Diabetes Care, Vol 21, Issue 12 2123-2128, Copyright © 1998 by American Diabetes Association
Mechanism of impaired left ventricular wall motion in the diabetic heart without coronary artery disease
K Sakamoto, Y Yamasaki, S Nanto, T Shimonagata, T Morozumi, T Ohara, Y Takano, H Nakayama, K Kamado, S Nagata, H Kusuoka, T Nishimura and M Hori
Department of Internal Medicine, Kansai Rosai Hospital, Hyogo, Japan.
OBJECTIVE: To elucidate whether impairment of the myocardial free fatty
acid (FFA) metabolism and small vessel abnormalities in the myocardium are
etiologic or contributory factors of myocardial dysfunction in patients
with NIDDM without any significant coronary artery disease. RESEARCH DESIGN
AND METHODS: We performed myocardial imaging with 123I-labeled
beta-methyl-p-iodophenyl pentadecanoic acid (BMIPP), a branched analog of
FFA, and dipyridamole-infusion 201thallium scintigraphy (Dip) in nine
patients who demonstrated left ventricular wall motion abnormalities
without any significant coronary artery disease and in fifteen control
cases. As an index of myocardial FFA metabolism, the heart-to-mediastinum
count ratio (H/M) of BMIPP was calculated from the mean count in the
regions of interest at the heart and the upper mediastinum. RESULTS: Nine
patients with reduced wall motion documented by left ventriculography
(LVG), (hypokinetic group) demonstrated significantly lower BMIPP uptake
(2.1 +/- 0.2, mean +/- SD) than fifteen patients with normal wall motion
(normokinetic group) (2.3 +/- 0.2, P < 0.05). Regional ventricular wall
motion observed by LVG, regional BMIPP uptake, and regional redistribution
phenomenon (RD) were evaluated for five regions of the left ventricle:
anterior, septal, apical, lateral, and inferoposterior regions. Wall motion
was abnormal in 24 out of 120 regions. Regional BMIPP uptake was reduced in
47 regions. RD in Dip was observed in 23 regions. In regional analysis, the
existence of defect in the BMIPP image showed significant correlation with
wall motion abnormality (P < 0.01), but there was no significant
relationship between the RD in Dip and regional wall motion abnormality (P
= 0.16). Myocardial biopsy specimens obtained from the right ventricle of
20 patients showed no pathologic changes, with the exception of two
patients. CONCLUSIONS: Our findings suggest that impairment of myocardial
FFA metabolism rather than small vessel abnormalities in the myocardium is
responsible for modest left ventricular dysfunction in patients with
diabetes.