Abstract 4084: The Influence of Heart Rate Variability and the Metabolic Profile on the Hypertensive Response to Exercise in Post-CABG Patients with Type 2 Diabetes
Background: Patients with type 2 diabetes are at increased risk of cardiovascular morbidity and mortality. Exercise-induced hypertension (EIH), which may be encountered during treadmill stress test, has never been assessed in post-CABG patients with type 2 diabetes. The aim of this study was to evaluate EIH prevalence in post-CABG patients with type 2 diabetes and to explore its potential relationship with heart rate variability (HRV) and metabolic variables.
Method: A total of 101 post-CABG patients with type 2 diabetes underwent a maximal symptom-limited treadmill exercise testing (Bruce protocol). Blood pressure (BP) was measured after 5 minutes rest (anticipatory) and every 3 minutes during exercise. EIH was defined as maximum systolic blood pressure (SBP) ≥ 220 mmHg and/or maximum diastolic blood pressure (DBP) ≥ 100 mmHg. Blood pressure, lipid profile, and glycated haemoglobin were assessed in the fasted state. HRV was derived from a 24 hours Holter system.
Results: Among the 101 subjects, 30 (30%) presented EIH. Baseline resting BP were 127±13/70±9 mmHg and 131±10/72±9 mmHg in patients without and with EIH, respectively. Maximal exercise SBP and DBP were 229±18/95±15 mmHg in the group with EIH compared to 185±23/77±12 mmHg in the group without EIH (p< 0.001). Anticipatory SBP and DBP were higher in the group with EIH (150±13 vs. 135±16 mmHg, p<0.001 and 76±9 vs. 72±8 mmHg, p<0.05). Apo B, LDL and total cholesterol were higher in patients with EIH (all p<0.05). Glycated haemoglobin was similar between groups (6.7±0.8 vs. 6.8±0.7 %; no EIH vs. EIH). Regarding HRV, 24 hours, day and night low frequency powers (Ln LF) were higher in patients with IEH (5.5±0.6, 5.0±0.7 and 6.1±0.7 vs. 5.0±1.0, 4.6±1.0 and 5.4±1.0, all p<0.05). There was a trend toward higher night LF/HF ratio in patients with EIH (5,0±3 vs. 3,7±2, p= 0,10). Apo B and LF correlated positively with maximal systolic blood pressure (r=0.30, p<0.01, r=0.30, p<0.003 respectively).
Conclusion: EIH is present in post-CABG patients with type 2 diabetes with well-controlled resting blood pressure. Patients with EIH presented a higher anticipatory blood pressure before exercise. Apo B and HRV may play a role in EIH in post-CABG patients with type 2 diabetes maybe by modulating vascular compliance.