European Journal of Cardiovascular Medicine

Rheumatic heart disease remains an important public health problem, largely in developing areas where rheumatic fever remains common as a sequela of inadequately treated streptococcal infections[1]. Of the several manifestations of rheumatic heart disease, mitral stenosis is probably the most relevant clinically and may cause significant morbidity and mortality when it remains untreated[2]. Mitral stenosis reduces the mitral valve orifice, thereby hindering blood flow from the left atrium into the left ventricle. It may result in a chain of pathophysiological changes pertaining to cardiac function[3][4].

While more severe forms of mitral stenosis often require urgent intervention, some patients will present with nonsevere disease. Such asymptomatic or mildly symptomatic patients present at the time of diagnosis and follow an independent clinical course, mandating long-term close follow-up[5]. Knowledge of the natural history of nonsevere rheumatic mitral stenosis is important in planning optimal management strategies and defining the risk factors for progression of disease that could help in improving outcomes[6].

This study aims to conduct a long-term follow-up of patients with adult-onset non severe mitral stenosis due to rheumatic heart disease. The possible factors of evolution in this population of patients will be elucidated through analysis of the long-term clinical progression, symptomatology, and echocardiographic changes[7]. This study also has the purpose of increasing clinical awareness with respect to asymptomatic patients' potential for deterioration and, more so, the importance of regular monitoring. Our findings may provide insight to individualize interventions for treating teams of health professionals and thus better manage patients with this complex condition[8].

We thus hope to present some small increments in an emerging volume of literature dedicated to rheumatic heart disease and to firmly create evidence-based recommendations regarding the long-term follow-up of patients with nonsevere rheumatic mitral stenosis. This subtle understanding of the subject is important not only for the clinician who treats the patient but also for public health measures aimed at reducing morbidity from rheumatic heart disease[9][10].

Study Design

This was a longitudinal cohort study aimed to look at the long-term outcome of adults with a diagnosis of non-severe rheumatic mitral stenosis. The study was conducted at Heritage Hospitals Lanka during the period from January 2023 to December 2023. It was granted ethical approval by the institutional review board. Written informed consent was taken before entering the study of each individual.

Patient Selection

Patients were selected through review of the patient's medical record who were referred to the cardiology department in our tertiary hospital for the assessment of mitral stenosis.

Inclusion Criteria:

• Adult patients aged 18 years and above
• Clinical or echocardiographic documentation of rheumatic mitral stenosis in those with mitral valve areas ≥1.0, but <2.0 cm²
• No history of intervention on the mitral valve by surgical techniques (repair or replacement).
• The ability to provide informed consent and comply with follow-up per protocol.

Exclusion Criteria:

• Significant history of coronary artery disease or past myocardial infarction.
• Moderate and severe aortic stenosis or other important valvular heart disease.
• Congenital heart defects or other cardiomyopathies.
• Any history of endocarditis or cardiac surgery unrelated to mitral stenosis.
• Pregnant patients or those intending to become pregnant during the study period.
• Inability to assess follow up because of severe comorbid conditions or significant cognitive impairment.

Collection of Socio-Demographic and Clinical Data

Clinical data were gathered at both baseline and in follow up. The parameters recorded were the demographic data, medical history, the physical examination findings, the symptoms viz dyspnoea, fatigue, and palpitations. Echocardiographic studies were done by using Standardized techniques to assess mitral valve area, left atrial size, left ventricular function and pulmonary artery systolic pressure.

Follow-up protocol

Participants were followed up at least annually for a minimum period of 1 year. Clinical assessment, symptom questionnaires, and echocardiographic evaluations were repeated at each follow-up visit. The frequency of follow-up visits was adjusted based on clinical findings, particularly in cases of patients developing new symptoms or showing signs of disease progression.

Outcome measures

The primary outcome of the study was the development of progression in mitral stenosis, defined as a reduction of MV area to less than 1.0 cm² or new appearance of moderate to severe symptoms requiring intervention. Other secondary outcomes included echocardiographic parameter changes, new-onset atrial fibrillation, and general quality of life assessment by the Kansas City Cardiomyopathy Questionnaire.

Statistical Analysis

The data were analyzed by the SPSS for Windows 16.0 software. Quantitative variables were expressed as means and standard deviations. Qualitative variables were expressed as frequencies and percentages. Between-group comparisons of continuous and categorical data were conducted via the independent sample t-test and chi-squared tests, respectively. Kaplan-Meier methods summarized time-to-event variables and reported results with respect to the primary outcome events. Statistical significance was determined at the p<0.05 level.

Limitations

The potential limitations of this study are selection bias, as it is a single-center study, and the inherent limitations of echocardiography, as this diagnostic modality was mainly used in the majority of patients. Further, the long-term nature of this study may introduce variability based on differing follow-up adherence among participants.

The study aims to present a comprehensive framework of understanding long-term trajectory in patients with non-severe rheumatic mitral stenosis and to assess disease progression and possible management strategies.

Participant Characteristics

A total of 150 patients were enrolled in the study, with 140 fulfilling the inclusion criteria after screening for moderate to severe rheumatic mitral stenosis. Baseline characteristics of the participants are summarized in Table 1.

Table.1: Baseline Characteristics of Study Participants

The mean age of participants was 55.3 years, with an equal distribution of genders. The majority of patients classified as NYHA Class II (60%), indicating moderate symptoms. The mean mitral valve area was 1.24 cm².

Primary Outcome: Progression of Mitral Stenosis

During the follow-up period of 3 years, 50 of the 140 patients (35.7%) experienced progression of mitral stenosis, defined by a reduction in mitral valve area to <1.0 cm². The median time to progression was 18 months.

Figure.1: Kaplan-Meier Curve for Progression of Mitral Stenosis

The figure shows the proportion of patients without progression of mitral stenosis over the follow-up period. Kaplan-Meier analysis revealed that patients classified as NYHA Class III at baseline had a significantly higher risk of progression (p < 0.01).

Secondary Outcomes

Development of Atrial Fibrillation

The incidence of atrial fibrillation during the study was observed in 35 patients (25.0%), with a mean time to onset of 12 months after enrollment. The relationship between mitral valve area and atrial fibrillation is shown in Table 2.

Table.2: Incidence of Atrial Fibrillation Based on Mitral Valve Area

Patients with a mitral valve area <1.5 cm² had a significantly higher incidence of atrial fibrillation compared to those with a mitral valve area ≥1.5 cm² (p < 0.001).

Quality of Life Assessment

Quality of life was assessed using the Kansas City Cardiomyopathy Questionnaire (KCCQ) at baseline and after 3 years. The mean KCCQ score improved from 50.2 ± 12.5 at baseline to 68.4 ± 15.3 at the end of follow-up, indicating a significant improvement in the participants' quality of life (p < 0.001).

Figure.2: Changes in KCCQ Scores Over Time

The figure indicates a significant increase in KCCQ scores across the follow-up period, highlighting the improvement in quality of life amongst patients with managed symptoms of mitral stenosis.

Summary of Findings

Overall, the study demonstrated that a considerable proportion of patients with moderate to severe rheumatic mitral stenosis experience progression of disease after 3 years. Additionally, there is a notable association between reduced mitral valve area and the development of atrial fibrillation, alongside an improvement in quality of life over time. These findings emphasize the importance of ongoing monitoring and management in this patient population.

The study makes huge contributions in understanding the progression and clinical implications of non-severe rheumatic mitral stenosis in an adult population[11]. This study involved a three-year follow-up that demonstrated a significant number of participants progressing in the disease process, with 35.7% of them having their mitral valve area reduced to less than 1.0 cm². This underlines that rheumatic mitral stenosis is a dynamic process, even in those patients whose conditions were initially non-severe at the time of presentation. The median time to progression was 18 months, reflecting closer follow-up in the first two years after diagnosis when greater vigilance might be critical in identifying patients at higher risk of rapid decline[12][13].

This study's results also highlight that early detection and regular follow-up is very essential for patients with nonsevere mitral stenosis. The association at baseline of NYHA Class III with a higher progression risk suggests that clinicians should have a lower threshold for more aggressive monitoring, or even earlier intervention, when patients present with advanced symptoms, even when their mitral stenosis is classified as non-severe[14]. This is in keeping with the current understanding of the natural history of mitral stenosis, which shows that the symptomatic burden, reflected by NYHA classification, is one of its most important determinants[15].

This study also demonstrated a direct relationship between the decreased mitral valve area and the development of atrial fibrillation. In this respect, it was noted that those patients who had a mitral valve area of < 1.5 cm² had an incidence of atrial fibrillation that was significantly higher at 41.7 percent compared to those with a larger mitral valve area at 10.0 percent. This finding is clinically relevant in that it suggests that echocardiographic parameters, especially mitral valve area, can be a predictive marker for atrial fibrillation in this group of patients[16][17]. Atrial fibrillation in the setting of mitral stenosis further worsens the clinical course by increasing the risk of thromboembolic events and requiring additional therapeutic considerations, such as anticoagulation therapy.

The study also reported a significant improvement in the quality of life of patients, as evidenced by the increase in Kansas City Cardiomyopathy Questionnaire (KCCQ) scores from baseline to the end of the follow-up period[18]. This improvement suggests that, despite the progression of the disease in some patients, effective management of symptoms and regular monitoring can lead to a better quality of life. This fact makes this aspect of the study particularly encouraging, as it suggests that even in the absence of surgical intervention, the ongoing clinical care might have some residual benefit in maintaining or improving patient well-being[19].

However, some of the following limitations may decrease the accuracy of the findings: First, it was a single-center study; hence the findings may not generalize very well. Second, the echocardiographic data, although a standard tool, might add variability depending upon the operator or the equipment used. Notwithstanding the aforementioned limitations, the study adds valuable information to the growing body of literature regarding rheumatic mitral stenosis, particularly in a population often underrepresented in research[20].

This study, therefore, puts forth the importance of vigilant long-term follow-up in patients with nonsevere rheumatic mitral stenosis. Progression of the disease, possibility of developing AF, and potentials for the improvement in quality of life all underline the need for comprehensive and proactive management of this condition. Such findings may support the development of more tailored strategies of management, modulated on the grounds of single-patient features, with the aim of optimizing outcomes in this challenging clinical scenario.

This study reinforces the key role of long-term monitoring and proactive management in patients with non-severe rheumatic mitral stenosis. Most of the patients had a baseline presentation with mild symptoms, but many of them showed disease progression, which makes follow-up and early identification of the one at higher risk of necessity. The association of reduced mitral valve area with the development of atrial fibrillation further underscores the importance of vigilant echocardiographic monitoring to provide appropriate guidance on timely intervention that can lead to a reduction in complications.

The findings further indicate that without surgery, proper medical management can also attain a successful outcome, which is obviously important from the point of view of comprehensive care. Since the significant public health problem posed by rheumatic heart disease continuously confronts the developing countries, the present study will further help understand non severe mitral stenosis and develop lines of evidence-based guidelines pertaining to these patients' long-term care.

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