Aortic root surgery in septuagenarians: impact of different surgical techniques

Aortic root replacement has become a generally accepted treatment modality for a variety of aortic root pathologies. Basically, two different surgical procedures and their modifications have been advocated. Composite graft valve replacement (CVR) of the aortic root applying different techniques for reimplantation of the coronary ostia, and different types of valve sparing aortic root replacement techniques [1–5]. Although results of these techniques have been extensively described only limited data from the literature are available about these surgical techniques in older patients [6–13]. Furthermore, different techniques for aortic root replacement in septuagenarians have not been evaluated yet. Thus, the aim of this study was to evaluate the impact and safety of different surgical techniques for aortic root replacement (ARR) on early and late morbidity and mortality as well as functional status in septuagenarians undergoing aortic root replacement.

This study was approved by the institutional review board; all patients gave written informed consent.

We obtained clinical data by retrospective review of the hospital archives and follow-up information was gathered from direct telephone interview of the patient or a close relative, and contact with the referring physician. Infectious, thrombembolic and bleeding complications were recorded as required by the guidelines of the American Association for Thoracic Surgery/Society of Thoracic Surgeons [14]. Furthermore current NYHA-Status and performance status scale (Karnofsky) were requested [15].

Thromboembolism, hemorrhage requiring hospitalisation, aortic valve re-operations or endocarditis were considered to be valve related. Follow-up was complete for 95.2% (79/83) of hospital survivors.

As a result of the surgical policy, there was a consistently increasing caseload of patient receiving either a biological composite graft or a valve sparing aortic root reimplantation over the study period (1988–1992: MECH 12 pts., 1993–1998: MECH 13 pts., BIO 3 pts., REIMPL 2 pts., 1998–2003: MECH 26 pts., BIO 19 pts., REIMPL 20 pts.).

Patient's preoperative data are depicted in Table 1. The patient groups were comparable beside the age, incidence of previous cardiac surgery and arterial hypertension as well as NYHA-status. Preoperative hemodynamics did not show any significant differences between groups. Five patients that were operated on an emergency basis received a mechanical conduit.

Intraoperative variables are shown in Table 2. The REIMPL-group had a significantly longer aortic cross clamp time compared to the MECH-group and BIO-group. The most frequent concomitant surgical procedure was aortic arch replacement (42.1%) and coronary artery bypass grafting (CABG) (29.5%). However, the BIO-group had a significantly higher number of aortic arch replacement performed compared to the MECH-group, furthermore, the percentage of selective antegrade cerebral perfusion (SACP) for cerebral protection was significantly higher in this BIO-group compared to the other patient groups. SACP is routinely performed in our institution since 1999.

Follow-up morbidity and mortality

The follow-up was 41 ± 42.3 months (1–173 months) for the entire cohort. The follow-up time showed a significant difference between groups (MECH-group 49 ± 48 months, BIO-group 25 ± 36.9 months, and REIMPL-group 40 ± 28 months, p = 0.028). Follow-up revealed 22 late deaths, 6 patients died of cardiac related reason, 3 of valve related reasons. Thus mean survival for the entire patient population was 8 ± 1 years and showed significant difference between groups as depicted in Figure 1 and Figure 2.

23 hospital survivors had to be readmitted to the hospital, 7 for valve related complications, 2 for cardiac related complications and 14 for other reasons. During follow-up 3 patients had to be re-operated on, all patients had prosthetic valve endocarditis, two of these patients died (freedom from re-operation 96.2%).

Postoperative NYHA-Status decreased significantly for the entire cohort as well as patients in the MECH-group and BIO-group (Figure 3). The performance status of the entire group (78 ± 7.5% to 81.1 ± 13.2%, p = 0.017) as well for the MECH-group (76.5 ± 7.8% to 82.6 ± 12.5%, p = 0.015) and BIO-group (76.4 ± 8.1% to 81.3 ± 14.1%, p = 0.027) slightly increased.

In this study we demonstrated that different complex surgical techniques for ARR can be performed with good results in septuagenarians. Our data indicate that valve sparing aortic root reimplantation is an excellent alternative to composite conduits with bioprostheses or mechanical prostheses for septuagenarians with favourable short and long-term outcome.

Composite valve replacement has become a generally accepted surgical technique for the treatment of aortic root pathology with acceptable perioperative mortality rates and good long-term results [6, 8, 9, 11, 12, 18–21]. The mortality rate for ARR with composite valve grafts in recent publications varies between 0.7% and 11% with a survival rate from 76% to 91.8% at 5 years and 62% to 76% at 10 years. Furthermore, Urbanski and associates showed in a case matched study with 200 patients, that ARR can be performed with a similar operative risk, valve related morbidity and late mortality as isolated aortic valve replacement [21]. However, recent published series showed that valve sparing aortic root replacement techniques are a valuable option for patients with macroscopically normal leaflets [3, 10]. The hospital mortalities in these studies vary around 3–5%. The functional results showed freedom from re-operation in 94 – 99% of different sub cohorts.

In the vast majority of these studies the patients were younger. Due to the limited data from the literature there is still an ongoing debate whether ARR should be performed in elderly patients >70 years due to an anticipated higher mortality rate for ARR compared to isolated aortic valve replacement. Only sparse data are available from the literature dealing with the problem of ARR in septuagenarians [8]. Ehrlich and co-workers described a hospital mortality of 8.3% (7 of 84). This is comparable to the 5%–11.4% hospital mortality after aortic valve replacement in the same age group [22–24].

In our study, two patients died intra-operatively, and another 10 within the first 30 day or during hospital stay (12/95 pts., 12.6%). Our institutional mortality for this age group ranges from 8% for cardiac surgery up to 29% in patients undergoing surgery for acute type A aortic dissection [25, 26]. In other studies we revealed age and co-morbidities as predictors for morbidity and mortality [27, 28]. We strongly believe that the mortality rate is influenced by the amount of co-morbidities rather than the surgical technique.

The standard approach to ARR is the use of composite grafts with a mechanical prosthesis [29]. Composite conduits with stented bioprosthesis have shown reasonable results [9, 17]. Etz and associates recently published their experience with 206 patients receiving custom made composite conduits with a stented bioprosthesis (mean age 53 years) with a hospital mortality rate of 2.9% and a 10 year survival rate of 89% [9]. Only a limited number of reports compared mechanical and biological ARR [6, 8]. Ehrlich and co-workers showed that overall probability of survival was similar for patients with composite grafts incorporating a mechanical or biological valve (mean age 73.9 years; n = 84) with a 5 year survival of approximately 60% in both groups. Interestingly in this study survival was similar to that of an age-matched population. Byrne et al. compared biological and mechanical root replacement in a younger patient cohort with a median age of 53 years respectively 54 years and could neither demonstrate a difference in hospital mortality (1.5% vs. 2.4%) nor in the 5 year survival rate (92.4% vs. 88.2%). However, in the biological root replacement group either aortic homografts or stentless aortic valves were implanted.

In the present study, mean survival was 7 ± 1 years for the entire cohort, with best results for patients in the REIMPL-group (5-year survival rate 80%). The impact of pure aortic insuffiency on results in this subgroup in controversially discussed. A substantial number of patients receiving a mechanical or biological composite graft had either mixed AS/AI or AS only; in contrast patients scheduled for aortic root reimplantation had pure AI only. The impact of different physiological subgroups (aortic regurgitation vs. aortic stenosis vs. stenosis/regurgitation) on early and late outcome after aortic valve surgery is still discussed controversially. Scott and associates analysed 1,479 isolated aortic valve replacement procedures and showed substantial differences in operative mortality rates among physiological subgroups [30]. In contrast Nowicki and colleagues reported on 5793 patients undergoing aortic valve surgery and found no impact of valve diagnosis on in-hospital mortality [31]. However, in both studies no long-term results have been analysed.

For surgeons not familiar with valve sparing aortic root procedures ARR with composite conduits is still a valuable option. Whereas in this patient composite graft replacement with stented bioprosthesis is omitting lifelong oral anticoagulation und consequent avoidance of bleeding complications [32].

The small number of patients in each group makes it difficult to draw definite conclusion about the impact of different surgical techniques for ARR on early and late outcome.

However, our data indicate that valve sparing aortic root Reimplantation is safe and effective in septuagenarians, and is associated with low early and late morbidity and mortality.