Strategy for Unstable Coronary Plaque in Patients Presenting to Emergency Department for Chest Pain Suspected of Coronary Artery Disease

Overview

Primary prevention of coronary disease and especially its major complication, inaugural myocardial infarction, is based on any prodromal symptoms identification and on risk profile establishment. About 50% of myocardial infarctions are caused by an unstable non-stenosing plaque, asymptomatic before the event since without significant reduction in coronary flow, particularly during a stress test or during stress imaging. Study purpose is to set up, in medical emergency department, check-up unit and cardiology department, a primary prevention strategy articulated around a routine examination: calcium scoring. The latter makes it possible to categorize patients according to their risk of generating atheromatous plaques and to classify them into several risk levels (groups) according to their score: low (\<40th percentile), intermediate (between the 40th percentile and the 65th percentile: group III) or high risk (\>65th percentile, group IV). 18F-Na PET scan can mark unstable coronary plaques. For the intermediate risk population who would demonstrate within 6 to 18 months after first calcium score either an increase of percentile of more than 20% or an increase above 20 points of the calcium score and for high risk population, 18F-Na PET scan will be recommended and repeated 6 months later. Secondary prevention treatment will then be administered in the event of an abnormal examination.

The purpose of this protocol is to determine the frequency and the mapping of unstable coronary plaques highlighted by 18F-Na PET in patients at intermediate and high risk, as well as their evolution under treatment. Aside from traditional risk factors collection and related biological assessments, risk establishment is based on calcium score, a simple non-injected and very little irradiating scanner which measures coronary calcifications, stigmata of healed atheroma plaques and, as a rule, non-evolving. Calcium score, which is interpreted according to age, sex and ethnicity, therefore makes it possible to assign a percentile within the distribution of all the patients and to classify patients in: * Group I: "absence of atheromatous plaques": Score 0 * Group II: patients generating few plaques (low risk): calcium score above zero and classifying the patient below the 40th percentile of a similar population; * Group III: patients generating moderate plaques (intermediate risk) with a calcium score classifying the patient equal or above the 40th percentile and less than the 65th percentile; * Group IV: patients generating a lot of plaques (high risk): calcium score classifying the patient equal or above the 65th percentile. These are more likely to be patients who will come from the cardiology / check-up sector because of a higher probability of symptoms or of already being treated for primary prevention. Study assumptions are: * apart from any hemodynamically significant coronary stenosis, the instability of a plaque can lead to symptomatic but transient micro-thrombotic phenomena which are spontaneously (or under the effect of an anti-aggregation/anticoagulation) resorbable. Regardless of this plaque fate (most frequently scarring, with calcifications, or much more rarely inaugural acute coronary syndrome and therefore infarction), it is a major coronary event which must switch the patient from primary prevention to secondary prevention; * on painful thoracic syndromes that are sufficiently suggestive to require immediately to rule out an acute coronary syndrome or secondarily myocardial ischemia (angina), identifying a rapid progression of the coronary involvement (on the basis of calcium score) or the direct demonstration of plaque instability (by 18F-Na coupled with a CT scan) is a major cardiovascular prevention endpoint; * in patients consulting for this clinical presentation, determining the frequency of those with rapid coronary evolution and/or instability of coronary plaque(s) represents a fundamental preliminary epidemiological study to modify prevention approach of primary coronary artery disease; * the evaluation by non-invasive coronary imaging of secondary prevention treatment impact on these same patients initially diagnosed as "rapidly progressive" and/or unstable would make it possible to consolidate this strategy if it proves to be effective on the basis of plaque images and clinical follow-up (in terms of events).