title: Evaluation of the metabolism of high energy phosphates in patients with Chagas' disease.
abstract: BACKGROUND
  Abnormalities in myocardial metabolism have been observed in patients with heart failure of different etiologies. Magnetic resonance spectroscopy (MRS) with phosphorus-31 is a noninvasive technique that allows detection of myocardial metabolic changes.
  
  
  OBJECTIVE
  To determine the resting metabolism of high-energy phosphates in patients with Chagas' disease (CD) by MRS with phosphorus-31.
  
  
  METHODS
  We studied 39 patients with CD, 23 with preserved ventricular function (PF Group) and 16 with ventricular dysfunction (VD Group), assessed by Doppler echocardiography. MRS of the anterosseptal region was performed in 39 patients and 8 normal subjects (C Group) through a Phillips 1.5 Tesla device, obtaining the phosphocreatine/beta-adenosine triphosphate myocardial ratio (PCr/β-ATP).
  
  
  RESULTS
  The levels of cardiac PCr/β-ATP were reduced in VD Group in relation to PF Group, and the latter presented reduced levels compared to C Group (VD Group: 0.89 ± 0.31 vs PF Group: 1.47 ± 0.34 vs C Group: 1.88 ± 0.08, p < 0.001). A correlation was found between left ventricular ejection fraction and PCr/β-ATP in 39 patients (r = 0.64, p < 0.001). Patients under functional class I (n = 22) presented PCr/β-ATP of 1.45 ± 0.35, and those in functional classes II and III (n = 17), PCr/β-ATP of 0.94 ± 0.36 (p < 0.001).
  
  
  CONCLUSIONS
  The 31-phosphorus MRS was able to detect non-invasively changes in the rest energy metabolism of patients with Chagas' disease, with and without systolic dysfunction. These changes were related to the severity of heart impairment.
authors.affiliation: Hospital das Clínicas, Instituto do Coração, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brasil.
authors.forename: Ana Maria Betim Paes
authors.initials: AM
authors.lastname: Leme
authors.forename: Vera Maria Cury
authors.initials: VM
authors.lastname: Salemi
authors.forename: José Rodrigues
authors.initials: JR
authors.lastname: Parga
authors.forename: Bárbara Maria
authors.initials: BM
authors.lastname: Ianni
authors.forename: Charles
authors.initials: C
authors.lastname: Mady
authors.forename: Robert G
authors.initials: RG
authors.lastname: Weiss
authors.forename: Roberto
authors.initials: R
authors.lastname: Kalil-Filho
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000328:Adult; D000368:Aged; D002311:Cardiomyopathy, Dilated / Q000150:complications; D002598:Chagas Cardiomyopathy / Q000175:diagnosis* / Q000378:metabolism; D014355:Chagas Disease / Q000378:metabolism; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006333:Heart Failure / Q000209:etiology; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism*; D010758:Phosphorus; D011446:Prospective Studies; D012720:Severity of Illness Index; D016276:Ventricular Function / Q000502:physiology*
chemical_list: D010710:Phosphates; D010758:Phosphorus; D000255:Adenosine Triphosphate