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 Table of Contents  
ORIGINAL ARTICLE
Year : 2023  |  Volume : 11  |  Issue : 1  |  Page : 40-45

Clinical and demographic profile of patients of rheumatic valvular heart disease: A cross-sectional analysis of Varanasi heart valve registry


Department of Cardiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India

Date of Submission19-Feb-2023
Date of Decision21-Feb-2023
Date of Acceptance03-Mar-2023
Date of Web Publication12-Apr-2023

Correspondence Address:
Soumik Ghosh
Block-A, Flat 81, New Teachers' Residential Flats, Jodhpur Colony, Banaras Hindu University, Varanasi - 221 005, Uttar Pradesh
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/heartindia.heartindia_16_23

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  Abstract 


Background: Rheumatic heart disease (RHD) is a preventable structural heart disease involving cardiac valves affecting the young population of productive age-group having considerable morbidity and mortality due to associated complications.
Aims and Objectives: To evaluate the clinic-demographical characteristics and complications of RHD patients and thus to build up a RHD valvular registry.
Materials and Methods: In this study, we enrolled 570 consecutive patients diagnosed with rheumatic valvular affection as defined by echocardiographic criteria, and studied their demographic, valvular pathology, symptomatology, prophylaxis and complication profile.
Results: Female patients dominated the population in number, mitral being the most affected valve, mitral stenosis the commonest lesion. Newly diagnosed patients constituting 20% of study population. One-fourth of the patients gave a proper history of acute rheumatic fever and oral prophylaxis was noted to be more compliant than parenteral. Case proportionality ratio for atrial fibrillation was highest with severe MS with AR and for pulmonary hypertension with severe MR with or without MS.
Conclusion: RHD is a preventable disease and health professionals and policy making institutions at all levels should strive in unison to mitigate its incidence, disease severity and complications.

Keywords: Atrial fibrillation, cardiac valves, echocardiography, pulmonary artery hypertension, rheumatic heart disease


How to cite this article:
Ghosh S, Prajapati R, Kela D, Mumtaz A, Shankar O M. Clinical and demographic profile of patients of rheumatic valvular heart disease: A cross-sectional analysis of Varanasi heart valve registry. Heart India 2023;11:40-5

How to cite this URL:
Ghosh S, Prajapati R, Kela D, Mumtaz A, Shankar O M. Clinical and demographic profile of patients of rheumatic valvular heart disease: A cross-sectional analysis of Varanasi heart valve registry. Heart India [serial online] 2023 [cited 2023 May 31];11:40-5. Available from: https://www.heartindia.net/text.asp?2023/11/1/40/374100




  Introduction Top


Rheumatic heart disease (RHD) is a significant cause of cardiovascular morbidity and mortality in developing countries with varied geographic distribution. It is generally considered due to recurrent episodes of rheumatic fever, which is an autoimmune inflammatory sequelae due to contagious affection of Group A streptococcal pharyngitis during childhood and adolescence.[1] The smoldering molecular mimicry reaction frequently leads to clinical or subclinical carditis, causing fibrosis, deformation, and dysfunction to cardiac valves. Thus, RHD may present as a single or multivalvular disease in young adults adding much disability to health, economy, and lifestyle due to its progressive complications such as altered cardiac hemodynamics, chamber dilatation, heart failure, atrial fibrillation (AF), pulmonary hypertension, infective endocarditis, cardioembolic stroke, and premature death.[2]

According to the WHO, RHD is the most commonly acquired heart disease in population below 25 years of age, commonly in low- and middle-income group nations, and claims over 0.28 million lives annually.[3] Nevertheless RHD still affects older adults, immigrants, marginalized and underprivileged population in high sociodemographic index countries. From data of the Global Disease Burden 2019, the incidence, prevalence, and disability-adjusted life year rates of RHD are estimated as 37.4, 513.7, and 132.9/100,000, respectively.[4] The overall prevalence of RHD is estimated to be around 1.5–2/1000 population in India in all age groups, suggesting about 2.5 million patients suffering from RHD.[5] In this context, this study was undertaken to demonstrate the demographic and clinical characteristics of RHD in Purvanchal region of India, where data regarding this neglected form of cardiovascular disease are lacking, and aimed to set up a local RHD valvular registry prospectively.


  Materials and Methods Top


The study was a cross-sectional, descriptive, single-center study conducted at a tertiary care teaching hospital of Eastern Uttar Pradesh. It was conducted for 12 months from January 2022 to December 2022. All patients attending the outpatient department of cardiology unit or being admitted to inpatient cardiology ward or cardiac care unit were screened. Patients referred to echocardiography division from various departments were also considered. All patients aged 14 years or more, diagnosed with RHD or newly detected rheumatic valvular lesions as laid down for RHD by the World Heart Federation criteria echocardiography guidelines were enrolled. Detailed consent was obtained for participation in the study, and ethical clearance was obtained from the Institutional Ethical Committee. Exclusion criteria were pregnancy, patient denying consent, causes of valvular affection other than RHD (like degenerative, bicuspid, or congenital etiology), prosthetic heart valves, established ischemic heart disease, and other forms of primary cardiomyopathy.

Patients enrolled in the study were interrogated with a brief history pertaining to their cardinal symptoms related to cardiovascular symptoms with durations of each, period of diagnosis of RHD, and follow-up, history of antecedent or recurrent acute rheumatic fever (ARF), and compliance with RHD prophylaxis. History of surgical or interventional procedures was also noted. Past medical records related to RHD and electrocardiogram (ECG) were traced to detect the presence of paroxysmal or permanent AF. Detailed echocardiographic examination was done with color Doppler study to identify the rheumatic valvular affection, specific valves involved, nature and severity of valvular lesion, and presence of pulmonary arterial hypertension (PAH). Data obtained were systematically recorded in tabular form for further evaluation and IBM SPSS Inc. Statistics 26.0 version, Chicago, Illinois, USA, was used for statistical analysis.


  Results Top


A total of 570 patients were enrolled in the study; out of which 354 were female patients, which formed the majority of patients in the study population (62.1%). The median age of our study population was 37.5 years; analyzing sex-wise median age revealed 34 years for males and 39 years for females. When analyzed the age of the patient according to the specific decade, most of the patients were found to be young in their 20–40's age group (76%). Twenty-nine percent of patients were in their fifth decade of life, which formed the peak age group of the study population decade wise [Table 1]. Except the age group of patients between 14 and 20 years, all other decade-wise population showed the female preponderance, with the highest proportion of female RHD cases noted in the fifth decade too (73.2%).
Table 1: Age (decade wise) and sex based demographic distribution of patients with rheumatic valvular heart disease

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Although majority of the patients were diagnosed with RHD on follow-up, 117 (20%) patients were newly detected. Among the newly diagnosed group, 52 (44%) patients were asymptomatic and were incidentally detected on routine echocardiographic examination for referral otherwise. Rest of the patients presented with the features of acute decompensated heart failure (ADHF) (n = 38, 59%), episodic palpitation (n = 23, 35%), and acute ischemic stroke (n = 4, 6%). Most of the patients (n = 335) on routine medical follow-up were asymptomatic; rest complained of breathlessness (n = 92), palpitation (n = 66), fatigue (n = 51), chest pain (n = 28), and near syncope (n = 4) [Table 2].
Table 2: Symptomatology of newly diagnosed and follow-up patients of rheumatic valvular heart disease

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Out of 570 patients, only one-fourth could elicit a proper history of ARF having polyarthritis of large joints after sore throat in childhood. However, barely 29 (5%) patients complained of symptoms of breathlessness, palpitation, and fatigue during the ARF episode in childhood. Recurrent attacks of ARF were obtained from 19 (3.3%) patients; all of them having severe multivalvular combined stenotic with regurgitant lesions (either severe mitral stenosis [MS] with severe aortic regurgitation [AR] or severe mitral regurgitation [MR] with severe AR) [Table 3]. Trends of penicillin prophylaxis maintained were also documented, which revealed that only one half of the follow-up population were prescribed on a regular basis, predominantly patients below 40 years of age. Oral penicillin V prophylaxis was followed by 161 individuals having good compliance, and 78 patients were noted to be on injectable penicillin therapy. Sixty-two patients (79.5%) were on regular injectable benzathine penicillin prophylaxis, who were in the follow up group of RHD cases. Thus, the compliance of injectable prophylaxis was found to be lesser popular among the study population.
Table 3: Acute rheumatic fever history and its complication and compliance of penicillin prophylaxis

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The mitral valve affection was noted in 547 (96%) patients, while the aortic valve was diseased in 243 (42.6%) patients. Stenosis of the mitral valve was the most common entity noted with 435 patients having severe MS (76.3%) and 75 patients with progressive stenosis (13.2%). MR lesions were noted in 229 patients constituting 40% of the study population; out of which severe disease was seen in 73 (12.8%) individuals and mild-to-moderate regurgitation in 156 (27.3%) patients. Isolated severe mitral valve stenosis was noted in 184 (32%) patients; concomitant severe MS with severe regurgitation in 36 (6.3%) patients; and severe MS with mild-to-moderate regurgitation in 121 (21.2%) patients. Isolated severe mitral valve regurgitation of rheumatic etiology was observed in only 14 patients (2.5%); and severe MR with progressive stenosis in 10 (1.7%) patients [Table 4].
Table 4: Valvular lesion wise distribution of prevalence of rheumatic heart disease

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Among the aortic valve rheumatic lesions, regurgitant lesions were commonly noted with isolated severe AR in 6 (1%) individuals; and severe AR with aortic stenosis (AS) in 4 (0.7%) patients. None of the patients were noted to have isolated severe AS of rheumatic etiology. Multivalvular affection of rheumatic lesions was noted in various proportions in the study cohort, with the most common lesion being severe MS with mild-to-moderate AR affecting 166 (29.1%) patients. Severe MR with varying severity of AR was found in 32 (5.6%) patients; severe MS with and both severe MR and AR in 5 (0.9%) patients. As many as 244 patients had evidence of moderate-to-severe tricuspid valve regurgitation, majority of which were diagnosed to be a secondary cause due to PAH and tricuspid annular dilatation. Only 17 (3%) patients out of 244 had evidence of direct rheumatic affection of the tricuspid valve in the form of severe tricuspid stenosis with or without regurgitation.

AF and PAH were documented as the most commonly occurring complications among the study population. AF was seen in 115 (20.2%) patients, either persistent or paroxysmal documented on ECG. It was more common in females (69.5%) and in the fifth decade age group cohort of the study population (51.3%). It was most commonly associated with patients with MS accounting of about 103 patients: about 90% of AF population [Table 5]. Lesion-wise incidence of AF was the highest in patients having concomitant severe MS with severe AR amounting to 50% (seven out of 14 patients).
Table 5: Prevalence of atrial fibrillation in the study population and its analysis with respect to sex, age group and individual type of valvular lesion

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PAH, defined by echocardiography as mean pulmonary artery pressure as more than 25 mmHg, was noted in 249 (43.7%) patients. Severe PAH was noted in 72 (12.6%) patients. Male preponderance was seen with PAH; 105 out of 216 male patients (49%) had PAH, whereas the incidence in females was 40%. Age-wise distribution for PAH revealed maximum incidence in the fifth decade of life; 36.2% of total population with PAH belonged to 41–50 years of age. Decade-wise age group-matched prevalence of PAH too revealed peak occurrence in the fifth decade of life and least in the younger age groups. Severe MS was the most common lesion associated with PAH; 205 patients out of 249 (82%). However, patients who had predominant lesion of severe MR had the highest proportionate occurrence of PAH (50%) [Table 6]. The most commonly occurring lesion, i.e. isolated severe MS (32%) and concomitant severe MS with mild/moderate AR (29.1%) showed a proportionate occurrence of 44.5% and 35.5%, respectively.
Table 6: Prevalence of pulmonary artery hypertension and its analysis with respect to sex, age group and individual type of valvular lesion

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  Discussion Top


Although RHD is a disappearing entity in the developed nations after the last industrial revolution, it still affects millions residing in the developing countries where poverty, sanitation, overcrowding, and access to health-care facility are a concern. Data on population-based statistics and demographic/clinical profile of patients of RHD with valvular affection and its complication are lacking in India except a few studies from teaching hospitals of certain regions of the country.[6],[7],[8] From the last survey from the Global Burden of Disease study on RHD, India accounts for the third of the global RHD burden. The state-wise distribution revealed the highest (>300) DALY/100,000 population from the states of Assam, Odisha, Bihar, Chhattisgarh, Madhya Pradesh, and Uttar Pradesh.[9] According to the medical literature, this is the first study reporting clinical and demographic profile of RHD patients in Purvanchal region comprising Eastern part of Uttar Pradesh and adjoining regions of states of Bihar, Jharkhand, Chhattisgarh, and Madhya Pradesh.

In this cross-sectional, observational study, 570 patients were enrolled including both newly diagnosed and those who were in follow-up. Female predominance of the study population was noted as with previous registries and studies done on RHD cohort. The median age of population was 37.5 years, indicating that RHD is a disease burden of younger population when individuals are at their peak of their livelihood capacity. Furthermore, in this study, we noted a nadir at the fifth decade of age group being the highest prevalence of patient population. Thereafter, there is a rapid decline in the population disease prevalence, which may be attributed by the fact that RHD and its complication have a higher rate of mortality after a few decades of disease burden. Another observation about age-matched groups revealed that although females were predominantly affected throughout the study population, male dominance in prevalence was noted in the youngest age group. This may also indicate that the age of detection or first medical diagnosis is delayed in female patients due to sociocultural structure and negligence of medical care to sex predilection in this region.

Dyspnea was the predominant symptom in both newly diagnosed and follow-up patients of RHD, comprising 59% of symptomatic individuals with ADHF and 78% with progressive breathlessness, respectively. This observation is like other studies reporting dyspnea of 72% by Rastogi et al, 90% by Dall et al, 67% by Dhar et al, and 66% by Sliwa et al [1],[7],[9],[10] among the study population. Palpitation and fatigue were other recurring symptomatology noted. However, 74% of the follow-up subset patients were asymptomatic on medical management. We could not gather any information regarding any prior study in the medical literature which documented proportion of asymptomatic patients in RHD follow-up cohort. Dhar et al.[7] reported an incidence of 12.6% of asymptomatic patients in their newly diagnosed cases of RHD from Uttarakhand, but Sliwa et al. documented as much 90% of patients to be asymptomatic with rheumatic affection predominantly of the mitral valve with regurgitant lesion in screening survey of school children aged 6–17 years from Mozambique.[10]

ARF has been considered a triggering factor and harbinger of the onset of chronic rheumatic carditis and valvular disease subsequently. In previous literature, the incidences of prior documented or possible ARF in chronic RHD patients have a myriad of proportions. In our study, we could elicit a history suggestive of ARF in only 25% of the patients in their childhood, and 3.3% having recurrences of these episodes. Dhar et al. reported an incidence of 37% of ARF in their population cohort. Lawrence et al. suggested the occurrence of RHD in 61% of patients suffering from ARF in 10-year follow-up in a 14-year registry from the Northern Territory of Australia.[11]

Secondary prophylaxis of antibiotic therapy in RHD patients on follow-up was recorded, and it revealed quite a lower prevalence of prescribing penicillin therapy of 52.7%. Antibiotic prophylaxis given mostly was penicillin; two-thirds were given oral penicillin V and the rest were injectable benzathine penicillin on once every 3 weeks periodicity. Compliance of oral penicillin was close to 100%, but more than 20% of the patients on injectable forms of prophylaxis were noncompliant with their prescribed regimen. Lilyasari et al. reported a noncompliance rate of 4.5%–70% of both oral and injectable penicillin as secondary prophylaxis in 6-year follow-up period of RHD cohort of children and young adults from Indonesia.[12] Joseph et al., in their study, revealed the use of oral penicillin prophylaxis in 57% of study population; however, the compliance rate was noted to be far less than expected.[6] The data from REMEDY study describing the Global RHD Registry disclose the use of secondary prophylaxis with penicillin antibiotic to the tune of 54.7%; intramuscular forms being the most common and compliance rate comparable between oral and parenteral forms of secondary prophylaxis.[13]

The pattern of valvular affection reported in our study had mitral valve predominance; 96% of patients were found having disease of the mitral valve in various stages of stenotic or regurgitation lesion. Aortic valve involvement was documented in 42.6% of patients and multivalvular lesions in 40.9%. MS constituted the single most commonly occurring valve lesion as isolated valvular pathology. Severe AS of trileaflet rheumatic etiology appeared to be the rarest variety next to tricuspid stenosis. No rheumatic affection of pulmonary valve was seen in our study. In multivalvular lesions, severe MS with mild-to-moderate AR was the most common occurring pathology noted. Thus, it appears that there may be a wide interpopulation variability in affection of various valves affected by rheumatic pathology across the globe, according to population-based studies in different geographic locations.[14],[15],[16],[17],[18] This observation may be due to demographic clusters, where the disease was investigated, were majorly of school-going children age group, and emerging data suggest that the disease prevalence is much higher in adults and among children in community settings who are not privileged to attend school.

The two most commonly occurring and dreaded complication of valvular heart disease, especially due to rheumatic affection, are AF and pulmonary artery hypertension. Both the sequelae have been extensively and adequately sampled and analyzed in our study. We estimated that as many as 20.2% of all patients. The prevalence of AF was influenced by age: the highest proportion noted in the fifth decade of life and more common in female patients. Ninety percent of AF cases were affected by MS, both progressive and severe; however, the case proportionality burden of AF was seen to be the highest with patients having concomitant severe MS with AR. Negi et al. also documented 23.9% prevalence of AF in his study population of RHD from Shimla.[8] Age, MS, and development of pulmonary hypertension were found to be the risk factors for AF in his study.

Pulmonary artery hypertension was observed in 43.7% of the population with a slight male preponderance. In a review article by Harikrishnan and Kartha. in 2009, PAH was described to be present in up to 70% of patients with RHD.[19] Age was predicted as a risk factor for development of PAH as patients above 40 years had an increased prevalence. MS was the most common valvular lesion associated with PAH (82%). However, severe MR with or without MS was seen to have the highest case proportionality burden for development of PAH.


  Conclusion Top


RHD is a devastating cardiac valvular disease which affects the poor and the vulnerable group of the society in their prime age of livelihood. In our study, females predominated the study population and mitral valve being the most affected. MS appeared to be the single most lesion and severe MS with AR being the commonest mixed valvular pathology. Almost half of the patients were asymptomatic in the newly diagnosed group, suggesting early echocardiographic screening of at-risk subjects with slightest of symptoms as prophylaxis proves to be a long way to prevent progression of the disease and its complications like AF and PAH.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

Ethical approval

Ethical clearance was approved from Institutional Ethical Committee.

Authors' contributions

SG prepared the manuscript and proofreading, RP was involved in patient recruitment, AM did the data collection, DK analysed the data and OS conceptualised the article.



 
  References Top

1.
Dall AQK, Shaikh MK, Shah SZA, Devrajani T, Memon AS, Karim I, et al. Clinical and echocardiographic profile of rheumatic heart disease: a cross-sectional study. Journal of Pharmaceutical Research International 2021; 33:1-7.  Back to cited text no. 1
    
2.
Noubiap JJ, Nyaga UF, Ndoadoumgue AL, Nkeck JR, Ngouo A, Bigna JJ. Meta-analysis of the incidence, prevalence, and correlates of atrial fibrillation in rheumatic heart disease. Glob Heart 2020;15:38.  Back to cited text no. 2
    
3.
Bennett J, Zhang J, Leung W, Jack S, Oliver J, Webb R, et al. Rising ethnic inequalities in acute rheumatic fever and rheumatic heart disease, New Zealand, 2000-2018. Emerg Infect Dis 2021;27:36-46.  Back to cited text no. 3
    
4.
Vos T, Lim SS, Cristiana A, Kalankesh LR, Zimsen SRM, Naghavi M, et al. Global burden of 369 diseases and injuries in 204 countries and territories 1990 – 2019: a systemic analysis for the Global Burden of Disease Study 2019. Lancet 2020; 396: 1204 – 22.  Back to cited text no. 4
    
5.
Negi PC, Sondhi S, Asotra S, Mahajan K, Mehta A. Current status of rheumatic heart disease in India. Indian Heart J 2019;71:85-90.  Back to cited text no. 5
    
6.
Joseph N, Madi D, Kumar GS, Nelliyanil M, Saralaya V, Rai S. Clinical spectrum of rheumatic fever and rheumatic heart disease: A 10 year experience in an Urban area of South India. N Am J Med Sci 2013;5:647-52.  Back to cited text no. 6
    
7.
Dhar M, Kaeley N, Bhatt N, Ahmad S. Profile of newly diagnosed adult patients with rheumatic heart disease in sub-Himalayan region – A 5-year analysis. J Family Med Prim Care 2019;8:2933-6.  Back to cited text no. 7
[PUBMED]  [Full text]  
8.
Negi PC, Sondhi S, Rana V, Rathoure S, Kumar R, Kolte N, et al. Prevalence, risk determinants and consequences of atrial fibrillation in rheumatic heart disease: 6 years hospital based-Himachal Pradesh– Rheumatic fever/rheumatic heart disease (HP-RF/RHD) registry. Indian Heart J 2018;70 Suppl 3:S68-73.  Back to cited text no. 8
    
9.
Rastogi A, Singh Y, Joshi A. A hospital based study on clinical profile in patients of rheumatic heart disease attending a tertiary care hospital in Kumaon region of Uttarakhand. Ann Int Med Dent Res 2016;2:154-8.  Back to cited text no. 9
    
10.
Sliwa K, Carrington M, Mayosi BM, Zigiriadis E, Mvungi R, Stewart S. Incidence and characteristics of newly diagnosed rheumatic heart disease in urban African adults: Insights from the heart of Soweto study. Eur Heart J 2010;31:719-27.  Back to cited text no. 10
    
11.
Lawrence JG, Carapetis JR, Griffiths K, Edwards K, Condon JR. Acute rheumatic fever and rheumatic heart disease: Incidence and progression in the Northern Territory of Australia, 1997 to 2010. Circulation 2013;128:492-501.  Back to cited text no. 11
    
12.
Lilyasari O, Prakoso R, Kurniawati Y, Roebiono PS, Rahajoe AU, Sakidjan I, et al. Clinical profile and management of rheumatic heart disease in children and young adults at a tertiary cardiac center in Indonesia. Front Surg 2020;7:47.  Back to cited text no. 12
    
13.
Zühlke L, Engel ME, Karthikeyan G, Rangarajan S, Mackie P, Cupido B, et al. Characteristics, complications, and gaps in evidence-based interventions in rheumatic heart disease: the Global Rheumatic Heart Disease Registry (the REMEDY study), European Heart Journal, Volume 36, Issue 18, 7 May 2015, Pages 1115–1122.  Back to cited text no. 13
    
14.
Koirala PC, Sah RK, Sharma D. Pattern of rheumatic heart disease in patients admitted at tertiary care centre of Nepal. Nepal Heart J 2018;15:29-33.  Back to cited text no. 14
    
15.
Boyarchuk O, Hariyan T, Kovalchuk T. Clinical features of rheumatic heart disease in children and adults in Western Ukraine. Bangladesh J Med Sci 2019;18:87-93.  Back to cited text no. 15
    
16.
Myint NP, Aung NM, Win MS, Htut TY, Ralph AP, Cooper DA, et al. The clinical characteristics of adults with rheumatic heart disease in Yangon, Myanmar: An observational study. PLoS One 2018;13:e0192880.  Back to cited text no. 16
    
17.
Watkins DA, Beaton AZ, Carapetis JR, Karthikeyan G, Mayosi BM, Wyber R, et al. Rheumatic heart disease Worldwide: JACC scientific expert panel. J Am Coll Cardiol 2018;72:1397-416.  Back to cited text no. 17
    
18.
Gemechu T, Mahmoud H, Parry EH, Phillips DI, Yacoub MH. Community-based prevalence study of rheumatic heart disease in rural Ethiopia. Eur J Prev Cardiol 2017;24:717-23.  Back to cited text no. 18
    
19.
Harikrishnan S, Kartha C. Pulmonary hypertension in rheumatic heart disease. PVRI Rev 2009;1:13.  Back to cited text no. 19
    



 
 
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  [Table 1], [Table 2], [Table 3], [Table 4], [Table 5], [Table 6]



 

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