The relationship between gated myocardial perfusion SPECT findings and heart rate recovery after exercise test

Background and aim: Abnormal heart rate recovery after exercise test, is a simple available parameter, that reflects autonomic nervous system disfunction. GATED myocardial perfusion SPECT is used in the diagnosis and prognosis of coronary artery disease. In this study we compared heart rate recovery with myocardial perfusion scintigraphy findings. Thus, we aimed to determine the role of heart rate recovery on diagnosis of coronary artery disease and prognosis.Methods: Patients (n = 50, 27 female 23 men) who underwent exercise technetium-99m sestamibi GATED myocardial perfusion SPECT were enrolled in this cross-sectional study. Exercise treadmill testing was performed according to a symptom-limited Bruce's protocol. HRR was obtained from the subtraction of heart rate at the first minute after exercise treadmill testing from maximal heart rate during exercise. Myocardial perfusion SPECT was semi-quantitatively analyzed using a 20-segment left ventricular model. Left ventricular quantitive parameters were automatically calculated using quantitative GATED SPECT software.Results: Multiple lineer regresion revealed strong independent negative assosiation between heart rate recovery and myocardial defect severity on stress images (ß= -0,957; SE= 0,650; p= 0,043). Age was also an independent predictor of heart rate recovery with negative assosiation (ß= -0,473; SE= 0,250; p= 0,022). Correlation coefficient (R) and R square (R2) of the model were 0,604, and 0,365 respectively.Conclusion: On stresss protocol, myocardial damage is more severe in patients who have decreased heart rate recovery. Since the severity of myocardial damage on stress is a strong predictor of cardiac events and prognosis, heart rate recovery was also have prognostic value on future cardiac events.Key words: Heart rate recovery, GATED myocardial SPECT, Coronary artery disease.