Objective: Systemic lupus erythematosus (SLE) is an autoimmune disorder resulting in multisystemic inflammatory damage. It is reported that cardiovascular diseases (CVD) are responsible for 20%-30% of deaths in patients with SLE. Heart rate recovery after exercise is a function of vagal reactivation, and its impairment is an independent prognostic indicator for cardiovascular and all-cause mortality. The aim of our study was to evaluate the heart rate recovery index in patients with SLE.
Methods: The study population included 48 patients with SLE (35 women, mean age 46.3 ± 12.8 yrs, mean disease duration 6.0 ± 2.3 yrs) and 44 healthy controls (30 women, mean age 45.7 ± 12.9 yrs). Basal electrocardiography, echocardiography, and treadmill exercise testing were performed on all patients and controls. The heart rate recovery index was defined as the reduction in the heart rate from the rate at peak exercise to the rate at the first minute (HRR(1)), second minute (HRR(2)), third minute (HRR(3)), and fifth minute (HRR(5)) after stopping exercise stress testing.
Results: There were significant differences in HRR(1) and HRR(2) indices between patients with SLE and the control group (24.1 ± 6.5 vs 33.3 ± 9.3; p < 0.001, and 44.6 ± 13.3 vs 53.7 ± 9.9; p < 0.001, respectively). Similarly, HRR(3) and HRR(5) indices of the recovery period were lower in patients with SLE, compared with indices in the control group (57.6 ± 13.0 vs 64.9 ± 11.7; p = 0.006, and 67.2 ± 12.3 vs 75.0 ± 15.4; p = 0.009, respectively). Effort capacity was markedly lower (9.0 ± 1.9 vs 11.1 ± 2.3 metabolic equivalents; p = 0.001, respectively) among the patients with SLE.
Conclusion: The heart rate recovery index is deteriorated in patients with SLE. When the prognostic significance of the heart rate recovery index is considered, these results may contribute to explain the increased occurrence of cardiac death. It points to the importance of the heart rate recovery index in the identification of high-risk patients.