Background:
Cardiovascular diseases (CVD) are the main cause of mortality in developed countries; its prevention is challenging. Advances in molecular imaging of the atherosclerotic plaque enhanced the study of its pathophysiology, including the positron emission tomography with computed tomography (PET-CT) scan. The marker 18F-sodium fluoride (NaF) has been studied in peripheral arteries plaque imaging as an in vivo marker of on-going calcification. The 18F ions deposit in the bone by exchange of hydroxyl group on the surface of the hydroxyapatite matrix to form fluoroapatite, so this tracer detects areas of active calcification and osteogenic remodeling. Coronary imaging with 18F-NaF labelled PET-CT was recently described and proposed to be able to discriminate between active and inactive coronary calcification, possibly identifying high-risk patients.
Statin therapy is approved for primary and secondary CVD prevention due to both its cholesterol-lowering effect and positive pleiotropic properties in the plaque. In particular, rosuvastatin diminishes mortality and vascular events when used in primary and secondary prevention. High doses of rosuvastatin resulted in atherosclerosis regression as assessed with coronary intravascular ultrasound, carotid intima-media thickness (CIMT) and lipid content reduction of the atherosclerotic plaque (near-infrared spectroscopy analysis).
We do not know the effects of statins in the 18F-NaF uptake.
Design:
Investigator's initiative prospective study of 18F-NaF-PET-CT coronary, aortic and carotid plaques imaging in primary prevention subjects, with a before and after experiment with rosuvastatin treatment and long-term follow-up. The protocol was approved by the Ethics Committee of Faculty of Medicine of the University of Coimbra and written according to Good Clinical Practice and the Declaration of Helsinki.
Taks:
1. Screening - visit 0:
Patients followed at the Arterial Hypertension clinic of Centro Hospitalar e Universitário de Coimbra will be screened and selected if they meet all of the inclusion criteria.
2. Baseline assessment:
Clinical questionnaire and standard physical examination. CV risk will be estimated according to SCORE equations and the American Heart Association atherosclerotic cardiovascular disease calculator. Patients' medical history and CV risk factors will be recorded, as well as physical examination findings, including age, race, gender, smoking status (current, past, quantification with pack-years), diabetes mellitus (type 1, 2, pre- diabetes), family history of premature coronary heart disease (first degree: men \< 55 and women \< 65 years old), relevant past medical history, blood pressure, heart rate, weight and height. Levels of total cholesterol, high and low-density lipoprotein cholesterol (HDL and LDL), triglycerides, creatinine, creatine kinase, alanine amino-transferase, aspartate amino- transferase, gamma-glutamyl transpeptidase, alkaline phosphatase, glycated hemoglobin, fasting glucose, high-sensitivity C-reactive protein and haemoglobin will be determined.
3. Baseline 18F-NaF labelled PET-CT - visit 1:
Patients will undergo whole body 18F-NaF-PET-CT for identification of coronary, carotid, thoracic and abdominal aorta arteries plaques and quantification of 18F-NaF uptake (tissue-to-background ratio (TBR)). Scans will be reviewed and analysed by experienced observers blinded to the clinical diagnosis. Subjects without 18F-NaF-positive plaques will be excluded from the pharmacological intervention study.
4. Rosuvastatin treatment:
At visit 1, patients with 18F-NaF-positive plaques will be treated with 20 mg of rosuvastatin daily for six months, except in patients who need a 55% LDL reduction to achieve recommended targets (rosuvastatin 40 mg).
5. Second 18F-NaF labelled PET-CT - visit 3:
Subjects will undergo a second PET-CT scan six months after statin treatment to assess changes in 18F-NaF plaque uptake. Medication compliance will be monitored, as well as adverse events reporting.
Statistical analysis:
18F-NaF uptake after rosuvastatin treatment will be compared to baseline values with paired samples T student test or Wilcoxon text according to the normality of the distribution. Sample size was estimated according to the preliminary results of 25 subjects (pilot study) and the primary endpoint of reducing maximum 18F-NaF uptake as assessed by TBR. Individuals with no significant 18F-NaF uptake were excluded from this analysis (n=4): mean TBR 2.16 and SD 0.40. At 90% power and a significance level of 0.05, assuming a correlation of 0.8 and 10% difference in TBR, the calculated sample size is 32. As only 21 out of 25 subjects in the pilot study displayed criteria for the pharmacological study, it is necessary to perform 44 baseline studies, followed by 36 subjects re-evaluation (drop-out margin of 4 subjects), totaling 80 PET-CT scans.
