European Journal of Cardiovascular Medicine

Ischemic heart disease (IHD), also known as coronary artery disease (CAD), is the leading cause of death globally, accounting for approximately 9 million deaths annually [1]. It is characterized by reduced blood flow to the heart muscle due to atherosclerotic plaque formation in coronary arteries [2]. While traditional risk factors such as hypertension, diabetes, smoking, and dyslipidemia are well-established, emerging evidence highlights hyperhomocysteinemia as an independent risk factor for IHD [3-7].

Homocysteine, a sulfur-containing amino acid derived from methionine metabolism, plays a crucial role in endothelial dysfunction, oxidative stress, and prothrombotic states [8-10]. Elevated homocysteine levels (>15 µmol/L) have been associated with accelerated atherosclerosis, inflammation and increased cardiovascular risk [11-13]. Additionally, dyslipidemia-particularly high LDL, low HDL and elevated triglycerides-further exacerbates vascular damage by promoting plaque deposition and arterial stiffness [14-17].

Despite advancements in cardiovascular medicine, a significant proportion of IHD cases occur in individuals with normal lipid profiles, suggesting that other biomarkers, such as homocysteine, may contribute to disease pathogenesis. Several studies have reported a synergistic effect between hyperhomocysteinemia and dyslipidemia in increasing cardiovascular risk [18-20].

However, data on the combined impact of these biomarkers in IHD patients remain inconsistent, particularly in smaller cohorts. Hence the present study was conducted with the aim to compare serum homocysteine and lipid profile parameters between IHD patients and healthy controls.

This study employs a case-control design to compare serum homocysteine levels and lipid profile parameters between ischemic heart disease (IHD) patients and healthy controls. The study was conducted at Department of Medicine, KBN Teaching and General hospital, Kalaburagi and ESIC Bengaluru for a period of 8 months, a tertiary care center specializing in cardiovascular diseases.

INCLUSION AND EXCLUSION CRITERIA

INCLUSION CRITERIA

FOR IHD GROUP:

• Adults (age ≥ 40 years).
• Diagnosis confirmed by coronary angiography (≥50% stenosis in one or more major coronary arteries).
• No acute coronary syndrome within the past 3 months.

FOR CONTROL GROUP:

• Age-and sex-matched healthy individuals.
• No clinical or biochemical evidence of IHD.
• Normal resting ECG and no history of chest pain.

Exclusion Criteria (Both Groups)

• Chronic kidney disease (serum creatinine >1.5 mg/dL).
• Liver dysfunction (ALT/AST >3× upper limit).
• Patients on lipid-lowering drugs (statins, fibrates) or B-vitamin supplements (which affect homocysteine levels).
• Active infections or inflammatory conditions (CRP >10 mg/L).

SAMPLE SIZE CALCULATION

Sample size (n=84) was determined based on previous studies (Ref: Ganguly & Alam, 2015)²⁰ showing a moderate effect size (d=0.6) in homocysteine levels between IHD patients and controls. Power analysis (80% power, α=0.05) using G*Power software suggested a minimum of 38 participants per group. To account for potential dropouts, 42 participants per group (total 84) were enrolled.

PROCEDURE FOR DATA COLLECTION

STEP 1: PARTICIPANT RECRUITMENT

• IHD patients were recruited from cardiology OPD/wards.
• Controls were selected from routine health check-up visitors.

STEP 2: BLOOD SAMPLE COLLECTION

• Fasting venous blood (5 mL) was drawn under aseptic conditions.
• Serum separated by centrifugation (3000 rpm, 10 min) and stored at -80°C until analysis.

STEP 3: BIOCHEMICAL ASSAYS

• HOMOCYSTEINE: Measured via ELISA (enzyme-linked immunosorbent assay).
• LIPID PROFILE: Analyzed using automated enzymatic methods (Beckman Coulter AU480).

STEP 4: DATA RECORDING

• Demographic and clinical data were recorded in a structured proforma.
• Laboratory results were entered into a password-protected database.

STATISTICAL ANALYSIS

DESCRIPTIVE STATISTICS: Mean ± SD for continuous variables, frequencies for categorical variables. Inferential statistics: Student’s t-test for group comparisons. Pearson’s correlation for assessing relationships. Multivariate regression to adjust for confounders (age, smoking).

Table 1: Baseline Characteristics of Study Participants

The study included 84 participants equally divided into IHD cases (n=42) and healthy controls (n=42). Both groups were well-matched for age (IHD: 58.4±7.2 vs Control: 56.9±6.8 years, p=0.32) and sex distribution (66.7% vs 61.9% males, p=0.65). However, IHD patients had significantly higher BMI (26.5±3.1 vs 24.8±2.9 kg/m², p=0.02), systolic BP (138±14 vs 122±11 mmHg, p<0.001), diastolic BP (86±8 vs 78±7 mmHg, p<0.001), and diabetes prevalence (35.7% vs 14.3%, p=0.03). Smoking rates showed a non-significant trend toward being higher in IHD group (42.9% vs 23.8%, p=0.07).

Table 2: Comparison of Biochemical Parameters

IHD patients demonstrated markedly elevated homocysteine levels (18.7±4.2 vs. 10.3±2.8 μmol/L, p<0.001) compared to controls. The lipid profile showed significant dysregulation with higher total cholesterol (218.5±32.6 vs. 178.4±28.4 mg/dL, p<0.001), LDL (145.6±26.8 vs. 102.3±20.5 mg/dL, p<0.001), and triglycerides (165.4±42.3 vs 132.6±38.7 mg/dL, p=0.001), along with lower HDL levels (38.2±6.4 vs. 48.7±7.2 mg/dL, p<0.001). These differences remained statistically significant after accounting for multiple comparisons.

Table 3: Correlation of Homocysteine with Lipid Parameters in IHD Group

In the IHD group, homocysteine showed strong positive correlations with LDL (r=0.52, p<0.001) and total cholesterol (r=0.46, p=0.002), while exhibiting a moderate inverse correlation with HDL (r=-0.41, p=0.008). The relationship with triglycerides was positive but non-significant (r=0.28, p=0.07). These correlations suggest a potential synergistic effect between hyperhomocysteinemia and atherogenic dyslipidemia in coronary artery disease pathogenesis.

Table 4: Multivariate Regression Analysis for IHD Risk Factors

Adjusted for age, sex, BMI, and diabetes. OR = Odds Ratio, CI = Confidence Interval.

After adjusting for age, sex, BMI and diabetes, both homocysteine (OR=1.32, 95% CI:1.12-1.56, p=0.001) and LDL (OR=1.18, 95% CI:1.05-1.33, p=0.006) emerged as independent predictors of IHD, while HDL showed a protective effect (OR=0.82, 95% CI:0.74-0.91, p=0.001). Age and smoking status did not reach statistical significance in the final model. The model explained approximately 68% of IHD risk variance (Nagelkerke R²=0.68).

This study demonstrates a significant association between elevated serum homocysteine levels, dyslipidemia, and ischemic heart disease (IHD). Our findings align with existing literature while providing novel insights into the interplay between these biomarkers in a well-characterized patient cohort. Below we contextualize our results within the current scientific understanding.

The IHD group exhibited markedly higher homocysteine levels (18.7 ± 4.2 μmol/L) compared to controls (10.3 ± 2.8 μmol/L), supporting its role as a cardiovascular risk marker [21]. These findings corroborate the seminal work of Clarke et al. [13], who reported a 20% increased IHD risk for every 5 μmol/L homocysteine elevation in their meta-analysis of prospective studies. Our results extend these observations by demonstrating that this association persists even after adjusting for conventional risk factors in regression analysis (OR=1.32, p=0.001). The pro-atherogenic mechanisms of homocysteine-including endothelial dysfunction [22], oxidative stress [23], and platelet activation [24]-likely contribute to this relationship [7].

The lipid profile alterations observed in our IHD patients mirror established patterns of atherogenic dyslipidemia: elevated LDL (145.6 vs 102.3 mg/dL) [25] and triglycerides (165.4 vs 132.6 mg/dL) [26] coupled with reduced HDL (38.2 vs 48.7 mg/dL) [27]. These findings are consistent with the INTERHEART study [5], which identified abnormal lipid ratios as the strongest modifiable risk factor for acute myocardial infarction across 52 countries. Notably, our correlation analysis revealed significant positive associations between homocysteine and both LDL (r=0.52) [28] and total cholesterol (r=0.46) [29], suggesting potential metabolic interplay between these pathways.

The co-occurrence of hyperhomocysteinemia and dyslipidemia in our cohort supports the "double-hit" hypothesis of vascular damage proposed by Ganguly and Alam [20]. Their longitudinal study demonstrated that patients with both elevated homocysteine (>15 μmol/L) and LDL (>130 mg/dL) had 3.2-fold greater coronary event risk compared to those with isolated abnormalities. Our multivariate analysis extends these findings by quantifying the independent contributions of each biomarker while controlling for confounders. This synergy suggests that combined therapeutic targeting (e.g., statins with B-vitamin supplementation) may offer additive benefits, though clinical trials have yielded mixed results [30-32].

Our findings strengthen the evidence linking homocysteine and lipid abnormalities to IHD pathogenesis. The robust correlations observed, even after multivariate adjustment, suggest these biomarkers may have clinical utility for risk stratification. While LDL remains the primary treatment target, homocysteine assessment could help identify high-risk patients who might benefit from personalized therapeutic approaches. Further research should explore the molecular mechanisms underlying these associations and evaluate targeted intervention strategies.

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