4th November 2011, Volume 124 Number 1345

Suresh Perera, Namal Wijesinghe, Elene Ly, Gerard Devlin, Sanjeevan Pasupati

Aortic stenosis accounts for the vast majority of aortic valve disease, with a prevalence of approximately 1–2% among people over 65 years and 4% among people over 85 years.1 The aetiology is mainly calcific stenosis due to senile degenerative valve disease. Management of aortic stenosis has been tailored based on the severity of the condition, presence of comorbidities, age of the patient and their operative risk. Usually, treatment is only needed when aortic stenosis is severe and patients are symptomatic.

Aortic stenosis is the commonest acquired valvular lesion with a prevalence of 1–2% in the over 65s.1 Calcific aortic stenosis, the commonest cause of aortic stenosis, shares the predisposing factors of coronary artery disease: age, male sex and hypercholesterolaemia.2

The onset of symptoms in patients with aortic stenosis is a poor prognostic indicator without valve replacement. More than half the patient will die within the next 12–18 months of symptom onset, unless the aortic valve is replaced reliving the afterload on the ventricle.2 In addition, quality of life is adversely affected with frequent hospital admissions during the remaining years of lives.

The management of the asymptomatic patient with severe aortic stenosis is less straightforward. Asymptomatic patients have an almost normal life expectancy without valve replacement with <1% incidence of sudden cardiac death3 precluding the need for aortic valve surgery.In patients in whom surgery is considered necessary, prompt aortic valve replacement (AVR) can return age-corrected prognosis to that of a normal population.4,5

Procedural mortality for isolated aortic valve replacement in the surgically accepted group is low (<4%) and long-term results are excellent. Worldwide, however, over 30% of patients with severe symptomatic AS are not accepted for surgery due to comorbidities or are not indeed referred for surgery.6–11

The emergence of transcatheter valve implantation techniques offers opportunities to expand treatment options to these patients. It is essential, therefore, in the assessment of this new technology, to understand the burden of untreated disease, not only for clinicians but also for the health administrators.

We describe our attempts to define the burden of aortic stenosis in a large tertiary care centre in New Zealand with the intent to improve the care of patients with aortic stenosis in our region with a better understanding of patient demographics and impact of the disease on not only mortality but also morbidity and cost to the health care system.

This study evaluates the burden of untreated severe aortic stenosis at Waikato Hospital.

The study aims are to:

  • Assess the outcome of patients with severe aortic stenosis who are managed with the surgical and medical option.
  • Improve the management of severe aortic stenosis by understanding the patients' demographics.
  • Assess the impact on the patients’ quality of life.
  • Assess the impact to the health care system.
  • Assess the impact on the survival of the patient.

Methods

All consecutive patients, with severe aortic stenosis who presented to the Echocardiography Laboratory at Waikato Hospital, New Zealand between 1 January 2005 and 31 December 2009, were identified retrospectively.
Definition of severe aortic stenosis—Echocardiography criteria for diagnosing severe aortic stenosis applied according to ACC/AHA guidelines3.
We used at least one of the following parameters:
  • Aortic valve area <1 cm2.
  • Maximum velocity across aortic valve >4 m/s.
  • Mean pressure gradient across aortic valve >40 mmHg.
If there was any discrepancies with these parameters, the Dimensionless Index was used to confirm severe aortic stenosis
Long-term outcome data was obtained by review of medical records and telephone contact with patients and their primary care physicians. All of the patients identified with severe aortic stenosis (106 patients) were divided into 3 groups according to the management strategy:
  • Group 1: Asymptomatic aortic stenosis.
  • Group 2: Symptomatic aortic stenosis not treated surgically.
  • Group 3: Symptomatic aortic stenosis treated surgically
The history of symptomology was assessed by the cardiologist and asymptomatic patients were followed 6–12monthly if felt they were operable in the future. All symptomatic patients were discussed at the combined meeting with cardiac surgeons and cardiologist for eligibility for surgery.
The mortality, number of days spent in hospital per year and symptomatic status (angina >CCS class II, dyspnoea >NYHA class II, syncope) during follow-up were compared between these three groups.
Statistical analysis—Continuous variables were presented as the mean value±SD. These variables were compared, in between the groups, by using Student t-test. Discrete variables including the outcome measures of severe aortic stenosis were compared using Chi-squared test (double classification) with Yates correction. Event-free survival was plotted using Kaplan-Meir curves (censored data).

Results

A total of 105 patients with severe aortic stenosis were identified (mean age 76±13 years, 51% men) over the 12-month study period. The majority (76% (80/105)) were symptomatic with aortic stenosis.The median follow-ups in Group 1, Group 2 and Group 3 were 35 months (interquartile range: 27–37 months), 24 months (interquartile range: 11–36 months) and 36 months (interquartile range: 32-37 months) respectively. The baseline demographics of these groups are shown in Table 1. Clinical endpoints are shown in Table 2. At 36-month follow-up patients with symptomatic severe aortic stenosis treated surgically with aortic valve replacement had an excellent survival outcome compared to symptomatic patients who were declined for surgery (82% versus 27%, p<0.0001) (Figure 1). Of interest, mortality was also increased in patients with asymptomatic aortic stenosis compared to mortality of patients with symptomatic aortic stenosis treated surgically with aortic valve replacement (36% versus 18%, p<0.001). Unfortunately, the precise cause of death in-group 1 is unknown as the majority (8 out of 9 patients) died in the community.

Table 1. Baseline demographic data
Baseline characteristics
Group 1
(n=25)
Group 2
(n=41)
Group 3
(n=39)
Mean age (± SD)
81.7±14.4
83.4±7.6
66.1±12.2
Gender:
Female
Male

44%
56%

56%
44%

44%
57%
Prior MI
22%
41%
17%
Coronary artery disease
34%
59%
50%
Previous PCI
4%
10%
17%
Previous CABG
0%
13%
26%
Prior stroke
20%
15%
2%
Prior TIA
16%
15%
7%
Peripheral vascular disease
16%
18%
12%
COPD
24%
31%
7%
Atrial fibrillation
40%
49%
43%
Diabetes Mellitus
20%
21%
24%
Hypertension
64%
69%
60%
Smoking:
Current smoker
Ex smoker

12%
28%

3%
44%

2%
36%
Logistic Euro Score
16%
26%
10%
-<10%
32%
19%
68%
-10%-20%
36%
19%
17%
->20%
32%
62%
15%
NYHA class I-II
100%
64%
60%
NYHA class III-IV
0%
36%
40%
CCS class I-II
100%
90%
83%
CCS class III-IV
0%
10%
17%
Syncope
8%
15%
10%
PCI=Percutaneous coronary intervention, CABG=Coronary artery bypass surgery, TIA=Transient ischemic accident, COPD=Chronic obstructive pulmonary disease, NYHA=New York Heart Association, CCS=Canadian Cardiovascular Society.
Table 2. Outcomes of patient groups during follow-up
Group
Number of patients
All-cause mortality
Hospital days
per 100 pt-years
Symptoms at follow-up
Group 1
Group 2
Group 3
25 (24%)
41 (39%)
39 (37%)
9 (36%)
30 (73%)
7 (18%)
3.5
10.1
6.4
0%
64%
0%

Patients with symptomatic severe aortic stenosis managed conservatively (Group 2) had significantly more recurrent hospitalisation and time in hospital related to cardiovascular causes compared to patients who underwent surgical valve replacement (10.1 versus 6.4 days/100 patient-years, p<0.0001).

Similarly, 2 of 3 symptomatic patients who were managed conservatively (Group 2) had on going symptoms, (greater than CCS class II angina or NYHA class II dyspnoea or syncope). Asymptomatic patients and patients with aortic valve replacement had remained free from significant valve related symptoms during follow-up.

Figure 1. Kaplan-Meier survival of the 3 patient groups

Perera-1

Limitations—As our study was a retrospective analysis and most death in our cohorts occurred in the community there were major limitations in finding the actual cause of death. This limits our ability to define the actual valve related mortality.

Discussion

Aortic stenosis is a common valvular heart disease in the western world. It is a disease that is increasing in prevalence as the population ages. The onset of symptoms in the patient with severe aortic stenosis is a poor prognostic sign. These patients should be closely monitored and should be treated with aortic valve replacement if appropriate.

While surgical aortic valve replacement offers excellent result for patients with symptomatic severe aortic stenosis, those who are not considered as suitable surgical candidates have poor survival.2,12–14

Almost half of the symptomatic patients in our study were declined for aortic valve replacement surgery. This was mainly due to presumedhigh-risk involved with open-heart surgery because of their multiple comorbidities and age. The mean logistic EuroScore in this group was significantly high compared to a mean logistic EuroScore of the symptomatic patients treated surgically (26.1±16.0 versus 10.4±12.3, p<0.0001). This implies that non-surgical patients had more co-morbidity and were of higher risk compared to the surgical patients. In addition, they were much older compared to the surgical group (mean age: 83.4±7.6 versus 66.1±12.2, p<0.0001).

Hence in our study as patients who were declined for surgery could have been done so appropriately due to multiple comorbidities which could have lead to an early mortality, we cannot assess the actual valve related mortality due to this decision.

Usually, symptomatic aortic stenosis patients, who are declined for aortic valve replacement surgery due to excessive risk, have a poor survival. In our study, their survival was as low as 27% at 36 months, which is consistent with the published literature. In a retrospective study of 144 symptomatic patients, survival at 3 years was 87% in 125 patients who underwent valve replacement compared to 21% in 19 patients who were managed conservatively.15

In our study, symptomatic patients treated surgically had not only a significant reduction in mortality (18% versus 73%, p value<0.001) but also in days spent in hospital for cardiac causes (6.4 versus 10.1 days/ 100 patient-years, p<0.0001) compared to those were declined for surgery. Although randomised trials comparing surgery to continued conservative therapy for severe symptomatic aortic stenosis have not been performed, observational studies have found that aortic valve replacement surgery in this setting is almost always followed by symptomatic improvement and a substantial increase in survival.4,5,16

There have been major advances in cardiac surgery, which affect the consideration of surgical treatment in elderly patients who in the past may not have been surgical candidates.17 Among patients who survive the surgery and perioperative period, the level of function, quality of life and survival are the same as in a general population of age-matched subjects.5,18-21 As a result, the classic view that surgery should be considered only for elderly patients in excellent general condition is being challenged as higher success rates for isolated aortic valve replacement is obtained in patients with comorbidities with pre existing good functional level.3,22–24

An unexpected finding of our study was that 1 in 3 of asymptomatic patients dying during the follow-up. Our study is also limited by being unable to define the exact cause of death in this group especially where the majority were elderly. Objective defining of the symptom status with a treadmill may have better categorise this group. Although exercise testing is contraindicated in patients with symptomatic aortic stenosis, it has been shown to be safe in asymptomatic patients and can identify the presence of exercise-induced haemodynamic compromise, which is a relative indication for elective surgery.3,25–27

High-risk echocardiographic features (presence of moderate to severe valvular calcification, a rapid progression in the aortic jet velocity (0.3 m/sec within one year) and a high aortic jet velocity >4.5 m/sec), advance age (>50 years) and raised plasma B-type natriuretic peptide concentration may help to identify the patients who are likely to rapidly progress to symptomatic state needing aortic valve surgery or dying from a cardiac cause.8,26–30For symptomatic patients who are declined surgery, alternative therapies such as transcatheter aortic valve implantation may be an option.31–34 This is a promising approach35–39 that is now being used at many highly specialised centres around the world for specific patients (elderly, surgically declined symptomatic aortic stenosis population).

Randomised study data using the Edwards SAPIEN™ valve (PARTNER NCT00530894) will be available in 2010 that looks at outcomes against surgery in the high-risk population and also in patients declined from surgery. Data on cost effectiveness and long-term durability of this valve will allow wider application of this program.

Conclusion

Untreated symptomatic severe aortic stenosis is associated with a poor prognosis and significant morbidity whileaortic valve replacement surgery results in improved survival and quality of life. A significant number of patients with symptomatic aortic stenosis are declined surgical aortic valve replacement due to comorbidities and new therapies such as transcatheter aortic valve implantation may be of value as alternative treatment options to manage these patients. Asymptomatic patients with severe aortic stenosis should be carefully monitored objectively for development of symptoms and early referral for surgery should be recommended.

Summary

Aortic stenosis once symptomatic can be debilitating and deadly. We attempted to assess the burden of this disease in New Zealand using Waikato Hospital as a reference centre. We found about half our patients referred for surgical aortic valve replacement are declined surgery. During our follow-up (34 months) 73% of patients were dead who were declined from surgery compared to 18% of operated patients. Also the surgically declined patients were significantly debilitated with symptoms leading to poor quality of life and required more hospital stay utilising the health dollar.

Abstract

Aim

To analyse the outcome of microvascular free flap reconstructions in Middlemore Hospital (South Auckland, New Zealand).

Method

100 consecutive free flap reconstructions from January 2004 to April 2010 were identified from the Middlemore Hospital Theatre Coding List. Basic patient demographics and indication for surgery along with free flap types were recorded and outcomes were analysed.

Results

The free flap success rate was 96%. There were 21 short term complications without any perioperative mortality. The most common complication was flap infection (7/21) followed by vascular thrombosis (6/21 venous and 1/21 arterial). Other complications included partial ischaemic flap (3/21), haematoma (2/21), venous congestion (1/21) and partial wound dehiscence (1/21). Fourteen flaps needed salvage procedures in the operating theatre including eight cases for re-anastomosis of vessels. The overall successful salvage rate was 71% resulting in four failures. The successful salvage rate following re-anastomosis of vessels was 63%.

Conclusion

Overall success and salvage rates for free flap reconstructions at our plastics and reconstruction centre are comparable to that of international literature. Diligent postoperative monitoring and early return to theatre for re-exploration is the key to ensuring maximal free flap success.

Author Information

Suresh Perera, Namal Wijesinghe, Elene Ly, Gerard Devlin, Sanjeevan Pasupati, Cardiologists, Department of Cardiology, Waikato Hospital, Hamilton

Correspondence

Dr Sanjeevan Pasupati, Department of Cardiology, Waikato Hospital, Private Bag 3200, Hamilton 3240, New Zealand

Correspondence Email

drspasupati@gmail.com

Competing Interests

None.

References

  1. Otto CM. Aortic stenosis—listen to the patient, look at the valve. N Engl J Med 2000;343:652-4.
  2. Ross J Jr. Braunwald E. Aortic stenosis. Circulation 1968;38:61-7.
  3. Bonow RO, Carabello BA, Chatterjee K, et al. ACC/AHA 2006 guidelines for the management of patients with valvular heart disease: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines (writing Committee to Revise the 1998 guidelines for the management of patients with valvular heart disease) developed in collaboration with the Society of Cardiovascular Anesthesiologists endorsed by the Society for Cardiovascular Angiography and Interventions and the Society of Thoracic Surgeons. J Am Coll Cardiol 2006;48:e1-148.
  4. Lindblom D, Lindblom U, Qvist J, Lundstrom H. Long-term relative survival rates after heart valve replacement. J Am Coll Cardiol 1990;15:566-73.
  5. Gilbert T, Orr W, Banning AP. Surgery for aortic stenosis in severely symptomatic patients older than 80 years: experience in a single UK centre. Heart 1999;82:138-42.
  6. Bouma BJ, van Den Brink RB, van Der Meulen JH, et al. To operate or not on elderly patients with aortic stenosis: the decision and its consequences. Heart 1999;82:143-8.
  7. Iung B, Cachier A, Baron G, et al. Decision-making in elderly patients with severe aortic stenosis: why are so many denied surgery? Eur Heart J 2005;26:2714-20.
  8. Pellikka PA, Sarano ME, Nishimura RA, et al. Outcome of 622 adults with asymptomatic, hemodynamically significant aortic stenosis during prolonged follow-up. Circulation 2005;111:3290-5.
  9. Charlson E, Legedza AT, Hamel MB. Decision-making and outcomes in severe symptomatic aortic stenosis. J Heart Valve Dis 2006;15:312-21.
  10. Bach DS, Cimino N, Deeb GM. Unoperated patients with severe aortic stenosis. J Am Coll Cardiol 2007;50:2018-9.
  11. Abdul-Hamid AR, Mulley GP. Why do so few older people with aortic stenosis have valve replacement surgery? Age Ageing 1999;28:261-4.
  12. Carabello BA. Timing of valve replacement in aortic stenosis. Moving closer to perfection. Circulation 1997;95:2241-3.
  13. Carabello BA. Ventricular function in aortic stenosis: how low can you go? J Am Coll Cardiol 2002;39:1364-5.
  14. Carabello BA, Crawford FA, Jr. Valvular heart disease. N Engl J Med 1997;337:32-41.
  15. Schwarz F, Baumann P, Manthey J, et al. The effect of aortic valve replacement on survival. Circulation 1982;66:1105-10.
  16. Kouchoukos NT, Davila-Roman VG, Spray TL, et al. Replacement of the aortic root with a pulmonary autograft in children and young adults with aortic-valve disease. N Engl J Med 1994;330:1-6.
  17. Gammie JS, Brown JW, Brown JM, et al. Aortic valve bypass for the high-risk patient with aortic stenosis. Ann Thorac Surg 2006;81:1605-10.
  18. Olsson M, Granstrom L, Lindblom D, et al. Aortic valve replacement in octogenarians with aortic stenosis: a case-control study. J Am Coll Cardiol 1992;20:1512-6.
  19. Shapira OM, Kelleher RM, Zelingher J, et al. Prognosis and quality of life after valve surgery in patients older than 75 years. Chest 1997;112:885-94.
  20. Kolh P, Kerzmann A, Lahaye L, et al. Cardiac surgery in octogenarians; peri-operative outcome and long-term results. Eur Heart J 2001;22:1235-43.
  21. Kolh P, Lahaye L, Gerard P, Limet R. Aortic valve replacement in the octogenarians: perioperative outcome and clinical follow-up. Eur J Cardiothorac Surg 1999;16:68-73.
  22. Asimakopoulos G, Edwards MB, Taylor KM. Aortic valve replacement in patients 80 years of age and older: survival and cause of death based on 1100 cases: collective results from the UK Heart Valve Registry. Circulation 1997;96:3403-8.
  23. Bramstedt KA. Aortic valve replacement in the elderly: frequently indicated yet frequently denied. Gerontology 2003;49:46-9.
  24. Langanay T, De Latour B, Ligier K, et al. Surgery for aortic stenosis in octogenarians: influence of coronary disease and other comorbidities on hospital mortality. J Heart Valve Dis 2004;13:545-52; discussion 552-3.
  25. Linderholm H, Osterman G, Teien D. Detection of coronary artery disease by means of exercise ECG in patients with aortic stenosis. Acta Med Scand 1985;218:181-8.
  26. Amato MC, Moffa PJ, Werner KE, Ramires JA. Treatment decision in asymptomatic aortic valve stenosis: role of exercise testing. Heart 2001;86:381-6.
  27. Otto CM, Burwash IG, Legget ME, et al. Prospective study of asymptomatic valvular aortic stenosis. Clinical, echocardiographic, and exercise predictors of outcome. Circulation 1997;95:2262-70.
  28. Rosenhek R, Binder T, Porenta G, et al. Predictors of outcome in severe, asymptomatic aortic stenosis. N Engl J Med 2000;343:611-7.
  29. Gerber IL, Stewart RA, Legget ME, et al. Increased plasma natriuretic peptide levels reflect symptom onset in aortic stenosis. Circulation 2003;107:1884-90.
  30. Lim P, Monin JL, Monchi M, et al. Predictors of outcome in patients with severe aortic stenosis and normal left ventricular function: role of B-type natriuretic peptide. Eur Heart J 2004;25:2048-53.
  31. Cribier A, Eltchaninoff H, Bash A, et al. Percutaneous transcatheter implantation of an aortic valve prosthesis for calcific aortic stenosis: first human case description. Circulation 2002;106:3006-8.
  32. Webb JG, Pasupati S, Humphries K, et al. Percutaneous transarterial aortic valve replacement in selected high-risk patients with aortic stenosis. Circulation 2007;116:755-63.
  33. Grube E, Laborde JC, Gerckens U, et al. Percutaneous implantation of the CoreValve self-expanding valve prosthesis in high-risk patients with aortic valve disease: the Siegburg first-in-man study. Circulation 2006;114:1616-24.
  34. Lichtenstein SV, Cheung A, Ye J, et al. Transapical Transcatheter Aortic Valve Implantation in Humans. Initial Clinical Experience. Circulation 2006.
  35. Webb JG. Percutaneous aortic valve replacement. Curr Cardiol Rep 2008;10:104-9.
  36. Webb JG, Altwegg L, Boone RH, et al. Transcatheter aortic valve implantation: impact on clinical and valve-related outcomes. Circulation 2009;119:3009-16.
  37. Piazza N, Grube E, Gerckens U, et al. Procedural and 30-day outcomes following transcatheter aortic valve implantation using the third generation (18 Fr) corevalve revalving system: results from the multicentre, expanded evaluation registry 1-year following CE mark approval. EuroIntervention 2008;4:242-9.
  38. Grube E, Buellesfeld L, Mueller R, et al. Progress and Current Status of Percutaneous Aortic Valve Replacement: Results of Three Device Generations of the CoreValve Revalving System. Circ Cardiovasc Intervent. 2008;1:167-175.
  39. Ye J, Cheung A, Lichtenstein SV, et al. Six-month outcome of transapical transcatheter aortic valve implantation in the initial seven patients. Eur J Cardiothorac Surg 2007;31:16-21.