title: Effect of spinal cord stimulation on cardiac adrenergic nerve function in patients with cardiac syndrome X.
abstract: BACKGROUND
  In patients with cardiac syndrome X (CSX) who present with refractory angina episodes, spinal cord stimulation (SCS) has beneficial effects. The mechanisms of SCS, however, remain speculative. We assessed the effects of SCS on cardiac sympathetic function in these patients.
  
  
  RESULTS
  We studied 11 CSX patients treated by SCS for refractory angina (mean age, 60 +/- 9 years; 5 men and 6 women), both during SCS therapy (SCS-ON) and after withdrawal of SCS therapy (SCS-OFF), using a randomized crossover design. Planar and single photon emission computed tomography iodine 123 metaiodobenzylguanidine (MIBG) myocardial scintigraphy and technetium 99m sestamibi (MIBI) bicycle exercise stress testing were performed at the end of each period. Compared with 10 healthy control subjects, CSX patients showed a lower heart-mediastinum ratio for MIBG uptake (2.19 +/- 0.3 vs 1.69 +/- 0.3, P = .001) and a higher cardiac MIBG uptake score (4.0 +/- 2.5 vs 19.7 +/- 27, P = .08). There were no differences in CSX patients during the SCS-ON and SCS-OFF phases of the study in heart-mediastinum ratio (1.74 +/- 0.3 vs 1.69 +/- 0.3, P = .13), cardiac washout rate of MIBG (42.9% +/- 14% vs 43.3% +/- 14%, P = .08), or MIBG defect score (18.7 +/- 25 vs 19.7 +/- 27, P = .22). Reversible perfusion defects during the SCS-OFF phase were detected in 8 patients; an improvement in perfusion defects was observed in 2 patients (25%) during the SCS-ON phase.
  
  
  CONCLUSIONS
  Our data confirm the presence of abnormal cardiac adrenergic nerve function in CSX patients. SCS was unable to result in significant improvement of cardiac MIBG uptake abnormalities, suggesting that its therapeutic effects are unlikely to be mediated by modulation of cardiac adrenergic nerve activity.
authors.affiliation: Cardiology Institute, Università Cattolica del Sacro Cuore, Rome, Italy.
authors.forename: Antonella
authors.initials: A
authors.lastname: Spinelli
authors.forename: Gaetano A
authors.initials: GA
authors.lastname: Lanza
authors.forename: Maria Lucia
authors.initials: ML
authors.lastname: Calcagni
authors.forename: Alfonso
authors.initials: A
authors.lastname: Sestito
authors.forename: Gregory A
authors.initials: GA
authors.lastname: Sgueglia
authors.forename: Antonio
authors.initials: A
authors.lastname: Di Monaco
authors.forename: Isabella
authors.initials: I
authors.lastname: Bruno
authors.forename: Priscilla
authors.initials: P
authors.lastname: Lamendola
authors.forename: Lucy
authors.initials: L
authors.lastname: Barone
authors.forename: Alessandro
authors.initials: A
authors.lastname: Giordano
authors.forename: Filippo
authors.initials: F
authors.lastname: Crea
mesh_terms: D019797:3-Iodobenzylguanidine / Q000494:pharmacology; D000368:Aged; D017023:Coronary Angiography / Q000379:methods; D005260:Female; D006801:Humans; D007457:Iodine Radioisotopes / Q000494:pharmacology; D008297:Male; D017566:Microvascular Angina / Q000175:diagnosis / Q000473:pathology*; D008875:Middle Aged; D009474:Neurons / Q000378:metabolism*; D011868:Radioisotopes / Q000494:pharmacology; D011941:Receptors, Adrenergic / Q000378:metabolism*; D013116:Spinal Cord / Q000473:pathology*; D017256:Technetium Tc 99m Sestamibi / Q000494:pharmacology; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods
chemical_list: D007457:Iodine Radioisotopes; D011868:Radioisotopes; D011941:Receptors, Adrenergic; D019797:3-Iodobenzylguanidine; D017256:Technetium Tc 99m Sestamibi