Terry Thompson

Prediction of Arrhythmic Events in Ischemic and Dilated Cardiomyopathy Patients Referred for Implantable Cardiac Defibrillator Evaluation of Multiple Scar Quantification Measures for Late Gadolinium Enhancement Magnetic Resonance Imaging

Background— Scar signal quantification using late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) identifies patients at higher risk of future events, both in ischemic cardiomyopathy (ICM) and nonischemic dilated cardiomyopathy (DCM). However, the ability of scar signal burden to predict events in such patient groups at the time of referral for implantable cardioverter-defibrillator (ICD) has not been well explored. This study evaluates the predictive use of multiple scar quantification measures in ICM and DCM patients being referred for ICD. Methods and Results— One hundred twenty-four consecutive patients referred for ICD therapy (59 with ICM and 65 with DCM) underwent a standardized LGE-CMR protocol with blinded, multithreshold scar signal quantification and, for those with ICM, peri-infarct signal quantification. Patients were followed prospectively for the primary combined outcome of appropriate ICD therapy, survived cardiac arrest, or sudden cardiac death. At a mean follow-up of 632 ± 262 days, 18 patients (15%) had suffered the primary outcome. Total scar was significantly higher among those suffering a primary outcome, a relationship maintained within each cardiomyopathy cohort (P<0.01 for all comparisons). Total scar was the strongest independent predictor of the primary outcome and demonstrated a negative predictive value of 86%. In the ICM subcohort, peri-infarct signal showed only a nonsignificant trend toward elevation among those having a primary end point. Conclusions— Myocardial scar quantification by LGE-CMR predicts arrhythmic events in patients being evaluated for ICD eligibility irrespective of cardiomyopathy etiology.

Creatine monohydrate supplementation does not increase muscle strength, lean body mass, or muscle phosphocreatine in patients with myotonic dystrophy type 1.

Creatine monohydrate (CrM) supplementation may increase strength in some types of muscular dystrophy. A recent study in myotonic muscular dystrophy type 1 (DM1) did not find a significant treatment effect, but measurements of muscle phosphocreatine (PCr) were not performed. We completed a randomized, double‐blind, cross‐over trial using 34 genetically confirmed adult DM1 patients without significant cognitive impairment. Participants received CrM (5 g, ∼0.074 g/kg daily) and a placebo for each 4‐month phase with a 6‐week wash‐out. Spirometry, manual muscle testing, quantitative isometric strength testing of handgrip, foot dorsiflexion, and knee extension, handgrip and foot dorsiflexion endurance, functional tasks, activity of daily living scales, body composition (total, bone, and fat‐free mass), serum creatine kinase activity, serum creatinine concentration and clearance, and liver function tests were completed before and after each intervention, and muscle PCr/β‐adenosine triphosphate (ATP) ratios of the forearm flexor muscles were completed at the end of each phase. CrM supplementation did not increase any of the outcome measurements except for plasma creatinine concentration (but not creatinine clearance). Thus, CrM supplementation at 5 g daily does not have any effects on muscle strength, body composition, or activities of daily living in patients with DM1, perhaps because of a failure of the supplementation to increase muscle PCr/β‐ATP content. Muscle Nerve 29: 51–58, 2004

Utility of Cardiovascular Magnetic Resonance in Identifying Substrate for Malignant Ventricular Arrhythmias

Background— Sudden cardiac death (SCD) and sustained monomorphic ventricular tachycardia (SMVT) are frequently associated with prior or acute myocardial injury. Cardiovascular magnetic resonance (CMR) provides morphological, functional, and tissue characterization in a single setting. We sought to evaluate the diagnostic yield of CMR-based imaging versus non–CMR-based imaging in patients with resuscitated SCD or SMVT. Methods and Results— Eighty-two patients with resuscitated SCD or SMVT underwent routine non-CMR imaging, followed by a CMR protocol with comprehensive tissue characterization. Clinical reports of non-CMR imaging studies were blindly adjudicated and used to assign each patient to 1 of 7 diagnostic categories. CMR imaging was blindly interpreted using a standardized algorithm used to assign a patient diagnosis category in a similar fashion. The diagnostic yield of CMR-based and non–CMR-based imaging, as well as the impact of the former on diagnosis reclassification, was established. Relevant myocardial disease was identified in 51% of patients using non–CMR-based imaging and in 74% using CMR-based imaging (P=0.002). Forty-one patients (50%) were reassigned to a new or alternate diagnosis using CMR-based imaging, including 15 (18%) with unsuspected acute myocardial injury. Twenty patients (24%) had no abnormality by non-CMR imaging but showed clinically relevant myocardial disease by CMR imaging. Conclusions— CMR-based imaging provides a robust diagnostic yield in patients presenting with resuscitated SCD or SMVT and incrementally identifies clinically unsuspected acute myocardial injury. When compared with non–CMR-based imaging, a new or alternate myocardial disease process may be identified in half of these patients.

Influence of pacing site characteristics on response to cardiac resynchronization therapy.

Background—Transmural scar occupying left ventricular (LV) pacing regions has been associated with reduced response to cardiac resynchronization therapy (CRT). However, spatial influences of lead tip delivery relative to scar at both pacing sites remain poorly explored. This study evaluated scar distribution relative to LV and right ventricular (RV) lead tip placement through coregistration of late gadolinium enhancement MRI and cardiac computed tomographic (CT) findings. Influences on CRT response were assessed by serial echocardiography. Methods and Results—Sixty patients receiving CRT underwent preimplant late gadolinium enhancement MRI, postimplant cardiac CT, and serial echocardiography. Blinded segmental evaluations of mechanical delay, percentage scar burden, and lead tip location were performed. Response to CRT was defined as a reduction in LV end-systolic volume ≥15% at 6 months. The mean age and LV ejection fraction were 64±9 years and 25±7%, respectively. Mean scar volume was higher among CRT nonresponders for both the LV (23±23% versus 8±14% [P=0.01]) and RV pacing regions (40±32% versus 24±30% [P=0.04]). Significant pacing region scar was identified in 13% of LV pacing regions and 37% of RV pacing regions. Absence of scar in both regions was associated with an 81% response rate compared with 55%, 25%, and 0%, respectively, when the RV, LV, or both pacing regions contained scar. LV pacing region dyssynchrony was not predictive of response. Conclusions—Myocardial scar occupying the LV pacing region is associated with nonresponse to CRT. Scar occupying the RV pacing region is encountered at higher frequency and seems to provide a more intermediate influence on CRT response.

Stress Hypoperfusion and Tissue Injury in Hypertrophic Cardiomyopathy: Spatial Characterization Using High-Resolution 3-Tesla Magnetic Resonance Imaging

Background— Ischemia and tissue injury are common in patients with hypertrophic cardiomyopathy. Cardiovascular magnetic resonance imaging offers combined evaluations of each phenomenon at sufficiently high resolution to examine transmural spatial distribution. In this prospective cohort study, we examine the spatial distribution of stress perfusion abnormalities and tissue injury in patients with hypertrophic cardiomyopathy. Methods and Results— One hundred consecutive patients with hypertrophic cardiomyopathy underwent cardiovascular magnetic resonance imaging. Cine, stress perfusion, late gadolinium enhancement, and T2-weighted imaging techniques were used. Each was spatially coregistered according to predefined segmental and subsegmental models and was blindly analyzed for abnormalities using validated techniques. Spatial associations among stress perfusion, late gadolinium enhancement, and T2 imaging were made at segmental and subsegmental levels. Of the 100 patients studied, the phenotype was septal in 86 and apical in 14. Late gadolinium enhancement imaging was abnormal in 79 patients (79%). Eighty-six patients met prespecified safety criteria to undergo stress perfusion, and ischemia was identified in 46 patients (57%). T2 imaging was available in 81 patients and was abnormal in 19 (29%). The dominant distribution of all 3 findings was to segment with hypertrophy. Subsegmental analysis revealed geographic dominance of ischemia within the subendocardial zones. However, this zone was most commonly spared from late gadolinium enhancement and T2 abnormalities, typically seen in midwall and subepicardial zones. Conclusions— Inducible hypoperfusion is a common finding in hypertrophic cardiomyopathy and is typically identified within segments exhibiting imaging markers of tissue injury. However, the respective transmural dominance of these phenomena seems distinct. Alternate factors contributing to a regional susceptibility to tissue injury are deserving of further study.Background— Ischemia and tissue injury are common in patients with hypertrophic cardiomyopathy. Cardiovascular magnetic resonance imaging offers combined evaluations of each phenomenon at sufficiently high resolution to examine transmural spatial distribution. In this prospective cohort study, we examine the spatial distribution of stress perfusion abnormalities and tissue injury in patients with hypertrophic cardiomyopathy. Methods and Results— One hundred consecutive patients with hypertrophic cardiomyopathy underwent cardiovascular magnetic resonance imaging. Cine, stress perfusion, late gadolinium enhancement, and T2-weighted imaging techniques were used. Each was spatially coregistered according to predefined segmental and subsegmental models and was blindly analyzed for abnormalities using validated techniques. Spatial associations among stress perfusion, late gadolinium enhancement, and T2 imaging were made at segmental and subsegmental levels. Of the 100 patients studied, the phenotype was septal in 86 and apical in 14. Late gadolinium enhancement imaging was abnormal in 79 patients (79%). Eighty-six patients met prespecified safety criteria to undergo stress perfusion, and ischemia was identified in 46 patients (57%). T2 imaging was available in 81 patients and was abnormal in 19 (29%). The dominant distribution of all 3 findings was to segment with hypertrophy. Subsegmental analysis revealed geographic dominance of ischemia within the subendocardial zones. However, this zone was most commonly spared from late gadolinium enhancement and T2 abnormalities, typically seen in midwall and subepicardial zones. Conclusions— Inducible hypoperfusion is a common finding in hypertrophic cardiomyopathy and is typically identified within segments exhibiting imaging markers of tissue injury. However, the respective transmural dominance of these phenomena seems distinct. Alternate factors contributing to a regional susceptibility to tissue injury are deserving of further study.

Validation of sub-segmental visual scoring for the quantification of ischemic and nonischemic myocardial fibrosis using late gadolinium enhancement MRI

To determine the accuracy and reproducibility of late gadolinium enhancement (LGE) MRI scar quantification using visual sub‐segmental analysis (VSSA) versus signal threshold‐based analysis in ischemic and nonischemic cardiomyopathy.

Validation of a novel modified wall motion score for estimation of left ventricular ejection fraction in ischemic and non-ischemic cardiomyopathy

BACKGROUND Visual determination of left ventricular ejection fraction (LVEF) by segmental scoring may be a practical alternative to volumetric analysis of cine magnetic resonance imaging (MRI). The accuracy and reproducibility of this approach for has not been described. The purpose of this study was to validate a novel segmental visual scoring method for LVEF estimation using cine MRI. METHODS 362 patients with known or suspected cardiomyopathy were studied. A modified wall motion score (mWMS) was used to blindly score the wall motion of all cardiac segments from cine MRI imaging. The same datasets were subjected to blinded volumetric analysis using endocardial contour tracing. The population was then separated into a model cohort (N=181) and validation cohort (N=181), with the former used to derive a regression equation of mWMS versus true volumetric LVEF. The validation cohort was then used to test the accuracy of this regression model to estimate the true LVEF from a visually determined mWMS. Reproducibility testing of mWMS scoring was performed upon a randomly selected sample of 20 cases. RESULTS The regression equation relating mWMS to true LVEF in the model cohort was: LVEF=54.23-0.5761×mWMS. In the validation cohort this equation produced a strong correlation between mWMS-derived LVEF and true volumetric LVEF (r=0.89). Bland and Altman analysis showed no systematic bias in the LVEF estimated using the mWMS (-0.3231%, 95% limits of agreement -12.22% to 11.58%). Inter-observer and intra-observer reproducibility was excellent (r=0.93 and 0.97, respectively). CONCLUSION The mWMS is a practical tool for reporting regional wall motion and provides reproducible estimates of LVEF from cine MRI.

Sci—Thur AM: YIS ‐ 08: Constructing an Attenuation map for a PET/MR Breast coil

In 2013, around 23000 Canadian women and 200 Canadian men were diagnosed with breast cancer. An estimated 5100 women and 55 men died from the disease. Using the sensitivity of MRI with the selectivity of PET, PET/MRI combines anatomical and functional information within the same scan and could help with early detection in high-risk patients. MRI requires radiofrequency coils for transmitting energy and receiving signal but the breast coil attenuates PET signal. To correct for this PET attenuation, a 3-dimensional map of linear attenuation coefficients (μ-map) of the breast coil must be created and incorporated into the PET reconstruction process. Several approaches have been proposed for building hardware μ-maps, some of which include the use of conventional kVCT and Dual energy CT. These methods can produce high resolution images based on the electron densities of materials that can be converted into μ-maps. However, imaging hardware containing metal components with photons in the kV range is susceptible to metal artifacts. These artifacts can compromise the accuracy of the resulting μ-map and PET reconstruction; therefore high-Z components should be removed. We propose a method for calculating μ-maps without removing coil components, based on megavoltage (MV) imaging with a linear accelerator that has been detuned for imaging at 1.0MeV. Containers of known geometry with F18 were placed in the breast coil for imaging. A comparison between reconstructions based on the different μ-map construction methods was made. PET reconstructions with our method show a maximum of 6% difference over the existing kVCT-based reconstructions.

Stress Hypoperfusion and Tissue Injury in Hypertrophic CardiomyopathyClinical Perspective: Spatial Characterization Using High-Resolution 3-Tesla Magnetic Resonance Imaging

Background— Ischemia and tissue injury are common in patients with hypertrophic cardiomyopathy. Cardiovascular magnetic resonance imaging offers combined evaluations of each phenomenon at sufficiently high resolution to examine transmural spatial distribution. In this prospective cohort study, we examine the spatial distribution of stress perfusion abnormalities and tissue injury in patients with hypertrophic cardiomyopathy. Methods and Results— One hundred consecutive patients with hypertrophic cardiomyopathy underwent cardiovascular magnetic resonance imaging. Cine, stress perfusion, late gadolinium enhancement, and T2-weighted imaging techniques were used. Each was spatially coregistered according to predefined segmental and subsegmental models and was blindly analyzed for abnormalities using validated techniques. Spatial associations among stress perfusion, late gadolinium enhancement, and T2 imaging were made at segmental and subsegmental levels. Of the 100 patients studied, the phenotype was septal in 86 and apical in 14. Late gadolinium enhancement imaging was abnormal in 79 patients (79%). Eighty-six patients met prespecified safety criteria to undergo stress perfusion, and ischemia was identified in 46 patients (57%). T2 imaging was available in 81 patients and was abnormal in 19 (29%). The dominant distribution of all 3 findings was to segment with hypertrophy. Subsegmental analysis revealed geographic dominance of ischemia within the subendocardial zones. However, this zone was most commonly spared from late gadolinium enhancement and T2 abnormalities, typically seen in midwall and subepicardial zones. Conclusions— Inducible hypoperfusion is a common finding in hypertrophic cardiomyopathy and is typically identified within segments exhibiting imaging markers of tissue injury. However, the respective transmural dominance of these phenomena seems distinct. Alternate factors contributing to a regional susceptibility to tissue injury are deserving of further study.Background— Ischemia and tissue injury are common in patients with hypertrophic cardiomyopathy. Cardiovascular magnetic resonance imaging offers combined evaluations of each phenomenon at sufficiently high resolution to examine transmural spatial distribution. In this prospective cohort study, we examine the spatial distribution of stress perfusion abnormalities and tissue injury in patients with hypertrophic cardiomyopathy. Methods and Results— One hundred consecutive patients with hypertrophic cardiomyopathy underwent cardiovascular magnetic resonance imaging. Cine, stress perfusion, late gadolinium enhancement, and T2-weighted imaging techniques were used. Each was spatially coregistered according to predefined segmental and subsegmental models and was blindly analyzed for abnormalities using validated techniques. Spatial associations among stress perfusion, late gadolinium enhancement, and T2 imaging were made at segmental and subsegmental levels. Of the 100 patients studied, the phenotype was septal in 86 and apical in 14. Late gadolinium enhancement imaging was abnormal in 79 patients (79%). Eighty-six patients met prespecified safety criteria to undergo stress perfusion, and ischemia was identified in 46 patients (57%). T2 imaging was available in 81 patients and was abnormal in 19 (29%). The dominant distribution of all 3 findings was to segment with hypertrophy. Subsegmental analysis revealed geographic dominance of ischemia within the subendocardial zones. However, this zone was most commonly spared from late gadolinium enhancement and T2 abnormalities, typically seen in midwall and subepicardial zones. Conclusions— Inducible hypoperfusion is a common finding in hypertrophic cardiomyopathy and is typically identified within segments exhibiting imaging markers of tissue injury. However, the respective transmural dominance of these phenomena seems distinct. Alternate factors contributing to a regional susceptibility to tissue injury are deserving of further study.

Stress Hypoperfusion and Tissue Injury in Hypertrophic CardiomyopathyClinical Perspective

Background— Ischemia and tissue injury are common in patients with hypertrophic cardiomyopathy. Cardiovascular magnetic resonance imaging offers combined evaluations of each phenomenon at sufficiently high resolution to examine transmural spatial distribution. In this prospective cohort study, we examine the spatial distribution of stress perfusion abnormalities and tissue injury in patients with hypertrophic cardiomyopathy. Methods and Results— One hundred consecutive patients with hypertrophic cardiomyopathy underwent cardiovascular magnetic resonance imaging. Cine, stress perfusion, late gadolinium enhancement, and T2-weighted imaging techniques were used. Each was spatially coregistered according to predefined segmental and subsegmental models and was blindly analyzed for abnormalities using validated techniques. Spatial associations among stress perfusion, late gadolinium enhancement, and T2 imaging were made at segmental and subsegmental levels. Of the 100 patients studied, the phenotype was septal in 86 and apical in 14. Late gadolinium enhancement imaging was abnormal in 79 patients (79%). Eighty-six patients met prespecified safety criteria to undergo stress perfusion, and ischemia was identified in 46 patients (57%). T2 imaging was available in 81 patients and was abnormal in 19 (29%). The dominant distribution of all 3 findings was to segment with hypertrophy. Subsegmental analysis revealed geographic dominance of ischemia within the subendocardial zones. However, this zone was most commonly spared from late gadolinium enhancement and T2 abnormalities, typically seen in midwall and subepicardial zones. Conclusions— Inducible hypoperfusion is a common finding in hypertrophic cardiomyopathy and is typically identified within segments exhibiting imaging markers of tissue injury. However, the respective transmural dominance of these phenomena seems distinct. Alternate factors contributing to a regional susceptibility to tissue injury are deserving of further study.Background— Ischemia and tissue injury are common in patients with hypertrophic cardiomyopathy. Cardiovascular magnetic resonance imaging offers combined evaluations of each phenomenon at sufficiently high resolution to examine transmural spatial distribution. In this prospective cohort study, we examine the spatial distribution of stress perfusion abnormalities and tissue injury in patients with hypertrophic cardiomyopathy. Methods and Results— One hundred consecutive patients with hypertrophic cardiomyopathy underwent cardiovascular magnetic resonance imaging. Cine, stress perfusion, late gadolinium enhancement, and T2-weighted imaging techniques were used. Each was spatially coregistered according to predefined segmental and subsegmental models and was blindly analyzed for abnormalities using validated techniques. Spatial associations among stress perfusion, late gadolinium enhancement, and T2 imaging were made at segmental and subsegmental levels. Of the 100 patients studied, the phenotype was septal in 86 and apical in 14. Late gadolinium enhancement imaging was abnormal in 79 patients (79%). Eighty-six patients met prespecified safety criteria to undergo stress perfusion, and ischemia was identified in 46 patients (57%). T2 imaging was available in 81 patients and was abnormal in 19 (29%). The dominant distribution of all 3 findings was to segment with hypertrophy. Subsegmental analysis revealed geographic dominance of ischemia within the subendocardial zones. However, this zone was most commonly spared from late gadolinium enhancement and T2 abnormalities, typically seen in midwall and subepicardial zones. Conclusions— Inducible hypoperfusion is a common finding in hypertrophic cardiomyopathy and is typically identified within segments exhibiting imaging markers of tissue injury. However, the respective transmural dominance of these phenomena seems distinct. Alternate factors contributing to a regional susceptibility to tissue injury are deserving of further study.