Patients with coronary artery disease (CAD) have a state of autonomic imbalance with a sympathetic predominance. Autonomic dysfunction has been linked to an increased risk of cardiovascular morbidity and mortality. Heart rate variability (HRV) analysis is one of the most encouraging non-invasive diagnostic models and is increasingly used for the assessment of autonomic dysfunction. Percutaneous coronary intervention (PCI) is considered the gold standard in CAD treatment. Revascularisation through PCI eliminates the state of sympathetic hyperactivity, restores the normal cardiac autonomic modulation that can be assessed by HRV measurement.