European Journal of Cardiovascular Medicine

Cardiovascular disease (CVD) remains the foremost cause of global mortality, accounting for approximately 19.1 million deaths in 2020, with acute myocardial infarction (AMI) constituting nearly half of these fatalities.¹ Despite advancements in management that have reduced AMI mortality in high-income regions, the burden is rising worldwide, driven by aging populations and epidemiological transitions. In India, age-adjusted CVD mortality rates exceed global averages, and over 52% of deaths before age 70 are attributable to cardiovascular causes, underscoring a substantial loss of productive years. ^2,1 Concurrently, diabetes mellitus has reached pandemic proportions; by 2019, an estimated 463 million adults were affected globally, a figure projected to approach 700 million by 2045. South Asia bears a disproportionate share, with India alone home to over 100 million people with diabetes and a prediabetic pool three times larger, particularly in central states such as Madhya Pradesh. ³

Chronic hyperglycaemia accelerates atherosclerosis through endothelial dysfunction, oxidative stress, and proinflammatory pathways, yielding more complex and unstable coronary plaques. ⁴ Glycated haemoglobin (HbA₁c), reflecting average glycaemia over 2–3 months, has evolved from a diabetes‐monitoring tool to a powerful cardiovascular risk marker. ⁵ Elevated HbA₁c correlates continuously with infarct size, left ventricular dysfunction, and short‐term mortality in both diabetic and non‐diabetic AMI patients. ^6,7,8,2 Importantly, many individuals presenting with AMI harbor undiagnosed dysglycaemia, and those with HbA₁c in prediabetic ranges face significantly worse outcomes than normoglycaemic peers. ^2,4 Given the scarcity of data from central India, this study aims to evaluate HbA₁c as an independent predictor of AMI severity and early outcomes in this high-risk population.

Aims and Objectives

1. To comprehensively characterize the clinical presentation and in-hospital complications of patients admitted with acute myocardial infarction and to determine their glycated haemoglobin (HbA1c) levels.
2. To assess the correlation between HbA1c concentrations and the severity of acute myocardial infarction, evaluating its prognostic significance for patient outcomes.

This prospective observational study was conducted in the Department of Medicine at Netaji Subhash Chandra Bose Medical College and Hospital, Jabalpur, Madhya Pradesh, India, over an 18-month period from July 7, 2023, to December 6, 2024.

Consecutive patients aged 18–60 years with a confirmed diagnosis of acute myocardial infarction (AMI)—based on electrocardiographic changes and elevated cardiac biomarkers—were enrolled. Exclusion criteria included age <18 or >60 years, history of severe anemia, significant organ failure (including chronic kidney disease and hepatic failure), active malignancy or chemotherapy, and any active infection such as pancreatitis or musculoskeletal infection. Participants who declined consent were also excluded.

The minimum sample size was calculated using the formula,

where Z=1.96 (95% confidence), P=0.064 (estimated AMI prevalence), Q=1–P, and d=0.04 (absolute error). The calculated sample was 144, and to ensure robust analysis, 160 patients were ultimately enrolled.

Demographic information, cardiovascular risk factors (smoking, alcohol use, tobacco chewing), clinical presentation, and comorbidities were recorded on a structured case report form. Vital signs (blood pressure, heart rate, respiratory rate, temperature, and SpO₂) and physical examination findings (e.g., presence of jugular venous distension, peripheral edema) were documented. All participants underwent: Twelve-lead ECG, Two-dimensional echocardiography to determine left ventricular ejection fraction (LVEF), Laboratory tests including complete blood count, liver and renal function tests, fasting and postprandial blood sugar, lipid profile, and cardiac biomarkers (CK-MB, troponin I/T). Venous blood (5 mL) was drawn under aseptic conditions; 2 mL was collected into EDTA tubes for HbA1c estimation using a colorimetric enzymatic method.

Data were entered into SPSS version 26.0. Categorical variables were summarized as frequencies and percentages; continuous variables were expressed as mean ± standard deviation. Associations between categorical variables were tested using Chi-square or Fisher’s exact test, as appropriate. Correlations between continuous variables were assessed with Pearson’s or Spearman’s tests. A two-sided p-value <0.05 was considered statistically significant.

Operational Definitions

1. Acute Myocardial Infarction (AMI): New ischemic ECG changes (ST-segment elevation or depression) with a rise in cardiac biomarkers above the 99th percentile upper reference limit.
2. STEMI: AMI presenting with persistent ST-segment elevation in ≥2 contiguous leads.
3. NSTEMI: AMI without ST elevation but with elevated biomarkers.
4. Glycemic Categories (HbA1c):
    – Normal: <6.1%
    – Prediabetes: 6.1–6.5%
    – Diabetes: >6.5% (with poor control defined as >8%)
5. Random Blood Sugar: Normal <200 mg/dL; hyperglycemia ≥200 mg/dL.
6. Left Ventricular Ejection Fraction (LVEF) by echocardiography:
    – Severe dysfunction: <20%
    – Moderate dysfunction: 20–40%
    – Mild dysfunction: 40–50%
    – Preserved: >50%.

Table 1. Baseline socio-demographic characteristics of study participants (N=160)

All age cohorts were represented in table 1, with the majority (59.4%) aged 51–60 years; men comprised three-quarters of the cohort, and over half reported tobacco chewing as a substance use habit.

Table 2. Clinical presentation and admission laboratory values (N=160)

Nearly all patients presented with chest pain and diaphoresis, while over one-third demonstrated hyperglycaemia (RBS ≥200 mg/dL) on admission, indicating both typical MI symptoms and significant acute dysglycaemia as depicted in table 2.

Table 3. Glycemic parameters on admission (N=160)

Table 3 depicts that long-term glycaemic control was poor in most patients, with over half exhibiting HbA1c ≥6.6% and nearly one-quarter exceeding 8%, highlighting a high prevalence of chronic dysglycaemia.

Table 4. Infarct classification and location (N=160)

Table 4 shows that ST-elevation MI predominated, accounting for over 80% of cases, with the anterior wall being the most frequently affected myocardial territory.

Table 5. Left ventricular ejection fraction among participants (N=160)

Echocardiography revealed that nearly two-thirds of patients had impaired systolic function (LVEF <50%), reflecting substantial myocardial injury in this cohort as per table 5.

Table 6. In-hospital complications following AMI (N=160)

Table 6 depicts that over 45% of patients experienced at least one major complication, most commonly left ventricular failure, underscoring the high acuity of post-infarction care required.

Table 7. In-hospital mortality by glycemic parameters (N=160)

All fatalities occurred in patients with poor chronic glycaemic control (HbA1c >8%), and admission hyperglycaemia was associated with a ten-fold higher mortality risk, indicating that both acute and chronic dysglycaemia critically influence survival (P < 0.001 and P = 0.009, respectively) as shown in table 7

The present study demonstrated that 36.3% of acute myocardial infarction (AMI) patients exhibited admission hyperglycaemia (RBS ≥200 mg/dL), aligning with findings by Hermanides et al. (2020) who reported that 38% of AMI patients had stress hyperglycaemia at presentation. ⁹ Chronic dysglycaemia was highly prevalent, with 70.0% of subjects displaying HbA₁c ≥6.1% and 22.5% exceeding 8.0%. This mirrors observations by Ghaffari et al. (2015), who found that non-diabetic STEMI patients often harbour mildly elevated HbA₁c, linked to more severe coronary involvement. ² Our data extend these findings by showing that poorly controlled chronic hyperglycaemia (HbA₁c >8%) was confined to one-quarter of patients yet accounted for 100% of in-hospital deaths (19.4% mortality in this subgroup; p < 0.0001). This threshold effect is consistent with the meta-analysis of Pan et al. (2019), which identified a marked rise in short-term mortality in acute coronary syndrome patients when HbA₁c exceeded 8%. ¹⁰

ST-elevation MI (STEMI) comprised 84.4% of cases, with the anterior wall most commonly affected (50.6%). Despite extensive literature linking high HbA₁c to multivessel disease and complex lesions—particularly in diabetic cohorts with HbA₁c >7.9% as shown by Sharma et al. (2020)—we found no significant association between HbA₁c strata and infarct territory (p = 0.217). ⁸ This suggests that chronic hyperglycaemia elevates overall plaque burden rather than directing infarction to a specific myocardial region.

Echocardiographic assessment revealed that 32.5% of patients had left ventricular ejection fraction (LVEF) <40%, predominantly those with anterior or inferior infarcts. A significant relationship between infarct location and systolic function (p = 0.044) underscores the impact of infarct extent on pump competence. These results corroborate cardiac magnetic resonance findings by Gao et al. (2023), who reported worse myocardial strain and lower LVEF in diabetics with HbA₁c ≥7.0% post-AMI. ¹¹ However, unlike some imaging studies that directly link HbA₁c to infarct size, our cohort did not show a linear correlation between HbA₁c and LVEF categories (p = 0.287), implying that anatomical injury remains the principal determinant of systolic impairment.

Admission hyperglycaemia independently predicted in-hospital mortality: patients with RBS ≥200 mg/dL experienced a 10.3% death rate versus 1.0% in those below this threshold (p = 0.009). This finding aligns with the stress-hyperglycaemia literature, including the ACS QUIK registry in India which showed that elevated glucose at presentation increases the odds of heart failure and death. ¹

Traditional substance-use risk factors were ubiquitous—tobacco chewing (56.3%), smoking (33.8%), alcohol (10.0%)—but bore no significant relationship to STEMI versus NSTEMI (p = 0.353) or infarct anatomy (p = 0.907). This contrasts with scarce regional data but supports the concept that while addiction accelerates atherosclerosis globally, it does not dictate the acute MI phenotype or location.

In this central Indian cohort of 160 AMI patients, chronic and acute dysglycaemia were pervasive and prognostically decisive. While substance-use habits were common, only elevated glucose metrics—particularly HbA₁c >8.0% and RBS ≥200 mg/dL—predicted in-hospital mortality. Infarct territory governed left ventricular dysfunction independently of glycaemic status. These findings underscore the need for routine admission assessment of both HbA₁c and random glucose to enhance risk stratification and guide acute management.

Recommendations

Implement mandatory measurement of RBS and HbA₁c for all AMI admissions. Introduce rapid glucose-lowering protocols for patients with RBS ≥200 mg/dL. Intensify multidisciplinary follow-up and glycaemic optimization for survivors with HbA₁c >8.0%.

Strengths and Limitations of the Study

The study’s prospective cohort design enrolled 160 AMI patients, surpassing the required sample size to secure statistical power and enable real-time data capture with minimal recall bias. Dual glycemic assessment (RBS and HbA₁c) distinguished acute stress hyperglycemia from chronic dysglycemia. Detailed clinical phenotyping—including infarct territory, LVEF measurement, and in-hospital complication tracking—and uniform institutional treatment protocols minimized confounding. Single-centre design limits external validity. Short-term, in-hospital follow-up precludes evaluation of medium- and long-term outcomes. Under-representation of women (24%) and patients >60 years may mask subgroup effects. Lack of angiographic scoring (e.g., SYNTAX) limits direct plaque burden analysis.

Relevance of the Study

This study fills a regional knowledge gap by quantifying the burden and prognostic impact of dysglycaemia in central Indian AMI patients, informing local protocol development and resource allocation.

Authors’ Contribution

Dr. Honey Suman: conceptualization, data collection, manuscript drafting. Dr. P. Punekar: supervision, methodological oversight, critical revisions. Dr. Atishay Jain: data validation, statistical analysis, manuscript editing.

Ethical Consideration

Ethical approval was obtained from the Institutional Ethics Committee, and written informed consent was secured from all participants.

Financial Support and Sponsorship

None.

Conflicts of Interest

The authors declare no conflicts of interest.

1. Alfaddagh A, Khraishah H, Romeo GR, Kassab MB, McMillan Z, Chandra-Strobos N, Blumenthal R, Albaghdadi M. Cardiovascular Outcomes Among Patients with Acute Coronary Syndromes and Diabetes: Results from ACS QUIK Trial in India. Global Heart. 2024 Apr 24;19(1):37.
2. Ghaffari S, Niafar F, Separham A, Niafar M, Pourafkari L, Nader ND. Association between HbA1c levels with severity of coronary artery disease and short-term outcomes of acute ST-elevation myocardial infarction in nondiabetic patients. Therapeutic advances in cardiovascular disease. 2015 Oct;9(5):305-13.
3. Sargowo D. The Importance of Managing HbA1c in Coronary Artery Disease: Keep It Low. Heart Science Journal. 2020 Oct 25;1(3):1-3.
4. Yan Y, Gao R, Zhang S, Gao Z, Chen A, Wang J, Zhang S, Dai W, Li F, Li X, Yang G. Hemoglobin A1c and angiographic severity with coronary artery disease: a cross-sectional study. International Journal of General Medicine. 2022 Feb 15:1485-95.
5. Khaw KT, Wareham N, Luben R, Bingham S, Oakes S, Welch A, Day N. Glycated haemoglobin, diabetes, and mortality in men in Norfolk cohort of European Prospective Investigation of Cancer and Nutrition (EPIC-Norfolk). Bmj. 2001 Jan 6;322(7277):15.
6. John WG, Mosca A, Weykamp C, Goodall I. HbA1c standardisation: history, science and politics. The Clinical Biochemist Reviews. 2007 Nov;28(4):163.
7. Koenig RJ, Peterson CM, Jones RL, Saudek C, Lehrman M, Cerami A. Correlation of glucose regulation and hemoglobin AIc in diabetes mellitus. New England Journal of Medicine. 1976 Aug 19;295(8):417-20.
8. Sharma V, Sharma K, Mansuri Z, Jain S, Bhatia S, Patel K. Does Angiographic Profile and Outcome of Diabetic Patients among Asian Indians Correlate with Presenting Glycated Hemoglobin During Acute ST-Elevation Myocardial Infarction? DECIPHER Study. Journal of the Practice of Cardiovascular Sciences. 2020 May 1;6(2):148-52.
9. Hermanides RS, Kennedy MW, Kedhi E, van Dijk PR, Timmer JR, Ottervanger JP, Dambrink JH, Gosselink AM, Roolvink V, Miedema K, Slingerland RJ. Impact of elevated HbA1c on long-term mortality in patients presenting with acute myocardial infarction in daily clinical practice: insights from a ‘real world’prospective registry of the Zwolle Myocardial Infarction Study Group. European Heart Journal: Acute Cardiovascular Care. 2020 Sep 1;9(6):616-25.
10. Pan W, Lu H, Lian B, Liao P, Guo L, Zhang M. Prognostic value of HbA1c for in-hospital and short-term mortality in patients with acute coronary syndrome: a systematic review and meta-analysis. Cardiovascular diabetology. 2019 Dec;18:1-2.
11. Gao Y, Shi R, Li Y, Guo YK, Xu HY, Shi K, Yang ZG. Association of diabetes mellitus and glycemic control with left ventricular function and deformation in patients after acute myocardial infarction: a 3 T cardiac magnetic resonance study. Cardiovascular Diabetology. 2023 Mar 11;22(1):55.