Diffuse myocardial fibrosis associates with incident ventricular arrhythmia in implantable cardioverter defibrillator recipients.

Background: Diffuse myocardial fibrosis (DMF) quantified by extracellular volume (ECV) may represent a vulnerable phenotype and associate with life threatening ventricular arrhythmias more than focal myocardial fibrosis. This principle remains important because 1) risk stratification for implantable cardioverter defibrillators (ICD) remains challenging, and 2) DMF may respond to current or emerging medical therapies (reversible substrate). Objectives: To evaluate the association between quantified by ECV in myocardium without focal fibrosis by late gadolinium enhancement (LGE) with time from ICD implantation to 1) appropriate shock, or 2) shock or anti-tachycardia pacing. Methods: Among patients referred for cardiovascular magnetic resonance (CMR) without congenital disease, hypertrophic cardiomyopathy, or amyloidosis who received ICDs (n=215), we used Cox regression to associate ECV with incident ICD therapy. Results: After a median of 2.9 (IQR 1.5-4.2) years, 25 surviving patients experienced ICD shock and 44 experienced shock or anti-tachycardia pacing. ECV ranged from 20.2% to 39.4%. No patient with ECV<25% experienced an ICD shock. ECV associated with both endpoints, e.g., hazard ratio 2.17 (95%CI 1.17-4.00) for every 5% increase in ECV, p=0.014 in a stepwise model for ICD shock adjusting for ICD indication, age, smoking, atrial fibrillation, and myocardial infarction, whereas focal fibrosis by LGE and global longitudinal strain (GLS) did not. Conclusions: DMF measured by ECV associates with ventricular arrhythmias requiring ICD therapy in a dose-response fashion, even adjusting for potential confounding variables, focal fibrosis by LGE, and GLS. ECV-based risk stratification and DMF representing a therapeutic target to prevent ventricular arrhythmia warrant further investigation.

Three-Dimensional Echocardiographic Left Atrial Appendage Volumetric Analysis.

BACKGROUND: Left atrial appendage (LAA) echocardiographic assessment is difficult because of the complex shape and relatively small size of the LAA. Three-dimensional (3D) echocardiographic imaging can overcome the limitations of two-dimensional imaging. Pulsed-wave Doppler is the only currently standard LAA functional parameter. The aim of this study was to test a new approach for 3D echocardiographic volumetric analysis to obtain LAA ejection fraction (EF), its size and shape. METHODS: Transesophageal two-dimensional and 3D LAA images were prospectively obtained in 159 consecutive patients. LAA volumes were measured from 3D echocardiographic images using available software. Pulsed-wave Doppler was considered the reference value for LAA function and was used for comparison with LAA EF. Comparison with cardiac computed tomography was performed in a subgroup of 32 patients. Comparisons included linear regression and Bland-Altman analyses. Repeated measurements were performed to assess measurement variability. RESULTS: Nine patients were excluded because of suboptimal image quality (94% feasibility). Three-dimensional LAA calculated EF was in good agreement with LAA pulsed-wave measurements. Three-dimensional morphologic evaluation showed that 43% of the patients had "chicken wing," 33% "cactus," 19% "windsock," and 5% cauliflower shapes. At the time of data acquisition, patients with atrial fibrillation had nonsignificantly larger LAA end-systolic and end-diastolic volumes, leading to lower calculated EFs. Three-dimensional echocardiographic LAA end-systolic volumes were in good agreement with cardiac computed tomography (r = 0.75), with small biases (mean, -2.5 ± 3.9 ml). Reproducibility was better for larger LAA volumes. CONCLUSIONS: A novel 3D echocardiographic approach can determine the geometry, size, and function of the LAA. A new parameter, LAA EF, provides functional quantitation.

Extracellular Volume and Global Longitudinal Strain Both Associate With Outcomes But Correlate Minimally.

OBJECTIVES: This study examined how extracellular volume (ECV) and global longitudinal strain (GLS) relate to each other and to outcomes. BACKGROUND: Among myriad changes occurring in diseased myocardium, left ventricular imaging metrics of either the interstitium (e.g., ECV) or contractile function (e.g., GLS) may consistently associate with adverse outcomes yet correlate minimally with each other. This scenario suggests that ECV and GLS potentially represent distinct domains of cardiac vulnerability. METHODS: The study included 1,578 patients referred for cardiovascular magnetic resonance (CMR) without amyloidosis, and it quantified how ECV associated with GLS in linear regression models. ECV and GLS were then compared in their associations with incident outcomes (death and hospitalization for heart failure). RESULTS: ECV and GLS correlated minimally (R2 = 0.04). Over a median follow-up of 5.6 years, 339 patients experienced adverse events (149 hospitalizations for heart failure, 253 deaths, and 63 with both). GLS (univariable hazard ratio: 2.07 per 5% increment; 95% CI: 1.86 to 2.29) and ECV (univariable hazard ratio: 1.66 per 4% increment; 95% CI: 1.51 to 1.82) were principal variables associating with outcomes in univariable and multivariable Cox regression models. Similar results were observed in several clinically important subgroups. In the whole cohort, ECV added prognostic value beyond GLS in univariable and multivariable Cox regression models. CONCLUSIONS: GLS and ECV may represent principal but distinct domains of cardiac vulnerability, perhaps reflecting their distinct cellular origins. Whether combining ECV and GLS may advance pathophysiological understanding for a given patient, optimize risk stratification, and foster personalized medicine by targeted therapeutics requires further investigation.

Extracellular Volume Associates With Outcomes More Strongly Than Native or Post-Contrast Myocardial T1.

OBJECTIVES: Because risk stratification data represents a key domain of biomarker validation, we compared associations between outcomes and various cardiovascular magnetic resonance (CMR) metrics quantifying myocardial fibrosis (MF) in noninfarcted myocardium: extracellular volume fraction (ECV), native T1, post-contrast T1, and partition coefficient. BACKGROUND: MF associates with vulnerability to adverse events (e.g., mortality and hospitalization for heart failure [HHF]), but investigators still debate its optimal measurement; most histological validation data show strongest ECV correlations with MF. METHODS: We enrolled 1,714 consecutive patients without amyloidosis or hypertrophic cardiomyopathy from a single CMR referral center serving an integrated healthcare network. We measured T1 (MOdified Look-Locker Inversion recovery [MOLLI]) in nonenhanced myocardium, averaged from 2 short-axis slices (basal and mid) before and 15 to 20 min after a gadolinium contrast bolus. We compared chi-square test values from CMR MF measures in univariable and multivariable Cox regression models. We assessed "dose-response" relationships in Kaplan-Meier curves using log-rank statistics for quartile strata. We also computed net reclassification improvement (NRI) and integrated discrimination improvement (IDI for Cox models with ECV vs. native T1). RESULTS: Over a median of 5.6 years, 374 events occurred after CMR (162 HHF events and 279 deaths, 67 with both). ECV yielded the best separation of Kaplan-Meier curves and the highest log-rank statistics. In univariable and multivariable models, ECV associated most strongly with outcomes, demonstrating the highest chi-square test values. Native T1 or post-contrast T1 did not associate with outcomes in the multivariable model. ECV provided added prognostic value to models with native T1, for example, in multivariable models IDI = 0.0037 (95% confidence interval [CI]: 0.0009 to 0.0071), p = 0.02; NRI = 0.151 (95% CI: 0.022 to 0.292), p = 0.04. CONCLUSIONS: Analogous to histological previously published validation data, ECV myocardial fibrosis measures exhibited more robust associations with outcomes than other surrogate CMR MF measures. Superior risk stratification by ECV supports claims that ECV optimally measures MF in noninfarcted myocardium.

Rasamsonia argillacea species complex myocarditis in a patient with chronic granulomatous disease.

Herein, we present a case of successfully treated biopsy-proven Rasamsonia argillacea species complex myocarditis, pericarditis, and pulmonary infection in a 35-year-old male with a history of chronic granulomatous disease. Computed tomography of the chest demonstrated numerous pulmonary nodules and mass-like pulmonary lesions, and subsequent cardiac magnetic resonance imaging demonstrated an infiltrating mass-like lesion within the interventricular septum and pericarditis. Endobronchial, thoracoscopic, and eventual myocardial biopsies with cultures were ultimately reported as positive for R. argillacea species and the patient was treated with tailored antifungal therapy resulting in a significant therapeutic response upon short interval follow-up. This case stresses the importance of recognizing unusual thoracic imaging manifestations of an atypical fungal infection in immunocompromised individuals in order to expedite treatment of an otherwise potentially fatal disease.