Impact of Long-Term Statin Pretreatment on Myocardial Damage in ST Elevation Myocardial Infarction (from the AIDA STEMI CMR Substudy)




Nonrandomized studies suggested lower mortality rates with statin pretreatment in patients with acute ST elevation myocardial infarction (STEMI). However, clinical data are still inconclusive and the mechanisms of these presumed beneficial effects require further exploration. Cardiac magnetic resonance (CMR) imaging offers the possibility of studying a variety of markers of myocardial damage and reperfusion injury after myocardial infarction. The aim of this study was to assess a possible link of statin pretreatment with myocardial damage in acute STEMI. The multicenter Abciximab i.v. versus i.c. in ST-elevation Myocardial Infarction CMR substudy enrolled 795 consecutive patients with acute STEMI who underwent primary angioplasty within 12 hours of symptom onset. CMR studies assessing left ventricular ejection fraction, infarct size, microvascular obstruction, area at risk, and myocardial salvage index were performed in a median of 3 days after the clinical event. We performed a retrospective analysis to evaluate the impact of statin pretreatment on myocardial damage. Information on statin pretreatment was available in 791 of 795 patients (99%). Of these, 122 (15%) had long-term statin pretreatment. CMR results showed no significant differences in the area at risk, left ventricular ejection fraction, infarct size, microvascular obstruction, and myocardial salvage index between patients with and without statin pretreatment. Furthermore, no differences in short- and long-term outcomes could be observed. In conclusion, in this CMR study, statin pretreatment in patients with STEMI was not associated with lesser myocardial damage.


Cardiac magnetic resonance (CMR) imaging is the current gold standard in visualization of myocardial damage in acute ST elevation myocardial infarction (STEMI). In addition to infarct size, the myocardial salvage index (MSI) and microvascular obstruction as markers of no reflow and/or reperfusion injury can be directly visualized and exactly quantified. Consequently, CMR may provide further insight into the mechanisms of the presumed beneficial effect of statins in STEMI. We present a large cohort of patients with STEMI to further clarify the role of statin pretreatment on myocardial damage and reperfusion injury assessed by CMR.


Methods


This study is a retrospective subanalysis of the prospective, randomized, multicenter, Abciximab i.v. versus i.c. in ST-elevation Myocardial Infarction (AIDA STEMI) trial. This trial randomized 2,065 patients with STEMI who underwent primary percutaneous coronary intervention to either an intracoronary or intravenous abciximab bolus. The detailed methods and design as well as the main results of the trial have been previously published. Patients were eligible if symptoms lasted <12 hours and if ST-segment elevation of ≥0.1 mV in ≥2 extremity leads or ≥0.2 mV in ≥2 precordial leads was present. In total, 22 centers participated in this study. In 8 of these centers, a CMR substudy was performed including 795 patients. In line with the results of the main clinical trial, no differences in CMR markers of reperfusion success (infarct size, MSI, microvascular obstruction, and intramyocardial hemorrhage) could be observed between groups. The study had been approved by the local ethics committees, and all patients gave written informed consent.


Long-term medication and history were prospectively assessed by a structured interview at admission in every patient, and long-term intake of statins was defined as prescription of statins in long-term medication before the index event. Patients were categorized on the basis of statin pretreatment.


CMR was performed using 1.5- or 3.0-T scanners in 8 centers with proved CMR expertise on days 1 to 10 after the index event using the same protocol. In brief, edema imaging was performed by T2-weighted imaging; cine sequences were used for functional analysis and/or volumes and delayed enhancement imaging for visualization of myocardial necrosis. Image analysis was performed in blinded fashion in a CMR core laboratory located at the University of Leipzig–Heart Center, which has proved excellent reproducibility for infarct size, microvascular obstruction, and MSI assessment in patients with STEMI. All quantitative analyses were assessed with certified CMR evaluation software (cmr 42 ; Circle Cardiovascular Imaging Inc, Calgary, Alberta, Canada).


Infarct size and area at risk were assessed by semiautomated computer-aided threshold detection and are expressed as percentage of left ventricular mass. The following calculations were applied:


Areaatrisk=volumeofedema/volumeofleftventricularmass×100
Area at risk = volume of edema / volume of left ventricular mass × 100

Infarctsize=volumeofinfarct/volumeofleftventricularmass×100
Infarct size = volume of infarct / volume of left ventricular mass × 100

Microvascularobstruction=volumeofmicrovascularobstruction/volumeofleftventricularmass×100
Microvascular obstruction = volume of microvascular obstruction / volume of left ventricular mass × 100

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Dec 1, 2016 | Posted by in CARDIOLOGY | Comments Off on Impact of Long-Term Statin Pretreatment on Myocardial Damage in ST Elevation Myocardial Infarction (from the AIDA STEMI CMR Substudy)

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