Iron-Sensitive Cardiac Magnetic Resonance Imaging for Prediction of Ventricular Arrhythmia Risk in Patients With Chronic Myocardial Infarction

Abstract

BACKGROUND Recent canines studies have shown that iron deposition within chronic myocardial infarction (CMI) influences the electrical behavior of the heart. To date, the link between the iron deposition and malignant ventricular arrhythmias (mVA) in humans with CMI is unknown. METHODS AND RESULTS CMI patients (n=94) who underwent late-gadolinium-enhanced CMR prior to ICD implantation for primary and secondary prevention were retrospectively analyzed. The predictive values of hypointense cores (HIC) in balanced steady-state free precession (bSSFP) images and conventional CMR and ECG mVA parameters for the prediction of primary combined outcome (appropriate ICD therapy, survived cardiac arrest or sudden cardiac death) were studied. The use of HIC within CMI on bSSFP as a marker of iron deposition was validated in a canine MI model (n=18). Nineteen patients met the study criteria with events occurring at a median of 249 (interquartile range (IQR) of 540) days after ICD placement. Of the 19 patients meeting the primary endpoint, 18 were classified as HIC+, while only 1 was HIC−. Among the cohort in whom the primary endpoint was not met, there were 28 HIC+ and 47 HIC− patients. ROC analysis demonstrated an additive predictive value of HIC for mVAs with an increased AUC to 0.87 when added to LVEF (LVEF alone 0.68). Both CMR and histological validation studies performed in canines demonstrated that HIC regions in bSSFP images within CMI likely result from iron depositions. CONCLUSIONS Hypointense cores within CMI on bSSFP CMR can be used as a marker of iron deposition and yields incremental information toward improved prediction of mVA.

Cardiovascular Magnetic Resonance in Acute ST-Segment–Elevation Myocardial Infarction

“…Furthermore, residual myocardial iron as a consequence of intramyocardial hemorrhage has also been shown to be pro-arrhythmic. 105 Although all these were relatively small and single-center studies, CMR has shown promise to improve the risk-stratification of STEMI patients at risk of ventricular arrhythmias. With the availability of inline, automated ECV-mapping 106 and free-breathing T2*-mapping 93 , characterization of the infarct size and peri-infarct zone and infarct core may become more objective and CMR would play an invaluable role to identify those most likely to benefit from a primary prevention ICD in a near future.…”

Recent Advances in Cardiovascular Magnetic Resonance

“…43 In patients with chronic ischemic cardiomyopathy who subsequently received an ICD, early evidence suggests that iron may be a strong predictor of ventricular arrhythmias with a 33-fold increase in odds for a significant arrhythmic event. 44 CMR has revealed hemorrhagic infarction and chronic iron deposition as potentially new physiological mechanisms of heart failure and arrhythmia in CAD.…”

Oxygenation‐sensitive cardiovascular magnetic resonance in hypertensive heart disease with left ventricular myocardial hypertrophy and non‐left ventricular myocardial hypertrophy: Insight from altered mechanics and cardiac BOLD imaging

“…[1][2][3] HTN induces myocardial inflammation, fibrosis, vascular and myocardial remodeling. 4,5 A paramagnetic effect can be observed by the iron deposits (e.g., intramyocardial hemorrhage of myocardial infarction, 6,7 iron overload of hemochromatosis and thalassemia, [8][9][10] and the net or relative increase of deoxygenated hemoglobin [compared with oxygenated hemoglobin] in the capillary blood, which ultimately shortens the T2* relaxation times, measured using BOLD (blood oxygen level dependent) MRI. 11,12 BOLD MRI can detect regional condition of myocardial oxygen supply and demand by means of paramagnetic properties.…”