Aim: To evaluate the diagnostic performance of ECG criteria and inflammatory markers—interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and C-reactive protein (CRP)—in detecting LVH. Materials and Methods: A total of 241 patients with concentric LVH confirmed by ECHO were included and categorised into ECG-positive and ECG-negative groups. Additionally, 50 age-matched controls without LVH were recruited. The diagnostic performance of Sokolow–Lyon, Cornell voltage, and Peguero–Lo Presti ECG criteria was assessed using sensitivity, specificity, and accuracy. Serum levels of IL-6, TNF-α, and CRP were analysed across different levels of left ventricular mass index (LVMI). Results: Significant differences were observed between ECG groups in interventricular septal thickness, left ventricular diameter, and LVMI (p < 0.05). ECG criteria demonstrated low sensitivity (10.37%–20.75%) but high specificity (up to 100%), with limited overall accuracy. In contrast, IL-6, TNF-α, and CRP levels were significantly elevated in patients with severe LVH (p < 0.001). Conclusions: ECG criteria show high specificity but limited sensitivity in diagnosing LVH. Elevated inflammatory markers correlate strongly with disease severity, suggesting their potential role in improving diagnostic accuracy.