Minimally Invasive Sutureless Aortic Valve Replacement is Associated With Improved Outcomes in Patients With Left Ventricular Dysfunction

Abstract

Objective

Patients with severe aortic stenosis and reduced left ventricular ejection fraction (LVEF) have a poor prognosis compared with patients with preserved LVEF. To evaluate the impact of sutureless Perceval (LivaNova, Italy) aortic bioprosthesis on LVEF and clinical outcomes in patients with baseline left ventricular (LV) dysfunction who underwent isolated aortic valve replacement (AVR).

Methods

Between March 2011 and August 2017, 803 patients underwent AVR with Perceval bioprosthesis implantation. Fifty-two isolated AVR had preoperative LVEF ≤45%. Mean age of these patients was 77 ± 6 years, 24 patients were female (46%), and mean EuroSCORE II was 9.4% ± 4.8%. Perceval bioprosthesis was implanted in 9 REDO operations. In 43 patients (83%), AVR was performed in minimally invasive surgery with an upper ministernotomy (n = 13) or right anterior minithoracotomy (n = 30).

Results

One patient died in hospital. Cardiopulmonary bypass and aortic cross-clamp times were 85.5 ± 26 minutes and 55.5 ± 19 minutes, respectively. At mean follow-up of 33 ± 20 months (range: 1 to 75 months), survival was 90%, freedom from reoperation was 100%, and mean transvalvular pressure gradient was 11 ± 5 mmHg. LVEF improved from 37% ± 7% preoperatively to 43% ± 8% at discharge (P < 0.01) and further increased to 47% ± 9% at follow-up (P = 0.06), LV mass decreased from 149.8 ± 16.9 g/m² preoperatively to 115.3 ± 11.6 g/m² at follow-up (P < 0.001), and moderate paravalvular leakage occurred in 1 patient without hemolysis not requiring any treatment.

Conclusions

AVR with sutureless aortic bioprosthesis implantation in patients with preoperative LV dysfunction demonstrated a significant immediate and early improvement in LVEF.

Keywords

aortic valve replacement sutureless aortic bioprosthesis echocardiography left ventricular dysfunction minimally invasive surgery

Introduction

Left ventricular (LV) dysfunction is associated with a dismal prognosis in patients with symptomatic severe aortic stenosis (AS). Patients with LV dysfunction undergoing surgical aortic valve replacement (SAVR) face increased early mortality risk compared with patients with normal LV function.^1

-6 Nonetheless, SAVR for severe AS is associated with a survival advantage and improvements in LV ejection fraction (LVEF) and clinical symptoms, regardless of baseline LV function.^2,7
-9 Despite these results, these patients referred for AVR have still worse outcomes and, therefore, might benefit from sutureless technology in order to reduce mortality and morbidity. In the last years, sutureless aortic valve implantation has gained interest because of the rapid development of new valve technologies. Perceval aortic valve (LivaNova, Italy) is a sutureless bioprosthesis and several reports have shown promising results in terms of mortality, morbidities, and hemodynamic performances.^10

-13 However, the impact of Perceval bioprosthesis implantation on LV functional recovery and of LVEF improvement on subsequent outcomes in patients with preoperative low ejection fraction is not known. The aim of this study was to report our single-center experience of this cohort of patients.

Methods

Patients

Between March 2011 and August 2017, 803 elective patients with symptomatic aortic valve disease underwent AVR with Perceval sutureless aortic bioprosthesis at Heart Hospital, Massa, Italy. Fifty-two isolated AVR had preoperative LVEF ≤45%. Baseline patient characteristics are listed in Table 1. Patient selection for this type of device was left to the discretion of the surgeon. Exclusion criteria were acute endocarditis, irregular aortic annulus, or ascending aorta geometry. The ratio between the diameter of the sinotubular junction and the diameter of the superior annulus should not exceed 1.3 (a ratio >1.3 can prevent a correct fixation of the valve-stent on the aorta). This ratio was routinely determined with echocardiography and also with computed tomography (CT) scan. We performed in all patients with isolated AS CT scan to plan minimally invasive approach. Informed consent was obtained from each patient and the study protocol conforms to the ethical guidelines of the 1975 Declaration of Helsinki as reflected in a priori approval by the institution’s human research committee. Transthoracic echocardiography was performed preoperatively, postoperatively, and at follow-up. Trivial and moderate paravalvular leakage are defined by Akins et al. and Généreux et al.^14,15Follow-up was complete. Mean clinical and echocardiographic follow-up time was 33 ± 20 months (range: 1 to 75 months). The follow-up was obtained from interview with the surviving patients in regard to their postoperative adverse events and actual functional status, and in all examined patients we performed echocardiography. In all patients the first visit was made after 1 month, the second after 6 months, the third after 1 year, and then 1 visit every year.

Table 1

Baseline Patient Characteristics.

Variables	Overall n = 52
Age, mean ± SD	77 ± 6
Sex, female (%)	24 (46)
BSA, mean ± SD (m²)	1.8 ± 3.8
Hypertension (%)	47 (90)
Diabetes mellitus (%)	20 (38)
COPD (%)	7 (13)
Hyperlipidemia (%)	29 (56)
Chronic renal failure (%)	5 (10)
Peripheral vascular disease (%)	13 (25)
EuroSCORE II, mean ± SD (%)	9.4 ± 4.8
STS score, mean ± SD (%)	7.5 ± 3.6

BSA, body surface area; COPD, chronic obstructive pulmonary disease; STS, Society of Thoracic Surgeons.

Technology

Perceval is a biological prosthesis composed of bovine pericardium stabilized in a buffered glutaraldehyde solution and assembled on a nitinol stent. This sutureless technique is achieved by the nitinol stent, which has the dual role of valve support and anchoring to the aortic root. This bioprosthesis can be collapsed through a dedicated device and positioned by means of a specific delivery system. The delivery system loaded with the collapsed stent-mounted valve is guided to its correct position by sliding it over the 3 guiding sutures (4/0 polypropylene), positioned at the nadir level of each resected cusp. Once the delivery system is in position, the prosthesis is deployed, the guiding sutures are removed, and the valve is finally in place; at this point a postdilation modeling is performed with a dedicated balloon (30 seconds at a pressure of 4 atmosphere) and the valve flushed with warm saline at 37°C to optimize final sealing. We instituted oral anticoagulation therapy with warfarin sodium for 3 months after Perceval implantation reaching an international normalized ratio between 2.0 and 3.0. After 3 months we recommend, when there are no contraindications to suspension, the replacement of warfarin with 100 mg daily of aspirin.

Operative Procedures

A standard median sternotomy was performed in 9 (17%) patients, 43 (83%) patients underwent minimally invasive AVR with an upper partial ministernotomy (n = 13) or right anterior minithoracotomy (n = 30) approach. Median sternotomy was performed in reinterventions (Table 2). In our Institution right anterior minithoracotomy and upper partial ministernotomy are the standard surgical access for isolated AVR. Cardioplulmonary bypass (CPB) was instituted with aortic-atrial cannulation and the heart arrested with anterograde normothermic blood or cold crystalloid cardioplegia. Transverse aortotomy was performed approximately 2 cm above the commissures and aortic valve was inspected. The aortic valve leaflets were totally excised, the aortic annulus decalcified, and the sutureless bioprostheses were implanted. The bioprosthesis selected for implant should match the measured diameter of the aortic annulus. The aortotomy was closed with a continuous 5-0 polypropylene suture and the patient was weaned from CPB. Good position and normal function of the prosthesis were assessed by intraoperative transesophageal echocardiography immediately after weaning from CPB. These procedures are performed by all staff surgeons.

Table 2

Intraoperative Data.

Variables	Overall N = 52
Valve size
S	5 (10%)
M	11 (21%)
L	29 (56%)
XL	7 (13%)
Surgical approaches
Sternotomy	9 (17%)
Ministernotomy	13 (25%)
Right anterior minithoracotomy	30 (58%)
Reintervention	9 (17%)
ACC time for stand-alone procedure, mean ± SD (minutes)	55.5 ± 19.0
CPB time for stand-alone procedure, mean ± SD (minutes)	85.5 ± 26.0

ACC, aortic cross-clamp; AVR, aortic valve replacement; CABG, coronary artery bypass grafting; CPB, cardiopulmonary bypass; MVR, mitral valve replacement.

Reinterventions include as primary procedure: 1 MVR +CABG; 5 AVR; 2 CABG; 1 MVR.

Statistical Analysis

All continuous variables are expressed as mean ± SD; categorical variables are expressed as percentage. Comparison among groups was performed using analysis of variance with Tukey’s post hoc test. Level of significance was set for P <0.05 to reject the null hypothesis. Survival analysis was performed using Kaplan–Meier method. All calculations are made using R statistical package (R core team; R Foundation for Statistical Computing, Vienna, Austria).

Results

All patients had preoperative aortic valve stenosis with or without regurgitation and preoperative mean pressure gradient were 57.5 ± 14.6 mmHg. Mean EuroSCORE II was 9.4% ± 4.8% and mean STS score was 7.5% ± 3.6%. Nine patients (17%) had previously undergone cardiac surgery. Prosthesis sizes implanted were S (n = 5), M (n = 11), L (n = 29), and XL (n = 7). CPB and ACC time were 85.5 ± 26 and 55.5 ± 19 minutes (Table 2). In right anterior minithoracotomy interventions CPB and ACC-clamp time were 89.3 ± 31.7 and 57 ± 22.3 minutes; in ministernotomy interventions CPB and ACC-clamp time were 86.8 ± 24.2 and 55.1 ± 18.4 minutes; in full sternotomy interventions CPB and ACC-clamp time were 61.6 ± 16.3 and 45.4 ± 17.2 minutes. At 30 days, 1 patient (1.9%) died for septic shock. This patient had severe preoperative chronic obstructive pulmonary disease and underwent AVR in ministernotomy approach. Mean hospital stay was 9 ± 5.3 days. Two patients developed acute renal failure requiring short-term dialysis. Nine patients had postoperative atrial fibrillation. Permanent pacemaker implantation within the first 30 days was necessary in 1 patient (Table 3). Four patients needed late pacemaker implantation.

Table 3

Postoperative Data.

Variables	Overall N = 52
At 30 days
Mortality, n (%)	1 (1.9)
AF, n (%)	9 (17.3)
Permanent PMK, n (%)	1 (1.9)
Renal insufficiency (CC <85 mL/min), n (%)	2 (3.8)
At follow-up
NYHA class, mean ± SD	1.5 ± 0.5
Permanent PMK, n (%)	4 (7.8)
Stroke, n (%)	2 (3.9)
Endocarditis, n (%)	1 (1.9)
Mortality, n (%)	5 (10)

AF, atrial fibrillation; CC, creatinine clereance; NYHA, New York Heart Association; PMK, pacemaker.

At a mean follow-up of 33 ± 20 months (range: 1 to 75 months) survival was 90% (Fig. 1). Two patients died of heart failure and not prosthesis related. One patient had cerebral trauma, 1 patient died of stroke, and 1 patient of neoplasia. Two patients had stroke. Freedom from reoperation was 100%. Prosthesis function and hemodynamic performance were assessed at discharge and at follow-up. Mean pressure gradient decreased significantly from a preoperative value of 57.5 ± 14.6 to 11 ± 5 mmHg at follow-up (P < 0.001). LVEF improved from 37% ± 7% preoperatively to 43% ± 8% at discharge (P < 0.01) and further increased to 47% ± 9% at follow-up (P = 0.06) (Fig. 2). At follow-up, LV mass decreased from 149.8 ± 16.9 to 115.3 ± 11.6 g/m² (P < 0.001), and marginal linear prediction of LV mass regression was 34.5 g/m². Moderate paravalvular leakage occurred in 1 patient without hemolysis not requiring any treatment, and trivial paravalvular leakage was present in 1 patient at follow-up (Table 4).

Table 4

Echocardiographic Findings.

Variables	Preoperative	At discharge	At follow-up	P
LVEF, mean ± SD, (%)	37 ± 7	43 ± 8*	47 ± 9**	<0.01*
				0.06**
Mean pressure gradient, mean ± SD, (mmHg)	57.5 ± 14.6	13.9 ± 7.3	11 ± 5	<0.001
LV mass, mean ± SD, (g/m²)	149.8 ± 16.9		115.3 ± 11.6	<0.001
Paravalvular leakage
Trivial		3 pts	1 pts
Moderate		1 pts	1 pts

LVEF, left ventricular ejection fraction; LV, left ventricular.

Discussion

This study shows the clinical and echocardiographic results with sutureless aortic bioprosthesis in 52 patients with preoperative low ejection fraction undergoing AVR. We demonstrated that the implantation of Perceval bioprosthesis in severe AS with LV dysfunction is a safe and feasible procedure associated with low mortality and excellent hemodynamic performance. Specifically, we found a dramatic improvement of LVEF at early follow-up.

Numerous studies have demonstrated that LV dysfunction is associated with increased early and late mortality after both SAVR and transcatheter aortic valve implantation (TAVI).^2,7
-9,16,17 Recovery of the LVEF after SAVR has been demonstrated in over two-thirds of patients with associated improved clinical outcomes.² However, less is known regarding the prognostic impact of early LVEF recovery on the subsequent survival rate among patients with severe LV dysfunction who implanted Perceval bioprosthesis.^17
-19

Sutureless bioprosthesis represents an innovative approach for surgical AVR and has been designed to allow faster implantation, reducing CPB and ACC time. This is an advantage for all patients, regardless of the risk profile. Therefore, sutureless aortic valve implantation might be an alternative treatment option for patients at high risk for mortality and morbidity after open heart surgery. First clinical results of Perceval bioprosthesis were reported in 2011 by Flameng et al.²⁰ A larger multicenter experience with Perceval aortic bioprosthesis was reported by Shrestha et al.¹³ Fischlein et al. reported low 1-year event rates in intermediate-risk patients undergoing AVR from a large multicenter cohort study.¹⁰ None of these studies analyze specifically the subcategory of patients with preoperative LV dysfunction. Our report included all patients with isolated AVR and excluded those with pre-existing comorbid conditions such as myocardial infarction or coronary artery bypass graft, which might influence the postoperative recovery of the LV function due to the extent of the irreversible myocardial damage.¹⁹ The immediate effects of valve replacement on LV performance are principally decreases in preload and afterload.²¹ Later effects include ventricular adaptation and remodeling with a regression of hypertrophy and LV mass.^22,23 Postoperative ejection fraction has been reported to be maintained or increased after SAVR both in patients with a normal preoperative LVEF and in patients with a preoperative impairment of LVEF.² Patients with LV dysfunction and severe AS are exquisitely sensitive to afterload, and previous studies have shown that the modest reduction in LV pressure load seen with percutaneous valvuloplasty can lead to improved LV function.^22,24 In our study the majority of patients demonstrated a rapid improvement in the ejection fraction before discharge. LVEF recovery after Perceval implantation was associated with a lower risk of clinical events, including significantly lower mortality and major adverse cardiac and cerebrovascular events.

In our experience 30-day mortality was 1.9% (1/52) and survival was 90% at follow-up. According to the 2-year follow-up of the PARTNER trial, paravalvular leakage was more frequent in patients undergoing TAVI and this was associated with increased risk of mid-term mortality, even in those with mild leakage.²⁵ In our single-center series, moderate paravalvular leakage occurred at follow-up in 1 patient, without hemolysis not requiring any treatment. Although the reduced time needed for implantation is a theoretical potential advantage of this prosthesis, in our experience mean CPB and ACC time were longer than other studies.^10

-13,20 This might certainly be related to surgical approach. In 43 (83%) patients Perceval was implanted in minimally invasive approach. A meta-analytical study showed a CPB time of 104.4 minutes for minimal-access group that underwent AVR versus 94.0 minutes for conventional access group (P < 0.001).²⁶ Our experience showed CPB time of 89.3 ± 31.7 minutes in right anterior minithoracotomy interventions and 86.8 ± 24.2 minutes in ministernotomy interventions. As minimally invasive AVR has shown longer CPB and ACC time than conventional surgery, we strongly believe that sutureless technology might be the solution for less invasive approaches. In our experience, regarding all isolated AVR, not only AVR with LV dysfunction, ACC and CPB times of minimally invasive AVR with conventional sutured bioprosthesis were 87 and 121 minutes versus 50.5 and 81.7 with Perceval bioprosthesis. Mean transvalvular gradient at mid-term follow-up was 11 ± 5 mmHg. The study of Rubens et al. demonstrates superior overall LV mass regression and LV mass regression over time with the Trifecta (St Jude Medical, St Paul, MN, USA) valve as well as improved freedom from the composite outcome of death, heart failure, and readmission compared with the Magna Ease valve (Edwards LifeSciences, Irvine, CA, USA) at 2.5 years. Marginal linear prediction of LV mass regression for the Trifecta group was 45.5 g/m² versus the Magna Ease group at 28.3 g/m².²⁷ In our study, marginal linear prediction of LV mass regression was 34.5 g/m². This shows that sutureless technology presents results in term of LV mass regression in line and often better than conventional bioprosthesis. In the era of TAVI it is important to compare the clinical outcomes between these 2 recent methods to treat aortic valve disease. A meta-analysis of Shinn et al. includes 7 observational studies comprising 617 sutureless AVR and 621 TAVI patients. This meta-analysis demonstrates that early mortality is lower after sutureless than after TAVI in selected patients. The rates of stroke and pacemaker implant are comparable between procedures; however, the incidence of paravalvular leak is higher after TAVI.²⁸ In our 52 patients the rate of perioperative pacemaker implantation was 7.8%. LVEF improved from 37% ± 7% preoperatively to 43% ± 8% at discharge (P < 0.01) and further increased to 47% ± 9% at follow-up (P = 0.06). The reported rate of 30-day mortality after SAVR in patients with severe impairment in LVEF ranges in the literature between 8% and 21%^3,9,29
-31 and it depends on the presence of contractile reserve. In our study, sample contractile reserve was not evaluated systematically, and there are insufficient data to draw any conclusion. Few studies in the literature have documented improvements in LVEF after AVR, and even fewer have focused on outcomes in patients with severe LV dysfunction at baseline.^32

-36 The improvement in LVEF obtained after Perceval seems to be rapid; this may be due, at least in part, to an excellent hemodynamic performance of sutureless prosthesis in terms of transprosthetic gradients and reduction of pressure overload on the left ventricle.³⁴ In addition, we must consider that Perceval reduces ischemia times and ensures an improved recovery of myocardial function.

Some limitations exist in our report. This is a retrospective study. Patient selection for this type of device was left to the discretion of the surgeon. Another limitation is that we do not have the implantation time from the moment the aortic valve is excised to the moment the new valve is fully expanded. Despite the collection of extensive echocardiographic and clinical data in the registry, some important variables were not collected in our analyses. For example, although previous studies have demonstrated the importance of contractile reserve as a predictor of long-term prognosis after both TAVI and SAVR, contractile reserve was not collected in the registry, and, therefore, its effect on LVEF recovery could not be evaluated.

Conclusions

In this retrospective analysis, patients with preoperative LV dysfunction demonstrated a significant early improvement in LVEF after Perceval implantation. The presence of rapid partial LVEF recovery was associated with an improvement in the clinical outcomes. Despite encouraging early and mid-term results, we need data documenting its long-term performance. Sutureless technology and its future evolutions, associated with minimally invasive approach, might be considered an alternative treatment option for AVR, especially in high-risk patients.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

*

Presented at ePoster Competition at 18 ISMICS Annual Scientific Meeting, Vancouver, Canada, 13-16 June 2018.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

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