A Study on Biochemical Markers in Myocardial Infarction in Patients at a Tertiary Hospital in Andhra Pradesh

Introduction

Cardiovascular diseases (CVDs) remain the leading cause of mortality worldwide, with myocardial infarction (MI) being a major contributor to this burden. MI occurs due to the interruption of blood supply to the heart, leading to ischemic damage. Acute MI can present as either ST-Elevation Myocardial Infarction (STEMI) or Non-ST-Elevation Myocardial Infarction (NSTEMI), with each form associated with varying clinical presentations, treatment strategies, and outcomes.¹ Studies have demonstrated that males are generally at a higher risk of MI compared to females, especially at younger ages, while this gap narrows or even reverses in older populations.² Despite the wealth of global data on MI, there is a paucity of studies examining gender and age-related differences in myocardial infarction within diverse population groups, particularly in rural and urban settings. Understanding these distinctions is critical for implementing targeted preventive and therapeutic measures. Earlier studies have also highlighted the importance of troponin as a biomarker in assessing the severity of myocardial injury.³ Elevated troponin levels, in particular, are a reliable indicator of myocardial cell death and provide valuable information on the extent of damage during MI.⁴ The present study investigated the gender and age-related disparities in the incidence of MI, focusing on STEMI and NSTEMI prevalence at a tertiary hospital in Andhra Pradesh, India, as well as the role of troponin as biomarker in determining myocardial damage severity. The findings of the study will provide valuable insights into the need for genderand age-specific interventions in both rural and urban populations.

Materials and Methods

Study Design

This prospective study was conducted at the Department of Emergency Medicine, Alluri Sitarama Raju Academy of Medical Sciences in Eluru, West Godavari District in Andhra Pradesh, India. The study was carried out between August 2023 and October 2024. Initially, 316 patients admitted with chest pain were included. However, patients with troponin levels below 40 ng/L were excluded, as their chest pain was likely due to unstable angina rather than myocardial infarction. Ultimately, only 249 cases with troponin levels above 40 ng/L were selected for the study. As there is no existing information on the incidence of MI in this population, the present study included 249 cases over a 15 month period, providing a reasonable representation of patients presenting to a tertiary hospital. This sample size allows for descriptive analysis of demographic and clinical characteristics, identification of potential associations between variables, and generation of hypotheses for future studies.

The study included patients aged above 20 years, admitted in the emergency department with acute myocardial infarction (MI). Patients showing classical electrocardiographic (ECG) signs of hyperacute or acute MI, accompanied by a transient rise in cardiac biomarkers, and exhibiting new-onset left bundle branch block (LBBB) with an associated rise in cardiac biomarkers, and also demonstrating wall motion abnormalities on 2D echocardiography, and showing pathological Q waves accompanied by ST-segment elevation and symmetrical T-wave inversion, along with an elevation in cardiac enzyme levels, were included in the study.

Approval of the Institutional Ethics Committee of ASRAM, Eluru was obtained for the study. The participants were informed about the purpose of the study and their consent was obtained. Participants who were unwilling to provide consent were excluded from the study.

Diagnosis

The diagnosis of acute myocardial infarction (AMI) was based on the revised criteria, which include a characteristic rise and gradual fall in biochemical markers of myocardial necrosis (troponin), along with at least one of the following ischemic symptoms: development of pathological Q waves on the ECG, or ECG changes indicative of ischemia, such as ST-segment elevation or depression.

Data Collection

A detailed history was obtained regarding symptoms such as chest pain, palpitations, sweating, vomiting, dyspnoea, and giddiness. Additionally, personal and family medical histories were recorded. General and systemic examinations were performed, with a particular focus on the cardiovascular system. Each patient was evaluated for common risk factors, including diabetes, hypertension, hypercholesterolemia, smoking, and alcohol use. Diagnosis of AMI was confirmed based on clinical presentation, ECG changes, and serum cardiac biomarker levels (Troponin-T). Serial ECGs were taken for all patients. Data were collected on age, gender, and locality to determine the association of MI with age group and gender, as well as to understand its prevalence in rural and urban populations. In addition, troponin and creatine levels were measured, and platelet counts were recorded in MI cases.

Statistical Analysis

Data were entered into Microsoft Excel, and statistical analysis was carried out using IBM SPSS Version 22.0. Categorical variables were represented as frequencies and percentages, while continuous variables were expressed as mean ± standard deviation. The categorical data were analysed using the Chi-Square test, while continuous data were analysed using independent t test. A P value of less than 0.05 was considered as significant.

Results

The distribution of study subjects across various age groups, categorized by gender, revealed distinct patterns as shown in the Table 1. The study analyzed 249 myocardial infarction cases, with a higher prevalence in males (62.7%) compared to females (37.3%). Notably, the 41-50 and 51-60 year age groups showed the highest incidence in both genders, accounting for 25.7% and 26.9% of total cases, respectively. Males predominated in the 21-50 year age range, while females had a higher representation in the older age groups, particularly 51-70 years. The 51-60 year age group had the highest proportion of cases overall, with 29.0% of females and 25.6% of males affected, indicating the critical importance of middle age in myocardial infarction risk across both the genders. Statistical analysis of the incidence of MI between males and females showed a significantly higher occurrence in males (P <0.05). However, no significant association was observed between gender and age group distribution (P ≈ 0.583).

Table 2 shows the distribution of study subjects based on their locality (rural vs. urban) and gender. The study examined the distribution of myocardial infarction cases based on rural and urban residence. Of the 249 cases, 49.0% (n=122) were from rural areas, and 51.0% (n=127) from urban areas. Among females, 45.2% (n=42) were from rural regions, and 54.8% (n=51) from urban areas. Among males, 51.3% (n=80) were from rural areas, and 48.7% (n=76) from urban areas. This distribution shows a nearly equal prevalence of myocardial infarction cases between rural and urban populations, with males showing a slightly higher rural incidence and females having a higher representation in urban areas. However, Chi-square test for the differences in disease distribution between rural and urban populations for males and females showed no significant association between gender and locality regarding the disease distribution (P>0.05).

The distribution of study subjects by ECG diagnosis across genders, as presented in Table 3, revealed important trends in the incidence of NSTEMI and STEMI among the 249 myocardial infarction cases. Overall, 35.7% (n=89) were diagnosed with NSTEMI, while 64.3% (n=160) were classified as STEMI. The differences between the two types of MI was found to be statically significant (P <0.05). Among females, 36.5% (n=34) were identified as NSTEMI, while 63.4% (n=59) were diagnosed with STEMI, indicating a higher prevalence of STEMI within this group. In contrast, among males, 35.3% (n=55) were classified as NSTEMI and 64.7% (n=101) as STEMI, showing a similar trend of predominance in STEMI. The total counts further emphasize that STEMI is the more common diagnosis across both genders, accounting for 64.3% of all myocardial infarction cases. The statistical analysis of MI cases indicate that the percentage of STEMI cases was significantly high. These findings suggest that both males and females have a higher incidence of STEMI compared to NSTEMI. The Chi-square analysis showed no statistically significant difference in the distribution of NSTEMI and STEMI between genders in the study population (P>0.05).

The study analyzed the mean troponin levels (ng/L) in relation to ECG findings for both NSTEMI and STEMI cases, stratified by gender. Among females, the mean troponin level for NSTEMI cases was 627.50 ng/L, with a standard error of 110.491, while for STEMI cases, it was 567.20 ng/L, with a standard error of 88.925. The overall mean troponin level for females was 589.25 ng/L, with a standard error of 69.086. In males, the mean troponin level for NSTEMI cases was 566.95 ng/L, with a standard error of 85.756, and for STEMI cases, it was 575.56 ng/L, with a standard error of 68.264. The overall mean troponin level for males was 572.56 ng/L, with a standard error of 53.384. Across the entire study population, the mean troponin level for NSTEMI cases was 590.08 ng/L, with a standard error of 67.435, while for STEMI cases, it was 572.52 ng/L, with a standard error of 53.980. The total mean troponin level for all cases was 578.80 ng/L, with a standard error of 42.160. These results indicate slightly higher mean troponin levels in females with NSTEMI compared to STEMI, while males had similar levels across both conditions (Table 4).

A t-test was performed to compare troponin levels between NSTEM1 and STEMI cases, and no significant difference was observed between the two groups. 

The analysis of creatinine levels by sex and ECG diagnosis revealed important distinctions (Table 5). Among females, those diagnosed with NSTEMI had a higher mean creatinine levels (1.53 mg/dL) compared to those with STEMI (1.24 mg/dL), suggesting a greater degree of renal impairment in NSTEMI cases. In contrast, among males, the mean creatinine level was lower in NSTEMI patients (1.09 mg/dL) than in STEMI patients (1.33 mg/dL), indicating lesser kidney involvement in NSTEMI cases. Overall, females had a slightly higher mean creatinine level (1.34 mg/dL) than males (1.25 mg/dL). The total population data showed relatively consistent creatinine levels across both STEMI (1.29 mg/dL) and NSTEMI (1.26 mg/dL) patients, with a minimal difference. These findings point to a pattern of higher creatinine levels in female NSTEMI patients and male STEMI patients, indicating possible sex-based differences in renal function related to the type of myocardial infarction.

The analysis of platelet counts by sex and ECG diagnosis highlights several key findings (Table 6). Among females, STEMI patients had a higher mean platelet count (3.26 lakh/cumm) compared to those with NSTEMI (2.75 lakh/cumm), indicating a potential increase in platelet activity or response in STEMI cases. For males, the difference between platelet counts in NSTEMI (2.83 lakh/cumm) and STEMI (2.90 lakh/cumm) patients was minimal, suggesting more consistent platelet levels across both types of myocardial infarction. Overall, females had a slightly higher mean platelet count (3.07 lakh/cumm) than males (2.88 lakh/cumm), with more variability observed among female NSTEMI patients (SE = 1.53). In the total population, STEMI patients had a higher mean platelet count (3.03 lakh/cumm) compared to NSTEMI patients (2.80 lakh/cumm), indicating a trend of elevated platelet counts in STEMI cases. These findings suggest that higher platelet levels are associated with STEMI, particularly in females, which may reflect a more pronounced thrombotic or inflammatory response.

Discussion

The results of this study highlight important gender and age-related disparities in the incidence and presentation of myocardial infarction (MI). The findings align with the broader body of literature, which has consistently demonstrated a higher prevalence of MI in males, particularly at younger ages, with the gender gap narrowing in older populations.⁵ This study also underscores the higher prevalence of ST-Elevation Myocardial Infarction (STEMI) over Non-ST-Elevation Myocardial Infarction (NSTEMI), a trend observed in both males and females across different age groups.

Our data showed that males accounted for 62.7% of MI cases, with a particular dominance in the younger age groups. This observation is consistent with previous studies suggesting that premenopausal women have lower rates of MI, likely due to the protective effects of oestrogen, which may help maintain vascular function and reduce atherogenesis.⁶ However, as women age and undergo menopause, this protective effect diminishes, which may explain the increasing incidence of MI in older women. Several studies have explored the biological mechanisms underlying these gender differences in MI risk. For instance, higher levels of androgens in males have been associated with increased platelet aggregation and atherogenesis, contributing to the earlier onset of MI in men.⁷ Additionally, differences in risk factor profiles between men and women, such as higher rates of smoking, alcohol consumption in males, have been identified as potential contributors to the gender disparity in MI incidence.⁸

Our study found that the gender distribution of MI was consistent across both rural and urban populations, with males making up a higher proportion of cases in both settings despite the disparities in access to health care and lifestyle factors between rural and urban populations. Previous research has demonstrated that rural populations tend to have higher rates of cardiovascular risk factors such as smoking, hypertension, and diabetes, which contribute to an elevated risk of MI.⁹

The higher prevalence of STEMI over NSTEMI observed in this study is consistent with prior research. Earlier studies have shown that STEMI tends to occur more frequently in younger populations and is associated with more severe coronary artery occlusion, leading to worse outcomes if not treated promptly.¹⁰ Our study adds to the growing body of evidence that, while STEMI is more common than NSTEMI, the differences in clinical presentation and outcomes between these two types of MI warrant tailored treatment strategies. Rapid reperfusion therapy for STEMI has been shown to significantly improve outcomes, particularly in younger patients, highlighting the importance of early recognition and treatment.¹⁰

Troponin is a well-established biomarker for MI, with higher levels correlating with greater myocardial injury.^4,11 Our findings showed troponin levels to be slightly higher in females with NSTEMI compared to STEMI, while males showed similar levels across both conditions. This variability suggests that individualized approaches to MI management may be necessary, particularly in patients with elevated troponin levels, who may require more aggressive interventions.

The findings of this study underscore the importance of age and gender-specific interventions in the management of MI. Males, particularly younger ones, are at a higher risk of MI, and therefore, preventive strategies such as lifestyle modification, early screening for cardiovascular risk factors, and education about the risks of smoking and alcohol consumption should be emphasized. In older females, closer monitoring during post-menopausal period is essential due to the increased risk of MI, particularly STEMI, as seen in this and other studies.⁶ Additionally, the variability in troponin levels observed in this study supports the need for personalized treatment strategies based on biomarker profiles. Troponin remains a critical tool for stratifying risk and guiding therapeutic decisions in MI patients.³ Future research should focus on further exploring the role of biomarkers in improving MI outcomes, particularly in diverse populations.

The study was conducted at a single tertiary hospital, making it difficult to generalize the findings to other populations. In addition, the sample size was relatively small, limiting the ability to draw definitive conclusions; therefore, studies with larger sample sizes are warranted. Nevertheless, the findings highlight the importance of using biomarkers such as troponin in the diagnosis of MI and emphasize the need for early intervention strategies in affected patients.

The study also underscores the importance of raising public awareness about MI and the need educating populations about its risk factors, clinical symptoms, and treatment options, with particular emphasis on rural communities. The findings may also assist healthcare professionals and policymakers in developing appropriate measures for the prevention, diagnosis and management of MI across the country.

Conclusion

In conclusion, this study underscores the substantial gender differences in the presentation, diagnosis, and severity of myocardial infarction, revealing critical insights into the demographic characteristics and clinical outcomes associated with this condition. The analysis demonstrates a clear predominance of myocardial infarction cases in males, comprising 62.7% of the total study population, with a notable concentration of cases in middle-aged individuals, particularly those aged 41 to 60 years. This demographic pattern highlights the increased vulnerability of this age group to myocardial infarction and emphasizes the importance of targeted prevention strategies for both genders. Moreover, the findings suggest that females diagnosed with NSTEMI may experience a greater degree of renal impairment, as indicated by elevated creatinine levels compared to their STEMI counterparts. This observation points to the need for clinicians to be particularly vigilant regarding renal function in female NSTEMI patients, as their renal health may be more adversely affected than males. Additionally, the study revealed that STEMI cases, particularly in females, are associated with significantly higher platelet counts and troponin levels, which may reflect a more pronounced thrombotic or inflammatory response. The elevated levels of these biomarkers in females with STEMI suggest that they may experience a more severe myocardial damage and warrant closer monitoring and aggressive management.

These findings highlight the necessity for tailored approaches in both the diagnosis and management of myocardial infarction, taking into account the gender-specific variations observed in clinical presentation and outcomes. It is crucial for healthcare providers to recognize these differences in order to optimize treatment strategies and improve overall patient outcomes. Future research should further explore the underlying mechanisms contributing to these gender disparities, as well as evaluate the effectiveness of gender-specific interventions in the prevention and management of myocardial infarction. Ultimately, a deeper understanding of these factors may lead to more personalized care and better prognostic assessments for patients suffering from this serious condition.

Conflict of Interest

None to declare.