Pathogenesis of acute rheumatic fever and rheumatic heart disease: evasive after half a century of clinical, epidemiological, and laboratory investigation

Transcatheter Therapy for Mitral Valve Stenosis

Mitral valve stenosis remains highly prevalent among the US population although with dramatically shifting demographics. The significance of rheumatic mitral disease in developing nations persists, despite improvements in preventative measures and early detection, and its presence in developed countries is still evident as observed through international migration. In addition, the substantial growth in the aging population with a heightened occurrence of concurrent cardiovascular risk factors is leading to an increased prevalence of chronic calcific degeneration and degeneration of previously repaired or replaced valves. This article aims to review various transcatheter therapies in the treatment of mitral valve stenosis.

Transcatheter Therapy for Mitral Valve Stenosis

Mitral valve stenosis remains highly prevalent among the US population although with dramatically shifting demographics. The significance of rheumatic mitral disease in developing nations persists, despite improvements in preventative measures and early detection, and its presence in developed countries is still evident as observed through international migration. In addition, the substantial growth in the aging population with a heightened occurrence of concurrent cardiovascular risk factors is leading to an increased prevalence of chronic calcific degeneration and degeneration of previously repaired or replaced valves. This article aims to review various transcatheter therapies in the treatment of mitral valve stenosis.

Age period cohort analysis of rheumatic heart disease in high-income countries

INTRODUCTION

Rheumatic heart disease is considered well-controlled in high-income countries; however, its actual trends in mortality remain unclarified. We analyzed trends in mortality from rheumatic heart disease in association with age, period, and birth cohort.

METHODS

We analyzed the WHO mortality database to determine trends in mortality from rheumatic heart disease in the UK, Germany, France, Italy, Japan, Australia, USA, and Canada from 2000 to 2020. We used age-cohort-period modeling to estimate cohort and period effects. Net drift (overall annual percentage change), local drift (annual percentage change in each age group) and heterogeneity were calculated.

RESULTS

In the most recent year, crude mortality rates and age-standardized mortality rates ranged from 1.10 in the USA to 6.17 in Germany, and 0.32 (95% CI 0.31-0.34) in Japan and 1.70 (95% CI 1.65-1.75) in Germany, respectively. During the observation period, while Germany had a constant trend in overall annual percentage change, all the other countries had significant decreasing trends (p < 0.0001, respectively). Annual percent change was not homogeneous across each group in all 8 countries (pheterogeneity < 0.0001), with 2 peaks in the younger and older age categories. In Germany, Italy, Australia, and Canada, we found increasing mortality rates among older patients. Improving period and cohort risks for rheumatic heart disease mortality were generally observed, excluding Germany where the period effect was worsening and the cohort effect was constant.

CONCLUSIONS

Mortality trends from rheumatic heart disease were decreasing in the study high-income countries except for Germany where higher mortality and two peaks in annual percentage change in younger and older age groups warrant further investigation.

Plausible Role of NLRP3 Inflammasome and Associated Cytokines in Pathogenesis of Rheumatic Heart Disease

Rheumatic heart disease (RHD) is a post-streptococcal sequela caused by Streptococcus pyogenes. The global burden of disease is high among people with low socio-economic status, with significant cases emerging every year despite global eradication efforts. The current treatment includes antibiotic therapies to target strep throat and rheumatic fever and valve replacement strategies as a corrective measure for chronic RHD patients. Valvular damage and valve calcification are considered to be the end-stage processes of the disease resulting from impairment of the endothelial arrangement due to immune infiltration. This immune infiltration is mediated by a cascade of events involving NLRP3 inflammasome activation. NLRP3 inflammasome is activated by wide range of stimuli including bacterial cell wall components like M proteins and leukocidal toxins like nicotinamide dehydrogenase (NADase) and streptolysin O (SLO) and these play a major role in sustaining the virulence of Streptococcus pyogenes and progression of RHD. In this review, we are discussing NLRP3 inflammasome and its plausible role in the pathogenesis of RHD by exploiting the host-pathogen interaction mainly focusing on the NLRP3 inflammasome-mediated cytokines IL-1β and IL-18. Different therapeutic approaches involving NLRP3 inflammasome inactivation, caspase-1 inhibition, and blockade of IL-1β and IL-18 are discussed in this review and may be promising for treating RHD patients.

Mitral valve diseases: Pathophysiology and interventions

Valvular heart disease is common and increasingly prevalent among the elderly. The end result of valvular pathologies is cardiac failure and can lead to sudden death; thus, diagnosis and interventions are very important in the early stages of these diseases. The usual treatment methods of mitral regurgitation include percutaneous mitral valve repair, mitral valve replacement and minimally invasive surgery, whereas the treatment methods of mitral stenosis include percutaneous transluminal mitral commissurotomy and mitral commissurotomy as well as open surgical repair. Nonetheless, ongoing clinical trials are a clear indicator that the management of valve diseases is ever evolving. The focus of this paper is on the various pathologies of the mitral valve, their etiology and clinical management, offering a comprehensive view of mitral valve diseases.

Histopathological Characterization of Mitral Valvular Lesions from Patients with Rheumatic Heart Disease

BACKGROUND

The underlying mechanisms by which rheumatic heart disease (RHD) lead to severe valve dysfunction are not completely understood.

OBJECTIVE

The present study evaluated the histopathological changes in mitral valves (MV) seeking an association between the pattern of predominant valvular dysfunction and histopathological findings.

METHODS

In 40 patients who underwent MV replacement due to RHD, and in 20 controls that underwent heart transplant, histological aspects of the excised MV were analyzed. Clinical and echocardiographic data were also collected. Histological analyses were performed using hematoxylin-eosin staining. Inflammation, fibrosis, neoangiogenesis, calcification and adipose metaplasia were determined. A p value<0.05 was considered to be statistically significant.

RESULTS

The mean age of RHD patients was 53±13 years, 36 (90%) were female, whereas the mean age of controls was 50±12 years, similar to the cases, with the majority of males (70%). The rheumatic valve endocardium presented greater thickness than the controls (1.3±0.5 mm versus 0.90±0.4 mm, p=0.003, respectively), and a more intense inflammatory infiltrate in the endocardium (78% versus 36%; p=0.004), with predominance of mononuclear cells. Moderate to marked fibrosis occurred more frequently in rheumatic valves than in control valves (100% vs. 29%; p<0.001). Calcification occurred in 35% of rheumatic valves, especially among stenotic valves, which was associated with the mitral valve area (p=0.003).

CONCLUSIONS

Despite intense degree of fibrosis, the inflammatory process remains active in the rheumatic mitral valve, even at late disease with valve dysfunction. Calcification predominated in stenotic valves and in patients with right ventricular dysfunction.

Raising awareness for rheumatic mitral valve disease

Rheumatic heart disease (RHD) is a major burden in low- to mid-income countries, where each year it accounts for over a million premature deaths associated with severe valve disease. Life-saving valve replacement procedures are not available to the majority of affected RHD patients, contributing to an increased risk of death in young adults and creating a devastating impact. In December 2017, a group of representatives of major cardiothoracic societies and industry, discussed the plight of the millions of patients who suffer from RHD. A comprehensive solution based on this global partnership was outlined in "The Cape Town Declaration on Access to Cardiac Surgery in the Developing World". The key challenge in controlling RHD is related to identification and removal of barriers to the translation of existing knowledge into policy, programs, and practice to provide high-quality care for patients with RHD. This review provides an overview on RHD by emphasizing the disease medical and economic burdens worldwide, risk factors, recent advance for early disease detection, and overall preventive strategies.

Echocardiography Screening for Latent Rheumatic Heart Disease: What Can We Do in Indonesia?

Rheumatic heart disease (RHD), a sequela of acute rheumatic fever (ARF), is a preventable disease but remains a significant health problem, especially in developing countries. It causes disability, poor quality of life, early mortality, and national economic burden. The World Heart Federation (WHF) aimed to achieve a 25% reduction in premature deaths from ARF and RHD among individuals aged <25 years by 2025. Primordial and primary prophylaxis of RHD is aimed to prevent the occurrence of ARF, while the goal of secondary and tertiary prophylaxis is to limit the progression and reduce the consequences of RHD. Early recognition of RHD is important for early prophylaxis strategies to inhibit any progression to advanced stages. In 2012, WHF introduced the latest echocardiographic criteria to recognize the early stage of RHD. This includes the evaluation of pathological regurgitation jet and morphological features of RHD based on 2D, color, and spectral Doppler criteria. In remote areas, portable echocardiography is preferable for RHD screening. Previous portable devices were only capable of producing 2D and color images. Hence, a simplified echocardiographic criterion without spectral Doppler evaluation is needed in selected areas. Indonesia is a developing country, an archipelago with a population of over 250 million. Currently, there are no data on ARF incidence and RHD prevalence nationwide. The only data available are the number of patients in advanced stages who came to referral centers for further management. The screening program has to be introduced in Indonesia as part of national RHD prophylaxis.

Mechanistic implications of altered protein expression in rheumatic heart disease

Rheumatic heart disease (RHD) is a major cause of cardiovascular morbidity and mortality in low- and middle-income countries, where living conditions promote spread of group A β-haemolytic streptococcus. Autoimmune reactions due to molecular mimicry of bacterial epitopes by host proteins cause acute rheumatic fever (ARF) and subsequent disease progression to RHD. Despite knowledge of the factors that predispose to ARF and RHD, determinants of the progression to valvular damage and the molecular events involved remain incompletely characterised. This review focuses on altered protein expression in heart valves, myocardial tissue and plasma of patients with RHD and pathogenic consequences on RHD. Proteins mainly involved in structural organization of the valve matrix, blood homeostasis and immune response were altered due to RHD pathogenesis. Study of secreted forms of these proteins may aid the development of non-invasive biomarkers for early diagnosis and monitoring outcomes in RHD. Valve replacement surgery, the single evidence-based strategy to improve outcomes in severe RHD, is costly, largely unavailable in low- and middle-income countries (LMIC) and requires specialised facilities. When diagnosed early, penicillin prophylaxis may be used to delay progression to severe valvular damage. Echocardiography and cardiovascular magnetic resonance and the standard imaging tools recommended to confirm early diagnosis remain largely unavailable and inaccessible in most LMIC and both require expensive equipment and highly skilled persons for manipulation as well as interpretation of results. Changes in protein expression in heart valves and myocardium are associated with progressive valvular deformation in RHD. Understanding these protein changes should shed more light on the mechanisms of pathogenicity, while secreted forms of these proteins may provide leads towards a biomarker for non-invasive early detection of RHD.

The burden of rheumatic heart disease among children in Lagos: how are we fairing?

INTRODUCTION

Rheumatic heart disease still remains a cause of morbidity and mortality in low and middle income countries, despite its eradication in developed societies. The study aimed to document the features of children with rheumatic heart disease using clinical evaluation and echocardiography and compare it with reports from other part of the country.

METHODS

A review of a prospectively collected data of patients with rheumatic heart disease who had echocardiography done from April 2007-Dec 2016. Information obtained from patients include age, sex, clinical indication for echocardiography, echocardiographic characterization of the valvular lesions and associated complications.

RESULTS

A total of 324,676 patients were seen at the Paediatric unit of LASUTH from 2007 to 2016, out of which 36 had Rheumatic heart disease. This translates to a prevalence of 1.1 per 10,000 patients who presented at the study site during the study period. The prevalence of RHD amongst all the patients with structural heart disease was 2.6%. The mean age of patients was 9.12 ± 2.75 years with a male to female ratio of 1.6: 1. The most common valve affected was mitral valve. Heart failure was the most common mode of presentation found in 91.6%. Other complications were pulmonary hypertension and pericardial effusion.

CONCLUSION

Rheumatic heart disease is still prevalent among children in Lagos although the prevalence is reducing. Heartfailure is the commonest mode of presentation and complication in them.

Accelerating the development of a group A Streptococcus vaccine: an urgent public health need

Group A Streptococcus (GAS) infections cause substantial worldwide morbidity and mortality, mostly associated with suppurative complications such as pharyngitis, impetigo, and non-suppurative immune syndromes such as acute rheumatic fever, rheumatic heart disease, and acute post-streptococcal glomerulonephritis. Deaths occur mostly in children, adolescents, and young adults in particular pregnant women in low- and middle-income countries. GAS strains are highly variable, and a GAS vaccine would need to overcome the issue of multiple strains. Several approaches have been used multivalent vaccines using N-terminal polypeptides of different M protein; conserved M protein vaccines with antigens from the conserved C-repeat portion of the M protein; incorporation selected T- and B-cell epitopes from the C-repeat region in a synthetic polypeptide or shorter single minimal B-cell epitopes from this same region; and non-M protein approaches utilizing highly conserved motives of streptococcal C5a peptidase, GAS carbohydrate and streptococcal fibronectin-binding proteins. A GAS vaccine represents urgent need for this neglected disease and should therefore deserve the greatest attention of international organizations, donors, and vaccine manufacturers.

Evaluation of the policy of secondary prevention against rheumatic fever among Egyptian children

OBJECTIVE

We evaluated the effectiveness of long acting penicillin (LAP) as a 2-weekly regimen in winter and a 3-weekly regimen in summer for prevention of streptococcal colonization and also studied the common complaints of patients during the period of compliance for LAP administration. We also attempted to determine the incidence of relapses or recurrence of rheumatic fever (RF) after the onset of first episode of RF.

PATIENTS & METHODS

210 rheumatic patients with good compliance to LAP (for at least one year) were included in the study. Demographic, clinical information, patients' complaints and echocardiographic data of rheumatic patients were collected both retrospectively and prospectively. Anti-streptolysin O titre (ASOT) and throat swab culture were done at the end of the study (on Day 14 in the 2-weekly regimen and on Day 21 in the 3-weekly regimen).

RESULTS

The age of onset of rheumatic fever was mostly between 5 and 15 years and the youngest patient was 2 years old. Subclinical carditis (SCC) was present in 79 (37%) of all the patients in the study population. Only 7 patients (3.3%) had a relapse within 2 years of the acute episode of RF. At the end of the study, ASOT was found to be high only in 11 patients (5.2%) and throat swab cultures were found negative in all patients

CONCLUSION

LAP regimen is fairly effective in eradicating streptococcal colonization. The incidence of relapse of RF within 2 years of the acute episode of RF is relatively low.

New Scores for the Assessment of Mitral Stenosis Using Real-Time Three-Dimensional Echocardiography

Nonsurgical management of patients with symptomatic mitral valve stenosis has been established as the therapeutic modality of choice for two decades. Catheter-based balloon dilation of the stenotic valvular area has been shown, at least, as effective as surgical interventions. Unfavorable results of catheter-based interventions are largely due to unfavorable morphology of the valve apparatus, particularly leaflets calcification and subvalvular apparatus involvement. A mitral valve score has been proposed in Boston, MA, about two decades ago, based on morphologic assessment of mitral valve apparatus by two-dimensional (2D) echocardiography to predict successful balloon dilation of the mitral valve. Several other scores have been developed in the following years in order to more successfully predict balloon dilatation outcome. However, all those scores were based on 2D echocardiography, which is limited by ability to distinguish calcification and subvalvular involvement. The introduction of new matrix-based ultrasound probe has allowed 3D echocardiography (3DE) to provide more detailed morphologic analysis of mitral valve apparatus including calcification and subvalvular involvement. Recently, a new 3DE scoring system has been proposed by our group, which represents an important leap into refinement of the use of echocardiography guiding mitral valve interventions.

Prevalence of rheumatic heart disease among school-children in Aden, Yemen

BACKGROUND

Rheumatic heart disease (RHD) is an important contributor to cardiovascular disease in children and adults in Yemen. This is the first report to determine the prevalence of RHD among school-children in the city of Aden.

METHODS

A cross-sectional case-finding survey of RHD was conducted in 6000 school-children aged 5-16 years. Echocardiography was undertaken in those with clinical signs of organic heart disease.

RESULTS

The prevalence of RHD was 36·5/1000 school-children, which is one of the highest reported among school echocardiography surveys in the world. RHD was more common in 10-16-year-old students. RHD was diagnosed in more than one member of the families of 53 (24·2%) of the children. Mitral regurgitation (MR) was detected in 49·8%, 26·6% had MR with mitral valve prolapse and 17·8% had combined MR and aortic regurgitation. Fifty-eight children were diagnosed with congenital heart disease (CHD), representing a prevalence of 9·7/1000. The main types of CHD were mitral valve prolapse, patent ductus arteriosus, atrial septal defect, pulmonary stenosis and aortic stenosis. Congenital mitral valve prolapse found in 36 children was three times more common in males than females. Children with RHD were more likely to be from low-income families with poor housing and greater overcrowding (49·3%, 39·3% and 64·8%) than children with CHD (44·8%, 32·8% and 48·3%, respectively).

CONCLUSIONS

The high prevalence of RHD is a major public health problem in Yemen. Urgent screening surveys and an RHD prophylactic programme of appropriate management of group A β-haemolytic streptococcal pharyngotonsilitis are required.

The worldwide epidemiology of acute rheumatic fever and rheumatic heart disease

Acute rheumatic fever (ARF) and rheumatic heart disease (RHD) are significant public health concerns around the world. Despite decreasing incidence, there is still a significant disease burden, especially in developing nations. This review provides background on the history of ARF, its pathology and treatment, and the current reported worldwide incidence of ARF and prevalence of RHD.

First-episode versus recurrent acute rheumatic fever: is it different?

BACKGROUND

Recurrent episodes of acute rheumatic fever (RF) can lead to rheumatic heart disease with considerable disability and mortality in children. RF can recur in the absence of secondary prophylaxis. The differences in clinical manifestations and outcome between first-episode and recurrent RF have been less studied.

METHODS

A cross-section of patients under 14 years was studied for 2 years (2003-2005) in order to compare the clinical, laboratory, echocardiographic profile and outcome of first-episode RF with recurrent attacks, and risk factors for recurrence and mortality. Patients without a previous history of RF and/or mitral stenosis (MS) and/or aortic stenosis (AS) were defined as first-episode patients, and patients with previous history of RF and/or MS and/or AS, were defined as recurrent RF patients based on the Jones criteria.

RESULTS

Of 51 patients in total, 26 had first-episode RF and 25 had recurrent RF. Arthritis occurred in a significantly higher number of first-episode patients (P = 0.047) whereas shortness of breath (SOB; P = 0.003), palpitation (P = 0.034), and aortic regurgitation (AR; P = 0.001) occurred in a significantly higher number of recurrent RF patients. Audible murmur of corresponding echocardiographic regurgitation was present in all recurrent RF patients whereas audible murmur was present in 61.5% and echocardiographic regurgitation in 81% in first-episode patients (P = 0.007). Palpitation, SOB, audible murmur, thrill, age and AR on admission were independent predictors of recurrence. Palpitation, age and AS on admission were independent predictors of mortality.

CONCLUSIONS

Subclinical carditis occurred only in the first-episode patients, which requires further evaluation for clinical significance. Because all deaths occurred in recurrent RF group (P = 0.02), secondary prophylaxis and management of sore throat need re-emphasis.

The efficacy of echocardiographic criterions for the diagnosis of carditis in acute rheumatic fever

BACKGROUND

There is a great need for echocardiographic criterions for accurate diagnosis of carditis in acute rheumatic fever.

AIM

To test the efficacy of proposed echocardiographic criterions for the diagnosis of carditis.

MATERIALS AND METHODS

We studied 333 patients suspected of having acute rheumatic fever, undertaking detailed clinical examination, laboratory tests and meticulous echocardiography in each case. We used previously established echocardiographic criterions for the diagnosis of carditis and subclinical valvitis. In 220 cases (66.06%), both the echo criterions, and the Jones' criterions, gave positive results. In 52 cases (15.61%), we found evidence of subclinical carditis, in that clinically no murmur was heard, meaning the Jones' criterions were negative, but the echocardiographic evaluation was positive. In 4 patients clinically diagnosed as having carditis, the Jones' criterions were positive, but echocardiographic evaluation showed them to have congenitally malformed hearts. In another 57 cases (17.11%), the Jones' criterions were negative, as were the results of echocardiographic evaluation. These patients were taken as control subjects. On this basis, the echocardiographic criterions had sensitivity of 81% and specificity of 93%.

CONCLUSION

Using our echocardiographic criterions, it is possible to make a precise diagnosis of carditis or subclinical valvitis. Hence, echocardiography should, in future, be included as a major criterion in the Jones' system.

Identification of a streptococcal octapeptide motif involved in acute rheumatic fever

Acute rheumatic fever is a serious autoimmune sequela of pharyngitis caused by certain group A streptococci. One mechanism applied by streptococcal strains capable of causing acute rheumatic fever is formation of an autoantigenic complex with human collagen IV. In some geographic regions with a high incidence of acute rheumatic fever pharyngeal carriage of group C and group G streptococci prevails. Examination of such strains revealed the presence of M-like surface proteins that bind human collagen. Using a peptide array and recombinant proteins with targeted amino acid substitutions, we could demonstrate that formation of collagen complexes during streptococcal infections depends on an octapeptide motif, which is present in collagen binding M and M-like proteins of different beta-hemolytic streptococcal species. Mice immunized with streptococcal proteins that contain the collagen binding octapeptide motif developed high serum titers of anti-collagen antibodies. In sera of rheumatic fever patients such a collagen autoimmune response was accompanied by specific reactivity against the collagen-binding proteins, linking the observed effect to clinical cases. Taken together, the data demonstrate that the identified octapeptide motif through its action on collagen plays a crucial role in the pathogenesis of rheumatic fever. Eradication of streptococci that express proteins with the collagen binding motif appears advisable for controlling rheumatic fever.

Immunology of obsessive-compulsive disorder

Childhood OCD often develops into a chronic illness that lasts decades. Proof that some type of immunotherapy (such as antibiotic prophylaxis) could significantly reduce recurrence or exacerbation of symptoms of OC or tics would suggest a supportive role for immune triggers in the onset or worsening of these conditions and provide additional tools for improving outcome. The validity of PANDAS will continue to be questioned, however,because demonstrating a clear causation will be difficult on a background ofa common childhood illness. Along with the previously mentioned immuno-therapy study, validation of the PANDAS phenotype (broadly interpreted)would be advanced from new and continued research in the following areas: (1) prospective studies to identify infectious triggers in the onset and exacerbations of OCD spectrum disorders, (2) biological measures for immune and genetic susceptibility, and (3) large scale epidemiological studies demonstrating the relationship between infection and OCD spectrum disorders. The assimilation of these study results should allow for elucidation of the immune system's role in the onset and maintenance of OCD.