Biomechanical and neuroautonomic adaptation to acute blood volume displacement in ischemic dilated cardiomyopathy: the predictive value of the CD25 test

We aimed to examine biomechanical and neuroautonomic adaptation to blood volume displacement induced by tilt test in patients with previous inferoapical/inferolateral (IA-IL) or basal/apical septal (BS-AS) myocardial infarction (MI). Twenty-four patients with heart failure (HF) and previous IA-IL MI and 30 patients with HF and previous BS-AS MI were enrolled. All patients underwent head-up tilt test, radionuclide ventricular function monitoring (VEST), sympathovagal balance evaluation, and chronotropic 25-dose isoproterenol infusion test (CD25). Physiopathological reactions to stress-tests were assessed in both groups. Follow-up lasted 36 mo. IA-IL patients showed lower stroke volume (SV), cardiac output (CO), and left ventricle ejection fraction (LVEF) compared with BS-AS. End-diastolic volume decreased in IA-IL group (F = 3.1, P = 0.043) more than in BS-AS group during tilt test. The time trend of end-systolic volume, SV, CO, LVEF, and peak filling rate were similar in the two groups. Norepinephrine (IA-IL supine→tilting 499.5 (SD:28.8)→719.3 (SD:41.5) pg/mL vs. BS-AS supine→tilting 533.9 (SD:33.3)→768.8 (SD:47.9) pg/mL; P < 0.001) and epinephrine plasma concentrations (IA-IL supine→ tilting 125.7 (SD:9.8)→193.7 (SD:9.6) pg/mL vs. BS-AS supine→ tilting 118.8 (SD:8.9)→191.7 (SD:10.2) pg/mL; P < 0.001) increased in both groups. Low-to-high frequencies ratio significantly increased in IA-IL and decreased in BS-AS patients. CD25 was similar in IA-IL and BS-AS patients (IA-IL = 4.6 (SD:0.94), BS-AS = 5.0 (SD:1.06) µg; P = 0.79). CD25 predicted all-cause mortality (hazard ratio 1.48, 95% confidence interval 1.32-1.67; P < 0.0001) after adjusting for age/heart rate. In conclusion, patients with ischemic HF show abnormal biomechanical adaptation to volume displacement and compensatory sympathetic overdrive. The association of reduced β-adrenergic sensitivity and sympathetic denervation in such patients warrants for careful therapeutic choices.NEW & NOTEWORTHY The adaptation to volume displacement induced by tilt test was assessed in patients with heart failure and previous inferoapical/inferolateral or basal/apical septal myocardial infarction. The responsiveness of cardiac muscle to sympathetic nervous system stimulation predicts the mortality in patients with ischemic heart failure and may represent a useful tool for clinicians in the general assessment of this kind of patients.