Learning curve predictors for minimally invasive mitral valve surgery; how far should the rabbit hole go?

OBJECTIVE: To analyze predictors that influence the learning curve of minimally invasive mitral valve surgery (MIMVS). METHODS: Patients who underwent MIMVS between March 2010 to March 2015 were retrospectively analyzed. Predictive factors that influence the learning curve were analyzed. RESULTS: One hundred and five patients were included in the analysis. Cardiopulmonary bypass (CPB) time in minutes was 158.72 ± 40.98 and the aortic cross-clamp (ACC) time in minutes was 114.48 ± 27.29. There were three operative mortalities, one stroke and five >2+ mitral regurgitation. ACC time in minutes was higher in the low logistic Euroscore II (LES) group (LES < 5% = 118.42 ± 27.94) versus (LES ≥ 5 = 88.66 ± 22.26), P < .05 while creatinine clearance in µmol/L was higher in the LES < 5% group (LES < 5% = 84.32 ± 33.7) versus (LES ≥ 5% = 41.66 ± 17.14), (P < .05). One patient from each group required chest tube insertion for pleural effusion P < .05. The cumulative sum analysis (CUSUM) for the first 25 patients had CPB and ACC times that reached the upper limits. Between 25 to 64 patients the curve remained stable while with the introduction of reoperations and complex surgical procedures the CUSUM reached the upper limits. CONCLUSIONS: The learning curve is affected by many factors but this should not desist surgeons from approaching this technique. The introduction of high-risk patients in clinical practice should be carefully measured based on surgeon experience.

Mitral regurgitation severity correlates with symptoms and extent of left atrial dysfunction: Effect of mitral valve repair.

PURPOSE: We aimed to assess the relationship between mitral regurgitation (MR) severity, symptoms, and left atrial (LA) structure and function, before and after mitral valve repair (MVR). METHODS: Global peak atrial longitudinal strain (PALS) was evaluated in 37 patients with severe symptomatic MR and preserved left ventricular (LV) ejection fraction (60.4% ± 4.6%) before and 3 months after MVR and was compared with values from 30 age- and gender-matched controls. RESULTS: Before surgery, PALS was worse in patients than in controls and indexed LA volume was greater (P < .0001 for both). After MVR, PALS deteriorated further and LA volume decreased (P = .001 and P = .05, respectively) as did LV ejection fraction, longitudinal strain (P = .05 and P < .001, respectively), and LV mass (P < .0001). Before surgery, LA volume correlated modestly with LV end-diastolic volume (R = 0.51; P = .01); effective regurgitant orifice area (EROA) correlated with PALS (R = -0.69, P < .001) and with LV longitudinal strain (R = 0.54, P = .01), and New York Heart Association class correlated with PALS (R = -0.69, P < .001), EROA (R = 0.69, P < .001), and LA volume (R = 0.51, P = .04). LA volume was the strongest predictor of global PALS reduction (P < .001), whereas global PALS was the main predictor of postoperative atrial fibrillation (AF) (P < .001). CONCLUSIONS: In patients with severe MR, EROA correlate with symptoms and LA PALS, which itself predicts the occurrence of postoperative AF. Strain values were superior to 2D data for the prediction of postoperative AF.

Left atrial strain as a pre-operative prognostic marker for patients with severe mitral regurgitation.

BACKGROUND: In patients with severe mitral regurgitation (MR), additional echocardiographic indices could be helpful to optimize surgical timing before irreversible left heart myocardial dysfunction has occurred. We investigated the correlation of left atrial (LA) strain by speckle tracking echocardiography with prognosis after mitral surgery for severe MR, and its association with LA fibrosis. METHOD: 71 patients with primary severe MR undergoing pre-operative echocardiographic assessment were initially enrolled. Exclusion criteria were: other valvular disease>moderate, history of coronary artery disease, heart failure (HF), hypertrophic cardiomyopathy, left bundle branch block, previous pacemaker implantation, heart transplantation, poor acoustic window. The primary endpoint was the occurrence of composite events (HF and mortality); the secondary endpoint was post-operative functional capacity (NYHA and Borg CR10 class). LA fibrosis was assessed by atrial biopsy specimens in a subset of patients. RESULTS: Of 65 eligible patients, the primary endpoint occurred in 30 patients (medium follow-up: 3.7 ± 1 years for event-group, 6.8 ± 1 years for non-event group). After Kaplan-Meier analysis, peak atrial longitudinal strain (PALS) provided good risk stratification (5-year event-free survival:90 ± 5% for PALS≥21% vs 30 ± 9% for PALS<21%, p < 0.0001); it was an independent and incremental predictor of outcome in four multivariate Cox adjusted models. There was also an association between PALS and the secondary endpoint (NYHA: r2 = 0.11, p = 0.04; Borg CR10: r2 = 0.10, p = 0.02) and an inverse correlation between PALS<21% and LA fibrosis (r2 0.80, fibrosis: 76.6 ± 20.7% vs 31.9 ± 20.8%;p < 0.0001). CONCLUSIONS: Global PALS emerged as a reliable predictor of outcome and functional capacity for severe primary MR, and as a marker of LA fibrosis.

Left ventricular twist in clinically stable heart transplantation recipients: a speckle tracking echocardiography study.

BACKGROUND AND AIM: Cavity twist is an integral part of LV function and its pattern in transplanted hearts is not well known. This study aimed at exploring LV twist in clinically stable heart transplant (HT) recipients with no evidence for rejection. METHODS: We studied 32 HT patients (54 ± 24 months after HT), 34 other cardiac surgery (CS) patients and compared them with 35 health controls using speckle tracking echocardiography, measuring peak twist angle, time-to-peak twist, and untwist rate. RESULTS: LV twist angle was smaller in the HT group (6.2 ± 3.3°) in comparison with the CS group and controls (13.2 ± 3.5° and 13.1 ± 4.5°, respectively; p<0.0001 for all) and untwist rate was reduced (HT group: -74 ± 30°/s; CS group: -118 ± 43°/s; controls: -116 ± 39°/s; p<0.0001 for all). Time-to-peak twist was not different between groups. Time after HT was the main independent predictor of both LV twist angle and untwist rate (ß=0.8, p<0.0001). CONCLUSION: Though clinically stable, LV twist dynamics are significantly impaired in HT recipients, even in comparison with patients who underwent other cardiac surgery.

Usefulness of atrial deformation analysis to predict left atrial fibrosis and endocardial thickness in patients undergoing mitral valve operations for severe mitral regurgitation secondary to mitral valve prolapse.

In patients with severe mitral regurgitation (MR) referred for cardiac surgery, left atrial (LA) remodeling and enlargement are accompanied by mechanical stress, mediated cellular hypertrophy, and interstitial fibrosis that finally lead to LA failure. Speckle tracking echocardiography is a novel non-Doppler-based method that allows an objective quantification of LA myocardial deformation, becoming useful for LA functional analysis. We conducted a study to evaluate the relation between the traditional and novel atrial indexes and the extent of ultrastructural alterations, obtained from patients with severe MR who were undergoing surgical correction of the valvular disease. The study population included 46 patients with severe MR, referred to our echocardiographic laboratory for a diagnostic examination before cardiac surgery. The global peak atrial longitudinal strain (PALS) was measured in all subjects by averaging all atrial segments. LA tissue samples were obtained from all patients. Masson's trichrome staining was performed to assess the extent of the fibrosis. The LA endocardial thickness was measured. A close negative correlation between the global PALS and grade of LA myocardial fibrosis was found (r = -0.82, p <0.0001), with poorer correlations for the LA indexed volume (r = 0.51, p = 0.01), LA ejection fraction (r = 0.61, p = 0.005), and E/E' ratio (0.14, p = NS). Of these indexes, global PALS showed the best diagnostic accuracy to detect LA fibrosis (area under the curve 0.89), and it appears to be a strong and independent predictor of LA fibrosis. Furthermore, we also demonstrated an inverse correlation between the global PALS and LA endocardial thickness (r = -0.66, p = 0.0001). In conclusion, in patients with severe MR referred for cardiac surgery, impairment of LA longitudinal deformation, as assessed by the global PALS, correlated strongly with the extent of LA fibrosis and remodeling.

Predictive role of pretransplant serum CXCL10 for cardiac acute rejection.

BACKGROUND: The detection of acute rejection in heart transplantation remains an important feature of transplant management, especially in the early phase. Frequent surveillance with endomyocardial biopsy is necessary, even though it is an invasive procedure and carries a certain risk. Hence, noninvasive biomarkers able to predict acute rejection could be a further helpful tool in patient management. The interferon-gamma-inducible chemokine CXCL10 is required for initiation and development of graft failure caused by acute or chronic rejection. It has been reported that CXCL10 serum level is predictive of graft loss in kidney graft recipients. In the present study, we investigated whether pretransplant CXCL10 serum level may be a predictive noninvasive biomarker in heart transplant (HTx) recipients, as well. METHODS: Sera from 143 patients undergoing orthotopic heart transplantation were collected before surgery and tested for CXCL10 and CCL22 and compared with serum samples from healthy subjects. RESULTS: We found that basal CXCL10 serum levels in HTx recipients were significantly higher than in healthy subjects, whereas no difference was seen in CCL22 levels. Among HTx recipients, CXCL10 serum levels of rejectors were significantly higher than in nonrejectors. Our results showed that CXCL10 was a significant independent risk factor of several variables and had the highest predictive value for early acute heart rejection, with 160 pg/mL cutoff value. CONCLUSIONS: In HTx recipients, measurement of pretransplant CXCL10 serum levels could be a clinically useful tool for predicting cardiac acute rejection, especially in the early posttransplant period.