Dynamic 123I-BMIPP single-photon emission computed tomography in patients with congestive heart failure: effect of angiotensin II type-1 receptor blockade.
BACKGROUND
Heart failure is a major and growing public health problem with a high mortality rate. Although recent studies have demonstrated that a variety of metabolic and/or neurohumoral factors are involved in the progression of this syndrome, the precise mechanisms responsible for this complex condition are poorly understood.


OBJECTIVE
To examine 123I-beta-methyl-iodophenylpentadecanoic acid (BMIPP) kinetics in the early phase soon after tracer injection in patients with congestive heart failure (CHF), we performed dynamic single-photon emission computed tomography (SPECT).


METHODS
Twenty-six patients with CHF and eight control subjects were examined. The consecutive 15 images of 2-min dynamic SPECT were acquired for 30 min after injection. In the early phase after injection (0-4 min), a significant amount of radioactivity existed in the blood pool. After 6 min, the myocardial 123I-BMIPP image was clear and thus the washout rate of 123I-BMIPP from 6 to 30 min was calculated.


RESULTS
The washout rate of 123I-BMIPP from the myocardium was faster in patients with CHF than in the controls (8 +/- 4 vs. -5 +/- 3%, p < 0.01). The washout rate of 123I-BMIPP demonstrated positive correlation with left ventricular (LV) end-diastolic volume index (R = 0.54, p < 0.02) and inverse correlation with LV ejection fraction (R = 0.53, p <0.02). Patients were given the angiotensin II type-1 receptor antagonist candesartan for 6 months, and dynamic SPECT was repeated. The enhanced washout rate of 123I-BMIPP in CHF was reduced after treatment with candesartan (p < 0.05).


CONCLUSIONS
These data suggest that (1) enhanced washout of 123I-BMIPP was observed soon after injection in patients with CHF, (2) the activation of angiotensin II signaling pathway is involved as an intracellular mechanism for enhanced 123I-BMIPP washout in heart failure, and (3) improvement in fatty acid metabolism may represent a new mechanism for beneficial effects of angiotensin II receptor blockade on cardiac function and survival in patients with heart failure. 123I-BMIPP washout in the early phase obtained from dynamic SPECT may be a new marker for evaluating the severity of heart failure and the effects of medical treatment.
Takeishi
Yasuchika
Y
First Department of Internal Medicine, Yamagata University School of Medicine, Yamagata, Japan. takeishi@med.id.yamagata-u.ac.jp
Minamihaba
Osamu
O
Yamauchi
Sou
S
Arimoto
Takanori
T
Hirono
Osamu
O
Takahashi
Hiroki
H
Akiyama
Hideyuki
H
Miyamoto
Takuya
T
Nitobe
Joji
J
Nozaki
Naoki
N
Tachibana
Hidetada
H
Okuyama
Masaki
M
Fukui
Akio
A
Kubota
Isao
I
Okada
Akio
A
Takahashi
Kazuei
K
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000804:Angiotensin II / Q000037:antagonists & inhibitors / Q000378:metabolism; D047228:Angiotensin II Type 1 Receptor Blockers; D016022:Case-Control Studies; D005227:Fatty Acids / Q000378:metabolism; D005260:Female; D006333:Heart Failure / Q000000981:diagnostic imaging*; D006801:Humans; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics; D007462:Iodobenzenes; D008297:Male; D008875:Middle Aged; D044140:Receptor, Angiotensin, Type 1 / Q000378:metabolism; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods
D047228:Angiotensin II Type 1 Receptor Blockers; D005227:Fatty Acids; D007457:Iodine Radioisotopes; D007462:Iodobenzenes; D044140:Receptor, Angiotensin, Type 1; C049338:iodofiltic acid; D000804:Angiotensin II