Appropriate and early detection of rheumatic heart disease

Rheumatic heart disease (RHD) is a devastating acquired cardiovascular disease (CVD) that mostly afflicts children and almost always results in shortened life expectancy with significant comorbidity including cardiovascular surgery, lifelong anticoagulation, heart failure and modification of lifestyle.1 Early identification of RHD allows secondary prophylactic penicillin use, preventing recurrent exposure and further damage to heart valves. Although this approach is widely used and its efficacy has been documented in patients with symptoms of rheumatic fever (RF) and established RHD, data in screened children and a clinical trial is currently investigating this.2 Nevertheless, many clinicians advocate early detection in children without clinical presentation and some treat these children on the basis of likely potential benefit or possibly for fear of not doing anything. Given the devastating consequences of RHD, this is understandably pragmatic.

RHD was nearly eliminated in the developed world.1 With some exceptions, the highest rates of RHD are observed in the developing world.3 However, indigenous children and those living in remote and socioeconomically deprived communities in Australia and New Zealand have very high rates of ARF and RHD.3, 4 Until recently, echocardiography has been somewhat isolated to the developed world but is the key tool for early detection of RHD as it is superior to auscultation.

The World Heart Federation (WHF) developed criteria for detection of RHD and rheumatic carditis using echocardiography5 that have been used throughout the world, including Australasia, to screen higher risk groups of children. But there still remains the questions about the role of echocardiography screening.6 For example, how often should it be done? In which age groups? In which children? By whom? And more recently, with which equipment? And can the images be streamed for remote reading?

Firstly, let’s consider who should be performing echocardiography. There is a worldwide shortage of qualified cardiac sonographers, and it simply is not possible to meet screening requirements with experts. In this issue of the journal, Anna Harris describes a project undertaken in Fiji to train local healthcare workers.7 Worldwide, this approach has been shown to be potentially useful.8 These so‐called ‘rookie scanners’ have been compared to expert sonographers and cardiologists, with variable results. The success of such programmes depends upon several factors. Firstly, the background of the rookie. Some, with higher levels of health expertise such as nurses, may find this easier to learn. Secondly, the support of experts. Each rookie programme needs expert support and over‐reading of the images. Either on the ground, perhaps reviewing images of several rookies, or indeed it is now possible to incorporate image review via the Internet. Thirdly, it depends on disease prevalence. It is probably easier to introduce a rookie programme where there is significant disease as exposure to cases will improve identification.

The sensitivity and specificity of screening programmes depend upon the underlying disease prevalence. But sensitivity and specificity in echo screening for early RHD are also dependent upon the criteria that are applied. It is likely that a child meeting the criteria for definite RHD according to WHF criteria probably will benefit from screening. But, increasingly, the identification of borderline RHD is a potential problem. With any screening programme, there will be inevitably be false positives and false negatives. Some would argue that missing a few cases (false negatives) is balanced by the identification of new cases. But others argue minimising false negatives should be a priority. This ‘softening’ of the WHF criteria will increase the number of borderline cases identified, creating a safety net, but also will increase the false‐positive rates. Is a few years of monthly penicillin injections a small price to pay for a false‐positive diagnosis? In developing nations, this represents a relatively large burden on the healthcare system and family with potentially more harmful unmeasured impacts. For example, a childhood diagnosis of borderline RHD may lead to lifestyle changes such as reduced participation in sport. In girls, it may reduce their chances of marriage. And whilst this may seem like an outdated statement in our developed 21^st century world, it has real and lasting implications for a girl in the developing world where childbearing remains a valued attribute.

Setting aside all of the questions about whether we should do this, the reality is that we are doing this and therefore need to ensure the training of non‐expert or rookie sonographers is high quality. Local solutions are required: no single approach will be applicable. That’s why Anna Harris’ article in this issue of the journal is important. We can learn from each other and together minimise the worldwide burden of this preventable childhood disease.

But in the time that this article was first prepared and published, the ultrasound imaging game has changed completely. We now have stand‐alone, inexpensive, transducers that work on phones or tablets. This makes ultrasound screening affordable across the globe, but that brings other challenges.

Current stand‐alone transducers do not have spectral pulsed wave Doppler (PWD). Bo Remenyi et al. have recently suggested it is possible to screen for RHD using a single parasternal‐long‐axis‐sweep of the heart (SPLASH) with and without colour Doppler in school screening programmes.9 The challenge with this approach is that it does not allow for PWD and therefore two of the criteria for WHF diagnosis of RHD are not available. Thus, the expert‐generated WHF criteria are unable to be applied. But if the sensitivity and specificity of SPLASH are comparable, it means the stand‐alone transducer without PWD is an absolute gamer changer for RHD detection.

The future challenge for us is to implement and maintain RHD screening in ways that maximises sensitivity and specificity, whilst minimising both false positives and false negatives. All screening programmes are slightly inferior to the controlled research setting in which they were developed, so it’s just a case of how different and how efficacious new approaches are, and how much we are prepared to compromise. The early identification and prevention of a childhood disease that markedly shortens life expectancy should be a high priority but RHD has traditionally been neglected in terms of funding relative to disease burden.10 The development of a vaccine is underway,11 but in the meantime, children are still being exposed and one of the most practical tools we have to identify RHD early is echocardiography. We need to use it innovatively and wisely.