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Objectives

Dobutamine Stress Testing as a Diagnostic Tool for Evaluation of Myocardial Contractile Reserve in Asymptomatic or Mildly Symptomatic Patients with Dilated Cardiomyopathy.

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Objectives

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  1. Dobutamine Stress Testing as a Diagnostic Tool for Evaluation of Myocardial Contractile Reserve in Asymptomatic or Mildly Symptomatic Patients with Dilated Cardiomyopathy Masakazu KobayashiHideo Izawa, Xian Wu Cheng, Hiroyuki Asano, Akihiro Hirashiki, Kazumasa Unno, Satoru Ohshima, Takashi Yamada, Yosuke Murase, Tomoko S. Kato, Koji Obata, Akiko Noda, Takao Nishizawa, Satoshi Isobe, Kohzo Nagata, Tatsuaki Matsubara, Toyoaki Murohara, and Mitsuhiro Yokota

  2. Objectives We examined the potential of dobutamine stress testing for evaluation of myocardial contractile reserve in asymptomatic or mildly symptomatic patients with DCM.

  3. Methods Dobutamine stress testing • Protocol Data acquisition DOB10 DOB 5 10 μg/kg/min baseline 5 μg/kg/min 10 min 10 min baseline DOB Hemodynamic measurements were made at baseline, and at the end of each 10-minute infusion period.

  4. LVdP/dtmaxDOB10 – LVdP/dtmax baseline LVdP/dtmax baseline =×100 Assessment of myocardial contractile reserve ⊿LVdP/dtmax (%) % Increase in LVdP/dtmaxduring DOB infusion (10μg/min/kg)

  5. GroupⅠ⊿LVdP/dtmax> 100% GroupⅡ⊿LVdP/dtmax≦ 100% Group Classification ⊿ LVdP/dtmax (%) 100 0 baseline DOB5 DOB10 baseline DOB5 DOB10 GroupⅡaLVEF > 25% GroupⅡbLVEF≦ 25% All patients in GroupⅠ hadLVEF> 25% (n=18) (n=17) (n=11)

  6. Patients Characteristics mean ± SD, *P<0.05 vs GroupⅠ, † P<0.05 vs GroupⅡa

  7. Patients Characteristics mean ± SD, *P<0.05 vs GroupⅠ, † P<0.05 vs GroupⅡa

  8. Hemodynamic response to dobutamine mean ± SD, *P<0.05 vs GroupⅠ

  9. RT-PCRanalysisoftheabundanceofmRNAs for contractile regulating proteins ( /GAPDH mRNA) mean ± SD, * P<0.05 vs GroupⅠ

  10. Relationbetween baseline LVEF and⊿LVdP/dtmax 250 200 ΔLV dP/dtmax (%) 150 100 20 25 40 50 30 50 0 LVEF (%)

  11. Comparison of the plasma NE levels P < 0.05 1500 P < 0.05 Plasma NE (pg/mL) 1000 500 0 Group I GroupIIa GroupIIb

  12. 2.5 2.0 1.5 1.0 Group I GroupIIa GroupIIb Comparison of the delayed H/M ratio in 123I-MIBG scintigraphy P < 0.05 P < 0.05 Delayed H/M ratio

  13. A representative case of Group I

  14. A representative case of Group IIa

  15. Ca2+ Ca channel norepinephrine β1-AR mRNA Gsα β-AR P GRK AC ATP cAMP FKBP12.6 P RyR Troponin PKA Ca2+ P P PLB mRNA SR SERCA2a mRNA In our study, the expression of β1-AR, PLB, SERCA2a were reduced in the patients with impaired contractile reserve determined by dobutamine stress testing.

  16. Conclusions Dobutamine stress testing is a useful diagnostic tool for identifying reduced adrenergic myocardial contractile reserve related to altered expression of β1-adrenergic receptor, SERCA2a, and phospholamban genes even in asymptomatic or mildly symptomatic patients with DCM.

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