Author + information
- Received April 9, 2001
- Revision received April 10, 2002
- Accepted April 19, 2002
- Published online July 17, 2002.
- Masunori Matsuzaki, MD, PhD, FACC*,* (, )
- Katsuhiko Hiramori, MD, PhD†,
- Tsutomu Imaizumi, MD, PhD, FACC‡,
- Akira Kitabatake, MD, PhD, FACC§,
- Hitoshi Hishida, MD, PhD¶,
- Masanori Nomura, MD, PhD∥,
- Takashi Fujii, MD, PhD*,
- Ichiro Sakuma, MD, PhD§,
- Kenichi Fukami, MD, PhD†,
- Takashi Honda, MD, PhD¶,
- Hiroshi Ogawa, MD# and
- Masakazu Yamagishi, MD, PhD, FACC**
- ↵*Reprint requests and correspondence:
Dr. Masunori Matsuzaki, Division of Cardiovascular Medicine, Department of Medical Bioregulation, Yamaguchi University School of Medicine, 1-1-1 Minamikogushi, Ube, Yamaguchi, 755-8505, Japan.
Objectives We sought to assess the effects of low density lipoprotein (LDL)-apheresis (LDL-A) for regression of coronary plaque in familial hypercholesterolemia (FH), we set up a one-year follow-up multicenter trial using coronary angiography and intravascular ultrasound (IVUS).
Background It is still unclear whether aggressive lipid-lowering therapy by LDL-A leads to the regression of coronary plaque in patients with FH.
Methods Eighteen patients with FH were assigned to one of two groups: medication + LDL-A (LDL-A group, n = 11) and medication only (medication group, n = 7). Total cholesterol, triglycerides, high density lipoprotein cholesterol and LDL cholesterol were measured in all subjects at the outset of treatment (baseline) and every three months thereafter. Coronary angiography and IVUS were performed at the outset and after the one-year follow-up period to measure minimal lumen diameter (MLD) by coronary angiogram and plaque area (PA) by IVUS.
Results The LDL-A group showed 28.4% reduction in total cholesterol (from 275 ± 27 mg/dl to 197 ± 19 mg/dl) and 34.3% reduction in LDL cholesterol (from 213 ± 25 mg/dl to 140 ± 27 mg/dl) after one-year follow-up, while the medication group showed no changes in cholesterol levels. There were significant interactions between both treatments in total cholesterol (p = 0.0001), LDL cholesterol (p = 0.0001), MLD (p = 0.008) and PA (p = 0.017) using two-way repeated-measures analysis of variance by the SAS system (SAS Institute Inc., Cary, North Carolina). Significant differences were seen in net change in MLD (p = 0.004) and PA (p = 0.008) during the one-year follow-up period between both groups.
Conclusions These results suggest that aggressive lipid-lowering therapy using the combination of LDL-A and lipid-lowering drugs may induce regression of coronary atherosclerotic plaque in FH patients.
Recent large-scale clinical trials of lipid-lowering drugs have demonstrated that intensive lowering of total cholesterol orlow density lipoprotein (LDL) cholesterol may retard progression of coronary atherosclerosis and lower the incidence of cardiac events despite the relatively small changes in the severity of lesions demonstrated in angiographic trials (1–8). True regression of coronary lesions has not beenproven using angiography; mainly slowing or stopping progression of luminal narrowing, as measured by minimal lumen diameter (MLD), has been reported. Percent stenosis can be misleading as a narrowing of the reference segment more than the MLD could lead to an erroneous result of “regression.”
Recent progress in intravascular ultrasound (IVUS) imaging has enabled quantitative diagnosis of coronary plaque size, which cannot be made by coronary angiography. The most pressing concern in the field is to determine how lipid-lowering therapy contributes to regression and stabilization of coronary plaques in the course of secondary prevention of cardiac events, and how it prevents the occurrence of acute coronary syndrome. Although there are many study reports evaluating the effects of lipid-lowering therapy by angiography, studies using IVUS are limited. As far as we are aware, no IVUS study has been performed to evaluate whether aggressive cholesterol-lowering therapy by low density lipoprotein-apheresis (LDL-A) reduces progression of coronary artery plaque in patients with familial hypercholesterolemia (FH). For this reason, our study is important because IVUS measurements did in fact show regression of plaque.
The present report was designed as a prospective multicenter study of drug refractory heterozygous FH patients with coronary artery disease. The objective was to evaluate the effects of aggressive lipid-lowering therapy, in this case the combination of LDL-A and standard lipid-lowering drugs, on regression of coronary plaques using computer-assisted analysis of quantitative coronary angiogram (QCA) and IVUS.
In this trial, 19 patients with heterozygous FH (14 men, 5 women) were recruited from eight clinical centers. Patients who met the following criteria were included: 20 to 70 years old, LDL cholesterol measuring 130 to 230 mg/dl at least once in the six months before registration and on a strict lipid-lowering diet and on hepatic hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors administrated (pravastatin [20 mg/day] or simvastatin [10 mg/day]), history of cardiac events—that is, myocardial infarction (MI), angina pectoris, asymptomatic myocardial ischemia, coronary artery bypass graft surgery (CABG) or percutaneous transluminal coronary angioplasty (PTCA), or with >50% stenosis of coronary artery on coronary angiogram. Patients were excluded if they were pregnant or if they had suffered MI or unstable angina pectoris within the previous three months; had undergone PTCA or CABG within the previous six months; had severe diabetes mellitus; had severe hypertension; had impaired hepatic or renal function; or had secondary hypercholesterolemia.
Although all patients were recommended for the LDL-A treatment because of their high LDL cholesterol levels and history of coronary heart disease (CHD), patients who refused LDL-A were included in the medication group. Patients were allocated to either the LDL-A group, receiving biweekly LDL-A + HMG-CoA reductase inhibitor (pravastatin [20 mg/day] or simvastatin [10 mg/day]) (n = 12), or the medication group, receiving HMG-CoA reductase inhibitor treatment alone (n = 7). Combined use of other lipid-lowering drugs (probucol, cholestyramine and fibrate) was approved in addition to the HMG-CoA reductase inhibitor. Patients gave informed consent to participate in this study, which was approved by each institutional’s ethics committee.
Determination of blood parameters
In the medication group, lipids (total cholesterol, triglycerides, high density lipoprotein [HDL] cholesterol) were measured every three months. In the LDL-A group, total cholesterol, triglyceride and HDL cholesterol concentrations were measured before and immediately after each LDL-A. The LDL cholesterol concentration was calculated using the following formula: Time-averaged concentrations (TAC) of total cholesterol and LDL cholesterol in the LDL-A group had to be calculated by applying a formula: where Cmin equals post-treatment level and Cmax equals pretreatment level, as reported by Kroon et al. (9). For triglycerides and HDL cholesterol, only pretreatment levels were used in the analysis because triglyceride returned to pretreatment levels within a few days after LDL-A, and HDL cholesterol was not influenced.
The LDL-A was performed using an automated system with two small-sized dextran sulfate cellulose columns (Liposorber LA-15 columns installed in an MA-01 Unit, Kaneka Corporation, Osaka, Japan). In this system, a polysulfone membrane separator separates the plasma, and apolipoprotein B-containing lipoproteins are adsorbed in one of two columns containing cellulose beads covalently bound with dextran sulfate used in rotation in an extracorporeal circuit. The total amount of plasma treated by each procedure was not <1.5 times the patient’s total plasma volume (>50 ml/kg body weight), and the treated plasma volume was 3,000 to 4,000 ml for the purpose of reducing total cholesterol levels to <100 mg/dl immediately after LDL-A. The LDL-A treatment was repeated in the outpatient clinic biweekly.
Coronary angiograms were obtained at the outset and after one year of treatment under the same conditions. During both procedures, the same cineangiographic techniques were used, according to standard methods for quantitative analysis. After intracoronary injection of an optimal amount nitroglycerin (NTG) (0.3 to 0.5 mg) or isosorbide dinitrate (ISDN) (5 mg) coronary angiography was performed. Angiograms were obtained in the 15° to 30° right anterior oblique and 40° to 60° left anterior oblique projections. An evaluation committee consisting of three experienced cardiologists blinded to lipid levels and treatment allocation viewed baseline and follow-up coronary arteriograms of each patient simultaneously on a double projector. Matching segments in both coronary arteriograms were carefully selected by use of identical projections.
After visual evaluation, quantitative analysis was performed using the automated edge-detection method of CARDIO 500 (Kontron, Munich, Germany). For calibration, the boundaries of a nontapering part of the catheter were determined automatically over a length of approximately 2 cm. Following selection of the boundaries of a segment, the arterial borders were defined by an automated edge-detection algorithm, and the MLD was calculated automatically for each available segment.
The IVUS studies were performed at the outset and after one year of follow-up, using a single-element 30 MHz, 2.9 or 3.2F intracoronary ultrasound catheter (Cardiovascular Imaging Systems/Boston Scientific, Fremont, California, or Hewlett-Packard, Palo Alto, California, respectively). After completion of the coronary angiography, optimal doses of intracoronary NTG or ISDN were administered for the prevention of catheter-induced coronary spasm. The IVUS catheter was advanced into the distal portion of the coronary artery, and it was then withdrawn proximally at a constant speed (1 mm/s) with a motorized pullback device (Cardiovascular Imaging Systems/Boston Scientific). The IVUS images were continuously recorded on S-VHS videotape. An evaluation committee blinded to lipid levels and treatment allocation selected the target coronary segments by the presence of an easily definable and reproducible branch point or calcified plaque to assist in the accurate and serial assessment of the region of interest.
In details, the target plaque qualified for the present study if it had not been influenced by any previous therapeutic intervention, if the diameter stenosis was <50% on QCA, and if the plaque was detected by IVUS. Four average segments per patients were selected for IVUS evaluation. Quantitative analysis of IVUS images in end-diastolic phase was performed off-line using specialized computer software (CARDIO 500, Kontron). Individual frames were digitized, and the following measurements were obtained: 1) cross-sectional vessel areas within the external elastic lamina, 2) lumen cross-sectional areas, and 3) plaque area (PA), which was calculated as external elastic area minus lumen area. Because media thickness cannot be measured accurately by the IVUS system, calculated PA including the media cross-sectional area was used as a measurement of the amount of atherosclerotic plaque. The IVUS images were analyzed by two reviewers who were unaware of treatment assignment. Measurements were averaged over five frames from the study segments.
Analyses were performed using two-way repeated-measures analysis of variance (ANOVA) for the interaction of both treatments. All analyses were done by the SAS system (SAS Institute Inc., Cary, North Carolina). For categorical variables within the patient characteristics, the chi-square test was used to compare the differences in proportions or trends for both treatment groups. In the LDL-A group, we calculated the TAC of total cholesterol and LDL cholesterol because the rebound curves were not linear. All values were expressed as means ± SD, and a two-sided probability value of <0.05 was considered statistically significant.
Nineteen patients with FH (14 men and 5 women) were included and underwent a first coronary angiography. Of these, one patient in the LDL-A group was unable to complete a second angiogram at the one-year follow-up because of severe respiratory failure; consequently, this patient was not involved in the analysis. Eleven heterozygous FH patients received biweekly LDL-A combined with lipid-lowering drugs (LDL-A group) and seven were given drug therapy alone (medication group). The clinical characteristics at the outset (baseline) of the 18 patients who completed the study, according to treatment allocation, are listed in Table 1. At baseline, the clinical, hemodynamic and angiographic characteristics in the LDL-A and medication groups were similar. No significant differences existed between the groups in terms of age, gender, risk factors, previous history, vessels with significant stenosis and medications. There was a greater tendency of Achilles’ tendon thickness in the LDL-A group than in the medication group.
Lipid and lipoprotein profiles
Baseline levels of triglyceride and HDL cholesterol in the LDL-A group were similar to those in the medication group. However, total cholesterol and LDL cholesterol in the LDL-A group were higher than those in the medication group (275 ± 27 mg/dl vs. 251 ± 57 mg/dl; 213 ± 25 mg/dl vs. 174 ± 39 mg/dl, respectively). After one-year of treatment, serum levels of total cholesterol and LDL cholesterol in the LDL-A group showed 28.4% and 34.3% reduction in comparison to the baseline, respectively (total cholesterol 275 ± 27 mg/dl to 197 ± 19 mg/dl; LDL-C 213 ± 25 mg/dl to 140 ± 27 mg/dl), whereas, in the medication group, lipid levels were not changed after one year of treatment. The p values of the interaction of total cholesterol, triglycerides, LDL cholesterol and HDL cholesterol with treatment analyzed using two-way repeated-measures ANOVA were 0.0001, 0.65, 0.0001 and 0.79, respectively (Table 2).
Analysis of coronary angiogram and IVUS
One hundred and five lesions from the LDL-A group and 47 lesions from the medication group were evaluated using paired measurements of angiograms. The MLD was increased in the LDL-A group during the one-year follow-up period (from 1.99 ± 0.73 mm to 2.11 ± 0.81 mm), whereas it was decreased in the medication group (from 2.24 ± 0.89 mm to 2.16 ± 0.84 mm). Thirty-four segments from the LDL-A group and 14 lesions from the medication group were evaluated using paired IVUS imaging. The PA was decreased in the LDL-A group (from 8.45 ± 4.22 mm2to 7.76 ± 4.34 mm2) over the one-year follow-up period, whereas it was increased in the medication group (from 7.19 ± 2.88 mm2to 8.08 ± 3.14 mm2). The changes of lumen areas and vessel areas were limited in both the LDL-A and medication groups over the one-year follow-up period (Table 3). Net changes in parameters measured by coronary angiogram and IVUS are shown in Figure 1. Net changes in MLD during the one-year follow-up period were significantly different between the LDL-A group and the medication group (p = 0.004) (Fig. 1A). Net changes in PA were also significantly different between the two groups (p = 0.008) (Fig. 1B). However, no significant differences existed in the net change in lumen area (Fig. 1C) and vessel area (Fig. 1D) between the two groups. The p values of the interaction of MLD, PA, lumen area and vessel area with treatment analyzed using two-way repeated-measures ANOVA were 0.008, 0.017, 0.52 and 0.26, respectively (Table 3).
Representative examples of coronary angiograms and IVUS images in a patient treated with combined LDL-A and cholesterol-lowering drugs over the one-year follow-up period are shown in Figure 2.
Results of the present study demonstrate that one-year treatment with pravastatin (20 mg/day) or simvastatin (10 mg/day) and other lipid-lowering drugs in combination with biweekly LDL-A led to marked regression in coronary plaques in comparison to medication alone in FH patients.
Effect of LDL-A on coronary plaque in FH patients
Considering that the number of patients with three-vessel stenosis was larger in the LDL-A group compared with the medication group (based on the patients’ backgrounds at registration) and that baseline LDL cholesterol level was significantly higher and Achilles’ tendon thickness far more progressed in the LDL-A group, it is possible that patients with severe FH or progressed coronary artery disease (CAD) tended to be assigned to the LDL-A group. However, total cholesterol and LDL cholesterol in the LDL-A group significantly decreased, by 28.4% and 34.3%, respectively, in the one-year study period.
In contrast, in the medication group, both total cholesterol and triglyceride levels increased slightly. Because patients were already on HMG-CoA reductase inhibitor when baseline lipid values were measured, changes in lipid levels observed in the medication group were small and quite different from those typically observed in many other trials using HMG-CoA reductase inhibitors (10–14). Consequently, the follow-up levels of total cholesterol and LDL cholesterol in the LDL-A group were significantly lower in comparison with the medication group.
Several clinical trials have demonstrated that lipid-lowering therapy by HMG-CoA reductase inhibitors may retard progression of coronary plaques despite the relatively small changes in the severity of lesions demonstrated in angiographic evaluations. In this study, no significant change was detected in MLD, as determined by coronary angiography, between the baseline and one-year follow-up in the medication group, whereas a small but significant increase in PA, as assessed by IVUS, was observed. These results demonstrated that LDL cholesterol-lowering therapy with drugs alone was insufficient, and the angiographical MLD of each segment did not change significantly; moreover, the coronary PA measured directly by IVUS increased gradually over one year of treatment.
In the LDL-A group, MLD was significantly increased after one year of treatment, and it was comparable to MLDs in previous LDL-A angiographic trials (15,16), but greater than those in the lipid-lowering group using diet and drugs in other angiographic studies (2,4,7). As evaluated by IVUS, the PA was significantly decreased in the LDL-A group after one year of follow-up. Takagi et al. (17)investigated the effects of pravastatin lipid-lowering therapy using IVUS, and they demonstrated that no significant change occurred in the areas of lumen and whole blood vessels after a three-year study period; however, the pravastatin group showed significantly less progression than the control group with regard to PA. To our knowledge, the present study is the first one to directly evaluate the combined effect of lipid-lowering drug therapy and LDL-A on coronary plaque using IVUS in severe hypercholesterolemic patients with CAD.
Possible role of LDL-A
Regression and/or retardation of coronary atherosclerosis (15,16,18)and reduction of cardiac event (19)have proved to be the major treatment effects of LDL-A. Several possible mechanisms have been suggested for the reduction in cardiac events—for example, improvement in vascular endothelial functions (20), stabilization of plaques (21), prolongation in oxidizability of low density lipoprotein (22,23), reduction or suppression of the expression of adhesion molecules (24,25)and suppression of platelet activation (26). The present study is the first to focus on quantification of the changes occurring in atherosclerotic plaque after LDL-A therapy, and it has demonstrated marked regression of coronary plaques by measurement with IVUS. The finding that aggressive lipid-lowering treatment in combination with LDL-A and lipid-lowering drugs leads to regression of coronary plaques indicated a possible role for the therapy in the restructuring and stabilization of coronary plaque, and in the prevention of the development of cardiac events.
Concern regarding acute coronary syndrome has recently been growing, and it is now recognized that regression and stabilization of coronary plaque is critical for prevention of its development. It is expected that aggressive lipid-lowering therapy using LDL-A could be beneficial not only for patients with drug refractory hypercholesterolemia, but also for patients with CHD at high risk of acute coronary syndrome as a strategy of treatment to modify the process of coronary remodeling and stabilization of atherosclerotic plaque. Recent study (ASAP) reported that aggressive LDL cholesterol reduction by atorvastatin was accompanied by regression of carotid intima media thickness in patients with FH (27). It was easy to recruit the study patients, and there was no ethical problem on the randomized study in the ASAP trials because it included patients without CHD, and severity of coronary atherosclerosis was relatively mild. In the present study, randomization was ethically impossible because the patients included in this study had history of CHD and severe coronary atherosclerosis, and lipid levels in all patients were not well controlled by using full medications with lipid-lowering drugs. The use of atorvastatin was not approved by the Japanese Ministry of Health and Welfare during the course of the present study. Atorvastatin was marketed in 2000, and the maximal clinical dose of atorvastatin was 40 mg per day in Japan. We hope that a comparative study with atorvastatin will be conducted in the near future.
In this study, the following limitations should be noted. First, the number of study patients was small owing to the strict inclusion criteria. In particular, the number of subjects in the medication group was limited because of the nonrandomized nature of the present study. Second, although baseline patient characteristics between the two groups were similar, the study was prospective and controlled but not randomized. Third, only a small portion of the epicardial coronary vasculature was studied by IVUS. Finally, because the present study aimed at evaluation of changes in coronary plaques over a relatively short period (i.e., one-year) and involved a small number of patients, analysis of the incidence of events was not possible.
Aggressive LDL cholesterol-lowering therapy in combination with LDL-A and administration of basic lipid-lowering drugs over a period of a year is associated with a statistically significant regression of coronary artery lesions in FH patients with advanced CAD compared with FH patients treated with medication alone. Therefore, LDL-A should be considered as an effective treatment for FH patients with CAD and high LDL cholesterol levels who are receiving maximally tolerated combination of lipid-lowering drug therapy.
We thank all members of the LACMART study group.
Chairmen of the LACMART study group: Masunori Matsuzaki, Yamaguchi University School, Katsuhiko Hiramori, Iwate Medical University.
The LACMART investigators and the clinical centers: Akira Kitabatake, Hokkaido University; Tetsuo Nishino and Yoshiyuki Suzuki, NTT Sapporo Hospital; Hitoshi Hishida and Masanori Nomura, Fujita Health University; Masakazu Yamagishi, National Cardiovascular Center; Hiroshi Ogawa, Tokuyama Chuo Hospital; Tsutomu Imaizumi and Takashi Ueno, Kurume University; Takashi Honda and Hiroyuki Shono, Saiseikai Kumamoto Hospital.
Committee for the Evaluation: Ichiro Sakuma, Hokkaido University; Kenichi Fukami, Iwate Medical University; Takashi Fujii, Yamaguchi University.
All members are medical doctors.
- analysis of variance
- coronary artery bypass graft surgery
- coronary artery disease
- coronary heart disease
- familial hypercholesterolemia
- high density lipoprotein
- hepatic hydroxymethylglutaryl-coenzyme A
- isosorbide dinitrate
- intravascular ultrasound
- low density lipoprotein
- low density lipoprotein-apheresis
- myocardial infarction
- minimal lumen diameter
- plaque area
- percutaneous transluminal coronary angioplasty
- quantitative coronary angiogram
- time-averaged concentrations
- Received April 9, 2001.
- Revision received April 10, 2002.
- Accepted April 19, 2002.
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