Comments on ‘Cardiac remodelling and clinical outcomes after mitral edge-to-edge repair with the PASCAL® system’

We read with great interest the article by Bladt et al., investigating the relationship between acute haemodynamic changes, subsequent cardiac remodelling, and clinical outcomes after mitral transcatheter edge-to-edge repair (M-TEER) using the PASCAL® system. The integration of invasive haemodynamic assessment with longitudinal echocardiographic evaluation provides valuable insight into the physiological response following transcatheter mitral repair.¹

The authors appropriately acknowledge several limitations related to the retrospective design, including variable timing of echocardiographic follow-up, unavailable periprocedural haemodynamic measurements, and the inability to assess post-procedural left ventricular global longitudinal strain (LV-GLS) in all patients because of limited image quality. We believe, however, that the implications of these missing data for the reported associations deserve further consideration.

Of the 130 patients enrolled, short-term haemodynamic data were available in 86 and long-term echocardiographic follow-up in 74, with incomplete datasets excluded from the respective analyses. Moreover, the number of patients contributing to individual longitudinal echocardiographic comparisons varied considerably. Although this limitation is acknowledged, the important distinction is not simply the reduction in sample size but whether the availability of longitudinal measurements was independent of patient prognosis.

This distinction may be particularly relevant to the study’s proposed pathophysiological pathway. The authors provide important patient-level evidence that greater periprocedural improvement in cardiac index was independently associated with subsequent improvement in LV-GLS and that improvement in LV-GLS was associated with fewer clinical events. However, these associations necessarily depend on patients in whom the corresponding serial measurements were available. If the probability of obtaining follow-up echocardiography or analysable LV-GLS differed according to clinical trajectory, the observed haemodynamic–remodelling–outcome relationships could be influenced by selection of the analysed population. For example, patients experiencing progressive heart failure, frailty, recurrent mitral regurgitation, or early clinical deterioration might have a different probability of undergoing scheduled and technically adequate echocardiographic reassessment than clinically stable patients.²

Importantly, adjustment for the interval between M-TEER and follow-up echocardiography addresses variation in the timing of available examinations, but does not address whether the availability of follow-up itself was informative. These represent distinct sources of potential bias.

We therefore believe that comparison of baseline, procedural, and early clinical characteristics between patients with and without analysable longitudinal echocardiographic data would provide useful additional information. If sufficient data are available, sensitivity analyses accounting for the probability of follow-up, such as inverse-probability-of-observation weighting, could further assess whether the reported associations remain robust under differential follow-up. Such analyses would complement, rather than challenge, the authors’ existing patient-level findings and help determine how confidently the observed haemodynamic–remodelling–outcome pathway can be generalized to the entire cohort.

We congratulate the authors on this clinically relevant study and believe that addressing the mechanism of missing follow-up, rather than its extent alone, would further strengthen the interpretation and generalizability of these findings.

Author contributions

Safa Özçelik (Conceptualization, Investigation, Writing—original draft [lead])

Data availability

No new data were generated or analysed in support of this research.

Lead author biography

Safa Özçelik, MD, graduated from Hacettepe University Faculty of Medicine. He completed his cardiovascular surgery residency at Dr. Siyami Ersek Thoracic and Cardiovascular Surgery Training and Research Hospital and is currently a cardiovascular surgeon at the same institution in Istanbul, Türkiye. During his early career at Koşuyolu Heart Training and Research Hospital, he developed a particular interest in minimally invasive cardiac surgery, especially minimally invasive coronary, mitral valve, aortic, and congenital cardiac procedures.