Prognostic significance of heart rate recovery in patients with diabetes mellitus and silent ischemia

Introduction: Heart rate recovery (HRR) after stress testing is an indicator of normal vagal activity which is in relation to the risk of premature death. Therefore, the prognostic value of this parameter for adverse events needs to be investigated, especially in patients with diabetes whose heart innervation is often disturbed. Methods: The research included 112 patients. The patient follow-up was performed via telephone interview. Patients were divided into groups with and without silent ischemia. Four major adverse events (MACE) were investigated: myocardial revascularization, heart failure with hospitalization, heart attack and all-cause death. Median follow up time was 5 years. Results: Patients with silent ischemia had significantly lower HRR compared to patients without it (22.8 ± 10.4 vs. 29.4 ± 13.8 beats per minute, p=0.031). The risk of MACE was significantly higher in patients with silent ischemia compared to patients without it (54.2% vs. 25%, p=0.006), with patients with silent ischemia having 2.88 times higher incidence of MACE during long-term follow-up (HR 2.882; 95% CI 1.449-5.174; p=0.03). The group of patients with slow HRR had almost 2 times higher incidence of MACE during long-term follow-up in comparison to the group of patients with normal HRR (HR 1.918; 95%CI: 0.939-3.916; p=0.074). Conclusion: Patients with diabetes and silent ischemia had significantly higher risk of MACE compared to patients without silent ischemia during long-term follow-up. To determine the importance of HRR in adverse event prediction in patients with silent ischemia, further research is needed with a larger number of patients.