Experience with cardiac valve operations in Cape York Peninsula and the Torres Strait Islands, Australia

Anna McLean, Michael Waters, Emma Spencer and Clive Hadfield
Med J Aust 2007; 186 (11): 560-563. || doi: 10.5694/j.1326-5377.2007.tb01053.x
Published online: 4 June 2007


Objective: To describe the outcome of valve surgery, for rheumatic heart disease (RHD) and non-RHD, in residents of Cape York Peninsula and the Torres Strait Islands referred to the Cairns Base Hospital specialist outreach service.

Design and participants: Retrospective review of medical records on all patients residing in the outreach area who had surgery for valvular heart disease between 1 January 1992 and 31 December 2004.

Main outcome measures: Operation type and perioperative characteristics; 5- and 10-year survival rates; reoperation rates; complications.

Results: Forty-seven patients met the selection criteria; the median age was 40 years (range, 4–76 years); and 39 patients were Indigenous. RHD was the predominant cause of valve dysfunction (30/47 patients). Thirty-seven patients had valve replacements, six had valve repair and four had balloon valvotomy as the initial procedure. There were three bleeding complications, two episodes of operated valve endocarditis, and six embolic complications. There were nine valve-related deaths (six in the first 5 years). At 5 years, all seven patients who had had valve repair or balloon valvotomy were alive. Seven of the 47 patients required reoperation. Survival analysis showed freedom from valve-related deaths to be 83% (95% CI, 66%–92%) at 5 years and 61% (95% CI, 33%–80%) at 10 years. Freedom from reoperation at 5 years was 88% (95% CI, 71%–95%). Among the 30 patients with RHD, freedom from valve-related death was 80% (95% CI, 60%–92%) at 5 years and 52% (95% CI, 21%–75%) at 10 years. In patients with RHD, freedom from reoperation at 5 years was 87% (95% CI, 65%–96%).

Conclusion: Valvular heart disease results in substantial morbidity and mortality, despite intervention. Efforts need to focus on prevention of rheumatic fever and closer follow-up.

Cape York Peninsula and the Torres Strait Islands are home to about 20 000 people, up to 75% of whom are Indigenous Aboriginals and Torres Strait Islanders.1 Although acute rheumatic fever is considered a rare disease in other developed countries, it has an unusually high incidence in this population and places a significant health burden on these communities.2-4 The annual incidence of acute rheumatic fever in children aged 5–14 years has been estimated at 107/100 000 in Cape York Peninsula and 136/100 000 in the Torres Strait Islands.5 This is less than in the Top End of the Northern Territory, where incidence is reported to be between 202/100 0005 and 245/100 000.6 Many of these patients eventually require surgery for rheumatic valvular disease.6

We describe here the outcome of valve surgery, for both rheumatic and non-rheumatic heart disease, in patients from Cape York Peninsula and the Torres Strait Islands over a 13-year period.

This region is serviced by specialist physicians and paediatricians from Cairns Base Hospital’s outreach service, in conjunction with local medical officers, the Royal Flying Doctor Service, remote area nurses and Indigenous health workers. For the cases we reviewed, cardiac surgery was performed at either Townsville General Hospital or Prince Charles Hospital in Brisbane. The outreach service provided portable echocardiography locally in these communities throughout the study period.

Inclusion criteria and data collection

To be included in the analysis, patients needed to be permanent residents of the catchment area and to have valvular heart disease of any cause that required surgery. Patients were identified from the specialist service records and the operation records of the relevant surgical centres. Clinical, echocardiographic and cardiac catheterisation data were obtained from the specialist clinical summaries and correspondence; medical records of Cairns Base Hospital and regional hospitals; and the relevant surgical centres. Mortality data were obtained from death certificates, medical records and autopsy reports.

Patients who had their first procedure between 1 January 1992 and 31 December 2004 were included, with the date of the valve procedure being taken as the entry point for each patient. Complete operative lists were available from January 1992, and we used this as the earliest entry date for survival analysis. End points included death and major complications. Complications included reoperation, bleeding (requiring hospitalisation), thromboembolism, and endocarditis of the operated valve. In the absence of death, patients were censored at 31 December 2004.

No patients were lost to follow-up. Two patients who had been reviewed in the outreach clinics were excluded, as they were not permanent residents of the region. Patients with reoperations during the study period who had initial surgery before 1992 were not included. Follow-up was by regular outpatient clinics in the community, or hospital admissions as required.


Forty-seven patients were included in our analysis (Box 1). Of 30 patients who had echocardiographic evidence of RHD, 20 gave a history of past rheumatic fever.

Valve procedures

Thirty-seven patients had valve replacements, 29 with mechanical valves and eight with bioprosthetic valves (Box 2). The mechanical valves used were produced by CarboMedics Inc (Austin, Tex, USA) (18 patients), St Jude Medical (St Paul, Minn, USA) (eight patients) and ATS Medical Inc (Minneapolis, Minn, USA) (three patients). The eight bioprosthetic valves were all singleton replacements.

Six patients had isolated open mitral repair and four had mitral balloon valvotomy. The balloon valvotomy patients were included because some of them then went on to have open surgery for the same disease. Six patients had combined valve replacement and valve repair.


Ours is the first study to document outcomes of cardiac surgery in Cape York Peninsula and the Torres Strait Islands. The 5-year survival rate of 83% in our study is similar to or better than survival figures published for valve surgery in older, non-Indigenous patients who are more likely to have degenerative valvular disease, in whom the 5-year survival rate is 70%–80%.10-15 Younger patients with rheumatic mitral valve repair or replacement alone typically have a 5-year survival rate of over 90%.16-20 These figures vary greatly depending on the type of surgery, the number of valves involved and the population studied. The question is whether outcomes in the population we studied could be improved, given that the median age of our cohort was only 40 years.

The only other comparable study of Indigenous patients undergoing cardiac valve replacement for RHD was done in the Northern Territory.21 The 5-year survival rate of 79% in the NT study was similar to the rate of 83% in our cohort. The 10-year survival rate was also similar (68% in the NT study compared with 61% in our study). Ninety-three per cent of the NT patients had mechanical valve replacements. As follow-up and data collection were noted to be very difficult in the NT cohort, it is possible that complication rates were under-reported.

The main limitation of our study was that it was too small to perform meaningful regression analysis to identify high-risk groups. For example, it would have been useful to know whether those who received anticoagulant had significantly higher rates of complications. We did observe that no valve-related deaths occurred in patients with normal or mildly elevated PAP. High PAP may be a surrogate marker for proceeding to “last resort” surgery in some patients. LV dysfunction has previously been shown to predict poorer outcomes,21 but 71% of our patients had normal preoperative LV function. Despite this, a large number of patients were symptomatic by the time of surgery. Another limitation of our study was the wide variation in review intervals: some patients would come for frequent assessment for a short time, then the review interval would be extended. The median follow-up interval of 20 months is still longer than ideal. The availability of close follow-up and ambulatory echocardiography is important for monitoring valve dimensions, LV function, PAP, symptoms, and the need for intervention.

A number of studies, including a recent meta-analysis,22 suggest that repair of rheumatic mitral valves is superior to replacement.20,22-27 The number of patients in our cohort was not high enough for our results to contribute directly to this comparison. However, it is worth noting that, of the seven patients who had dual mechanical valves placed, three have died and one is in a vegetative state after multiple embolic strokes. A further patient had dual mechanical valves placed at reoperation, then had a valvular thrombosis and died shortly afterwards. Thus, five of eight patients with dual mechanical prostheses had a poor outcome, the four deaths occurring within 5 years. In contrast, all seven patients with valve repairs or valvotomies and no valve replacement were alive at 5 years. The proportion of procedures that were repairs in our study is lower than that reported in some centres,20 and it may be that conservative surgery should be more readily available. Repair of rheumatic valves can be difficult, and perhaps procedures should be performed in a small number of centres by surgeons with expertise and extensive experience in this field.

Careful selection of patients is important, particularly if multiple valves require replacement. The many complications of anticoagulation therapy can be a problem in remote areas. Some patients manage anticoagulation reliably and should not be denied best treatment. Others find compliance very difficult. Even hospital anticoagulation clinics in the United Kingdom have historically achieved poor results with anticoagulation therapy, with less than 50% of patients achieving therapeutic international normalised ratios (INRs).28 Using “finger prick” INR testing is being trialled in some communities to provide timely feedback on anticoagulation.

Valvular heart disease in north-eastern Australia results in significant morbidity and mortality. Outcomes may be improved by closer preoperative and postoperative observation. As experience grows, more repairs, rather than mitral valve replacements, may be beneficial. Our main focus should be on primary and secondary prevention of RHD, as this will be the most effective treatment in the long run.

Received 20 May 2006, accepted 12 March 2007

  • Anna McLean1
  • Michael Waters2
  • Emma Spencer3
  • Clive Hadfield1

  • 1 Cairns Base Hospital, Cairns, QLD.
  • 2 Lyell McEwin Hospital, Adelaide, SA.
  • 3 Royal Darwin Hospital, Darwin, NT.



We would like to acknowledge the assistance of Brad McCulloch of the Queensland Health Tropical Public Health Unit with statistical analysis.

Competing interests:

None identified.

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