title: Prognostic value of coronary and microvascular flow reserve in patients with nonischemic dilated cardiomyopathy.
abstract: BACKGROUND
  Coronary and microvascular blood flow reserve have been established as important predictors of prognosis in patients with cardiovascular disease. The aim of this study was to assess the value of coronary flow velocity reserve (CFVR) and real-time myocardial perfusion echocardiography (RTMPE) for predicting events in patients with nonischemic dilated cardiomyopathy.
  
  
  METHODS
  One hundred ninety-five patients (mean age 54 ± 12 years; 66% men) with dilated cardiomyopathy (left ventricular ejection fraction < 35% and no obstructive coronary disease on invasive angiography or multidetector computed tomography) who underwent dipyridamole stress (0.84 mg/kg over 10 min) RTMPE were prospectively studied. CFVR was calculated as the ratio of hyperemic to baseline peak diastolic velocities in the distal left anterior coronary artery. The replenishment velocity (β), plateau of acoustic intensity (A(N)), and myocardial blood flow reserve were obtained from RTMPE.
  
  
  RESULTS
  Mean CFVR was 2.07 ± 0.52, mean A(N) reserve was 1.05 ± 0.09, mean β reserve was 2.05 ± 0.39, and mean myocardial blood flow reserve (A(N) × β) was 2.15 ± 0.48. During a median follow-up period of 29 months, 45 patients had events (43 deaths and two urgent transplantations). Independent predictors of events were left atrial diameter (relative risk, 1.16; 95% confidence interval, 1.08-1.26; P < .001) and β reserve ≤ 2.0 (relative risk, 3.22; 95% confidence interval, 1.18-8.79; P < .001). After adjustment for β reserve, CFVR and myocardial blood flow reserve no longer had predictive value. Left atrial diameter added prognostic value over clinical factors and left ventricular ejection fraction (χ2 = 36.8-58.5, P < .001). Beta reserve added additional power to the model (χ2 = 70.2, P < .001).
  
  
  CONCLUSIONS
  Increased left atrial diameter and depressed β reserve were independent predictors of cardiac death and transplantation in patients with nonischemic dilated cardiomyopathy. Beta reserve by RTMPE provided incremental predictive value beyond that provided by current known prognostic clinical and echocardiographic factors.
authors.affiliation: Heart Institute, University of São Paulo Medical School, São Paulo, Brazil.
authors.forename: Marta F
authors.initials: MF
authors.lastname: Lima
authors.forename: Wilson
authors.initials: W
authors.lastname: Mathias
authors.forename: João C N
authors.initials: JC
authors.lastname: Sbano
authors.forename: Victória Yezinia
authors.initials: VY
authors.lastname: de la Cruz
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Abduch
authors.forename: Márcio S M
authors.initials: MS
authors.lastname: Lima
authors.forename: Edmar A
authors.initials: EA
authors.lastname: Bocchi
authors.forename: Ludhmila A
authors.initials: LA
authors.lastname: Hajjar
authors.forename: José A F
authors.initials: JA
authors.lastname: Ramires
authors.forename: Roberto
authors.initials: R
authors.lastname: Kalil Filho
authors.forename: Jeane M
authors.initials: JM
authors.lastname: Tsutsui
mesh_terms: D000704:Analysis of Variance; D001783:Blood Flow Velocity / Q000502:physiology; D002311:Cardiomyopathy, Dilated / Q000000981:diagnostic imaging* / Q000401:mortality / Q000503:physiopathology* / Q000601:surgery; D016009:Chi-Square Distribution; D017023:Coronary Angiography; D003326:Coronary Circulation / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D016027:Heart Transplantation / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008833:Microcirculation / Q000502:physiology; D008875:Middle Aged; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed; D014463:Ultrasonography