Author + information
- Received January 12, 2011
- Revision received March 2, 2011
- Accepted March 17, 2011
- Published online August 2, 2011.
- Mario Gaudino, MD⁎ (, )
- Amedeo Anselmi, MD,
- Mauro Morelli, MD,
- Claudio Pragliola, MD,
- Vasileios Tsiopoulos, MD,
- Franco Glieca, MD and
- Gianfederico Possati, MD
- ↵⁎Reprint requests and correspondence:
Dr. Mario Gaudino, Department of Cardiac Surgery, Catholic University, L.go Gemelli 1, 00168 Rome, Italy
Objectives This study was conceived to describe the evolution of aortic dimensions in patients with moderate post-stenotic ascending aorta dilation (50 to 59 mm) submitted to aortic valve replacement (AVR) alone.
Background The appropriate treatment of post-stenotic ascending aorta dilation has been poorly investigated.
Methods Ninety-three patients affected by severe isolated calcific aortic valve stenosis in the tricuspid aortic valve accompanied by moderate dilation of the ascending aorta (50 to 59 mm) were submitted to AVR only. All patients were followed for a mean of 14.7 ± 4.8 years by means of periodic clinical evaluations and echocardiography and tomography scans of the thorax.
Results Operative mortality was 1.0% (1 patient). During the follow-up, 16 patients died and 2 had to be reoperated for valve dysfunction. No patients experienced acute aortic events (rupture, dissection, pseudoaneurysm), and no patient had to be reoperated on the aorta. There was not a substantial increase in aortic dimensions: mean aortic diameter was 57 ± 11 mm at the end of the follow-up versus 56 ± 02 mm pre-operatively (p = NS). The mean ascending aorta expansion rate was 0.3 ± 0.2 mm/year.
Conclusion In the absence of connective tissue disorders, AVR alone is sufficient to prevent further aortic expansion in patients with moderate post-stenotic dilation of the ascending aorta. Aortic replacement can probably be reserved for patients with a long life expectancy.
Aortic stenosis is becoming one of the most frequent indications for surgery in the Western world, with enormous clinical and economic implications (1,2); both the industry and surgical communities are employing considerable resources to develop new methods of treatment of the disease (3,4).
Because aortic stenosis is accompanied in more than one-half of patients by dilation of the ascending aorta (which is currently not treatable by the new percutaneous techniques), the definition of the optimal treatment of post-stenotic dilation (ascending aorta replacement or not) is an issue of major relevance. In this study, we report the evolution of aortic dimensions in patients with moderate post-stenotic ascending aorta dilation submitted to aortic valve replacement (AVR) alone in the initial 15 years after surgery.
Patients included in this study represent a consecutive cohort of 93 patients operated in our institution from January 1990 to December 2000. Based on pre-operative echocardiography, all patients were affected by severe isolated calcific stenosis of a tricuspid aortic valve accompanied by dilation of the ascending aorta with a maximum diameter between 50 and 59 mm.
The diagnosis of tricuspid aortic valve was always confirmed at surgery by visual inspection, as outlined in the operative report. The criteria for the diagnosis of bicuspid or tricuspid aortic valve were those initially described by Roberts (5). The presence of a bicuspid aortic valve and/or more than slight aortic insufficiency were considered absolute exclusion criteria, and patients with these features were submitted to ascending aorta replacement. In fact, during the study period, no patient with tricuspid stenotic aortic valve, absence of connective tissue disease, and dilated ascending aorta <60 mm was submitted to aortic surgery, whereas 381 patients with bicuspid or insufficient aortic valve and aortic dilation >50 mm were submitted to ascending aorta replacement.
Seventy-three patients underwent pre-operative computed tomography (CT) scan of the thorax; at the time of the study, pre-operative CT scans were available for review for 64 of these patients.
All patients were submitted to conventional AVR by full median sternotomy and moderately hypothermic cardiopulmonary bypass. No plication or replacement of the ascending aorta was performed.
After surgery, all surviving patients were submitted to periodic (6 months after surgery and then every 12 months) physical and echocardiographic examinations. Transthoracic echocardiography was performed at each follow-up visit, whereas transesophageal examination or CT scan were reserved for patients who needed a more in-depth evaluation.
For the purpose of the present study, all patients were re-evaluated physically and by transthoracic echocardiography. In the 64 patients for whom a pre-operative CT scan was available, a follow-up contrast-enhanced CT scan of the thorax was also performed.
In the cases of in-hospital death during the follow-up, all medical and autopsy reports were reviewed for the cause of death; for out-of-hospital fatalities the death certificate was requested.
The mean duration of follow-up was 14.7 ± 4.8 years. Follow-up was 100% complete.
Continuous data are presented as mean ± SD and categorical variables as percentages. Intergroup comparison (pre-treatment aortic diameter vs. aortic diameter at the end of follow-up) was performed using the Student t test for paired data. The statistical analysis was conducted using SPSS version 13.0 for Windows (SPSS Inc., Chicago, Illinois).
The ascending aortic expansion rate was calculated for those individuals who demonstrated some degree of aortic growth during the follow-up. Conversely, the average aortic diameter at the end of follow-up was calculated in the entire population, including those who demonstrated unchanged aortic diameter at the end of the follow-up.
The pre-operative and intraoperative characteristics of the population are summarized in Table 1. The mean age was 67.1 years, with a male/female ratio of 2.87; most of the patients were in New York Heart Association functional class I or II, and only a few had a poor left ventricular ejection fraction. Hypertension, peripheral vasculopathy, and chronic pulmonary disease were the most frequent comorbidities. The mean pre-operative aortic diameter was 56 ± 2 mm.
The mean cardiopulmonary bypass and cross-clamp times were 54 and 66 min, respectively. In 71 patients, we implanted a mechanical prosthesis, whereas a stented porcine bioprosthesis was used in the remaining 22 patients. This is because we favor the use of mechanical prostheses and reserve biological valves for very old patients or patients with clear contraindications to lifetime anticoagulation. Most of the implanted prostheses were in the 19 to 23 mm range, with very few 25 mm.
Operative mortality was 1.0% (n = 1) and was related to a massive perioperative stroke. Other major complications, as well as details of the early post-operative course of the patients, are summarized in Table 2.
The mean duration of follow-up was 14.7 ± 4.8 years. During this period, 16 patients died (17.3%); 11 of these deaths occurred in-hospital. Causes of deaths are detailed in Table 3. Nine of the 16 follow-up deaths (7 of the patients who died from cardiovascular cases) were submitted to autopsy. In no cases was death attributed to an aortic event.
One patient had to be reoperated for endocarditis 69 months after the initial surgery; he died on the 42nd operative day owing to uncontrollable sepsis. Another patient was successfully reoperated for valve thrombosis 113 months after the initial operation. Three patients were submitted to coronary artery bypass surgery and 4 to percutaneous coronary interventions. No patients experienced acute aortic events (rupture, dissection, pseudoaneurysm) during the follow-up, and no patient had to be reoperated for thoracic aortic pathology.
There was not a substantial increase in aortic dimensions during the 10 years after surgery: the mean aortic diameter was 57 ± 11 mm at the end of the follow-up vs. 56 ± 2 mm pre-operatively (p = NS). The mean ascending aorta expansion rate was 0.3 ± 0.2 mm/year. No statistically significant association was found between ascending aorta dilation and any of the clinical variables examined. Figure 1 shows the frequency distribution of absolute change in ascending aorta diameter during the follow-up period, whereas Figure 2 details the modifications of aortic diameter with time in patients for whom pre-operative CT scans were available.
The approach to patients with moderate post-stenotic dilation of the ascending aorta remains controversial.
In patients with connective tissue disorder or bicuspid aortic valve, the intrinsic disease of the vascular media mandates ascending aorta replacement. However, when aortic dilation is the consequence of the modified flow patterns through the stenotic valve and the vascular wall histology is normal, it is assumed that valve replacement alone can interrupt the process; in these cases, the opportunity of adding aortic replacement surgery is questionable.
Because the prevalence of ascending aorta dilation in association with aortic valve disease is estimated at approximately 60% of the total (although the moderate degree is less frequent), the impact of this controversy on clinical practice is of major relevance (6–8).
In the literature, only a few studies have specifically analyzed the evolution of untreated post-stenotic aortic dilation in patients without connective tissue disorders submitted to isolated AVR. Andrus et al. (6), reporting on 107 patients with an aortic diameter ≥3.5 cm, found no evidence of further dilation in the first 3 years after isolated AVR. In the same year, Yasuda et al. (9) reported a mean ascending aorta expansion rate of −0.08 ± 0.08 mm/m2/year in a small series of 14 patients followed for 9.7 years after surgery. More recently, Botzenhardt et al. (10) described a reduction of the aortic diameter in 10 patients with pre-operative ascending aorta ≥4 cm at a mean follow-up of 4.8 years after isolated valve surgery. In the other series, bicuspid and tricuspid valves and patients with slight and moderate dilation are usually considered together, not allowing meaningful clinical conclusions.
The present report is to date the largest series of patients with moderate post-stenotic aortic dilation submitted to valve replacement alone and followed for almost 10 years.
The fact that none of our patients experienced acute aortic events or had to be reoperated for thoracic aortic disease is worthy of consideration. Concordantly, CT scans and echocardiographic evaluations showed that there was not a substantial increase in aortic dimensions during the 10 years after surgery, with a mean ascending aorta expansion rate of 0.3 ± 0.2 mm/year. These data suggest that once the hemodynamic derangement has been corrected by replacement of the stenotic valve in these patients, the aortic wall remained stable and no further dilation occurred.
The researchers who have evaluated the natural history of post-stenotic ascending aorta dilation in the absence of valvular surgery have reported mean growth rates almost 10 times faster than that described in our series (11,12). Moreover, the accepted expansion rate of aortic aneurysms is by far higher than that reported in our patients (1.0 mm/year vs. 0.3 mm/year) (12–14). All of these observations support the concept that atherosclerotic or degenerative aneurysms and post-stenotic dilations have a different physiopathology: the first are derived from a derangement of the aortic wall, and the hemodynamic effect of the valvular stenosis is the cause of the dilatation in the latter. This physiopathological difference has obvious therapeutic implications: if aortic replacement is mandatory in the first type of aneurysms, correction of the pathological flow patterns by valve replacement alone is sufficient to prevent further aortic expansion in cases of post-stenotic dilations.
Although our study is a case series, it must be considered that all data were prospectively collected and that our follow-up was 100% complete. Moreover, all of the patients for whom pre-operative CT scans were available underwent control CT scans of the thorax. In addition, the number of patients is the largest reported and the follow-up the longest in the literature. All of these considerations maximize the affordability of our observations, although further investigation on this issue is necessary to confirm our findings.
We are aware of the fact that our data contradict the published guidelines for the treatment of diseases of the ascending aorta. However, it must be noted that these guidelines do not make specific recommendations for the different subtypes of aortic dilations, although it seems likely that the physiopathology, natural history, and treatment can be different between degenerative or atherosclerotic and post-stenotic aneurysms.
In the absence of connective tissue disorders or bicuspidy, valve replacement alone is sufficient to prevent further aortic expansion in patients with moderate post-stenotic dilation of the ascending aorta. Ascending aorta replacement should be considered only for very young patients with extremely long life expectancy. Further studies are necessary to develop specific therapeutic guidelines for the different types of ascending aorta aneurysms.
The authors have reported that they have no relationships to disclose.
Presented as an abstract at the 47th meeting of the Society of Thoracic Surgery, January 31 to February 2, 2011, San Diego, California.
- Abbreviations and Acronyms
- aortic valve replacement
- computed tomography
- Received January 12, 2011.
- Revision received March 2, 2011.
- Accepted March 17, 2011.
- American College of Cardiology Foundation
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