The Effects of Lipid-Lowering Therapy on Serum Eicosapentaenoic Acid to Arachidonic Acid Ratio: An HIJ-PROPER Sub-Analysis

Abstract

Background:

Controversy remains regarding the influence of lipid-lowering therapy on the eicosapentaenoic acid/arachidonic acid ratio.

Objective:

This study aimed to clarify the effects of lipid-lowering therapy on the eicosapentaenoic acid/arachidonic acid ratio in patients with acute coronary syndrome (ACS).

Methods:

This was a post hoc sub-analysis of the Heart Institute of Japan-PRoper level of lipid-lowering with pitavastatin and ezetimibe in ACS study. We compared the eicosapentaenoic acid/arachidonic acid ratio changes from baseline to the 3-month follow-up after contemporary lipid-lowering therapy with pitavastatin + ezetimibe therapy and pitavastatin mono-therapy.

Results:

Among patients with ACS and dyslipidemia, the eicosapentaenoic acid/arachidonic acid increased significantly in the pitavastatin mono-therapy group (0.40 ± 0.26 to 0.46 ± 0.34, P < .0001) but did not increase in the pitavastatin + ezetimibe group (0.37 ± 0.22 to 0.38 ± 0.27, P = .18). When the analysis was limited to patients who received 2 mg/day of pitavastatin during the follow-up period, these trends in changes of the eicosapentaenoic acid/arachidonic acid ratio remained unchanged. Multivariate analysis showed that ezetimibe use (P = .005; β = 0.09), ST-elevation myocardial infarction (P = .04; β = −0.01), and baseline low-density lipoprotein cholesterol (LDL-C) level (P = .0003; β = 0.12) were independent predictors of the percentage change in the eicosapentaenoic acid/arachidonic acid ratio. These trends were similar even when the analysis was limited to patients who did not take statins at enrollment.

Conclusion:

Standard lipid-lowering therapy with pitavastatin mono-therapy improved the eicosapentaenoic acid/arachidonic acid ratio for patients with ACS. Intensive lipid-lowering therapy with pitavastatin + ezetimibe did not improve the eicosapentaenoic acid/arachidonic acid ratio, although LDL-C decreased significantly. Inhibition of the improvement in the eicosapentaenoic acid/arachidonic acid ratio by adding ezetimibe may affect cardiovascular disease prognosis.

Keywords

lipid-lowering therapy eicosapentaenoic acid arachidonic acid acute coronary syndrome pitavastatin ezetimibe

Introduction

Polyunsaturated fatty acids (PUFAs) are essential nutrients that play an important role in maintaining cell membranes and function in humans. Various studies about the eicosapentaenoic acid to arachidonic acid (EPA/AA) ratio have been conducted to improve clinical end points, such as atherosclerosis lesions and mortality, in patients with cardiovascular disease,^1

-6 and these trials have shown a correlation between the EPA/AA ratio and a reduction in cardiovascular events. Humans cannot synthesize PUFAs, and almost all PUFA requirements are fulfilled through dietary intake. Usually, the EPA/AA ratio reflects a patient’s nutritional condition. However, previous studies have suggested that lipid-lowering therapy, including statins and ezetimibe therapy, might affect serum EPA/AA ratio.^7

-11 Bird et al pointed out that statins affect the metabolism of PUFA, but this effect may depend on the type of statin used.¹² The results of previous studies on the influence of statin therapy on the EPA/AA ratio are controversial, and the statin type used in these studies was not uniform. Furthermore, previous studies have suggested that ezetimibe, which has a low-density lipoprotein cholesterol (LDL-C)-lowering effect by inhibition of intestinal cholesterol absorption, may also suppress PUFA absorption.¹³ Another author suggested that several trials have failed to demonstrate the efficacy of ezetimibe in reducing cardiovascular risk and events.^14,15 This might be due to the adverse side effects of ezetimibe; therefore, the potential of lipid-lowering therapy on serum EPA/AA ratio could not be thoroughly examined. We have previously published results of the Heart Institute of Japan-PRoper level of lipid-lowering with pitavastatin and ezetimibe in acute coronary syndrome (ACS; HIJ-PROPER) study, a randomized controlled trial that tested the efficacy of intensive lipid-lowering treatment and compared it with standard lipid-lowering therapy in patients with ACS.^16,17 This study aimed to clarify the effects of lipid-lowering therapy with statin monotherapy and statin plus ezetimibe therapy on the EPA/AA ratio in patients with acute ACS with dyslipidemia.

Methods

Patient Enrollment

This was a post hoc sub-analysis of the HIJ-PROPER study. The HIJ-PROPER study was a prospective, multicenter, randomized trial comparing 2 lipid-lowering treatment strategies involving 19 Japanese centers of cardiovascular disease.¹⁶ In the PROPER study, participants were randomized into an intensive lipid-lowering therapy (pitavastatin + ezetimibe group) or a standard lipid-lowering therapy (pitavastatin monotherapy group). We limited the present analysis to patients in the HIJ-PROPER study who underwent EPA/AA ratio measurements at baseline and a 3-month follow-up.

Study Drugs

Pitavastatin was started at a dose of 2 mg daily in both groups after randomization. Ezetimibe was started at a dose of 10 mg daily in patients assigned to the pitavastatin + ezetimibe group. The goal of the LDL-C level in the pitavastatin + ezetimibe group and pitavastatin monotherapy group was <70 mg/dL and 90 mg/dL to 100 mg/dL, respectively. During the entire study period, pitavastatin dose (1-4 mg daily) was titrated to provide the LDL-C level target specified for each group. Patients already receiving statins other than pitavastatin discontinued the previous agents and started receiving pitavastatin.

Lipid Profile

The serum lipid profile, including the EPA/AA ratio, total cholesterol, LDL-C, high-density lipoprotein cholesterol (HDL-C), and triglycerides were assessed at the time of enrollment and the 3-month follow-up. Lipid profile changes in the pitavastatin + ezetimibe group and pitavastatin monotherapy group were compared. A lipid profile change was defined as the absolute change and the percentage change from baseline to 3 months after lipid-lowering therapy.

Since the dose of pitavastatin during follow-up influences the results, the analysis compared limited patients who received 2 mg per day of pitavastatin during the follow-up period. Moreover, the previous use of statins at enrollment might affect the analysis, and the analysis also compared patients who did not take statins at the time of enrollment. All laboratory analyses were performed exclusively at SRL Inc, an external laboratory.

The study was conducted in accordance with the principles of the 1975 Declaration of Helsinki. The institutional review board or the relevant ethics committee of each participating medical center approved the protocol, and all patients provided written informed consent for trial enrollment.

Statistical Analysis

Continuous variables data were reported as mean ± SD and categorical data as absolute values and percentages. The comparisons were made using Welch t test for normally distributed continuous variables or Mann-Whitney U test for non-normally distributed continuous variables and Pearson χ² test for categorical variables. A paired t test compared the differences in lipid profile data at the 2 time points. Correlations between parameters were tested with Pearson or Spearman correlation coefficient. Multivariate regression analysis was performed to determine predictors of percentage changes in EPA/AA ratio. Variables were included in the multivariable model if they reached P < .10 after univariable regression analysis. A P value of <.05 was considered to indicate statistical significance unless stated otherwise. All statistical analyses were performed using statistics software JMP Pro version14 (SAS Institute Inc).

Results

Between January 2010 and April 2013, 1734 patients were randomized in the HIJ-PROPER original study. A total of 13 patients were excluded from the original study. A total of 713 patients did not have EPA/AA data, either at baseline or 3 months or both. Therefore, a total of 1008 patients were included in this study. Patients excluded from the analysis were equivalent to those included in the analysis concerning most baseline characteristics. However, a different distribution of the clinical classification of ACS was observed between patients included in the analysis and excluded from the analysis. In addition, patients excluded from the analysis used β-blockers and renin–angiotensin system inhibitors less frequently (Supplemental Table 1).

Most of baseline clinical characteristics of the patients in the pitavastatin monotherapy group (n = 506) and pitavastatin + ezetimibe group (n = 502) were well matched (Table 1), except that EPA/AA ratio at baseline in pitavastatin monotherapy group was higher than that in pitavastatin + ezetimibe group (0.40 ± 0.26 vs 0.37 ± 0.26, P = .03). The mean dose of pitavastatin during follow-up was higher in the pitavastatin + ezetimibe group than the pitavastatin monotherapy group (2.4 ± 0.04 mg vs 2.0 ± 0.04 mg, P < .0001). The mean dose of ezetimibe during follow-up in the pitavastatin + ezetimibe group was 10.0 ± 0.6 mg.

Table 1.

Baseline Characteristics of the Study Population.^a

	All patients (n = 1008)	Pitavastatin monotherapy group, (n = 506)	Pitavastatin +ezetimibe group, (n = 502)	P value
Age (years)	65.4 ± 11.6	65.6 ± 11.4	65.2 ± 11.8	.54
Men	767 (76.1%)	393 (77.7%)	374 (74.5%)	.27
BMI (kg/m²)	24.3 ± 3.5	24.2 ± 3.5	24.4 ± 3.5	.46
GFR (mL/min/1.73 m²)	72.5 ± 18.9	71.8 ± 18.9	73.2 ± 18.9	.23
Statin naïve	828 (82.1%)	412 (81.4%)	416 (82.9)	.57
Hypertension	680 (67.1%)	334 (66.0%)	346 (68.9%)	.35
Diabetes mellitus	294 (29.2%)	147 (29.1%)	147 (29.3%)	.94
Current smoker	349 (34.6%)	184 (36.4%)	165 (32.9%)	.26
Previous myocardial infarction	70 (6.9%)	35 (6.9%)	35 (7.0%)	.97
Previous revascularization	86 (8.5%)	42 (8.3%)	44 (8.8%)	.82
Type of index event				.51
STEMI	486 (48.2%)	253 (50.0%)	233 (46.4%)
Non-STEMI	105 (10.4%)	52 (10.3%)	53 (10.6%)
Unstable angina pectoris	417 (41.4%)	201 (39.7%)	216 (43.0%)
Medication
Beta-blocker	91 (9.0%)	47 (9.3%)	44 (8.8%)	.83
ACEIs/ARBs	309 (30.7%)	158 (31.2%)	151 (30.1%)	.73
Calcium channel blocker	298 (29.6%)	144 (28.5%)	154 (30.7%)	.45
Aspirin	168 (16.7%)	81 (16.0%)	87 (17.3%)	.61
Cholesterol metabolism
Total cholesterol (mg/dL)	210 ± 35.2	212 ± 36.6	210 ± 33.8	.29
HDL cholesterol (mg/dl)	48.5 ± 12.69	48.7 ± 13.0	48.4 ± 12.7	.71
LDL cholesterol (mg/dL)	135 ± 29.3	136 ± 30.1	135 ± 28.4	.51
Triglyceride (mg/dL)	134 ± 70.5	136 ± 72.8	131 ± 68.1	.36
EPA/AA ratio	0.39 ± 0.24	0.40 ± 0.26	0.37 ± 0.22	.03

Abbreviations: AA, arachidonic acid; ACEIs, angiotensin-converting enzyme inhibitors; ARBs, angiotensin II receptor blockers; BMI, body mass index; EPA, eicosapentaenoic acid; GFR, glomerular filtration rate; STEMI, ST-elevation myocardial infarction; HDL, high-density lipoprotein; LDL, low-density lipoprotein.

a Data are expressed as mean ± SD or as number (percentage).

Change in Lipid Profile

Absolute change and percentage change from baseline to 3-month follow-up of each lipid profile among patients in the pitavastatin monotherapy group and pitavastatin + ezetimibe group are shown in Table 2 and Figure 1. The levels of LDL-C decreased significantly in both groups (pitavastatin monotherapy group, 136 ± 30.1 to 85.1 ± 22.5, P < .0001; pitavastatin + ezetimibe group, 135 ± 28.4 to 64.7 ± 21.6, P < .0001). The percentage change in LDL-C was significantly greater in the pitavastatin + ezetimibe group than the pitavastatin monotherapy group (−51% vs −36%, P < .0001). No significant difference in absolute change was observed for HDL-C levels in the pitavastatin monotherapy group. The levels of HDL-C in the pitavastatin + ezetimibe group increased numerically but not statistically (48.4 ± 12.7 to 49.2 ± 11.5, P = .12). The levels of triglyceride had increased significantly in the pitavastatin monotherapy group; however, no significant increase was observed in the pitavastatin + ezetimibe group (pitavastatin monotherapy group, 136 ± 72.8 to 154 ± 96.9, P < .0001; pitavastatin + ezetimibe group, 131 ± 68.1 to 129 ± 73.2, P = .50).

Table 2.

Absolute Change of Each Lipid Profiles.^a

	Baseline	Three-month follow-up	P value^b
Total cholesterol (mg/dL)
Pitavastatin monotherapy	212 ± 36.6	163 ± 28.5	<.0001
Pitavastatin + ezetimibe	210 ± 33.8	139 ± 26.8	<.0001
HDL cholesterol (mg/dL)
Pitavastatin mono-therapy	48.7 ± 13.0	48.8 ± 12.5	.95
Pitavastatin + ezetimibe	48.4 ± 12.7	49.2 ± 11.5	.12
LDL cholesterol (mg/dL)
Pitavastatin monotherapy	136 ± 30.1	85.1 ± 22.5	<.0001
Pitavastatin + ezetimibe	135 ± 28.4	64.7 ± 21.6	<.0001
Triglyceride (mg/dL)
Pitavastatin monotherapy	136 ± 72.8	154 ± 96.9	<.0001
Pitavastatin + ezetimibe	131 ± 68.1	129 ± 73.2	.50
EPA (μg/mL)
Pitavastatin monotherapy	62.9 ± 34.6	71.8 ± 45.6	<.0001
Pitavastatin + ezetimibe	58.4 ± 30.5	61.9 ± 41.3	.03
AA (μg/mL)
Pitavastatin monotherapy	167 ± 44.0	168 ± 46.6	.74
Pitavastatin + ezetimibe	166 ± 44.3	172 ± 46.9	.002
EPA/AA
Pitavastatin mono-therapy	0.40 ± 0.26	0.46 ± 0.34	<.0001
Pitavastatin + ezetimibe	0.37 ± 0.22	0.38 ± 0.27	.18

Abbreviations: AA, arachidonic acid; EPA, eicosapentaenoic acid; HDL, high-density lipoprotein; LDL, low-density lipoprotein.

a Data are expressed as mean ± SD.

^b P value refers to the difference between baseline and 3-month follow-up by a paired t test.

Figure 1.

Percentage change of each lipid profile among patients in the pitavastatin + ezetimibe group and pitavastatin monotherapy group. AA, arachidonic acid; EPA, eicosapentaenoic acid; HDL-C, high-density lipoprotein cholesterol; LDL-C, low-density lipoprotein cholesterol; TC, total cholesterol; TG, triglyceride. *Data are expressed as mean (SD).

Change in EPA/AA Ratio

The levels of EPA increased significantly in both groups (pitavastatin monotherapy group, 62.9 ± 34.6 to 71.8 ± 45.6, P < .0001; pitavastatin + ezetimibe group, 58.4 ± 30.5 to 61.9 ± 41.2, P = .03). The levels of AA increased significantly in the pitavastatin + ezetimibe group but not in the pitavastatin monotherapy group (pitavastatin monotherapy group, 167 ± 44.0 to 168 ± 46.6, P = .74; pitavastatin + ezetimibe group, 166 ± 44.3 to 172 ± 46.9, P = .002). As a result, EPA/AA ratio increased significantly in the pitavastatin monotherapy group (0.40 ± 0.26 to 0.46 ± 0.34, P < .0001) but did not increase in the pitavastatin + ezetimibe group (0.37 ± 0.22 to 0.38 ± 0.27, P = .18). The percentage change in EPA/AA ratio in the pitavastatin monotherapy group and pitavastatin + ezetimibe group was 28.5% and 13.1%, respectively (P = .003; Table 2; Figure 1).

When the analysis was limited to 335 patients who received 2 mg/d of pitavastatin during the follow-up period, these trends in changes of the EPA/AA ratio remained unchanged (pitavastatin monotherapy group [n = 120], 0.36 ± 0.21 to 0.41 ± 0.33, P = .02; pitavastatin + ezetimibe group [n = 215], 0.37 ± 0.21 to 0.39 ± 0.27, P = .37; Table 3). Moreover, when the analysis was limited to patients who did not take statins at the time of enrollment (number of statin naïve patients = 828), pitavastatin monotherapy group increased the EPA/AA ratio from baseline to the 3-month follow-up, but pitavastatin + ezetimibe group did not (0.40 ± 0.25 to 0.46 ± 0.34, P < .0001; Supplemental Table 2).

Table 3.

Absolute Change of Each Lipid Profiles.^a,b,c

	Baseline	Three-month follow-up	P value^d
Total cholesterol (mg/dL)
Pitavastatin monotherapy	206 ± 32.3	162 ± 25.1	<.0001
Pitavastatin + ezetimibe	202 ± 25.9	134 ±22.6	<.0001
HDL cholesterol (mg/dL)
Pitavastatin monotherapy	46.5 ± 11.3	46.6 ± 11.3	.80
Pitavastatin + ezetimibe	48.5 ± 12.0	49.6 ± 11.4	.16
LDL cholesterol (mg/dL)
Pitavastatin monotherapy	132 ± 26.8	82.4 ± 20.8	<.0001
Pitavastatin + ezetimibe	127 ± 21.4	59.5 ± 18.8	<.0001
Triglyceride (mg/dL)
Pitavastatin monotherapy	139 ± 68.5	170 ± 116	.002
Pitavastatin + ezetimibe	128 ± 67.7	124 ± 70.2	.43
EPA (μg/mL)
Pitavastatin monotherapy	57.6 ± 33.5	66.9 ± 45.7	.02
Pitavastatin + ezetimibe	58.9 ± 29.3	63.0 ± 43.5	.11
AA (μg/mL)
Pitavastatin monotherapy	170 ± 43.4	173 ± 45.9	.33
Pitavastatin + ezetimibe	166 ± 40.2	171 ± 43.0	.01
EPA/AA
Pitavastatin monotherapy	0.36 ± 0.21	0.41 ± 0.33	.02
Pitavastatin + ezetimibe	0.37 ± 0.21	0.39 ± 0.27	.37

Abbreviations: AA, arachidonic acid; EPA, eicosapentaenoic acid; HDL, high-density lipoprotein; LDL, low-density lipoprotein.

^a Analysis was limited to 335 patients who received 2 mg per day of pitavastatin during follow-up period.

^b Data are expressed as mean ± SD.

^c A total of 120 patients were received pitavastatin monotherapy and a total of 215 patients were received pitavastatin + ezetimibe therapy.

^d P value refers to the difference between baseline and 3-month follow-up by a paired t test.

Independent Predictors of Percentage Change in EPA/AA Ratio

Table 4 shows the predictors of percentage change of EPA/AA ratio. Univariable analysis revealed that the potential predictors of percentage change in EPA/AA ratio were age (P = .001), body mass index (P = .06), use of ezetimibe (P = .003), current smoking (P = .004), ST-elevation myocardial infarction (P = .0002), unstable angina pectoris (P = .003), use of beta-blockers (P = .07), baseline LDL-C level (P < .0001), and baseline triglyceride level (P = .04). Multivariate analysis showed that the use of ezetimibe (P = .005; β = 0.09), ST-elevation myocardial infarction (P = .04; β = −0.01), and baseline LDL-C level (P = .0003; β = 0.12) were independent predictors of the percentage change in EPA/AA ratio. Even if the baseline EPA/AA ratio was added to the multivariate analysis, the use of ezetimibe was independent predictors of the percentage change in EPA/AA ratio (P = .001; β = 0.10; Supplemental Table 3).

Table 4.

Predictors for Percent Change of EPA/AA Ratio.

	Univariable analysis		Multivariable analysis
	R ²	P value	β	P value
Age	0.01	.001	−0.03	.39
Men	0.002	.16
Body mass index	0.004	.06	0.04	.21
Glomerular filtration rate	0.0004	.51
Statin naïve	0.001	.97
Use of ezetimibe	0.01	.003	0.09	.005
Hypertension	0.0007	.39
Diabetes mellitus	0.0005	.48
Current smoking	0.01	.004	−0.04	.21
Previous myocardial infarction	0.001	.95
Previous revascularization	0.002	.21
Type of index event
STEMI	0.01	.0002	−0.11	.04
Non-STEMI	0.001	.24
Unstable angina pectoris	0.009	.003	−0.02	.65
Medication
Beta blockers	0.003	.07	0.03	.36
ACEIs/ARBs	0.0004	.44
Calcium channel blockers	0.0007	.60
Aspirin	0.0002	.37
Cholesterol metabolism at baseline
HDL-cholesterol	0.001	.97
LDL-cholesterol	0.02	<.0001	0.12	.0003
Triglyceride	0.004	.04	0.03	.44
Percent change of cholesterol metabolism
HDL-cholesterol	0.001	.37
LDL-cholesterol	0.001	.77
Triglyceride	0.0003	.62

Abbreviations: AA, arachidonic acid; ACEIs, angiotensin-converting enzyme inhibitors; ARBs, angiotensin II receptor blockers; EPA, eicosapentaenoic acid; HDL, high-density lipoprotein; LDL, low-density lipoprotein STEMI, ST-elevation myocardial infarction.

Discussion

The primary findings of this subgroup analysis of HIJ-PROPER were as follows. First, among patients with ACS and dyslipidemia, standard lipid-lowering therapy with pitavastatin monotherapy increased the EPA/AA ratio, but intensive lipid-lowering therapy with pitavastatin + ezetimibe therapy did not increase the EPA/AA ratio. Second, multivariate analysis showed that the use of ezetimibe, ST-elevation myocardial infarction, and baseline LDL-C level were independent predictors of the percentage change in the EPA/AA ratio.

Change in EPA/AA Ratio

A previous study suggested that the pleiotropic effects of statins, including enhancing endothelial function, inhibiting the production of inflammatory cytokine, and lowering of LDL-C overlap with those of PUFAs.¹⁸ Moreover, statins enhance the conversion of EPA to their long-chain derivatives.¹⁹ Considering these commonalities, statin and EPA/AA ratio may interact either competing with or complementing each other. Most of the previous clinical studies on patients with coronary artery disease have reported that statin monotherapy does not affect the EPA/AA ratio. Nozue et al reported that statin monotherapy did not influence the EPA/AA ratio from baseline to an 8-month follow-up among 101 statin naïve patients with coronary artery disease.⁹ Kurisu et al described that statin monotherapy decreased EPA from baseline to the 3-month follow-up but did not affect the EPA/AA ratio in 46 patients with coronary artery disease.¹⁰ In contrast, our results indicate that pitavastatin monotherapy significantly increased EPA/AA ratio from baseline to the 3-month follow-up. Even though the analysis was limited to patients who received a similar dose of pitavastatin or the analysis was limited to patients who did not take statins at the time of enrollment, pitavastatin monotherapy still increased the EPA/AA ratio from baseline to the 3-month follow-up.

There were several differences between previous studies and our study. The type of statin differed among studies. Our study was a post hoc analysis of a prospective randomized controlled study that only examined patients with ACS. In contrast, the frequency of ACS in the previous study was 29%, and ACS was excluded in the latter study. The mean age of our study population was lower, and comorbidities were different compared to previous studies; hence, direct comparisons are difficult. In addition, the sample sizes of previous studies were relatively small and, therefore, might have been subject to bias.

In the current study, pitavastatin monotherapy increased the EPA/AA ratio, but pitavastatin + ezetimibe therapy did not. This result was similar to that of a previous study that investigated whether ezetimibe affects PUFAs.⁷ Blackwood et al reported that ezetimibe could inhibit the absorption of α-linoleic acid, which is one of the PUFAs.¹³ The author suggested that it is possible that drugs that inhibit cholesterol metabolism in the intestine may also inhibit the absorption of PUFAs s like EPA. Although the specific mechanism that induces the different change of EPA/AA ratio between pitavastatin monotherapy group and pitavastatin + ezetimibe therapy group in the current study remains unknown, the differences in the absorption ability of EPA or AA in the pitavastatin monotherapy group and pitavastatin + ezetimibe group may have influenced the results of this study.

Predictor of EPA/AA Ratio

In this study, the use of ezetimibe, ST-elevation myocardial infarction, and LDL-C level at baseline were independent predictors of the percentage change in EPA/AA ratio. There was a difference in EPA/AA ratio at baseline between the pitavastatin monotherapy group and pitavastatin + ezetimibe group, suggesting that this could affect the results in the current study. However, when the baseline EPA/AA ratio was added to the multivariate analysis, the use of zetimibe was also a predictor of EPA/AA ratio changes.

No previous studies have reported EPA/AA ratio changes and the clinical classification of ACS. Previous studies have reported that the length of hospital stay in patients with acute myocardial infarction tended to be longer than that of unstable angina pectoris.^20,21 The EPA/AA ratio is mainly affected by the patient’s dietary intake, so EPA/AA ratio change from baseline to 3-month follow-up may be influenced by whether patients have been educated about dietary intake during admission. Patients who have been hospitalized for a long time are likely to have had the opportunity to receive lifestyle modification advice and nutrition-controlled dietary intake.

Low-density lipoprotein cholesterol at baseline was also an independent predictor of the change in EPA/AA ratio. The mechanism of LDL-C at baseline being an independent predictor of the change in the EPA/AA ratio is not clear. When our analysis was limited to patients who did not take statins at the time of enrollment, the use of ezetimibe and LDL-C level at baseline was still an independent predictor (β = 0.09, P = .01 for the use of ezetimibe; β = 0.12, P = .001 for LDL-C at baseline, Supplementary Table 4). This analysis reinforced LDL-C at baseline as an independent predictor of change in EPA/AA ratio. Some previous studies reported a correlation between percent change in LDL-C and percentage change in EPA/AA ratio.^9,10 In our study, no significant correlation was seen between percentage change in LDL-C and percentage change in EPA/AA ratio in the pitavastatin + ezetimibe group among entire participants. Only a weak inverse correlation between percentage change in LDL-C and percentage change in EPA/AA ratio was seen in the pitavastatin monotherapy group (R ² = 0.01, P = .04; Figure 2).

Figure 2.

Correlation between percentage change in LDL-C and percentage change in EPA/AA ratio; (A) in all participants, (B) in pitavastatin monotherapy group, (C) in pitavastatin + ezetimibe group. AA indicates arachidonic acid; EPA, eicosapentaenoic acid; LDL-C, low-density lipoprotein cholesterol

Our study suggested that the standard lipid-lowering therapy with pitavastatin monotherapy increased the EPA/AA ratio for patients with ACS. Considering the previously reported effects of EPA/AA ratio on improving outcomes in cardiovascular patients, favorable effects are expected with this improvement in EPA/AA ratio. On the other hand, intensive lipid-lowering therapy with pitavastatin + ezetimibe therapy did not improve the EPA/AA ratio, although LDL-C decreased significantly. Inhibition of the improvement in the EPA/AA ratio by adding ezetimibe may affect the prognosis of cardiovascular disease. Our data suggest that further improvement of cardiovascular events might be expected by using a combination of PUFAs when adding ezetimibe to patients with ACS treated with statins. Further large and prospective trials are required to confirm this result for this specific subset.

Limitations

This study had some limitations. First, this study was retrospective and based on a subgroup analysis of a prospective study. Second, measurements of PUFAs were conducted only at baseline and at 3 months. Third, we did not examine patient dietary intake and PUFA supplements during the follow-up period.

Conclusions

Standard lipid-lowering therapy with pitavastatin monotherapy improved the EPA/AA ratio in patients with ACS. Intensive lipid-lowering therapy with pitavastatin + ezetimibe did not improve the EPA/AA ratio, although LDL-C decreased significantly. Inhibition of the improvement in the EPA/AA ratio by adding ezetimibe may affect the prognosis of cardiovascular disease. Further clinical trials are required to confirm this result.

Supplemental Material

Supplemental_Table_1 - The Effects of Lipid-Lowering Therapy on Serum Eicosapentaenoic Acid to Arachidonic Acid Ratio: An HIJ-PROPER Sub-Analysis

Supplemental_Table_1 for The Effects of Lipid-Lowering Therapy on Serum Eicosapentaenoic Acid to Arachidonic Acid Ratio: An HIJ-PROPER Sub-Analysis by Hiroyuki Arashi, Junichi Yamaguchi, Erisa Kawada-Watanabe, Hisao Otsuki, Haruki Sekiguchi, Hiroshi Ogawa and Nobuhisa Hagiwara in Journal of Cardiovascular Pharmacology and Therapeutics

Supplemental Material

Supplemental_Table_2 - The Effects of Lipid-Lowering Therapy on Serum Eicosapentaenoic Acid to Arachidonic Acid Ratio: An HIJ-PROPER Sub-Analysis

Supplemental_Table_2 for The Effects of Lipid-Lowering Therapy on Serum Eicosapentaenoic Acid to Arachidonic Acid Ratio: An HIJ-PROPER Sub-Analysis by Hiroyuki Arashi, Junichi Yamaguchi, Erisa Kawada-Watanabe, Hisao Otsuki, Haruki Sekiguchi, Hiroshi Ogawa and Nobuhisa Hagiwara in Journal of Cardiovascular Pharmacology and Therapeutics

Supplemental Material

Supplemental_Table_3 - The Effects of Lipid-Lowering Therapy on Serum Eicosapentaenoic Acid to Arachidonic Acid Ratio: An HIJ-PROPER Sub-Analysis

Supplemental_Table_3 for The Effects of Lipid-Lowering Therapy on Serum Eicosapentaenoic Acid to Arachidonic Acid Ratio: An HIJ-PROPER Sub-Analysis by Hiroyuki Arashi, Junichi Yamaguchi, Erisa Kawada-Watanabe, Hisao Otsuki, Haruki Sekiguchi, Hiroshi Ogawa and Nobuhisa Hagiwara in Journal of Cardiovascular Pharmacology and Therapeutics

Supplemental Material

Supplemental_Table_4 - The Effects of Lipid-Lowering Therapy on Serum Eicosapentaenoic Acid to Arachidonic Acid Ratio: An HIJ-PROPER Sub-Analysis

Supplemental_Table_4 for The Effects of Lipid-Lowering Therapy on Serum Eicosapentaenoic Acid to Arachidonic Acid Ratio: An HIJ-PROPER Sub-Analysis by Hiroyuki Arashi, Junichi Yamaguchi, Erisa Kawada-Watanabe, Hisao Otsuki, Haruki Sekiguchi, Hiroshi Ogawa and Nobuhisa Hagiwara in Journal of Cardiovascular Pharmacology and Therapeutics

Footnotes

Acknowledgments

The authors thank the HIJ-PROPER patients as well as the staff and investigators of the HIJ-PROPER study for their contributions. They also thank Hiromi Hasegawa, Yoshie Kuwahara, Yoshiko Shimomura, and Kyoko Tottori who assisted with administrative tasks of HIJ-PROPER study. The clinical centers that participated in this study were Tokyo Women’s Medical University, Sakakibara Heart Institute, Saisei-Kai Kumamoto Hospital, Cardiovascular Center of Sendai, Seirei Hamamatsu General Hospital, Saisei-Kai Kurihashi Hospital, National Yokohama Medical Center, Tokyo Metropolitan Tama Medical Center, Kosei General Hospital, NTT-East Kanto Medical Hospital, Tokyo Metropolitan Tama-Hokubu Medical Center, Shin-Matsudo Central General Hospital, JCHO Sagamino Hospital, Nishiarai Heart Center, Ogikubo Hospital, Shiseikai-Daini Hospital, Tokyo Metropolitan Ebara Hospital, Tokyo Women’s Medical University, Medical Center East, and Tokyo Women’s Medical University Yachiyo, Medical Center.

Author Contributions

J.Y., Hiroshi O, and N.H. conceptualized and designed the study. H.A., Hisao O, and S.H. collected data, enrolled patients, and followed-up patients. H.A. analyzed and interpreted the data. H.A. and J.Y. drafted and wrote the manuscript. H.S., Hisao O, Hiroshi O, and N.H. reviewed the manuscript. All authors, external and internal, had full access to all of the data (including statistical reports and tables) in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Declaration of Conflicting Interests

The author(s) declared the following potential conflicts of interest with respect to the research, authorship, and/or publication of this article: All members of the HIJ-PROPER study group report having received research support to perform clinical trials from the Japan Research Promotion Society for Cardiovascular Diseases, which is sponsored by Abbott Vascular Japan Co., Ltd., AstraZeneca K.K., Bayer Yakuhin, Ltd., Boston Scientific Corporation, Bristol-Myers K.K., Daiichi Sankyo Company Limited, Kowa Pharmaceutical Co., Ltd., Mochida Pharmaceutical Co., Ltd., MSD K.K., Nippon Boehringer Ingelheim Co., Ltd., Novartis Pharma K.K., Pfizer Japan Inc., Sanofi K.K., and Takeda Pharmaceutical Company Limited. N. Hagiwara reports that he has received honoraria from Bristol-Myers K.K. and Nippon Boehringer Ingelheim Co., Ltd., and grants from Astellas Pharma Inc., Daiichi Sankyo Company, Limited, Eisai Co., Ltd., Mitsubishi Tanabe Pharma Corporation, Otsuka Pharmaceutical Co., Ltd., Shionogi & Co., Ltd., and Takeda Pharmaceutical Company Limited. J. Yamaguchi reports that he belongs to the division (Clinical Research division for Cardiovascular Catheter Intervention) financially maintained by the donation from Abbott, Boston Scientific, Medtronic, and Terumo. The HIJ-PROPER Steering Committee had full access to all data in the study and had final responsibility for the decision to submit for publication.

Funding

The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The HIJ-PROPER trial was funded by the Japan Research Promotion Society for Cardiovascular Diseases.

ORCID iD

Hiroyuki Arashi

Supplemental Material

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