Heart rate variability and turbulence to determine true coronary artery disease in patients with ST segment depression without angina during exercise stress testing.

Purpose: ST segment depression without angina during an exercise stress test causes diagnostic problems, particularly in non-diabetic patients. Heart rate variability (HRV) and heart rate turbulence (HRT) are used to evaluate the changes in cardiac autonomic functions and are also both decreased in patients with coronary artery disease. The aim of this study was determine the values of HRV and HRT that discriminate true coronary artery disease from false positive stress test results.

Methods: Ninety non-diabetic patients who underwent diagnostic coronary angiography (CA) due to suspected coronary artery disease after ST segment depression without angina during an exercise stress test were enrolled in the study. Prior to CA, 24 hour ambulatory electrocardiogram recordings were taken and HRV and HRT parameters were calculated.

Results: Patients were divided into three groups according to the severity of their coronary lesions: (group 1 normal, group 2 non-obstructive and group 3 obstructive. There were no differences among the groups with regards to age, sex, medical history, medications, systolic and diastolic blood pressures, body mass index, fasting glucose, anemia and thyroid status, lipid profile and creatinine clearance. HRV parameters and turbulence slope (TS) were significantly lower while turbulence onset (TO) was significantly higher in group 3 than groups 1 and 2. According to the cut-off values calculated using ROC analysis, SDNN≤69.63 msec, TO > 0.14%, and TS≤2.78 msec/RR have high diagnostic accuracy for predicting obstructive coronary artery disease.

Conclusion: HRV and HRT parameters may provide additional information for discriminating between patients who do and do not truly need CA.