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Background Neuronal death may be an overlooked and unaddressed component of disability following neonatal nerve injuries, such as obstetric brachial plexus injury. N-acetylcysteine and acetyl-L-carnitine improve survival of neurons after adult nerve injury, but it is unknown whether they improve survival after neonatal injury, when neurons are most susceptible to retrograde neuronal death. The authors' objective was to examine whether N-acetylcysteine or acetyl-L-carnitine treatment improves survival of neonatal motor or sensory neurons in a rat model of neonatal nerve injury. Methods Rat pups received either a sciatic nerve crush or transection injury at postnatal day 3 and were then randomized to receive either intraperitoneal vehicle (5% dextrose), N-acetylcysteine (750 mg/kg), or acetyl-L-carnitine (300 mg/kg) once or twice daily. Four weeks after injury, surviving neurons were retrograde-labeled with 4% Fluoro-Gold. The lumbar spinal cord and L4/L5 dorsal root ganglia were then harvested and sectioned to count surviving motor and sensory neurons. Results Transection and crush injuries resulted in significant motor and sensory neuron loss, with transection injury resulting in significantly less neuron survival. High-dose N-acetylcysteine (750 mg/kg twice daily) significantly increased motor neuron survival after neonatal sciatic nerve crush and transection injury. Neither N-acetylcysteine nor acetyl-L-carnitine treatment improved sensory neuron survival. Conclusions Proximal neonatal nerve injuries, such as obstetric brachial plexus injury, produce significant retrograde neuronal death after injury. High-dose N-acetylcysteine significantly increases motor neuron survival, which may improve functional outcomes after obstetrical brachial plexus injury.

We sought to examine whether elongation of the mitral valve leaflets in patients with hypertrophic cardiomyopathy (HCM) is synergistic to septal wall thickness (SWT) in the development of left ventricular outflow tract obstruction (LVOTO). HCM is a common genetic cardiac disease characterized by asymmetric septal hypertrophy and predisposition towards LVOTO. It has been reported that elongation of the mitral valve leaflets may be a primary phenotypic feature and contribute to LVOTO. However, the relative contribution of this finding versus SWT has not been studied. 152 patients (76 with HCM and 76 non-diseased age, race and BSA-matched controls) and 18 young, healthy volunteers were studied. SWT and the anterior mitral valve leaflet length (AMVLL) were measured using cine MRI. The combined contribution of these variables (SWT × AMVLL) was described as the Septal Anterior Leaflet Product (SALP). Peak LVOT pressure gradient was determined by Doppler interrogation and defined as “obstructive” if ≥ 30 mmHg. Patients with HCM were confirmed to have increased AMVLL compared with controls and volunteers (p

© 2017, Springer Science+Business Media Dordrecht. Cardiac Resynchronization Therapy (CRT) fails to provide benefit in up to one-third of patients. Maximizing the geographic separation of right and left ventricular pacing lead sites has been suggested as one way to improve response. Cardiac CT provides an opportunity to explore 3-dimensional inter-lead distance (ILD) measures for the prediction of CRT response. The objective of this study was to investigate associations between standardized measures of ILD by cardiac CT and echocardiographic response to CRT. Forty-two consecutive patients undergoing CRT had serial clinical and echocardiographic evaluations performed in addition to a post-procedural cardiac-gated CT with blinded measurement of direct and circumferential (via the myocardium) ILD measures. Clinical response to CRT, the primary clinical outcome, was defined as a ≥15% reduction in LVESV using echocardiography at 6-months. The mean age and ejection fraction was 63.6 ± 8.9 years and 25.2 ± 7.8%, respectively. The primary outcome occurred in 35 of 42 patients (83%). Both direct and circumferential CT-based ILD measures were associated with the primary outcome by univariate analysis. Receiver Operator Characteristic analysis identified Circumferential ILD to have the strongest predictive accuracy (AUC 0.78). Inter- and intra-observer reproducibility of CT-derived ILD measures was excellent. Circumferential ILD measures on cardiac CT are predictive of clinical response to CRT. Incorporation of these measures into the selection of optimal pacing targets, particularly from pre-procedural CT coronary vein imaging may be of therapeutic benefit and warrants further investigation.

Background Retrograde labeling permits the investigation of the number, distribution and axonal projections of neurons in the peripheral nervous system. The well technique for labeling peripheral nerves consists of incubating the exposed peripheral nerve in a well for one hour, a time intensive technique. However, other techniques that inject tracers directly into the nerve or muscle may result in variable labeling depending on nerve preparation and location of injection. New method We describe a method of retrograde labeling peripheral nerves that increases tracer uptake and improves labeling efficiency. This technique utilizes a silicone cap over the nerve that is kept in place with fibrin glue, permitting closure of the incision with the cap in place, mitigating the need to wait one hour for back-labeling as with the standard well technique. Results In the rat common peroneal nerve, the new silicone cap technique, compared to the standard well technique, labeled 405 ± 11 (SEM) vs. 378 ± 21 motoneurons and 953 ± 40 vs. 948 ± 57 sensory neurons. These counts were not statistically different. Labeling intensity was greater in DRG neurons with the silicone cap technique, but this difference was not evident in motoneurons. Comparison with existing method Retrograde-labeling with silicone caps labels an equal number of motor and sensory neurons in comparison with the standard well technique and labels sensory neurons with greater intensity. Conclusions Retrograde-labeling with silicone caps reliably labels neurons and significantly decreases the time required for labeling, reducing anesthetic exposure and improving the efficiency of the technique.

UNLABELLED Although treating facial palsy is considered debilitating for patients, trigeminal nerve palsy and sensory deficits of the face are overlooked components of disability. Complete anesthesia leaves patients susceptible to occult injury, and facial sensation is an important component of interaction and activities of daily living. Sensory reconstruction is well established in the restoration of hand sensation; however, only one previous report proposed a surgical strategy for sensory nerve reconstruction of the face with use of nerve transfers. Nerve transfers, when used alone, have limited application because of their restricted arc of rotation in the face; extending their arc by adding nerve grafts greatly expands their utility. The following cases demonstrate the early results after V2 and V3 reconstruction with cross-face nerve grafts in three patients with acquired trigeminal nerve palsy. Cross-face nerve grafts using the sural nerve permit more proximal reconstruction of the infraorbital and mental nerves, which allows reinnervation of their entire cutaneous distribution. All patients demonstrated improved sensation in the reconstructed dermatomes, and no patients reported donor-site abnormalities. Cross-face nerve grafts result in minimal donor-site morbidity and are promising as a surgical strategy to address sensory deficits of the face. CLINICAL QUESTION/LEVEL OF EVIDENCE Therapeutic, V.

Hypertrophic cardiomyopathy (HCM) is a common genetic disorder associated with elevated risk of lethal ventricular arrhythmias. While the absence of myocardial fibrosis on late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) appears to identify lower risk individuals, approximately two

Background— Left ventricular (LV) and right ventricular pacing site characteristics have been shown to influence response to cardiac resynchronization therapy (CRT). This study aimed to determine the clinical feasibility of image-guided lead delivery using a 3-dimensional navigational model displaying both LV and right ventricular (RV) pacing targets. Serial echocardiographic measures of clinical response and procedural metrics were evaluated. Methods and Results— Thirty-one consecutive patients underwent preimplant cardiac MRI with the generation of a 3-dimensional navigational model depicting optimal segmental targets for LV and RV leads. Lead delivery was guided by the model in matched views to intraprocedural fluoroscopy. Blinded assessment of final lead tip location was performed from postprocedural cardiac computed tomography. Clinical and LV remodeling response criteria were assessed at baseline, 3 months, and 6 months using a 6-minute hall walk, quality of life questionnaire, and echocardiography. Mean age and LV ejection fraction was 66±8 years and 26±8%, respectively. LV leads were successfully delivered to a target or adjacent segment in 30 of 31 patients (97%), 68% being nonposterolateral. RV leads were delivered to a target or adjacent segment in 30 of 31 patients (97%), 26% being nonapical. Twenty-three patients (74%) met standard criteria for response (LV end-systolic volume reduction ≥15%), 18 patients (58%) for super-response (LV end-systolic volume reduction ≥30%). LV ejection fraction improved at 6 months (31±8 versus 26±8%, P =0.04). Conclusions— This study demonstrates clinical feasibility of dual cardiac resynchronization therapy lead delivery to optimal targets using a 3-dimensional navigational model. High procedural success, acceptable procedural times, and a low rate of early procedural complications were observed. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT01640769.

Background Before PCR testing of cerebrospinal fluid (CSF), laboratory diagnosis of herpes encephalitis (HSE) was based on virus isolation from brain biopsy. Viral isolation from CSF has limited clinical value due to low virus recovery; the cause for which has not been demonstrated. Objective To investigate the role of anti-HSV antibodies on recovery of HSV from CSF via cell culture. Study design HSV-positive CSF samples were evaluated for their ability to neutralize HSV in cell culture. The presence of HSV-specific IgG and IgM antibodies were analyzed using HSV-infected cells. To identify whether HSV-specific IgG is the cause of viral inhibition, IgG was removed using anti-human IgG magnetic beads. Viral inhibition from CSF originating from asymptomatic patients was examined as a comparison. Results CSF from 13 patients with acute HSV CNS disease was analyzed. All displayed high levels of viral neutralization to both HSV-1 and HSV-2 regardless of the infecting subtype. Interestingly, all the CSF samples stained strongly for anti-IgG antibody but none for anti-IgM antibody. Removal of IgG from CSF eliminated the viral inhibitory activity. Neutralizing IgG antibody was also found to be common in CSF of most patients, even in the absence of HSV disease. Conclusions Viral specific IgG is the major determinant of viral inhibition in CSF and prevents virus recovery in cell culture. In CSF from HSE un-infected patients, viral inhibitory IgG originates from circulating serum antibody and is commonly present in CSF. However, this inhibitory IgG is not protective for the development of HSV disease.

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.

© 2014, Springer Science+Business Media Dordrecht. The quantification and modeling of myocardial scar is of expanding interest for image-guided therapy, particularly in the field of arrhythmia management. Migration towards high-resolution, three-dimensional (3D) MRI techniques for spatial mapping of myocardial scar provides superior spatial registration. However, to date no systematic comparison of available approaches to 3D scar quantification have been performed. In this study we compare the reproducibility of six 3D scar segmentation algorithms for determination of left ventricular scar volume. Additionally, comparison to two-dimensional (2D) scar quantification and 3D manual segmentation is performed. Thirty-five consecutive patients with ischemic cardiomyopathy were recruited and underwent conventional 2D late gadolinium enhancement (LGE) and 3D isotropic LGE imaging (voxel size 1.3 mm3) using a 3 T scanner. 3D LGE datasets were analyzed using six semi-automated segmentation techniques, including the signal threshold versus reference mean (STRM) technique at >2, >3, >5 and >6 standard deviations (SD) above reference myocardium, the full width at half maximum (FWHM) technique, and an optimization-based technique called hierarchical max flow (HMF). The mean ejection fraction was 32.1 ± 12.7 %. Reproducibility was greatest for HMF and FWHM techniques with intra-class correlation coefficient values ≥0.95. 3D scar quantification and modeling is clinically feasible in patients with ischemic cardiomyopathy. While several approaches show acceptable reproducibility, HMF appears superior due to maintenance of accuracy towards manual segmentations.

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 Myocardial scar volume quantification has been shown to predict response to medical, surgical, and device therapy. Phase sensitive inversion recovery (PSIR)-based Late Gadolinium Enhancement (LGE) image reconstruction is clinically attractive for its reduced dependence on accurate prescription of the Time from Inversion (TI time), and is becoming a preferred approach for many centers. However, while an efficient approach for the visual interpretation of myocardial injury, the influence of this approach on signal-threshold based scar volume quantification has been poorly explored. Methods A total of 80 patients with obvious myocardial scar by LGE imaging (40 ischemic, 40 non-ischemic) underwent blinded evaluations of total scar volume (%LV mass) using matched MIR and PSIR short axis images. Analysis was performed using the Signal Threshold Versus Reference Myocardium (STRM) technique at ≥2, ≥3, and ≥5 SD thresholds. In those with ischemic scar the Full Width at Half Maximum (FWHM) approach was incrementally evaluated. Linear regression and BlandAltman analyses comparing MIR verses PSIR-based scar quantification was performed. Results Linear regression analysis demonstrated an excellent correlation between PSIR and MIR-based STRM scar volumes at all 3 STRM-based thresholds for both ischemic scar (r=0.96, 0.95, and 0.88, respectively) and non-ischemic scar (r=0.86, 0.89, 0.90, respectively). FWHM analysis showed good correlation in ischemic scar (r=0.83). Bland-Altman analysis of STRM analysis showed a systematic bias with lower scar volumes produced by PSIR reconstruction images for both ischemic and non-ischemic scar. These differences were modest using STRM for ischemic scar (-3.3, -4.0 and -4.9%

Myocardial fibrosis (MF) is a common pathophysiologic endpoint in non-ischemic cardiomyopathy and may be identified by late gadolinium enhancement (LGE) MRI. While associated with future cardiovascular events in hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM) the influence of MF on interim quality of life (QOL) has not been explored. In this study we investigate for associations between MF and validated indices of QOL in patients with HCM and DCM. Ninety-eight patients with known cardiomyopathy (n = 56-HCM/n = 42-DCM) underwent LGE-MRI in addition to standardized testing for QOL using the disease-specific Minnesota Living With Heart Failure (MLWHF) and the generic SF-12 questionnaires. LGE-MRI images were blindly analyzed for the presence and volume of MF using validated techniques. All analyses were stratified according to cardiomyopathy sub-type. The mean age of the population was 56.8 ± 12.9 years. MF was identified in 82 % of patients with HCM and 74 % of patients with DCM with respective mean MF burdens of 20.0 and 13.7 % of the left ventricular mass (p = 0.008). QOL scores for those with HCM or DCM, as assessed by both MLWHF and SF-12, were not significantly different between those with versus those without MF, and showed no association with MF burden by quantitative signal analysis. In this study we identified no association between QOL and MF burden by LGE-MRI in patients with HCM or DCM. Therefore, the severity of underlying myocardial tissue disease, a recognized substrate for ventricular arrhythmia, cannot and should not be inferred from the patient's symptom status or QOL.

Background: Patients with ischemic cardiomyopathy (ICM) and non-ischemic cardiomyopathy (NICM) are at risk of sudden cardiac arrest (SCA). Delayed enhancement (DE) MRI may identify sub-populations at higher risk of arrhythmic events. This study evaluates the role of DE MRI scar quantification for the prediction of future events in both ICM and NICM populations. Methods: 125 consecutive patients referred for cardiac MRI to determine ICD eligibility (ICM = 61 pts, NICM =64 pts) were enrolled. DE MRI was done in a standard fashion and signal threshold analysis blindly performed. Total scar was defined as any signal ≥2SD above normal reference myocardium, while the difference between 3 and 5SD thresholds being defined as “borderzone”. All patients were prospectively followed for the primary combined endpoint of appropriate ICD therapy or SCA. A composite secondary endpoint of major adverse events (SCA, appropriate ICD therapy and all-cause mortality) was also evaluated. Results: The mean age and EF was 61.4±11.2 yo and 26.5±7.5% (range 8.9 to 40%), respectively. A total of 76 pts received an ICD. During a median follow-up of 412±191days, 16 patients (13%) had a primary endpoint (15 ICD therapies and 1 aborted SCA). An additional 6 patients had death from any cause contributing to the secondary endpoint. The mean total scar mass was significantly higher in pts with a primary outcome (65.1±27.8 g vs. 31.3±18.7 g, p

In this study, we aimed to identify the respective and combined influences of AMVL length and septal thickening on the development of LVOT obstruction in a population of patients with HCM.

Risk prediction of first sudden cardiac arrest (SCA) in patients with ischemic cardiomyopathy (ICM) and non-ischemic cardiomyopathy (NICM) is imperfect and based solely upon ejection fraction. Delayed enhancement (DE) MRI has been shown in both populations to identify those at higher risk of cardiovascular events. However, how this technique may predict arrhythmic events in ICD candidates is poorly understood, especially in those with NICM.

Background and objectives Patients with Dilated Cardiomyopathy (DCM) and Hypertrophic Cardiomyopathy (HCM) frequently demonstrate non-ischemic pattern myocardial fibrosis (MF) on delayed enhancement magnetic resonance imaging (DE-MRI). The clinical significance of this finding with respect to impact on Quality of Life (QOL) is poorly understood. In this study we identify the prevalence of MF in patients with HCM and DCM and assess its relationship with standardized measures of QOL. Methods One-hundred and seven consecutive patients with either DCM (n=50) or HCM (n=57) referred for MRI evaluation were identified. DCM was defined as a LVEF 3SD above reference myocardium) using validated commercial software. Results

We show that an in situ Kerr rotation measurement is a very effective technique for the study of antiferromagnetic (AF) ferromagnetic (F) film couples. Magnetic signals can be obtained even in the case where the (AF) is the top layer up to at least 200 A of AF thickness. We have used this in situ approach combined with ion milling to study the thickness dependence of the magnetic properties of Mn50Fe50/Ni80Fe20 systems. We observe that the exchange bias field has a surprisingly sharp onset at a critical thickness of AF∼50 A. We show that this is consistent with a simple model and that the magnetic anisotropy of MnFe can be estimated from the observed critical thickness to be ∼1.35×105 erg/cm3. The exchange field showed the predicted proportionality to the inverse of the F thickness from ∼50 to 400 A. Auger spectroscopy and spin polarized secondary electron emission have been used to rule out gross artifacts due to ion milling.

Background The presence and extent of late gadolinium enhancement (LGE) has been associated with adverse events in patients with hypertrophic cardiomyopathy (HCM). Signal intensity (SI) threshold techniques are routinely employed for quantification; Full-Width at Half-Maximum (FWHM) techniques are suggested to provide greater reproducibility than Signal Threshold versus Reference Mean (STRM) techniques, however the accuracy of these approaches versus the manual assignment of optimal SI thresholds has not been studied. In this study, we compared all known semi-automated LGE quantification techniques for accuracy and reproducibility among patients with HCM. Methods Seventy-six HCM patients (51 male, age 54 ± 13 years) were studied. Total LGE volume was quantified using 7 semi-automated techniques and compared to expert manual adjustment of the SI threshold to achieve optimal segmentation. Techniques tested included STRM based thresholds of >2, 3, 4, 5 and 6 SD above mean SI of reference myocardium, the FWHM technique, and the Otsu-auto-threshold (OAT) technique. The SI threshold chosen by each technique was recorded for all slices. Bland-Altman analysis and intra-class correlation coefficients (ICC) were reported for each semi-automated technique versus expert, manually adjusted LGE segmentation. Intra- and inter-observer reproducibility assessments were also performed. Results Fifty-two of 76 (68%) patients showed LGE on a total of 202 slices. For accuracy, the STRM >3SD technique showed the greatest agreement with manual segmentation (ICC = 0.97, mean difference and 95% limits of agreement = 1.6 ± 10.7 g) while STRM >6SD, >5SD, 4SD and FWHM techniques systematically underestimated total LGE volume. Slice based analysis of selected SI thresholds similarly showed the STRM >3SD threshold to most closely approximate manually adjusted SI thresholds (ICC = 0.88). For reproducibility, the intra- and inter-observer reproducibility of the >3SD threshold demonstrated an acceptable mean difference and 95% limits of agreement of −0.5 ± 6.8 g and −0.9 ± 5.6 g, respectively. Conclusions FWHM segmentation provides superior reproducibility, however systematically underestimates total LGE volume compared to manual segmentation in patients with HCM. The STRM >3SD technique provides the greatest accuracy while retaining acceptable reproducibility and may therefore be a preferred approach for LGE quantification in this population.

Background Cardiac resynchronization therapy (CRT) is an established treatment for severe heart failure. However, up to 40% of patients do not respond. While regional scar distribution has received focused attention, the predictive utility of global markers of remodeling and irreversible injury has not been well explored. Methods Sixty-eight patients receiving CRT underwent pre-implant cardiovascular MRI followed by serial echocardiography at 3 and 6 months. Blinded measurement of Left Ventricular (LV) and Right Ventricular (RV) chamber dimensions, volumes and mass were performed from short axis cine datasets. LV dysynchrony was measured by septal to lateral wall delay. Total LV scar burden was determined from Late Gadolinium Enhancement (LGE) images using manual contour tracing of endocardial and epicardial borders with application of a signal threshold ≥5SD above reference myocardium. Response to CRT was defined as a reduction in LV end-systolic volume (ESV) ≥15% at 6 months. Results The mean age was 66.3 ± 8.9 years with a mean LV Ejection fraction (EF) of 25.2 ± 7.2%. Overall, 47 patients (69%) responded. Among all baseline measures LVEDV (p=0.03), LVESV (p=0.045), RV EF (p=0.0349) and total scar burden (p=0.018) were the only significant predictors of CRT response. Multivariate analysis showed total scar burden to be the only independent predictor of CRT response (p=0.015). Conclusions Pre-implantation MRI offers markers for the prediction of response to CRT. Of these, total scar burden appears to be an independent predictor of response and may be of assistance in the selection of optimal candidates. Funding None

Background Cardiac resynchronization therapy (CRT) aims to reduce dyssynchronous contraction through simultaneous pacing of the right ventricular (RV) septum and left ventricular (LV) lateral wall. Up to 40% of patients do not respond, largely attributed to lack of dysynchrony and/ or transmural scar at pacing sites. In this pilot study we tested the feasibility of guiding LV and RV leads to “optimal” segmental targets using a MRI-based 3D surface rendered cardiac model. Methods Ten consecutive patients planned for CRT were recruited. All patients underwent cardiac MRI inclusive of cine and delayed enhancement (DE) imaging using a 3T scanner. A blinded interpreter determined the time to maximal radial wall thickening (TmWT) and myocardial scar burden for each of 16 segments. All potential LV lead targets were ranked according to scar burden (lowest first) and then sub-ranked by TmWT (highest first). All potential RV lead targets were ranked according to scar burden (lowest first). These rankings were encoded onto a surface rendered cardiac model, displayed in standard fluoroscopic views (Figure 1A) and used to direct lead placement by fluoroscopy. A cardiac gated CT was then performed at a 1-month follow-up visit (Figure 1B) to assess procedural success for target achievement. Results

Cardiac Resynchronization Therapy (CRT) has been shown to improve quality of life and decrease mortality in heart failure patients. However, up to 40% of patients fail to respond to this therapy. Validation of a response prediction model that incorporates both myocardial scar and dyssynchrony of the paced myocardial segments would allow for a targeted approach to CRT lead delivery.