title: Association between cardiopulmonary exercise and dobutamine stress testing in ambulatory patients with idiopathic dilated cardiomyopathy: a comparison with peak VO₂ and VE/VCO₂ slope.
abstract: BACKGROUND
  Both peak VO(2) and VE/VCO(2) slope are considered to be useful predictors of cardiovascular events. The left ventricular (LV) response to dobutamine stress testing (DST) also provides useful prognostic information. However, the relationship between these variables has not been fully investigated. Therefore, the aim of this study is to investigate the association between myocardial contractile reserve measured by DST and cardiopulmonary exercise testing (CPX) variables in patients with idiopathic dilated cardiomyopathy (IDCM).
  
  
  METHODS
  Thirty-eight patients were subjected to CPX as well as cardiac catheterization for measurement of LV pressure. The maximum first derivative of LV pressure (LV dP/dt(max)) was measured at baseline and during dobutamine infusion at incremental doses of 5, 10, and 15 μg kg(-1)min(-1). LV dP/dt(max) at baseline and the percentage increase in LV dP/dt(max) (ΔLV dP/dt(max)) induced by DST served as indices of LV contractility and myocardial contractile reserve, respectively.
  
  
  RESULTS
  Peak VO(2), and VE/VCO(2) slope were 18.6 mL kg(-1)min(-1) and 32.3, respectively. Peak VO(2) was not correlated with LV dP/dt(max) at baseline. However, peak VO(2) was significantly correlated with ΔLV dP/dt(max), and the correlation became more pronounced as the dose of dobutamine was increased. There was no correlation between VE/VCO(2) slope and ΔLV dP/dt(max). Multivariate regression analysis revealed that ΔLV dP/dt(max) was independently correlated with peak VO(2) (p=0.011).
  
  
  CONCLUSIONS
  Peak VO(2), but not VE/VCO(2) slope, may reflect myocardial contractile reserve in ambulatory patients with IDCM. This study population is small, and therefore large confirmatory studies are needed.
authors.affiliation: Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Okumura
authors.forename: Akihiro
authors.initials: A
authors.lastname: Hirashiki
authors.forename: Sumio
authors.initials: S
authors.lastname: Yamada
authors.forename: Hidehito
authors.initials: H
authors.lastname: Funahashi
authors.forename: Satoru
authors.initials: S
authors.lastname: Ohshima
authors.forename: Yuji
authors.initials: Y
authors.lastname: Kono
authors.forename: Xian Wu
authors.initials: XW
authors.lastname: Cheng
authors.forename: Kyosuke
authors.initials: K
authors.lastname: Takeshita
authors.forename: Toyoaki
authors.initials: T
authors.lastname: Murohara
mesh_terms: D000328:Adult; D000553:Ambulatory Care / Q000379:methods; D002311:Cardiomyopathy, Dilated / Q000097:blood* / Q000175:diagnosis*; D004280:Dobutamine; D005080:Exercise Test / Q000379:methods; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D012123:Pulmonary Ventilation / Q000502:physiology*; D012129:Respiratory Function Tests / Q000379:methods; D014692:Ventilation-Perfusion Ratio / Q000502:physiology
chemical_list: D004280:Dobutamine