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 (CD). 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 ( = 3.1, = 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; < 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; < 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; = 0.79). CD predicted all-cause mortality (hazard ratio 1.48, 95% confidence interval 1.32-1.67; < 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. 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.