• heart valve diseases
• epidemiology
• mitral valve insufficiency
• tricuspid valve insufficiency

In this issue of Heart, Cahill et al report an analysis of the OxValve cohort assessing the prevalence, presentation and outcome of atrioventricular valve regurgitations.1 The strength of the OxValve cohort is that it was prospectively designed to specifically study heart valve disease using systematic echocardiographic examination in an unselected population aged 65 years or more in a community setting. Echocardiography is the only means to reliably assess the prevalence of heart valve disease since auscultation correctly identifies only around 10% of patients with heart valve disease.2 Unbiased assessment of the prevalence and characteristics of patients with heart valve disease needs to be performed in a community setting, as illustrated by differences between the OxValve and the hospital database cohorts. Moreover, contemporary guideline-based criteria were used in the OxValve cohort for the quantification of the severity of regurgitations and the identification of their mechanisms. Such detailed analyses were not performed in the rare previous population-based studies on the epidemiology of heart valve disease. The collection of detailed and standardised echocardiographic data in a large population-based study is therefore highly relevant in the field of heart valve disease.

The unadjusted prevalence of moderate or severe mitral or tricuspid regurgitation was estimated at 2.0% in subjects aged 65–75 years and 7.7% in those aged ≥75 years. This considerable increase in the prevalence with age is consistent with previous findings. In addition, a unique particularity of the paper by Cahill et al is the analysis of the prevalence of mitral regurgitation (MR) according to its mechanism. This is the first time that estimations of prevalence are available for primary and secondary MR in a large population-based study. This is of particular importance since there are major differences in the prognosis and management of patients with primary or secondary MR. The burden of degenerative mitral valve disease has increased worldwide over the last three decades,3 and as for aortic stenosis, is expected to continue to rise in the future due to population ageing and the lack of prevention strategies.

The diagnosis of heart valve disease was not known in almost half of patients with at least moderate atrioventricular regurgitation in this cohort, in particular when few or no symptoms. Although the sensitivity of auscultation is not optimal, its insufficient use in routine practice in primary care setting is likely to contribute to underdiagnosis of heart valve disease. As a consequence of underdiagnosis, left ventricular ejection fraction was ≤60% in as many as 25% of patients with significant MR, which is associated with impaired late survival.

The paper by Cahill et al further highlights the additional dismal prognosis of moderate or severe tricuspid regurgitation, even more so when combined with moderate or severe MR. These findings support the need for a careful assessment of tricuspid valve function in any patient presenting with left-sided heart valve disease, in particular mitral valve disease. The ‘forgotten valve’ should definitely not continue to be so.4

Another relevant finding of this study is to strongly suggest an underuse of interventions in patients with severe symptomatic MR. A total of 54 patients had severe MR and more than 1/3 of patients with significant MR were in New York Heart Association class ≥II, which contrasts with the fact that only five patients underwent mitral valve surgery during a median 5-year follow-up. It would have been interesting to compare the number of patients with severe primary MR who would have theoretically required an intervention according to guidelines and those who actually underwent a correction of MR. However, these numbers suggest a very low rate of surgery even when taking into account that mean age was 79 years and that older age and inherent comorbidities make the estimation of the risk–benefit ratio of interventions more difficult. The high proportion of mitral annular calcification (>one-third of patients on the OxValve cohort) may also account for a reluctance to intervene since this condition increases the risk of surgery, while current transcatheter alternatives are associated with suboptimal results in these particular patients.5 Indeed, while aortic stenosis treatment has considerably increased in recent years due to the advent of transcatheter aortic valve implantation, transcatheter interventions play a less important role in atrioventricular valve regurgitations. Edge-to-edge transcatheter mitral valve repair is by far the most widely used transcatheter procedure in the treatment of primary and secondary MR; however, it requires suitable anatomical conditions and is not applicable to all patients with MR presentations. In the most recent guidelines, indications of transcatheter mitral valve repair remain restrictive.6 Experience with mitral prostheses dedicated to transcatheter implantation remains limited, and the majority of procedures are still performed with transcatheter aortic valves (mounted upside-down). Regarding the treatment of tricuspid regurgitation, a number of devices have been developed for transcatheter techniques, but experience relies mainly on small observational series.4

In the recent Valvular Heart Disease II survey, the adherence to class I recommendation for surgery in symptomatic patients with severe primary MR was 71%.7 This rate has improved as compared with previous surveys performed in the 2000s in which almost half of patients with severe symptomatic MR were denied surgery. Adherence to guidelines cannot be explained only by age since patients with aortic stenosis were older than those with MR, and 79% were operated on as recommended in guidelines.7 Since adherence to guidelines was mainly studied in patients referred to hospital, the true adherence to guidelines in the community is of course expected to be markedly lower, as attested by a rate as low as 27% of intervention in patients with primary MR and a class I indication in a dedicated cohort.8

The OxValve cohort has the merit to draw attention on the high prevalence and poor prognosis of atrioventricular valve regurgitation in the community, in particular in the elderly. Besides implications on healthcare planning, this study further confirms that heart valve disease remains underdiagnosed and undertreated. These findings highlight the need for educational programmes to increase the awareness on heart valve disease, for evaluation of the adherence to guidelines and for the continuous development and evaluation of less invasive interventions targeting elderly patients.