Platelet reactivity in response to loading dose of atorvastatin or rosuvastatin in patients with stable coronary disease before percutaneous coronary intervention: The STATIPLAT randomized study

Abstract

Background

The acute effects of statin loading dose (LD) on platelet reactivity in patients with chronic stable angina (CSA) are not completely clear.

Hypothesis

We hypothesized that LDs of atorvastatin and rosuvastatin have different pharmacodynamic acute effects on platelet aggregability in CSA patients with baseline normal platelet reactivity while on dual antiplatelet therapy (DAPT).

Methods

From September 2011 to February 2014, all consecutive CSA patients on chronic DAPT (aspirin and clopidogrel) were evaluated before elective percutaneous coronary intervention (PCI). An initial assessment of platelet reactivity in response to thrombin receptor agonist, ADP, and ASP (respectively, indicative of the response to clopidogrel and aspirin) was performed with impedance aggregometry. Patients with high platelet reactivity to ADP test (area under the curve >47) were excluded. The remaining patients were randomized into 3 treatment groups: Group A, atorvastatin LD 80 mg; Group B, rosuvastatin LD 40 mg; and Group C, no statin LD (control group). A second assessment of platelet reactivity was performed ≥12 hours after statin LD.

Results

682 patients were screened and 145 were randomized into the 3 groups. At baseline and after statin LD, no significant difference was found in platelet reactivity in response to 3 different agonists between the 3 groups. Subgroup analysis showed that platelet reactivity to ADP test was significantly lower in patients chronically treated with low‐dose statins (n = 94) compared with statin‐naïve patients (n = 51; 15.32 ± 1.50 vs 18.59 ± 1.30; P = 0.007).

Conclusions

Loading dose of atorvastatin (80 mg) or rosuvastatin (40 mg) did not induce significant variation in platelet reactivity in CSA patients with baseline reduced platelet reactivity as in chronic DAPT. Our data confirm that chronic concomitant treatment with low‐dose statins and clopidogrel resulted in significantly lower platelet reactivity compared with clopidogrel alone.

1. INTRODUCTION

Statins are the cornerstone of medical treatment for hypercholesterolemia and have led to a marked reduction in morbidity and mortality from adverse cardiac and cerebrovascular events. Interestingly, a wealth of both experimental and clinical evidence reveals that the beneficial effects of statins extend beyond those obtained by simply lowering serum cholesterol levels and are mediated by other mechanisms, the so‐called pleiotropic effects.1, 2, 3 In this context, the Atorvastatin for Reduction of Myocardial Damage During Angioplasty (ARMYDA) and ARMYDA‐ACS trials4, 5 demonstrated a significant reduction of periprocedural myocardial infarction after a short‐term pretreatment with atorvastatin in statin‐naïve patients with chronic stable angina (CSA) and acute coronary syndromes (ACS) before percutaneous coronary intervention (PCI). In addition, the ARMYDA‐RECAPTURE trial6 suggests that reloading with a high dose of atorvastatin improves the clinical outcome of patients on chronic statin therapy before PCI, without reporting which was the mechanism of this favorable effect. At the moment, the physiological mechanisms supporting such a positive effect are still not clear. From the relevant literature, we know that statins have antiaggregatory effects beyond the lipid‐lowering effect.2, 3, 7, 8 The statins most commonly used in clinical practice are atorvastatin, metabolized by the cytochrome P450 (CYP) 3A4 system (the same one that helps to transform the clopidogrel active metabolite), and rosuvastatin, which is independent from the aforementioned mechanism.9 The chronic pharmacodynamic effects of atorvastatin and rosuvastatin in CSA patients with baseline normal platelet aggregability while on dual antiplatelet therapy (DAPT) were evaluated in the Pharmacodynamic Effects of Atorvastatin Versus Rosuvastatin in Coronary Artery Disease Patients With Normal Platelet Reactivity While on Dual Antiplatelet Therapy (PEARL) trial, which reported that 1 month of statins did not negatively affect platelet reactivity.10 However, the acute pharmacodynamic effects of different loading doses (LDs) on platelet aggregability remain undefined.

To address this issue, we designed the Evaluation of Platelet Function After Statin Loading Dose in Patients Before Percutaneous Coronary Intervention (STATIPLAT) trial (http://www.clinicaltrials.gov NCT01526460), a prospective, randomized, single‐center, open‐label study designed to evaluate the acute effects on platelet aggregability in response to high doses of atorvastatin or rosuvastatin administered in CSA patients with baseline reduced platelet reactivity, as in chronic DAPT, according to the study protocol definition.

2. METHODS

2.1. Population

The STATIPLAT trial included all consecutive statin‐naïve or patients treated with low‐dose statins who underwent elective PCI between September 2011 and February 2014 at the Cardiology Department of San Raffaele Hospital for CSA without evidence of high platelet reactivity (HPR) at platelet impedance aggregometer (Multiplate analyzer). All patients with CSA on DAPT (clopidogrel 75 mg/d and aspirin 100 mg/d) were screened. The study included CSA patients waiting for coronary angiography because of CSA (with stable ischemic threshold over the past 6 months), silent myocardial ischemia (with positive stress test), or waiting for second PCI in the context of a 2‐step procedure (≥1 month after the index procedure). Low‐dose statin treatment was defined as chronic use of atorvastatin 10 mg to 20 mg or rosuvastatin 5 mg to 10 mg once daily.11

Exclusion criteria were patients treated with fluvastatin, lovastatin, pravastatin, and simvastatin; patients treated with other antiplatelet agents (nonsteroidal anti‐inflammatory drugs, dipyridamole, cilostazol); patients with ACS (ST‐segment elevation myocardial infarction, non–ST‐segment elevation myocardial infarction, and unstable angina); CSA patients in DAPT for <5 days; contraindication to statin therapy; unexplained transaminase or creatine phosphokinase (CPK) increase >2× the upper limit of normal; patients with acute or chronic inflammatory disease; and patients with anemia (hemoglobin <8.5 mg/dL), leukocytosis (white blood cell count >12 000 mm³), leukopenia (white blood cell count <3000 mm³), platelet count <100 000/μL, and malignancy.

In that time period, 682 patients were screened for the trial. According to the inclusion and exclusion criteria, 531 patients were excluded (Figure 1). Therefore, 151 patients were enrolled and evaluated at baseline with the Multiplate analyzer. Of these, 6 patients (4%) presenting increased HPR to adenosine diphosphate (ADP) test (AUC >47) were treated with different antiplatelet therapy (eg, prasugrel 10 mg/d) and were excluded.12 Finally, 145 patients were randomized into 3 different treatment groups: Group A, patients treated with LD of atorvastatin 80 mg (48 patients); Group B, LD of rosuvastatin 40 mg (48 patients); and Group C, who did not receive any statin LD (control group; 49 patients).

Figure 1.

Study flow diagram. Abbreviations: CSA, chronic stable angina; DAT, dual antiplatelet therapy; HPR, high platelet reactivity; PCI, percutaneous coronary intervention.

Blood samples for platelet function testing were collected at baseline, 2 hours after the ingestion of the last clopidogrel dose, and at second measurement, ≥12 hours after ingestion of the statin LD (which was administered at 10 pm in all patients) accordingly with ARMYDA‐RECAPTURE and ARMYDA‐ACS time points.5, 6 Values were also measured for levels of CPK, aspartate aminotransferase, alanine aminotransferase, and γ‐glutamyl transferase. Then, all patients underwent PCI as scheduled and were discharged with statin therapy according to their clinical condition. Other medications such as β‐blockers, angiotensin‐converting enzyme inhibitors, and angiotensin II receptor blockers were given as appropriate. No other lipid‐lowering treatment or medication that affects CYP3A4‐mediated drug metabolism was permitted during the study. These included erythromycin, antimycotic agents, and cyclosporine. Any other change in other medication was not permitted during the short study period.

2.2. Multiplate analyzer system

Platelet aggregability was evaluated by means of Multiplate assay. Complete details of the method were previously reported.13 Briefly, the Multiplate is a platelet impedance aggregometer. Analysis was based on platelet adhesion upon activation in response to different agonist such as arachidonic acid (ASP; aspirin‐sensitive platelet reactivity), the substrate of the platelet enzyme cyclooxygenase, which transforms arachidonic acid into thromboxane A2, a potent platelet activator. The test uses adenosine diphosphate (ADP), which triggers platelet activation via platelet receptors P2Y₁₂ receptor and thrombin receptor agonist peptide (TRAP), which stimulates platelet reactivity via the thrombin receptor PAR‐1. This leads to a strong platelet activation that may be inhibited by the presence of thrombin receptor antagonists or glycoprotein IIb/IIIa receptor antagonists. Increased impedance due to attachment of platelets to the electrodes is continuously measured for each sensor unit over a period of 6 minutes. Reactivity measured by Multiplate was quantified as the area under the aggregation curve (AUC, [AU*min]). Alternatively, the analyzer's software allows for the expression of AUC values in [U], where 10 [AU*min] corresponds to 1 [U]. A duplicate sensor served as an internal control to reduce the occurrence of systematic errors.

2.3. Statistical analysis

Continuous variables were reported as mean ± SD or median (interquartile range) and compared with the t test, Mann‐Whitney test, or Wilcoxon test, based on the normality of the data (verified by Kolmogorov‐Smirnov goodness‐of‐fit test). Categorical variables (such as frequencies or percentage) were compared with χ² test with Yates correction for continuity or the Fisher exact test as appropriate for the available data.14 No previous data are available regarding platelet reactivity after loading dose of statins. The null hypothesis was that no difference in clopidogrel effect exist after loading dose of atorvastatin and rosuvastatin, and the study was powered to reject this hypothesis. Considering the average value of residual platelet aggregability to ADP test reported by Sibbing et al12 in patients treated with aspirin and clopidogrel (AUC, 27 ± 15), we estimated to include a minimum of 34 patients per group to be able to detect at least ± 10 difference in the mean AUC values (SD1 = 10 and SD2 = 8) and to obtain a statistically significant difference (P < 0.05) with a statistical power of 95% (significance 2‐tailed; z for 1‐power = 1.64, z for α double‐sided = 1.96).

A prespecified subanalysis was considered also to evaluate whether any differences in platelet aggregability were present between statin‐naïve patients (n = 51) and those chronically treated with low‐dose statins (n = 94). The statistical analyses were performed using SPSS version 16.0.2 (SPSS Inc., Chicago, IL) and SISA Sample Size Calculation. Figures were generated with GraphPad Prism software (version 4; GraphPad, Inc., San Diego, CA). Written informed consent, approved by the San Raffaele Hospital Ethics Committee, was obtained from all patients for the procedure, for the study data collection, and for the subsequent analysis and publication.

3. RESULTS

Study patient characteristics and demographics are reported in Table 1. All patients enrolled underwent all tests as scheduled, and time intervals were similar for the 3 groups of randomization. More than 84% of patients were in DAPT for >2 months (mean time, 56 ± 14 days); the other 16% of patients were in DAPT therapy (clopidogrel 75 mg) for >5 days (34 ± 12 days). No enrolled patient was treated with an LD of clopidogrel. According to European Society of Cardiology cardiovascular risk guidelines, 40% of patients have low‐density lipoprotein cholesterol (LDL‐C) levels within normal range (<70 mg/dL), whereas 60% have LDL‐C levels above normal limits, even though none of the patients had severe dyslipidemia (>180 mg/dL). In Figure 2 are the reported results of platelet reactivity at each time point. At baseline, no significant differences were found in terms of absolute values of ASP test, ADP test, and TRAP test between the 3 groups. After statin LD, no significant differences were found in terms of absolute values of the ASP test, ADP test, and TRAP test. In addition, no significant differences were found between the 3 groups for CPK, creatine kinase‐MB, aspartate aminotransferase, alanine aminotransferase, γ‐glutamyl transferase, and cholesterol levels at baseline and after statin LD.

Table 1.

Clinical and angiographic characteristics of study patients

	Group A, n = 48	Group B, n = 48	Group C, n = 49	P Value
Sex, M/F	39/9	35/13	36/13	0.988
Age, y	68.5 ± 9.4	68.0 ± 9.21	68.0 ± 8.2	0.401
Statin‐naïve patients	15 (30)	21 (43)	15 (31)	0.552
Statin low‐dose patients	34 (70)	27 (57)	33 (69)	0.304
DAPT for >1 mo	41 (85)	41 (85)	40 (82)	0.900
Mean DAPT period, d	56 ± 14	56 ± 14	56 ± 14	—
DM	17 (35)	15 (31)	14 (29)	0.301
HTN	33 (68)	33 (68)	37 (75)	0.700
Dyslipidemia	32 (67)	36 (75)	34 (69)	0.223
Smoker	8 (17)	7 (15)	9 (18)	0.854
Former smoker	15 (31)	16 (33)	13 (26)	0.345
Chronic renal failure 1	3 (6)	3 (6)	4 (8)	0.103
Previous MI	14 (29)	14 (29)	10 (20)	0.080
Previous PCI	28 (58)	22 (46)	25 (51)	0.099
Previous CABG	5 (11)	5 (11)	5 (10)	—
Multivessel coronary disease	22 (45)	24 (50)	24 (49)	0.888
Previous PCI	25 (52)	26 (54)	28 (57)	0.300
Multivessel PCI	5 (11)	1 (2)	6 (12)	0.080
Lesion location
LAD	15 (31)	12 (25)	7 (14)	0.004
LCx	5 (11)	3 (6)	9 (18)	0.005
Left main	2 (4)	0 (0)	0 (0)	0.064
RM	6 (13)	1 (2)	12 (24)	<0.0001
Saphenous vein graft	1 (2)	2 (4)	0 (0)	0.063
Marginal/diagonal branch	1 (2)	1 (2)	1 (2)	—
Stent type
BMS	0 (0)	0 (0)	0 (0)	—
DES	25 (52)	25 (52)	28 (57)	0.076
Bioabsorbable stent	0 (0)	1 (2)	0 (0)	—
Drug therapy at admission
β‐Blocker	33 (68)	33 (68)	37 (75)	0.700
CCB	16 (33)	15 (31)	13 (26)	0.345
Long‐acting nitrates	3 (6)	3 (6)	4 (8)	0.103
ACEI	24 (50)	22 (45)	24 (49)	0.888
ARB	1 (2)	5 (11)	6 (12)	0.080
OAC therapy (warfarin)	1 (2)	1 (2)	1 (2)	—

Abbreviations: ACEI, angiotensin‐converting enzyme inhibitor; ARB, angiotensin II receptor blocker; BMS, bare‐metal stent; CABG, coronary artery bypass grafting; CCB, calcium channel blocker; DAPT, dual antiplatelet therapy; DES, drug‐eluting stent; DM, diabetes mellitus; eGFR, an estimated glomerular filtration rate; F, female; HTN, hypertension; LAD, left anterior descending artery; LCx, left circumflex artery; M, male; MI, myocardial infarction; OAC, oral anticoagulant; PCI, percutaneous coronary intervention; RM, right main coronary artery; SD, standard deviation.

Data are presented as n (%) or mean ± SD unless otherwise specified.

¹Chronic renal failure was defined as eGFR <60 mL/min/1.73 m².

Figure 2.

Platelet reactivity before (pre) and after (post) statin LD. Abbreviations: ADP, adenosine diphosphate; ASP, aspirin‐sensitive platelet reactivity; AUC, area under the curve; LD, loading dose; TRAP, thrombin receptor agonist peptide.

The prespecified subanalysis, between statin‐naïve patients (n = 51) and those chronically treated with low‐dose statins (n = 94), showed no significant differences in terms of age, sex, body mass index, and major cardiovascular risk factors. At baseline, a statistically significant difference was found only in terms of platelet aggregation to the ADP test, which was lower in patients chronically treated with low‐dose statins (15.32 ± 1.50 vs 18.59 ± 1.30; P = 0.007; Figure 3). After statin LD, we did not find any differences in platelet reactivity compared with baseline in each subgroup (Table 2).

Figure 3.

Platelet reactivity evaluated at baseline in patients chronically treated with low‐dose statin (Low‐D) and in patients who were not treated with statin (naïve). Abbreviations: ADP, adenosine diphosphate; ASP, aspirin‐sensitive platelet reactivity; TRAP, thrombin receptor agonist peptide.

Table 2.

Platelet aggregation in statin‐naïve patients and in low‐dose statin patients before (pre) and after (post) statin LD

	ASP		P Value	ADP		P Value	TRAP		P Value
	Pre‐LD	Post‐LD		Pre‐LD	Post‐LD		Pre‐LD	Post‐LD
Chronic low‐dose statin patients, n = 94	10.23 ± 1.58	9.07 ± 1.08	0.301	15.16 ± 1.20	17.70 ± 1.38	0.095	67.62 ± 4.83	72.10 ± 4.02	0.123
Statin‐naïve patients, n = 51	9.13 ± 1.49	8.97 ± 1.20	0.988	18.59 ± 1.30	16.96 ± 2.10	0.347	66.02 ± 4.90	68.87 ± 5.79	0.502

Abbreviations: ADP, adenosine diphosphate; ASP, aspirin‐sensitive platelet reactivity; LD, loading dose; TRAP, thrombin receptor agonist peptide.

4. DISCUSSION

The main result of this randomized trial is that both an LD of atorvastatin (80 mg) and rosuvastatin (40 mg) did not confer acute variation on platelet reactivity when administered in CSA patients with baseline reduced platelet reactivity as in chronic DAPT according to the study protocol definition. This negative observation leads to 3 main considerations.

First of all, the most important novelty of the present study is that LD of statins in CSA patients (independently of whether CYP3A‐metabolized statin or not) does not induce acute variation on platelet reactivity in patients with baseline reduced platelet reactivity. According to our results, in CSA patients with reduced platelet reactivity on DAPT, any additional benefit on platelet function cannot to be expected after an LD of statins. For this reason, we can speculate that other non–platelet‐mediated mechanisms can improve patients’ clinical outcome during PCI after a reloading dose of statin, as previously reported in the ARMYDA‐RECAPTURE trial.6 In the present study, the selection of clinically stable patients before PCI was done to minimize the confounding influence from an acute atherothrombotic condition and/or invasive interventions. Moreover, the observation that only 4% of eligible patients had HPR is strongly indicative of a stable patient population (usually at a low risk and with low HPR), accordingly with the narrow inclusion criteria. Even if this 4% seems too low, it was reported in different studies a so wide prevalence of HPR, which can range between 5% up to 25%, accordingly with the variability of patient selection.15, 16, 17 In addition, this low percentage of HPR also can be justified by 2 other possible considerations: >80% of patients were chronically treated with clopidogrel,18 and many of our patients had already been tested to see if they are low responders to clopidogrel during a previous hospital stay, and therefore were excluded because they were treated with other antiplatelet drugs.

Second, our result further contributes to the debate about possible drug‐to‐drug interference in patients receiving clopidogrel treated with atorvastatin, which may inhibit the CYP3A4 enzyme and therefore decrease the formation of the active metabolite of clopidogrel. Our data, focused on the acute term, are in agreement with the PEARL study,10 which shows, over the long term (1 month), that a maintenance dose of atorvastatin does not negatively affect DAPT as compared with rosuvastatin when administrated to CSA patients with normal platelet aggregability, as also observed by other authors.18, 19 Instead, opposite results were reported in the Accelerated Platelet Inhibition by Switching From Atorvastatin to a Non–CYP3A4‐Metabolized Statin in Patients With High Platelet Reactivity (ACCEL) study,9 in which switching from atorvastatin to a non‐CYP3A4‐metabolized statin (rosuvastatin and pravastatin) resulted in significant decrease in platelet aggregability. In addition, the Pharmacodynamic Comparison of Pitavastatin Versus Atorvastatin on Platelet Reactivity in Patients With Coronary Artery Disease Treated With Dual Antiplatelet Therapy (PORTO) trial showed that the use of pitavastatin for 30 days is associated with improved rates of optimal clopidogrel response as compared with atorvastatin, mainly in patients showing HPR (PRU > 208) while on DAPT.20 However, both the ACCEL and PORTO studies included patients with HPR, and, therefore, a completely different condition was evaluated compared with the STATIPLAT and PEARL studies. All these data lead us to conclude that statins have no effect on platelet aggregation in patients without baseline HPR regardless of the length of therapy, whereas a positive effect can be observed with less lipophilic statins (non–CYP3A4‐metabolized) when administered in patients with baseline HPR. More recently, the Simultaneous Administration of High‐Dose Atorvastatin and Clopidogrel Does Not Interfere With Platelet Inhibition During Percutaneous Coronary Intervention (ESTATE) trial21 showed that, at the time of PCI, high‐dose atorvastatin does not significantly alter platelet inhibition also after simultaneous administration with clopidogrel LD.

Third, we confirm that chronic concomitant treatment with low‐dose statins and clopidogrel results in an improved platelet inhibition when compared with clopidogrel given alone (statin‐naïve patients), as previously reported.7, 19, 22

According to the literature, statins have antiaggregatory effects beyond the lipid‐lowering effect.2, 3 Statins may inhibit platelets directly via yet‐unknown mechanisms, possibly in relation to the regulation of the PAR‐1 thrombin receptors.22 In the present study, we tested 3 different agonists in patients before and after 12 hours of a statin LD. Specifically, the TRAP test was utilized as an internal control to assess the correct functioning of this methodology. The TRAP test stimulates platelet reactivity via the thrombin receptor PAR‐1, which is not affected by the presence of DAPT (aspirin and clopidogrel). Because the platelet response to TRAP is independent of the capacity of platelets to generate TxA2 well as the PY12 receptor, the lack of alteration of platelet response to TRAP after statins indicates that treatment with statins not commits platelet functionality.

4.1. Study limitations

Our data should be interpreted with some limitations in mind. First, only the Multiplate assay was used to evaluate platelet aggregability. Second, the study had an open‐label design, even if patients were randomized through a preformed list. Third, the relatively small sample size does not allow for definite conclusions regarding the biological link between platelet reactivity and statin therapy in CSA patients. Moreover, assessing platelet function 12 hours after a statin LD is far too soon to evaluate pleiotropic effects resulting from chronic treatment with high‐dose statin. Finally, given the pilot nature of the STATIPLAT study, another study will be useful to evaluate and confirm the effect of statin LD in CSA DAPT‐naïve patients and to evaluate clinical endpoints.

5. CONCLUSION

An LD of atorvastatin (80 mg) or rosuvastatin (40 mg) did not confer acute variation on platelet reactivity when administrated to CSA patients with baseline normal platelet aggregability while on chronic DAPT.

Conflicts of interest

The authors declare no potential conflicts of interest.

Godino C, Pavon AG, Mangieri A, et al. Platelet reactivity in response to loading dose of atorvastatin or rosuvastatin in patients with stable coronary disease before percutaneous coronary intervention: The STATIPLAT randomized study. Clin Cardiol. 2017;40:605–611. 10.1002/clc.22709