Masayoshi Kawabata

Increased Angiotensin-Converting Enzyme Activity in Coronary Artery Specimens From Patients With Acute Coronary Syndrome

Background —Angiotensin-converting enzyme (ACE) inhibitors are effective in the secondary prevention of ischemic heart disease, but they do not reduce the rate of restenosis. Vascular ACE activity in the culprit coronary lesions of these patients, however, has never been quantified. Methods and Results —We measured the ACE activity of vascular tissue obtained by directional coronary atherectomy in patients with acute coronary syndrome (n=17) and in patients with stable ischemic heart disease (n=36), with and without restenosis. The ACE activity of the culprit coronary lesions was significantly increased in patients with acute coronary syndrome (0.87±0.12 nmol · min–1 · mg protein–1;P <0.01) but not in patients with ischemic heart disease with restenosis (n=11, 0.19±0.05 nmol · min–1 · mg protein–1) when compared with those patients with ischemic heart disease without restenosis (n=25, 0.20±0.05 nmol · min–1 · mg protein–1). There was no difference between the ACE activity of the coronary tissue of the in-stent (n=5) and stent-unrelated (n=6) restenosis patients (0.24±0.10 versus 0.15±0.04 nmol · min–1 · mg protein–1). Serum ACE activity did not differ significantly among the patients. Conclusions —The present study demonstrates increased ACE activity in culprit lesions in acute coronary syndrome, indicating that enhanced ACE activity is related to the causative mechanism of active coronary lesions.

Relationship between evaluation by quantitative fatty acid myocardial scintigraphy and response to β-blockade therapy in patients with dilated cardiomyopathy

Predicting the effect of β-blockade therapy on the clinical outcome of patients with dilated cardiomyopathy (DCM) is difficult prior to the initiation of therapy. Myocardial fatty acid metabolism has been shown to be impaired in patients with DCM. We examined whether the extent of myocardial injury, as assessed by iodine-123 15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid (BMIPP) myocardial scintigraphy, is related to the response of patients with DCM to β-blockade therapy. Thirty-seven patients with DCM were examined using BMIPP myocardial scintigraphy before and after 6 months of treatment with metoprolol. Myocardial BMIPP uptake (%BM uptake) was estimated quantitatively as a percentage of the total injected count ratio. The left ventricular end-diastolic and end-systolic dimensions (LVDd, LVDs) and ejection fraction (LVEF) were also evaluated. The patients were divided into two groups according to their functional improvement (>10% elevation of LVEF) after 6 months of metoprolol therapy. Twenty-eight patients responded to the therapy, while nine did not. Prior to the therapy, no significant differences in LVDd, LVDs or LVEF were observed between the responders and non-responders. However, the %BM uptake was significantly lower in the non-responders than in the responders (1.0%±0.2% vs 2.1%±0.5%, P<0.001). The %BM uptake could be used to distinguish the responders from the non-responders with a sensitivity of 0.93 and a specificity of 1.00 at a threshold value of 1.4. After the metoprolol therapy, the %BM uptake improved significantly in the responders (2.5%±0.5%, P<0.01) but did not change in the non-responders. These results indicate that myocardial BMIPP uptake could predict the response of DCM patients to β-blockade therapy.

Evaluation of contrast agents for delineation of vessel wall boundary by intracoronary ultrasound after coronary angioplasty in human.

We evaluated the potential for improving visualization at intervention sites using contrast‐enhanced intracoronary ultrasound (ICUS) and the suitable contrast agents for this procedure in humans. In 37 patients, ICUS (30 MHz) was performed with intracoronary bolus injection (3 mL) of seven different contrast preparations and without the contrast agents (control) after coronary intervention. The contrast agents used were as follows: saline solution, standard iomeprol, standard ioxaglate, sonicated iomeprol, sonicated ioxaglate, 50% Albunex, and 100% Albunex. Homogeneous and complete opacification of the vessel lumen and false lumen was observed with sonicated ioxaglate, 50% and 100% Albunex. Shadowing was not observed at all with sonicated ioxaglate and was uncommon with 50% Albunex, whereas 100% Albunex caused shadowing in all cases. The coronary delineation rate with the other contrast agents was only 60%–70%, and the homogeneity and peak intensity were relatively low. Thus, sonicated ioxaglate and 50% Albunex both achieved good visualization, but the latter is more expensive, more difficult to handle, and takes longer to prepare. Of the agents we studied, sonicated ioxaglate appears to be best suited for contrast‐enhanced ICUS. ICUS using suitable contrast agents could only visualize the large dissections and the strategy was changed according to the contrast‐enhanced ICUS results in five cases. Thus, suitable contrast agents, e.g., sonicated ioxaglate, should be used during ICUS after intracoronary intervention.Cathet. Cardiovasc. Intervent. 47:6–13, 1999.