Clinical and Functional Effects of Restrictive Mitral Annuloplasty at Midterm Follow-Up in Heart Failure Patients

Left ventricular regional dyssynchrony predicts improvements in moderate ischaemic mitral regurgitation after off-pump coronary artery bypass

OBJECTIVES

The aim of this study was to explore the predictors of the improvement in moderate ischaemic mitral regurgitation (IMR) after off-pump coronary artery bypass grafting (OPCAB) focusing on left ventricular (LV) dyssynchrony.

METHODS

A prospective study was performed among 135 patients (age at surgery, mean ± SD: 67.0 ± 8.2 years, 33.3% women) with prior myocardial infarction and moderate IMR undergoing OPCAB from 2008 to 2015. Preoperative and follow-up clinical and echocardiographic parameters were analysed, focusing on LV global/regional dyssynchrony. Patients were grouped by IMR at 1 year postoperatively: improved group with no or mild IMR (n = 61) and failure group with moderate or severe IMR (n = 67). Data were compared between groups to explore the predictors of IMR improvement after OPCAB.

RESULTS

Seven patients who died before the 1-year postoperative assessment were excluded. At the 1-year follow up, there were 61 patients in the improved group and 67 patients in the failure group. Preoperatively, the improved group had smaller LV global dyssynchrony, LV regional dyssynchrony (papillary muscle systolic dyssynchrony; improved group versus failure group: 48.5 ± 4.5 ms vs 57.1 ± 3.9 ms; P < 0.001) and greater LV ejection fraction (improved group versus failure group: 44.7 ± 5.0% vs 36.7 ± 6.7%; P < 0.001) than the failure group. Papillary muscle systolic dyssynchrony (odds ratio 1.556, 95% confidence interval 1.313-1.845; P < 0.001) and preoperative ejection fraction (odds ratio 0.799, 95% confidence interval 0.691-0.924; P = 0.002) were independent predictors of moderate IMR improvement after OPCAB.

CONCLUSIONS

In the selected patients, preoperative moderate IMR could be relieved by coronary artery bypass grafting. Greater ejection fraction and absence of LV regional dyssynchrony may predict the improvement in moderate IMR after coronary artery bypass grafting, suggesting that LV dyssynchrony especially regional dyssynchrony and preserved ventricular function would be important to the outcome of patients with moderate IMR.

The quest for load-independent left ventricular chamber properties: exploring the normalized pressure-volume loop

Left ventricular (LV) pressure–volume (P–V) loop analysis is the gold standard for chamber function assessment. To advance beyond traditional P–V and pressure phase plane (dP/dt‐P) analysis in the quest for novel load‐independent chamber properties, we introduce the normalized P–V loop. High‐fidelity LV pressure and volume data (161 P‐V loops) from 13 normal control subjects were analyzed. Normalized LV pressure (P_N) was defined by 0 ≤ P(t) ≤ 1. Normalized LV volume (V_N) was defined as V_N=V(t)/V_diastasis, since the LV volume at diastasis (V_diastasis) is the in‐vivo equilibrium volume relative to which the LV volume oscillates. Plotting P_N versus V_N for each cardiac cycle generates normalized P‐V loops. LV volume at the peak LV ejection rate and at the peak LV filling rate (peak −dV/dt and peak +dV/dt, respectively) were determined for conventional and normalized loops. V_N at peak +dV/dt was inscribed at 64 ± 5% of normalized equilibrium (diastatic) volume with an inter‐subject variation of 8%, and had a reduced intra‐subject (beat‐to‐beat) variation compared to conventional P‐V loops (9% vs. 13%, respectively; P < 0.005), thereby demonstrating load‐independent attributes. In contrast, V_N at peak −dV/dt was inscribed at 81 ± 9% with an inter‐subject variation of 11%, and had no significant change in intra‐subject (beat‐to‐beat) variation compared to conventional P‐V loops (17% vs. 17%, respectively; P = 0.56), therefore failing to demonstrate load‐independent tendencies. Thus, the normalized P‐V loop advances the quest for load‐independent LV chamber properties. V_N at the peak LV filling rate (≈sarcomere length at the peak sarcomere lengthening rate) manifests load‐independent properties. This novel method may help to elucidate and quantify new attributes of cardiac and cellular function. It merits further application in additional human and animal physiologic and pathophysiologic datasets.

Parametrization of an in-silico circulatory simulation by clinical datasets - towards prediction of ventricular function following assist device implantation

BACKGROUND

Left ventricular assist device (LVAD) therapy has revolutionized the way end stage heart failure is treated today. Analysis of LVAD interaction with the whole cardiovascular system and its biological feedback loops is often conducted by means of computer models. Generating real time pressure volume loops (PV-loops) in patients, not using conductance catheters but routine diagnostics to feed an in-silico model could help to predict postoperative complications.

METHODS

Routinely obtained hemodynamic measurements to evaluate myocardial function prior to LVAD implantation like pressure readings in the aorta, the left atrium and the left ventricle and simultaneous three-dimensional (3D) echocardiography recordings were assessed to parametrize a reduced computational model of the cardiovascular system. An automatic parameter identification procedure has been developed.

RESULTS

The results constitute a patient-individual computational simulation model. An exemplary in-silico study focusing on the effect of different ventricular assist device (VAD) speeds has been conducted. Results allow for estimation of the resulting hemodynamic parameters and changes of the PV-loops.

CONCLUSION

The model improves understanding and prediction of the interaction between pump and ventricles. Future modifications in exporting and merging routinely assessed real time hemodynamic patient data are necessary to investigate various clinical and pathological conditions of LVAD recipients.

New Insights in the Diagnosis and Treatment of Heart Failure

Cardiovascular disease is the leading cause of mortality in the US and in westernized countries with ischemic heart disease accounting for the majority of these deaths. Paradoxically, the improvements in the medical and surgical treatments of acute coronary syndrome are leading to an increasing number of “survivors” who are then developing heart failure. Despite considerable advances in its management, the gold standard for the treatment of end-stage heart failure patients remains heart transplantation. Nevertheless, this procedure can be offered only to a small percentage of patients who could benefit from a new heart due to the limited availability of donor organs. The aim of this review is to evaluate the safety and efficacy of innovative approaches in the diagnosis and treatment of patients refractory to standard medical therapy and excluded from cardiac transplantation lists.

A computational model that predicts reverse growth in response to mechanical unloading

Ventricular growth is widely considered to be an important feature in the adverse progression of heart diseases, whereas reverse ventricular growth (or reverse remodeling) is often considered to be a favorable response to clinical intervention. In recent years, a number of theoretical models have been proposed to model the process of ventricular growth while little has been done to model its reverse. Based on the framework of volumetric strain-driven finite growth with a homeostatic equilibrium range for the elastic myofiber stretch, we propose here a reversible growth model capable of describing both ventricular growth and its reversal. We used this model to construct a semi-analytical solution based on an idealized cylindrical tube model, as well as numerical solutions based on a truncated ellipsoidal model and a human left ventricular model that was reconstructed from magnetic resonance images. We show that our model is able to predict key features in the end-diastolic pressure-volume relationship that were observed experimentally and clinically during ventricular growth and reverse growth. We also show that the residual stress fields generated as a result of differential growth in the cylindrical tube model are similar to those in other nonidentical models utilizing the same geometry.

Mitral valve repair or replacement for ischemic mitral regurgitation? The Italian Study on the Treatment of Ischemic Mitral Regurgitation (ISTIMIR)

OBJECTIVE

It is uncertain whether mitral valve replacement is really inferior to mitral valve repair for the treatment of chronic ischemic mitral regurgitation. This multicenter study aimed at providing a contribution to this issue.

METHODS

Of 1006 patients with chronic ischemic mitral regurgitation and impaired left ventricular function (ejection fraction < 40%) operated on at 13 Italian institutions between 1996 and 2011, 298 (29.6%) underwent mitral valve replacement whereas 708 (70.4%) received mitral valve repair. Propensity scores were calculated by a nonparsimonious multivariable logistic regression, and 244 pairs of patients were matched successfully using calipers of width 0.2 standard deviation of the logit of the propensity scores. The postmatching median standardized difference was 0.024 (range, 0-0.037) and in none of the covariates did it exceed 10%.

RESULTS

Early deaths were 3.3% (n = 8) in mitral valve repair versus 5.3% (n = 13) in mitral valve replacement (P = .32). Eight-year survival was 81.6% ± 2.8% and 79.6% ± 4.8% (P = .42), respectively. Actual freedom from all-cause reoperation and valve-related reoperation were 64.3% ± 4.3% versus 80% ± 4.1%, and 71.3% ± 3.5% versus 85.5% ± 3.9 in mitral valve repair and mitral valve replacement, respectively (P < .001). Actual freedom from all valve-related complications was 68.3% ± 3.1% versus 69.9% ± 3.3% in mitral valve repair and mitral valve replacement, respectively (P = .78). Left ventricular function did not improved significantly, and it was comparable in the 2 groups postoperatively (36.9% vs 38.5%, P = .66). At competing regression analysis, mitral valve repair was a strong predictor of reoperation (hazard ratio, 2.84; P < .001).

CONCLUSIONS

Mitral valve replacement is a suitable option for patients with chronic ischemic mitral regurgitation and impaired left ventricular function. It provides better results in terms of freedom from reoperation with comparable valve-related complication rates.

Mitral valve surgery for dilated cardiomyopathy: current status and future roles

There are a large number of patients with functional mitral regurgitation resulting from dilated cardiomyopathy. The decision between surgical correction and medical management of severe mitral regurgitation in heart failure can be difficult. The data regarding long-term benefits and mortality after surgical intervention are contradictory. Recent data suggest that mitral regurgitation can be surgically corrected in heart failure with symptomatic improvements and beneficial reverse remodeling. Contrary to prior beliefs, mitral valve repair can be performed safely with minimal postoperative mortality. Data from multi-institutional, randomized prospective trials will help to elucidate many of the questions and concerns regarding repair of severe functional mitral regurgitation.

Left ventricular dyssynchrony is associated with recurrence of ischemic mitral regurgitation after restrictive annuloplasty

BACKGROUND

In our study, we investigated the impact of papillary muscle systolic dyssynchrony (DYS-PAP) obtained by 2D speckle-tracking echocardiography (2D-STE) in the prediction of recurrent ischemic mitral regurgitation (MR) after restrictive annuloplasty.

METHODS

The study population consisted of 524 consecutive patients who survived coronary artery bypass grafting (CABG) and restrictive annuloplasty, performed between 2001 and 2010 at 3 different Institutions and who met inclusion criteria. The assessment of DYS-PAP was performed preoperatively and at follow-up (median 45.3 months [IQR 26-67]) by 2D-STE in the apical four-chamber view for the anterolateral papillary muscle (ALPM) and apical long-axis view for the posteromedial papillary muscle (PMPM).

RESULTS

Recurrence of MR (≥ 2+ in patients with no/trivial MR at discharge) was found in 112 patients (21.3%) at follow-up. Compared to patients without recurrence of MR, these patients had higher DYS-PAP values at baseline (60.6 ± 4.4 ms vs. 47.2 ± 2.9 ms, p<0.001) which significantly worsened at follow-up (74.4 ± 5.2 ms, p=0.002 vs. baseline). In contrast, in patients with no MR recurrence, DYS-PAP was significantly reduced (25.3 ± 4.4 ms, p=0.002 vs. baseline). At logistic regression analysis DYS-PAP (odds ratio [OR]: 4.8, 95% Confidence Interval [CI]: 3.4-8.2, p<0.001), was the strongest predictor of recurrent MR with a cutoff ≥ 58 ms (95%CI 51-66 ms). The model showed an area under the Receiver Operating Characteristic (ROC) curve of 0.97 (CI 0.94-0.99 [optimism-corrected 0.94; CI 0.89-0.95]) with 98% sensitivity (CI 96-100% [optimism-corrected 95%; CI 91-96%]) and 90% specificity (CI 85-94% [optimism-corrected 87%; CI 82-90%]).

CONCLUSIONS

DYS-PAP represents a reliable tool to identify patients with ischemic MR who can benefit from restrictive annuloplasty.

Preexisting heart failure is an underestimated risk factor in cardiac surgery

BACKGROUND

Heart failure is characterised as a strong risk factor for systemic failure after cardiac surgery. However, the impact has never been substantiated.

METHODS

Patients with heart failure (n = 48) - scheduled for elective ventricular reconstruction or external constraint device-were compared with a one-to-one matched control group of patients without heart failure undergoing cardiac surgery between 2006 and 2009.

RESULTS

As expected, patients with heart failure more frequently experienced complications definitely related to pump failure (p = 0.01). However, complications not related to their pump failure were also more often observed, such as prolonged mechanical ventilation, sepsis and vasoplegia (p = 0.01). Overall, organ dysfunction-circulatory, renal, and pulmonary failure-was often observed in heart failure patients, contributing to a prolonged stay in the intensive care unit (p < 0.001) as well as in hospital (p = 0.01).

CONCLUSION

The adverse postoperative course in patients with heart failure is not only directly related to circulatory failure, but merely reflects a systemic dysregulation. Our findings suggest that heart failure impacts outcome and should therefore be included in prevailing risk classification systems. Offensive perioperative treatment strategies, focused on the main complications in patients with heart failure, will lead to improved results after cardiac surgery.

The year in review: the surgical treatment of valvular disease-2011

This review highlights important advances in techniques, guidelines, outcomes and innovations in valve surgery during 2011.

[Current topics in cardiology. Heart failure and heart transplantation]

The mission of the Heart Failure and Heart Transplantation Section of the Spanish Society of Cardiology is to study, promote interest in, and disseminate information about all aspects of myocardial dysfunction and heart transplantation. Heart failure is a highly prevalent disorder that consumes a substantial proportion of healthcare resources. Consequently, there is a very high level of interest in the condition and a wide range of preclinical and clinical research is being carried out, including research into new ways of looking at the disease that will increase our understanding. The aim of this article was to describe current developments concerning this disease and its treatment. Firstly, the latest publications on heart failure are summarized. Then, the most recent studies on advanced heart failure and ventricular assist devices are reviewed. Finally, the latest findings on heart transplantation are reported.

Importance of anterior leaflet tethering in predicting recurrence of ischemic mitral regurgitation after restrictive annuloplasty

OBJECTIVE

We investigated the relationship between anterior mitral leaflet (AML) tethering and recurrent ischemic mitral regurgitation (MR) after restrictive annuloplasty. We also explored whether the effect of AML tethering was secondary to modifications in left ventricular size and geometry.

METHODS

The study population consisted of 435 consecutive patients with chronic ischemic MR who survived combined coronary artery bypass grafting and undersized mitral ring annuloplasty performed at 3 institutions (University Hospital, Maastricht, The Netherlands; Careggi Hospital, Florence, Italy; and Civic Hospital, Brescia, Italy) from 2001 to 2008. The median follow-up was 44.7 months (interquartile range 25.9-66.4). The patients were divided by the baseline measurements into quintiles of AML tethering angle α' as follows: group 1, normal/slight AML tethering; group 2, mild AML tethering; group 3, moderate AML tethering; group 4, moderate-to-severe AML tethering; and group 5, severe AML tethering.

RESULTS

Recurrence of MR was significantly greater in patients with moderate-to-severe (28.3%) and severe (39.4%) AML tethering (P < .001). A strong correlation was found between α' (r = 0.83, P < .001) and recurrent MR but a weak correlation with the posterior mitral angle β' (r = 0.12, P = .05). On logistic regression analysis corrected for other echocardiographic risk factors, moderate-severe AML tethering or worse (adjusted odds ratio, 3.6; 95% confidence interval, 3.0-4.1; P < .001) was a strong predictor of MR recurrence. Compared with patients with β' of 45 or greater, those with severe and moderate-severe AML tethering had more than 3.7 and 1.7 times greater odds of MR recurrence, respectively. No significant interactions were found between α' and the indexes of left ventricular function and geometry.

CONCLUSIONS

Preoperative moderate-severe AML tethering or worse was strongly associated with MR recurrence. Thus, assessment of leaflet tethering should be incorporated into clinical risk assessment and prediction models.

Impact of preoperative anterior leaflet tethering on the recurrence of ischemic mitral regurgitation and the lack of left ventricular reverse remodeling after restrictive annuloplasty

BACKGROUND

The aim of this multicenter study was to investigate the impact of the preoperative anterior mitral leaflet tethering angle, α', on the recurrence of mitral regurgitation (MR) and left ventricular (LV) reverse remodeling (LVRR) after undersized mitral ring annuloplasty.

METHODS

The study population consisted of 362 patients, who were divided into two groups by baseline α': group 1, α' < 39.5° (n = 196), and group 2, α' ≥ 39.5° (n = 166). End points were recurrent MR ≥ 2+; LVRR, defined as a reduction in end-systolic volume index > 15%; and LV geometric reverse remodeling, defined as a reduction in systolic sphericity index to a normal value of <0.72 in patients with altered baseline geometry.

RESULTS

MR occurred in 9.6% (n = 19) and 43.3% (n = 72) of the patients in groups 1 and 2, respectively (P < .001). LVRR (85.7% vs 22.2%) at follow-up was higher in group 1 (P < .001). On multivariate regression analysis, α' ≥ 39.5° was a strong predictor of MR recurrence, lack of LV reverse remodeling and lack of LV geometric reverse remodeling (all P values < .001). In contrast, the posterior mitral leaflet tethering angle, β', was not significant (all P values > .05). When we allowed for interactions between α' and other risk factors, this effect occurred also in low-risk subgroups, and it was equivalent or generally attenuated in higher risk patients. There were no significant interactions between α' and any of the covariates (all P values > .05).

CONCLUSIONS

Anterior mitral leaflet tethering is a powerful predictor of MR recurrence and lack of LVRR after undersized mitral ring annuloplasty. Evaluation of leaflet tethering should be incorporated into clinical risk assessment and prediction models.