascular events, bleeding, and length of stay (LOS).

Methodological quality was assessed using the Newcastle-Ottawa Scale (NOS). Statistical syntheses and data analyses were performed via R software with the specific use of the meta package.

Selection results and cohort characteristics

The systematic search identified 6 observational studies (2 prospective and 4 retrospective) meeting the eligibility criteria, for a total population of 34,812 patients treated with mitral TEER. The studies were conducted primarily in Germany (n=4) and the United States (n=2) between 2008 and 2024.

Cohort analysis and clinical implications

This systematic review and meta-analysis compiles data from six observational studies (including Iliadis, Khurrami, Kaneko, Bhardwaj, Al Yami, and Hellhammer), representing a total sample of 34,812 patients. The analysis of baseline characteristics (Table 4) reveals a particularly fragile population: a mean age often exceeding 77 years, a predominance of advanced NYHA classes, and a high prevalence of chronic kidney disease (up to 74.1% in the Kaneko study). In this context, anemia — with a prevalence reaching 53.9% according to the cited baseline data — emerges as a major systemic risk marker for mitral TEER candidates.

The extracted data show a significant disparity in follow-up durations, ranging from the intra-hospital period (Bhardwaj and Al Yami) to a maximum follow-up of 12.3 years (mean 5.5 years in Khurrami). This temporal heterogeneity is an intrinsic limitation to the synthesis, as is the retrospective nature of the majority of the included studies. Furthermore, although anemia is correlated with unfavorable outcomes in other structural cardiology contexts (heart failure, valvular surgery), this review highlights the need for a standardized analysis for TEER, where comorbidities often intertwine with hemoglobin levels.

For the practitioner, these results mean that the pre-TEER biological assessment must not be overshadowed by the technical complexity of the procedure. Preprocedural anaemia appears to act as an indicator of the patient's overall vulnerability, potentially impacting not only survival, but also post-operative complications such as acute kidney injury or length of hospital stay.

Summary of results

This systematic review including 6 studies (34,812 patients) confirms that preprocedural anemia is a robust predictor of mortality and morbidity after mitral TEER. With a prevalence reaching 53.9% in some cohorts, low baseline hemoglobin levels are significantly associated with worsening clinical outcomes and reduced short- and medium-term survival.

In concrete terms, for the practitioner:

• Systematic screening: Integrate hemoglobin measurement as a critical frailty biomarker during the pre-MitraClip assessment, as anemia affects more than one in two patients.
• Decision support: Use anaemic status within the Heart Team to refine post-procedural prognosis and weigh the benefits of TEER in polypathological patients.
• Post-operative vigilance: Strengthen the monitoring of complications (bleeding, acute renal failure) in anaemic patients, identified as a high-vulnerability subgroup.

Technical lexicon of the study

TEER (Transcatheter Edge-to-Edge Repair): Minimally invasive technique for mitral edge-to-edge repair. Performed via the femoral vein with transseptal puncture, it consists of bringing the mitral leaflets together under echocardiographic guidance to reduce regurgitation in patients deemed inoperable.

MitraClip: The first TEER device extensively documented and used in the analyzed cohorts. This system is directly inspired by the Alfieri surgical technique to create an artificial coaptation of the leaflets, transforming severe mitral regurgitation into a functional double orifice.

PASCAL system: Alternative edge-to-edge repair device mentioned in the selection criteria of this review. Although using specific implantation mechanisms, it shares the therapeutic objective of the MitraClip for the percutaneous management of complex mitral valve diseases.

Alfieri technique: Original surgical concept that served as the basis for the development of transcatheter interventions. This approach consists of suturing the free edges of the mitral leaflets at the level of the regurgitant jet, a strategy now replicated endovascularly using clip devices.

Preprocedural anemia: Documented hemoglobin deficiency prior to the procedure, constituting the major exposure variable of this meta-analysis. In patients candidates for TEER, it is identified as a marker of frailty and a potential predictor of post-operative morbi-mortality.

PRISMA 2020: Standardised reporting protocol acting as a methodological safeguard for systematic reviews. It ensures transparency and reproducibility of the study selection process, from the identification of records on PubMed/Embase to the final data analysis.

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