Rosario J. Perea

Pulmonary Sarcoidosis: Typical and Atypical Manifestations at High-Resolution CT with Pathologic Correlation

Sarcoidosis is a multisystem disorder that is characterized by noncaseous epithelioid cell granulomas, which may affect almost any organ. Thoracic involvement is common and accounts for most of the morbidity and mortality associated with the disease. Thoracic radiologic abnormalities are seen at some stage in approximately 90% of patients with sarcoidosis, and an estimated 20% develop chronic lung disease leading to pulmonary fibrosis. Although chest radiography is often the first diagnostic imaging study in patients with pulmonary involvement, computed tomography (CT) is more sensitive for the detection of adenopathy and subtle parenchymal disease. Pulmonary sarcoidosis may manifest with various radiologic patterns: Bilateral hilar lymph node enlargement is the most common finding, followed by interstitial lung disease. At high-resolution CT, the most typical findings of pulmonary involvement are micronodules with a perilymphatic distribution, fibrotic changes, and bilateral perihilar opacities. Atypical manifestations, such as masslike or alveolar opacities, honeycomb-like cysts, miliary opacities, mosaic attenuation, tracheobronchial involvement, and pleural disease, and complications such as aspergillomas, also may be seen. To achieve a timely diagnosis and help reduce associated morbidity and mortality, it is essential to recognize both the typical and the atypical radiologic manifestations of the disease, take note of features that may be suggestive of diseases other than sarcoidosis, and correlate imaging features with pathologic findings to help narrow the differential diagnosis.

Integration of 3D Electroanatomic Maps and Magnetic Resonance Scar Characterization Into the Navigation System to Guide Ventricular Tachycardia Ablation

Background— Scar heterogeneity identified with contrast-enhanced cardiac magnetic resonance (CE-CMR) has been related to its arrhythmogenic potential by using different algorithms. The purpose of the study was to identify the algorithm that best fits with the electroanatomic voltage maps (EAM) to guide ventricular tachycardia (VT) ablation. Methods and Results— Three-dimensional scar reconstructions from preprocedural CE-CMR study at 3T were obtained and compared with EAMs of 10 ischemic patients submitted for a VT ablation. Three-dimensional scar reconstructions were created for the core (3D-CORE) and border zone (3D-BZ), applying cutoff values of 50%, 60%, and 70% of the maximum pixel signal intensity to discriminate between core and BZ. The left ventricular cavity from CE-CMR (3D-LV) was merged with the EAM, and the 3D-CORE and 3D-BZ were compared with the corresponding EAM areas defined with standard cutoff voltage values. The best match was obtained when a cutoff value of 60% of the maximum pixel signal intensity was used, both for core (r 2=0.827; P<0.001) and BZ (r 2=0.511; P=0.020), identifying 69% of conducting channels (CC) observed in the EAM. Matching improved when only the subendocardial half of the wall was segmented (CORE: r 2=0.808; P<0.001 and BZ: r 2=0.485; P=0.025), identifying 81% of CC. When comparing the location of each bipolar voltage intracardiac electrogram with respect to the 3D CE-CMR–derived structures, a Cohen &kgr; coefficient of 0.70 was obtained. Conclusions— Scar characterization by means of high resolution CE-CMR resembles that of EAM and can be integrated into the CARTO system to guide VT ablation.

Incidence of pulmonary vein stenosis in patients submitted to atrial fibrillation ablation: a comparison of the Selective Segmental Ostial Ablation vs the Circumferential Pulmonary Veins Ablation.

Introduction: Pulmonary vein (PV) stenosis is an important complication of the AF ablation and could be underestimated if their assessment is not systematically done. Selective Segmental Ostial Ablation (SSOA) and Circunferential Pulmonary Veins Ablation (CPVA) have demonstrated efficacy in atrial fibrillation (AF) treatment. In this study the real incidence of PV stenosis in patients (pts) submitted to both SSOA and CPVA was compared.Methods: Those pts with focal activity and normal left atrial size were submitted to SSOA, remaining pts were submitted to CPVA to treat refractory, symptomatic AF. Contrast enhanced magnetic resonance angiography (MRA) was routinely performed in all patients 4 months after the procedure.Results: A series of 73 consecutive patients (mean age of 51 ± 11 years; 75% male) were included. SSOA was performed in 32 patients, and the remaining 41 patients underwent to CPVA, obtaining similar efficacy rates (72% vs 76% arrythmia free probability at 12 months; log rank test p = NS). Six patients had a significant PV stenosis, all in SSOA group none in CPVA group (18.8% vs 0%; p = 0.005). All patients were asymptomatic and the stenosis was detected in routine MRA. No predictors of stenosis has been identified analysing patient procedure characteristics.Conclusion: PV stenosis is a potential complication of SSOA not seen in CPVA. The study confirms than MRA is useful for identifying patients with asymptomatic PV stenosis.

Three-dimensional Architecture of Scar and Conducting Channels Based on High Resolution ce-CMR: Insights for Ventricular Tachycardia Ablation

Background—Conducting channels are the target for ventricular tachycardia (VT) ablation. Conducting channels could be identified with contrast enhanced–cardiac magnetic resonance (ce-CMR) as border zone (BZ) corridors. A 3-dimensional (3D) reconstruction of the ce-CMR could allow visualization of the 3D structure of these BZ channels. Methods and Results—We included 21 patients with healed myocardial infarction and VT. A 3D high-resolution 3T ce-CMR was performed before CARTO-guided VT ablation. The left ventricular wall was segmented and characterized using a pixel signal intensity algorithm at 5 layers (endocardium, 25%, 50%, 75%, epicardium). A 3D color-coded shell map was obtained for each layer to depict the scar core and BZ distribution. The presence/characteristics of BZ channels were registered for each layer. Scar area decreased progressively from endocardium to epicardium (scar area/left ventricular area: 34.0±17.4% at endocardium, 24.1±14.7% at 25%, 16.3±12.1% at 50%, 13.1±10.4 at 75%, 12.1±9.3% at epicardium; P<0.01). Forty-five BZ channels (2.1±1.0 per patient, 23.7±12.0 mm length, mean minimum width 2.5±1.5 mm) were identified, 85% between the endocardium and 50% shell and 76% present in ≥1 layer. The ce-CMR–defined BZ channels identified 74% of the critical isthmus of clinical VTs and 50% of all the conducting channels identified in electroanatomic maps. Conclusions—Scar area in patients with healed myocardial infarction decreases from the endocardium to the epicardium. BZ channels, more commonly seen in the endocardium, display a 3D structure within the myocardial wall that can be depicted with ce-CMR. The use of ce-CMR–derived maps to guide VT ablation warrants further investigation.

Left atrial posterior wall isolation does not improve the outcome of circumferential pulmonary vein ablation for atrial fibrillation: a prospective randomized study.

Background—Ablation of the pulmonary veins (PVs) for atrial fibrillation treatment is often combined with linear radiofrequency lesions along the left atrium (LA) to improve the success rate. The study was designed to assess the contribution of LA posterior wall isolation to the outcome of circumferential pulmonary vein ablation (CPVA). Methods and Results—CPVA consisted of continuous radiofrequency lesions encircling both ipsilateral PVs plus an ablation line along the mitral isthmus. Patients were then randomized into 2 groups. In the first group, superior PVs were connected by linear lesions along the LA roof (CPVA-1 group). In the second group, the LA posterior wall was isolated by adding a second line connecting the inferior aspect of the 2 inferior PVs (CPVA-2 group). The study included 120 patients (53±11 years, 77% male, 60% paroxysmal atrial fibrillation, LA of 41.3±5.4 mm, 46% with hypertension, and 22% with structural heart disease). After a single ablation procedure and a mean follow-up of 10±4 months, 24 (40%) patients of the CPVA-1 group had atrial fibrillation recurrences and 3 (5%) had new-onset LA flutter. In the CPVA-2 group, recurrences were due to atrial fibrillation episodes in 23 patients (38%) and LA flutter in 4 (7%). Freedom from arrhythmia recurrences was not statistically different in the CPVA-1 group as compared with the CPVA-2 group (log rank P=0.943). Conclusion—Isolation of the LA posterior wall did not increase the success rate of CPVA.

Usefulness of contrast-enhanced cardiac magnetic resonance in identifying the ventricular arrhythmia substrate and the approach needed for ablation

AIMS The endocardial vs. epicardial origin of ventricular arrhythmia (VA) can be inferred from detailed electrocardiogram (ECG) analysis. However, despite its clinical usefulness, ECG has limitations. Alternatively, scarred tissue sustaining VAs can be identified by contrast-enhanced cardiac magnetic resonance (ce-CMR). The objective of this study was to determine the clinical value of analysing the presence and distribution pattern of scarred tissue in the ventricles to identify the VA site of origin and the ablation approach required. METHODS AND RESULTS A ce-CMR study was carried out before the index ablation procedure in a cohort of 80 patients with non-idiopathic VA. Hyper-enhancement (HE) in each ventricular segment was coded as absent, subendocardial, transmural, mid-myocardial, or epicardial. The endocardial or epicardial VA site of origin was also assigned according to the approach needed for ablation. The clinical VA was successfully ablated in 77 (96.3%) patients, all of them showing HE on ce-CMR. In segments with successful ablation of the clinical ventricular tachycardia, HE was absent in 3 (3.9%) patients, subendocardial in 19 (24.7%), transmural in 36 (46.7%), mid-myocardial in 8 (10.4%), and subepicardial in 11 (14.3%) patients. Epicardial ablation of the index VA was necessary in 3 (6.1%) ischaemic and 12 (42.9%) non-ischaemic patients. The presence of subepicardial HE in the successful ablation segment had 84.6% sensitivity and 100% specificity in predicting an epicardial origin of the VA. CONCLUSION Contrast-enhanced cardiac magnetic resonance is helpful to localize the target ablation substrate of non-idiopathic VA and also to plan the approach needed, especially in non-ischaemic patients.

Use of myocardial scar characterization to predict ventricular arrhythmia in cardiac resynchronization therapy

AIMS There is insufficient evidence to implant a combined cardiac resynchronization therapy (CRT) device with defibrillation capabilities (CRT-D) in all CRT candidates. The aim of the study was to assess myocardial scar size and its heterogeneity as predictors of sudden cardiac death (SCD) in CRT candidates. METHODS AND RESULTS A cohort of 78 consecutive patients with dilated cardiomyopathy and class I indication for CRT-D were prospectively enrolled. Before CRT-D implantation, a contrast-enhanced cardiac magnetic resonance (ce-CMR) was performed. The core and border zone (BZ) of the myocardial scar were characterized and quantified with a customized post-processing software. The first appropriate implantable cardioverter defibrillator (ICD) therapy was considered as a surrogate of SCD. During a mean follow-up of 25 months (25-75th percentiles, 15-34), appropriate ICD therapy occurred in 11.5% of patients. In a multivariate Cox proportional hazards regression model for clinical and ce-CMR variables, the scar mass percentage [hazards ratio (HR) per 1% increase 1.1 (1.06-1.15), P < 0.01], the BZ mass [HR per 1 g increase 1.06 (1.04-1.09), P < 0.01], and the BZ percentage of the scar [HR per 1% increase 1.06 (1.02-1.11), P < 0.01], were the only independent predictors of appropriate ICD therapy. Receiver-operating characteristic curve analysis showed that a scar mass <16% and a BZ < 9.5 g had a negative predictive value of 100%. CONCLUSIONS The presence, size, and heterogeneity of myocardial scar independently predict appropriate ICD therapies in CRT candidates. The ce-CMR-based scar analysis might help identify a subgroup of patients at relatively low risk of SCD.

Left Atrial Contractility is Preserved After Successful Circumferential Pulmonary Vein Ablation in Patients with Atrial Fibrillation

Introduction: Circumferential pulmonary vein ablation (CPVA) for atrial fibrillation (AF) consists of creating extensive lesions in the left atrium (LA). The aim of the study was to evaluate changes in LA contractility after ablation and their relationship with procedure outcome.

3D delayed-enhanced magnetic resonance sequences improve conducting channel delineation prior to ventricular tachycardia ablation.

AIMS Non-invasive depiction of conducting channels (CCs) is gaining interest for its usefulness in ventricular tachycardia (VT) ablation. The best imaging approach has not been determined. We compared characterization of myocardial scar with late-gadolinium enhancement cardiac magnetic resonance using a navigator-gated 3D sequence (3D-GRE) and conventional 2D imaging using either a single shot inversion recovery steady-state-free-precession (2D-SSFP) or inversion-recovery gradient echo (2D-GRE) sequence. METHODS AND RESULTS We included 30 consecutive patients with structural heart disease referred for VT ablation. Preprocedural myocardial characterization was conducted in a 3 T-scanner using 2D-GRE, 2D-SSFP and 3D-GRE sequences, yielding a spatial resolution of 1.4 × 1.4 × 5 mm, 2 × 2 × 5 mm, and 1.4 × 1.4 × 1.4 mm, respectively. The core and border zone (BZ) scar components were quantified using the 60% and 40% threshold of maximum pixel intensity, respectively. A 3D scar reconstruction was obtained for each sequence. An electrophysiologist identified potential CC and compared them with results obtained with the electroanatomic map (EAM). We found no significant differences in the scar core mass between the 2D-GRE, 2D-SSFP, and 3D-GRE sequences (mean 7.48 ± 6.68 vs. 8.26 ± 5.69 and 6.26 ± 4.37 g, respectively, P = 0.084). However, the BZ mass was smaller in the 2D-GRE and 2D-SSFP than in the 3D-GRE sequence (9.22 ± 5.97 and 9.39 ± 6.33 vs. 10.92 ± 5.98 g, respectively; P = 0.042). The matching between the CC observed in the EAM and in 3D-GRE was 79.2%; when comparing the EAM and the 2D-GRE and the 2D-SSFP sequence, the matching decreased to 61.8% and 37.7%, respectively. CONCLUSION 3D scar reconstruction using images from 3D-GRE sequence improves the overall delineation of CC prior to VT ablation.

Role of Circulating Angiotensin Converting Enzyme 2 in Left Ventricular Remodeling following Myocardial Infarction: A Prospective Controlled Study

Angiotensin-converting enzyme 2 (ACE2) cleaves Angiotensin-II to Angiotensin-(1–7), a cardioprotective peptide. Serum soluble ACE2 (sACE2) activity is raised in chronic heart failure, suggesting a compensatory role in left ventricular dysfunction. Our aim was to study the relationship between sACE2 activity, infarct size, left ventricular systolic function and remodeling following ST-elevation myocardial infarction (STEMI). A contrast-enhanced cardiac magnetic resonance study was performed acutely in 95 patients with first STEMI and repeated at 6 months to measure LV end-diastolic volume index, ejection fraction and infarct size. Baseline sACE2 activities, measured by fluorescent enzymatic assay 24 to 48 hours and at 7 days from admission, were compared to that obtained in 22 matched controls. Patients showed higher sACE2 at baseline than controls (104.4 [87.4–134.8] vs 74.9 [62.8–87.5] RFU/µl/hr, p<0.001). At seven days, sACE2 activity significantly increased from baseline (115.5 [92.9–168.6] RFU/µl/hr, p<0.01). An inverse correlation between sACE2 activity with acute and follow-up ejection fraction was observed (r = −0.519, p<0.001; r = −0.453, p = 0.001, respectively). Additionally, sACE2 directly correlated with infarct size (r = 0.373, p<0.001). Both, infarct size (β = −0.470 [95%CI:−0.691:−0.248], p<0.001) and sACE2 at 7 days (β = −0.025 [95%CI:−0.048:−0.002], p = 0.030) were independent predictors of follow-up ejection fraction. Patients with sACE2 in the upper tertile had a 4.4 fold increase in the incidence of adverse left ventricular remodeling (95% confidence interval: 1.3 to 15.2, p = 0.027). In conclusion, serum sACE2 activity rises in relation to infarct size, left ventricular systolic dysfunction and is associated with the occurrence of left ventricular remodeling.