Post-mitral surgery ventricular dysfunction: the challenge of the occult substrate
In chronic mitral regurgitation surgery, a preserved preoperative left ventricular ejection fraction (LVEF) may mask actual myocardial vulnerability. For the cardiac surgeon, the risk of early postoperative systolic dysfunction remains a major concern, as standard assessment tools sometimes struggle to identify fragile patients before the intervention.
This retrospective study analyzed 279 consecutive patients who underwent isolated mitral valve replacement between January 2022 and June 2025, with or without concomitant tricuspid annuloplasty. The specific objective was to evaluate the prognostic value of fragmented QRS (fQRS) — detected on a 12-lead ECG — as a marker of a deleterious myocardial substrate. The authors test the hypothesis that preoperative fQRS can predict a drop in LVEF below the 50% threshold after surgery, thus offering a lead to refine perioperative risk stratification.
Methodology: Analysis of the myocardial substrate by ECG
This retrospective study included 279 consecutive patients who underwent elective isolated mitral valve replacement to treat chronic mitral regurgitation between January 2022 and June 2025. The procedure could include, depending on the case, a concomitant tricuspid annuloplasty.
The evaluation protocol was structured around the following axes:
- Biomarker evaluation: Systematic analysis of preoperative 12-lead electrocardiograms (ECG) to identify the presence of fragmented QRS (fQRS).
- Definition of the primary endpoint: Postoperative left ventricular (LV) systolic dysfunction was defined as an ejection fraction (LVEF) of less than 50% on early postoperative echocardiography.
- Statistical analysis: Use of multivariable logistic regression models with an exploratory backward stepwise approach.
- Predictive tools: Evaluation of model performance by measuring the area under the ROC curve (AUC) and development of a nomogram for individualized perioperative risk estimation.
The data allowed for a comparison of the incidence of complications between the group with fQRS (n=71) and the group without fQRS (n=208).
Prevalence and incidence of ventricular dysfunction
In the cohort of 279 patients who underwent mitral valve replacement, fragmented QRS (fQRS) was identified in 71 individuals, representing a prevalence of 25.4%. Overall, postoperative left ventricular (LV) systolic dysfunction, defined as LVEF < 50%, was observed in 92 patients (33.0%).
Comparative analysis: fQRS vs non-fQRS
Although the preoperative left ventricular ejection fraction was similar between the two groups, patients presenting with fQRS displayed significantly impaired postoperative outcomes. The following table summarizes the major disparities observed:
| Parameter | fQRS group (n=71) | Group without fQRS (n=208) | p-value |
|---|---|---|---|
| Incidence of postoperative LV systolic dysfunction | 45.1 % | 28.8 % | 0.012 |
| Postoperative LVEF (mean) | Lower Respond ONLY with the HTML EN translation, without markdown, without prefix. | Higher | 0.036 |
Risk factors and predictive model performance
Adjusted multivariate analysis revealed a strong trend for fQRS as an independent predictor of LV systolic dysfunction (OR 1.90; 95% CI 0.99–3.64; p = 0.052), although the conventional significance threshold was narrowly missed in this comprehensive model.
However, in the exploratory multivariate model (stepwise approach), three key variables stood out as being significantly associated with the risk of systolic dysfunction:
- Preoperative fragmented QRS: OR 2.00 (95% CI 1.06–3.81; p = 0.033).
- Chronic kidney disease: OR 3.06 (95% CI 1.11–8.56; p = 0.030).
- Aortic clamp time: OR 1.015 per additional minute (95% CI 1.010–1.020; p < 0.001).
This exploratory model demonstrates an acceptable discriminatory capacity, with an area under the ROC curve (AUC) of 0.78. These data suggest that fQRS, as a marker of a vulnerable myocardial substrate, reacts negatively to perioperative ischemic stress, particularly during prolonged procedures.
Clinical analysis: fQRS, evidence of silent vulnerability
The major challenge highlighted by this study lies in the discrepancy between a preserved preoperative ejection fraction (LVEF) and the occurrence of systolic dysfunction after mitral surgery (33.0% of cases). The fragmented QRS (fQRS) emerges here as a simple marker of the adverse myocardial substrate. Clinically, its presence doubles the risk of postoperative dysfunction (OR 2.00), acting as a warning signal for a fragility that standard echocardiography fails to detect.
Interpretation of results and limitations
Although the association between fQRS and postoperative dysfunction borders on statistical significance in the fully adjusted model (p = 0.052), the signal strength in the exploratory model highlights its relevance. This study demonstrates that fQRS is not an isolated indicator: it is part of a synergy of risks including aortic clamping duration and chronic renal failure. The main limitation lies in the retrospective nature of the analysis, requiring prospective validation before strict integration into guidelines. However, the area under the ROC curve of 0.78 demonstrates a robust discriminative capacity for a purely clinical tool.
Implications for practice
The fQRS likely reflects myocardial fibrosis or structural remodeling that makes the ventricle more sensitive to perioperative ischemic stress. For the surgeon and cardiologist, identifying this sign on a simple 12-lead ECG allows for the anticipation of a more laborious recovery, even in the face of a reassuring preoperative LVEF. The use of the developed nomogram offers an opportunity to personalize the myocardial protection strategy and immediate postoperative follow-up.
Summary of results
Preoperative fragmented QRS (fQRS) doubles the risk of systolic dysfunction after mitral valve replacement (OR 2.00; p=0.033). The study shows that 45.1% of fQRS+ patients develop postoperative ventricular failure (LVEF < 50%) compared to 28.8% in fQRS- patients, a risk correlated with aortic cross-clamp time and chronic kidney disease.
In concrete terms, for the practitioner:
- Screening for occult vulnerability: Systematically look for fQRS on the preoperative 12-lead ECG; they indicate a fragile myocardial substrate even if the LVEF appears preserved.
- Clamping time management: Be increasingly vigilant regarding the duration of intraoperative ischemia in fQRS+ patients, as their myocardial reserve is less tolerant of prolonged clamping.
- Risk stratification: Incorporate the presence of fQRS and renal function into your assessment to anticipate slower systolic recovery and adapt postoperative support.
Technical lexicon of the study
Fragmented QRS (fQRS): Morphological abnormality of the QRS complex on the surface electrocardiogram, reflecting asynchronous ventricular depolarization related to a pathological myocardial substrate (fibrosis or ischemia).
LV systolic dysfunction: Impairment of the left ventricular contractile capacity, defined in this study by a postoperative left ventricular ejection fraction (LVEF) of less than 50%.
Aortic clamping time: Duration of coronary blood flow interruption during surgery; a factor identified as significantly associated with postoperative ventricular dysfunction (OR 1.015).
Chronic renal failure: Systemic comorbidity associated, in the study's multivariate model, with a three-fold increased risk (OR 3.06) of developing systolic dysfunction after the procedure.
Nomogram: A graphical prediction tool developed to allow an individualized estimation of perioperative risk by integrating clinical and electrophysiological variables.
Mitral valve replacement: Surgical procedure for mitral valve substitution, studied here in the context of chronic mitral regurgitation to evaluate ventricular functional recovery.
Source
- Original title: Preoperative fragmented QRS as a predictor of postoperative left ventricular systolic dysfunction after isolated mitral valve replacement
- Authors: İsmail Balaban, Seda Tanyeri, Ahmet Karaduman, Zeynep Esra Güner, Barkın Kültürsay, Cemalettin Yılmaz, Mustafa Ferhat Keten, Kadir Bıyıklı
- Publication: BMC Cardiovascular Disorders - 2026-07-09
- DOI: https://doi.org/10.1186/s12872-026-06266-x
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