Rheumatic Heart Disease Revisited: Patterns of Valvular Involvement from a Consecutive Cohort in Eastern Nepal

Author(s): Nikesh Shrestha1, T. Pilgrim2, P. Karki1, R. Bhandari1, S. Basnet1, S. Tiwari1, P. Urban3
Affiliation(s): 1B.P. Koirala Institute of Health Sciences, Dharan, Nepal, 2Swiss Cardiovascular Centre, Bern, Switzerland, 3Hopital de la Tour, Geneva, Switzerland
1st country of focus: Nepal
Relevant to the conference theme: Non-communicable chronic diseases
Summary (max 100 words): Rheumatic heart disease is a major contributor to morbidity and premature death in poor and developing countries. We investigated the patterns of valvular involvement in patients with RHD in a large tertiary care hospital in eastern Nepal. Among 10,860 transthoracic echocardiography studies, 1055 female and 658 male patients were diagnosed with RHD, 25.7% of the patients being <20 years of age. Mitral regurgitation was the most common valvular lesion. Female patients were older and presented with mitral stenosis. Aortic regurgitation was more common in males. Involvement of both mitral and the aortic valve was observed in 49.8% of the patients.
Background (max 200 words): Although there has been a decline in the incidence of rheumatic heart disease (RHD) in industrialized nations, the burden of RHD in poor and developing countries has remained a major contributor to the morbidity and premature death in the working age population. RHD is estimated to affect at least 15.6 million people worldwide and causes 233,000 deaths each year. Several observational studies have reported the prevalence of rheumatic heart disease among various populations in different parts of the world. A particularly high prevalence of acute rheumatic fever (ARF) and RHD has been reported in Southeast Asia, the Western Pacific and Africa. Primary prevention with timely antibiotic treatment of group A β hemolytic streptococci (GABHS) pharyngitis and secondary antibiotic prophylaxis in patients who have undergone ARF is often inappropriate in developing countries due to ineffective health resources and lack of awareness of the disease.
Objectives (max 100 words): The objective of this study was to investigate patterns of left-sided valvular involvement as assessed by echocardiography in a large consecutive cohort from a tertiary care referral hospital in eastern Nepal.
Methodology (max 400 words): We retrospectively reviewed all consecutive transthoracic echocardiography reports from patients diagnosed with rheumatic heart disease collected from the echocardiography laboratory from June 1999 to February 2011. The data collected included age, gender, clinical diagnosis and findings on transthoracic echocardiography (TTE). Echocardiographic studies were performed with Hewlett Packard Sonos 1500 using a 5 MHz  transducer. All patients underwent a standard echocardiographic examination, including M-mode, two-dimensional and Doppler echocardiography.  Mitral stenosis was diagnosed on the presence of valve thickening, diastolic doming, restriction of leaflet motions and was quantified by pressure half time and planimetry. Presence of calcification, fibrosis, and limited leaflet excursion and fusion of commisures and chordate tendinae were also identified. Mitral regurgitation was diagnosed in the presence of thickened valves, dilated mitral valve annuli, and left atrial and left ventricular dilatation and lack of coaptation of the mitral valve leaflets in systole. Doppler echocardiographic analyses identified the presence and severity of regurgitation of the aortic, mitral and tricuspid valves. Thickened and calcified aortic valve leaflets with reduced leaflet motion (aortic cusp separation less than 9 mm) suggested aortic stenosis along with a peak gradient of more than 15mmHg in continuous-wave doppler. Aortic regurgitation was diagnosed when echocardiography with Doppler interrogation of the aortic valve showed the spatial extent of the colour Doppler aliasing in the outflow tract and was used as a rough guide of the severity of aortic insufficiency. Echocardiographic findings associated with pulmonary hypertension included a dilated pulmonary artery and dilation and hypertrophy of the right ventricle (RV), diastolic flattening of the interventricular septum and Doppler evidence of pulmonary hypertension.  SPSS Statistics Version 17.0 was used for all statistical analyses. Countinuous variables are expressed as mean ± standard deviation (SD), whereas categorical data are  presented as frequency (percentages). Two-sided T-tests were used to compare continuous variables, categorical variables were compared by using the chi-square test. A p value <0.05 was considered statistically significant.
Results (max 400 words): Among 10,860 transthoracic echocardiography studies performed between June 1999 and February 2011, a diagnosis of RHD was made in 1713 patients (15.8%), of which 1055 females and 658 males were diagnosed to have RHD (gender ratio 1.6:1). Patients presented for TTE at an average age of 31.1±15.4 years, females being significantly older than males at the time of presentation (32.8±15.2 years versus 28.5±15.4 years, p<0.001). One in four patients presenting with RHD was younger than 20 years of age. Mitral stenosis (MS) was more common in females as compared to males (62.8% versus 51.5%, p<0.001), whereas aortic regurgitation (AR) was more common in males as compared to females (55.6% versus 48.9%, p=0.007). Involvement of both the mitral and the aortic valve was observed in 49.8% of the patients and was more common in males as compared to females (52.7% versus 47.8%, p=0.047); there was no significant difference with regard to age at presentation between patients with single-valve involvement versus patients with involvement of both the mitral and the aortic valve (31.2 ±15.4 years versus 31.1 ±15.4 years, p=0.89). A combination of MR with MS (19.3%) or with AR (17.9%) was the most common finding. MR was the most common valvular pathology across all age groups (n=1321, 77.1%), followed by MS with the exception of patients <20 years of age which presented more frequently with AR than with MS. Aortic stenosis was the least common valvular lesion found in this cohort, but was increasingly observed with advancing age. The prevalence of pulmonary hypertension amounted to 34.9% in our cohort and increased with advancing age from 27.0% in patients <20 years to 43.7% in patients ≥50 years. Echocardiographic evidence of infective endocarditis was documented in 212 (12.4%) patients.
Conclusion (max 400 words): The major findings of our retrospective analysis can be summarized as follows: (1) The prevalence of RHD among patients referred for transthoracic echocardiography in this single-center experience from eastern Nepal was high, (2) one in four patients diagnosed with RHD was younger than 20 years of age, (3) more than 60% of the patients diagnosed with RHD were females, and (4) differential patterns of valvular involvement were observed across gender and age categories. A combination of poverty, lack of awareness, limited access to primary prevention and secondary prophylaxis entertain ARF and make RHD an  unresolved problem in this part of the world. Once significant valvular disease has developed medical options are limited; cardiac surgery for valve replacement is available in the capital city of Kathmandu 500 kilometers west of Dharan and percutanoeous mitral valvotomy has only recently been introduced in our centre.  This was a hospital based study and patients who were symptomatic did come to the hospital to get an echocardiography performed and have the disease diagnosed. However RHD can remain clinically silent and may produce no symptoms in the early course of the disease and if these patients could be diagnosed earlier by means of a community screening program especially in school going children we could probably contribute considerably in reducing the morbidity and mortality due to RHD with simple yet effective secondary prophylaxis with penicillin.
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