Gideon Paul

Multicontrast late gadolinium enhancement imaging enables viability and wall motion assessment in a single acquisition with reduced scan times.

To determine the accuracy of multicontrast late enhancement imaging (MCLE) in the assessment of myocardial viability and wall motion compared to the conventional wall motion and viability cardiac magnetic resonance imaging (MRI) pulse sequences.

Magnetic resonance estimates of the extent and heterogeneity of scar tissue in ICD patients with ischemic cardiomyopathy predict ventricular arrhythmia

BACKGROUND The majority of patients receiving implantable cardioverter-defibrillator (ICD) implantation under current guidelines never develop sustained ventricular arrhythmia; therefore, better markers of risk for sustained ventricular tachycardia and/or ventricular fibrillation are needed. OBJECTIVE The purpose of this study was to identify cardiac magnetic resonance arrhythmic risk predictors of ischemic cardiomyopathy before ICD implantation. METHODS Forty-three subjects (mean age, 64.5 ± 11.9 years) with previous myocardial infarction who were referred for ICD implantation were evaluated by cardiac magnetic resonance imaging (MRI). The MRI protocol included left ventricular functional parameter assessment using steady-state free precession and late gadolinium enhancement MRI using inversion recovery fast gradient echo. Left ventricular functional parameters were measured using cardiac magnetic resonance software. Subjects were followed up for 6-46 months, and the events of appropriate ICD treatments (shocks and antitachycardia pacing) were recorded. RESULTS Twenty-eight patients experienced 46 spontaneous episodes during a median follow-up duration of 30 months. The total myocardial infarct (MI) size (18.05 ± 11.44 g vs 38.83 ± 19.87 g; P = .0006), MI core (11.63 ± 7.14 g vs 24.12 ± 12.73 g; P = .0002), and infarct gray zone (6.43 ± 4.64 g vs 14.71 ± 7.65 g; P = .0004) were significantly larger in subjects who received appropriate ICD therapy than in those who did not experience an episode of ventricular tachycardia and/or ventricular fibrillation. Multivariate regression analyses for the infarct gray zone and MI core adjusted for New York Heart Association class, diabetes, and etiology (primary or secondary prevention) revealed that the gray zone and MI core were predictors of appropriate ICD therapies (P = .0018 and P = .007, respectively). CONCLUSION The extent of MI scar may predict which patients would benefit most from ICD implantation.

Papillary muscle involvement in myocardial infarction: Initial results using multicontrast late‐enhancement MRI

We hypothesized that multicontrast late‐enhancement (MCLE) MRI would improve the identification of papillary muscle involvement (PM‐MI) in patients with myocardial infarction (MI), compared with conventional late gadolinium enhancement (LGE) MRI using the inversion recovery fast gradient echo (IR‐FGRE) technique. Cardiac LGE‐MRI studies using both MCLE and IR‐FGRE pulse sequences were performed on a 1.5 Tesla (T) MRI system in 23 patients following MI. In all patients, PM‐MI was confirmed by the diagnostic criteria as outlined below: (a) the increased signal intensity of PM was the same or similar to that of adjacent hyper‐enhanced left ventricular (LV) infarct segments; and (b) the hyper‐enhanced PM region was limited to the PM area defined by precontrast cine images of steady‐state free precession (SSFP). Visual contrast score was rated according to the differentiation between LV blood pool and hyper‐enhanced infarct myocardium. Quantitative contrast‐noise ratios (CNR) of infarct relative to blood pool and viable myocardium were also measured on MCLE and IR‐FGRE images. Of these 23 patients, 13 studies demonstrated primarily involvement of the territories of the right coronary (RCA, 8 patients) and/or left circumflex (LCX, 5 patients) arteries and 10 involved the territories of left anterior descending artery (LAD) with some LCX involvement. Although both IR‐FGRE and MCLE determined the presence and extent of LV MI, better visual contrast scores were achieved in MCLE (2.9 ± 0.3) compared with IR‐FGRE (1.6 ± 0.8, P < 0.001). The CNRs of infarct relative to LV blood pool showed a significant statistical difference (n = 23, P < 0.00001) between MCLE (16.2 ± 7.2) and IR‐FGRE images (4.8 ± 4.1), which is consistent with the result of visual contrast scores between infarct and LV blood pool. The CNRs of infarct versus viable myocardium did not demonstrate a significant statistical difference (n = 23, P = 0.61) between MCLE (14.4 ± 7.0) and IR‐FGRE images (13.6 ± 6.1). MCLE clearly demonstrated PM‐MI in all cases (100%, 23/23) while only 39% ( 9/23 ) could be visualized on the corresponding IR‐FGRE images. In conclusion, MCLE imaging provides better contrast between blood pool and infarct myocardium, thus improving the determination of PM‐MI. J. Magn. Reson. Imaging 2011;33:211–216.

The Effect of Percutaneous Coronary Intervention of Chronically Totally Occluded Coronary Arteries on Left Ventricular Global and Regional Systolic Function

BACKGROUND Percutaneous coronary intervention (PCI) is frequently attempted to open chronic total occlusions (CTOs) and restore epicardial coronary flow. Data suggest adverse outcomes in the case of PCI failure. We hypothesized that failure to open a CTO might adversely affect regional cardiac function and promote deleterious cardiac remodelling, and success would improve global and regional cardiac function assessed using cardiac magnetic resonance and velocity vector imaging. METHODS Thirty patients referred for PCI to a CTO underwent cardiac magnetic resonance examination before and after the procedure. Left ventricular function and transmural extent of infarction was assessed in these patients. Regional cardiac function using Velocity Vector Imaging version 3.0.0 (Siemens) was assessed in 20 patients. RESULTS Successful CTO opening (thrombolysis in myocardial infarction 3 flow) occurred in 63% of patients. Left ventricular ejection fraction significantly increased after successful PCI (50 ± 13% to 54 ± 11%; P < 0.01). Global longitudinal strain (GLS) fell significantly in the failed group (Δ = -25 ± 17%; P = 0.02) in contrast with successful PCI in which GLS did not change (Δ 20 ± 32%; P = 0.17). GLS rate followed a pattern similar to GLS (failed, Δ -30 ± 17%; P < 0.01 vs success Δ 25 ± 48%; P = 0.34). In contrast, radial and circumferential strain/strain rate were not different between groups after success/failed PCI. CONCLUSIONS Regional cardiac function assessment using velocity vector imaging showed a significant decline in GLS and GLS rate in patients in whom PCI failed to open a CTO, with no change in global measures of cardiac function.

31 Assessment of left ventricular function with cardiac MRI after percutaneous coronary intervention for chronic total occlusion

Objective To assess the role of CMR in the treatment of true chronic total occlusions (CTO) with percutaneous coronary intervention (PCI) and drug eluting stent implantation. Introduction Successful PCI for CTO may confer an improved prognosis and a reduction in major adverse cardiac events (MACE). However most trials have included occlusions of short duration (less than 4 weeks). In this study we assessed the impact of PCI on LV function in patients with true CTOs (TIMI flow grade 0 and greater than 12 weeks duration) using serial CMR imaging as well as the predictive value of late gadolinium enhancement when performed prior to revascularisation. Methods Thirty patients referred for PCI to a single vessel CTO underwent CMR examination prior to and 6 months after PCI. Technical success was defined as recanalisation of the occluded vessel and DES implantation with a final residual diameter stenosis <30%. LV function and infarct size were assessed using a 1.5T GE MRI system. Segmental wall thickening (SWT) was measured within the perfusion territory of the CTO using the 16-segment model and segments were dysfunctional if the SWT was ≤45%. The transmural extent of infarction (TEI) was calculated by dividing the hyperenhanced area by the total area×100; a score of ≤25% were considered viable. Results Technical success was achieved in 19 of the 30 patients (63%). CTO duration was greater in patients with failed revascularisation but other baseline demographics were well matched between groups (Abstract 31 table 1). PCI-CTO success resulted in a significant increase in LVEF when compared to both baseline (50±13 vs 54±11; p<0.01) and with PCI-CTO failure (11.8±19.8 vs -2.3±5.1, p<0.01, Abstract 31 figure 1). In dysfunctional but viable segments only PCI success conferred a significant improvement in SWT compared to baseline (26±6 vs 40±10; p<0.001, Abstract 31 figure 2). There were no episodes of MACE in either group at 21 months follow-up.Abstract 31 Table 1 Total (n=30) CTO-PCI Success (n=19) CTO-PCI Failure (n=11) p value Age/ years 62.2±10.2 62.4±9.8 61.8±11.4 0.89 Male, n (%) 25 (83) 14 (74) 11 (100) 0.13 CCS Anginal Class 2.13±0.68 2.21±0.63 2.0±0.77 0.42 LVEF/ % 53.0±11.6 50.3±12.6 57.6±8.1 0.09 CTO duration, months 36.9±70.8 12.6±26.4 78.8±101.1 0.01 Vessel, n (%) RCA 16 (53) 9 (47) 7 (64) 0.35 LAD 11 (37) 7 (37) 4 (36) LCx 3 (10) 3 (16) 0 Prior MI, n (%) 17 (59) 11 (58) 6 (56) 0.61 Diabetes Mellitus, n (%) 7 (23) 5 (26) 2 (18) 0.61 Hypertension 23 (77) 14 (74) 9 (82) 0.61Abstract 31 Figure 1 Abstract 31 Figure 2 Conclusion PCI-CTO success of true CTOs can improve global LV function. The TEI, assessed with CMR, can be used to help predict improvements in regional wall function. PCI-CTO failure was not associated with increased MACE at medium-term follow-up.

Characterizing myocardial edema and hemorrhage using T2, T2*, and diastolic wall thickness post acute myocardial infarction

Methods Patients were enrolled post AMI (creatine kinase >500 IU/ L) and underwent CMR on a GE Signa Excite, 1.5 T scanner with a 8-channel receive coil at 48 hours and 3 weeks post MI. T2 maps were computed from a previously validated cardiac-gated spiral imaging sequence with T2 preparations yielding TEs = 2.9, 24.3, 88.2, 184.2 ms to assess myocardial edema. The T2* sequence was a multiecho acquisition with 8 echoes (between 1.4 and 12.7 ms) acquired at TR = 14.6 ms. T2-weighted imaging using a breath-hold triple IR fast spin echo sequence and delayed hyperenhancement (DHE) were also performed.

CMR measurements of myocardial infarct heterogeneity using MCLE and IR-FGRE: correlation with arrhythmia inducibility and severe ICD events in patients with ischemic heart disease

Summary This study used CMR to evaluate patients with IHD prior to ICD implantation and correlated CMR measurements to VA inducibility and spontaneous VA events during follow-up. The results demonstrated that the gray-zone measurement using MCLE may be more sensitive in predicting appropriate ICD therapy for VA. Background In addition to measures of left ventricular ejection fraction (LVEF) and clinical staging of heart failure, myocardial infarct (MI) heterogeneity including MI and periinfarct gray-zone (GZ) has the potential to predict the occurrence of inducible sustained ventricular arrhythmia (VA) and spontaneous VA events after implantation of implantable defibrillator (ICD) in patients with ischemic heart disease (IHD). Late-gadolinium (Gd)-enhancement (LGE) cardiac MR (CMR) using inversion-recovery fastgradient-echo (IR-FGRE) is commonly used for the determination of infarct heterogeneity in these patients. Recently, a multi-contrast late-enhancement (MCLE) sequence has been developed for better infarct heterogeneity quantification. Compared to IR-FGRE, we hypothesized that MCLE may be a more sensitive method to predict the occurrence of inducible VA and severe events post-ICD implantation. Methods This study used CMR to evaluate patients with IHD prior to ICD implantation and correlated CMR measurements to VA inducibility and spontaneous VA events during follow-up. The MRI protocol included LV functional parameter assessment using steady-state free precession (SSFP), as well as LGE-MRI using IR-FGRE and MCLE post double-dose Gd injection. LV functional parameters were measured using Q-Mass or CMR42 software. The GZ analysis in IR-FGRE used a full-width half-maximum method. For MCLE, GZ analysis used a semi-automated data clustering algorithm. An unpaired t-test with unequal variance was used for the statistical analysis of the proportion of GZ, MI core and total MI relative to LV myocardium mass. Results

Impact of successful and failed revascularization of chronic total occlusion on left ventricular function and infarct size

Introduction Non-randomised studies have reported a prognostic advantage with percutaneous coronary intervention (PCI) in the treatment of chronic total occlusions (CTO). Failure to cross and successfully open a CTO confers a worse clinical outcome, however most trials have included occlusions of short duration (7-30 days). PCI success rates are inversely related to the age of vessel occlusion reflecting temporal, cellular changes within a CTO, namely progressive collagen deposition.

Relationship between infarct gray zone and characteristics of ventricular tachycardia using multi-contrast delayed enhancement: preliminary results

Introduction: A myocardial infarct (MI) is comprised of a central fibrous scar which may be surrounded by a heterogeneous region of viable and non-viable myocytes. This heterogeneous region, or the “gray zone”, as detected by delayed enhancement cardiac MRI has been shown to correlate with all-cause post-infarct mortality and inducibility for ventricular tachycardia (VT). We have recently shown that the quantification of the gray zone using the conventional inversion-recovery gradient echo (IR-GRE) sequence is sensitive to image noise and to the accuracy of the required manual contours of the blood pool. A new multi-contrast delayed enhancement (MCDE) sequence has been developed that provides images at multiple inversion times (TI) in a single breath-hold; an automated analysis of MCDE images has been shown to provide a more robust measure of the gray zone. In this study, preliminary results in patients are presented examining the relationship between the extent of the gray zone (measured with IR-GRE and MCDE methods) and inducibility of VT as well as VT cycle length.