Magnetic Resonance Imaging Characterization and Clinical Outcomes of Dilated and Arrhythmogenic Left Ventricular Cardiomyopathies.

BACKGROUND: Nondilated left ventricular cardiomyopathy (NDLVC) has been recently differentiated from dilated cardiomyopathy (DCM). A comprehensive characterization of these 2 entities using cardiac magnetic resonance (CMR) and genetic testing has never been performed. OBJECTIVES: This study sought to provide a thorough characterization and assess clinical outcomes in a large multicenter cohort of patients with DCM and NDLVC. METHODS: A total of 462 patients with DCM (227) or NDLVC (235) with CMR data from 4 different referral centers were retrospectively analyzed. The study endpoint was a composite of sudden cardiac death or major ventricular arrhythmias. RESULTS: In comparison to DCM, NDLVC had a higher prevalence of pathogenic or likely pathogenic variants of arrhythmogenic genes (40% vs 23%; P < 0.001), higher left ventricular (LV) systolic function (LV ejection fraction: 51% ± 12% vs 36% ± 15%; P < 0.001) and higher prevalence of free-wall late gadolinium enhancement (LGE) (27% vs 14%; P < 0.001). Conversely, DCM showed higher prevalence of pathogenic or likely pathogenic variants of nonarrhythmogenic genes (23% vs 12%; P = 0.002) and septal LGE (45% vs 32%; P = 0.004). Over a median follow-up of 81 months (Q1-Q3: 40-132 months), the study outcome occurred in 98 (21%) patients. LGE with septal location (HR: 1.929; 95% CI: 1.033-3.601; P = 0.039) was independently associated with the risk of sudden cardiac death or major ventricular arrhythmias together with LV dilatation, older age, advanced NYHA functional class, frequent ventricular ectopic activity, and nonsustained ventricular tachycardia. CONCLUSIONS: In a multicenter cohort of patients with DCM and NDLVC, septal LGE together with LV dilatation, age, advanced disease, and frequent and repetitive ventricular arrhythmias were powerful predictors of major arrhythmic events.

Vaccination-Associated Myocarditis and Myocardial Injury.

SARS-CoV-2 vaccine-associated myocarditis/myocardial injury should be evaluated in the contexts of COVID-19 infection, other types of viral myocarditis, and other vaccine-associated cardiac disorders. COVID-19 vaccine-associated myocardial injury can be caused by an inflammatory immune cell infiltrate, but other etiologies such as microvascular thrombosis are also possible. The clinical diagnosis is typically based on symptoms and cardiac magnetic resonance imaging. Endomyocardial biopsy is confirmatory for myocarditis, but may not show an inflammatory infiltrate because of rapid resolution or a non-inflammatory etiology. Myocarditis associated with SARS-COVID-19 vaccines occurs primarily with mRNA platform vaccines, which are also the most effective. In persons aged >16 or >12 years the myocarditis estimated crude incidences after the first 2 doses of BNT162b2 and mRNA-1273 are approximately 1.9 and 3.5 per 100 000 individuals, respectively. These rates equate to excess incidences above control populations of approximately 1.2 (BNT162b2) and 1.9 (mRNA-1273) per 100 000 persons, which are lower than the myocarditis rate for smallpox but higher than that for influenza vaccines. In the studies that have included mRNA vaccine and SARS-COVID-19 myocarditis measured by the same methodology, the incidence rate was increased by 3.5-fold over control in COVID-19 compared with 1.5-fold for BNT162b2 and 6.2-fold for mRNA-1273. However, mortality and major morbidity are less and recovery is faster with mRNA vaccine-associated myocarditis compared to COVID-19 infection. The reasons for this include vaccine-associated myocarditis having a higher incidence in young adults and adolescents, typically no involvement of other organs in vaccine-associated myocarditis, and based on comparisons to non-COVID viral myocarditis an inherently more benign clinical course.

Safety and efficacy of IV theophylline for regadenoson-associated side effect reversal.

BACKGROUND: Aminophylline injection has been on an intermittent nation-wide shortage due to manufacturing delays leaving a need for an alternative reversal agent for regadenoson-associated side effects. Intravenous theophylline should be a logical acceptable pharmacological alternative; however, data regarding its safety and efficacy as a reversal agent are lacking. METHODS: Utilizing electronic medical records at the University of Colorado hospital, we identified patients ≥ 18 years of age who had a pharmacologic stress test using regadenoson during periods of aminophylline shortage (3/1/2013 to 5/31/2013 and 4/1/2018 to 8/30/2018) in which theophylline was used as an alternative antidote for side effect reversal. Intravenous theophylline was prepared by the inpatient pharmacy to a concentration of 0.8 mg/mL in a total volume of 100 mL D5W. Specific side effects and side effect resolution were evaluated. RESULTS: Of the 122 patients evaluated, theophylline was administered in doses ranging from 40 to 75 mg with the majority receiving 40 mg. Complete resolution of regadenoson side effects occurred in 98 patients with 12 experiencing partial resolution and 1 without resolution. No adverse effects or events were reported. CONCLUSION: Due to limited availability of aminophylline, theophylline may be a safe and effective alternative to reverse regadenoson-associated side effects.

Myocardial Injury and Altered Gene Expression Associated With SARS-CoV-2 Infection or mRNA Vaccination.

SARS CoV-2 enters host cells via its Spike protein moiety binding to the essential cardiac enzyme angiotensin-converting enzyme (ACE) 2, followed by internalization. COVID-19 mRNA vaccines are RNA sequences that are translated into Spike protein, which follows the same ACE2-binding route as the intact virion. In model systems, isolated Spike protein can produce cell damage and altered gene expression, and myocardial injury or myocarditis can occur during COVID-19 or after mRNA vaccination. We investigated 7 COVID-19 and 6 post-mRNA vaccination patients with myocardial injury and found nearly identical alterations in gene expression that would predispose to inflammation, coagulopathy, and myocardial dysfunction.

Aortic valve chordae tendineae: A rare cause of aortic stenosis.

We describe a rare case of severe low-flow, low-gradient aortic stenosis due to a calcified aortic valve chordae tendineae. The chordae was captured on cardiac computed tomography (CT) using advanced 3-dimensional image reconstruction to reveal the fibrous strand tethering the non-coronary cusp to the left ventricular outflow tract, rendering it functionally immobile. This is one of the first reported cases of severe aortic stenosis from an aortic valve chordae tendineae which highlights the utility of advanced image processing techniques in cardiac CT.

Right Ventricular Dysfunction During Endurance Exercise as Determined by Pressure-Volume Analysis.

A 37-year-old athlete completed invasive endurance (90 km) bicycle exercise testing for right ventricular pressure-volume analysis. Increased right ventricular afterload caused declines in ventricular-arterial coupling and cardiac output, causing increased arteriovenous oxygen difference to maintain oxygen uptake. These findings demonstrate effects of changes in right ventricular performance on exercise capacity. (Level of Difficulty: Intermediate.).

Transcatheter Closure of Left Ventricle to Coronary Sinus Fistula Post-MVR and Septal Myectomy.

This paper describes the case of a patient who developed refractory heart failure due to a fistula from the left ventricle to the coronary sinus that was unintentionally created after a surgical myectomy and mitral valve replacement. Advanced image guidance with a pre-procedure 3-dimensional physical model and intraprocedure echocardiography fusion facilitated transcatheter plugging of the shunt with symptom resolution. (Level of Difficulty: Advanced.).

Update in Paravalvular Leak Closure.

PURPOSE OF REVIEW: Given the low occurrence of clinically important paravalvular leak (PVL), there are no large registries or trials in this space to investigate management strategies. This review integrates newer evidence, particularly in imaging guidance for these complex procedures, novel techniques and approaches that our group has taken, as well as approaches to more complex PVL plugging reported in case reports. RECENT FINDINGS: Perhaps the largest area of growth in the management of PVL is the use of advanced imaging in both pre-procedure evaluation and intra-procedural guidance with gated cardiac CT, 3D TEE, and fluoroscopy fusion technologies. Outside the USA, a new device, the Occlutech PLD, has become available with early data indicating high success rates. There remains little randomized data to support the efficacy of percutaneous PVL closure. Gated cardiac CT has become key to the pre-procedure evaluation for transcatheter closure as it allows for increased procedural efficiency and more accurate pre-procedure planning, particularly when combined with 3D printing. Intra-procedural TEE-fluoro fusion allows for more rapid crossing of defects by providing a visual target for interventionalists. The advent of purpose-built devices for PVL closure may further increase the efficacy and efficiency of percutaneous closure, but significant barriers remain for approval of these devices in the USA.

Echocardiography-fluoroscopy fusion imaging: The essential features used in congenital and structural heart disease interventional guidance.

Increased catheter-based interventions in congenital and structural heart disease require imaging modalities to be oriented in the same visual perspective. The use of echocardiography-fluoroscopy fusion (EFF) imaging has been developed for better characterization of complex anatomy and to facilitate key steps in interventional procedures. This review will detail the technology behind EFF, the differences between the two ultrasound fusion systems, and essential features of EFF imaging in congenital and structural heart disease interventions.

Congenital and Structural Heart Disease Interventions Using Echocardiography-Fluoroscopy Fusion Imaging.

With the increasing frequency of catheter-based interventions in congenital heart disease and structural heart disease, the use of fusion imaging has become a major enhancement for understanding complex anatomy and facilitating key steps in interventional procedures. Because transesophageal echocardiography and fluoroscopy are displayed in different visual perspectives, the interventional cardiologist must mentally reregister the images from the two modalities during the procedure. Echocardiography-fluoroscopy fusion (EFF) imaging displays the x-ray and ultrasound overlay images in the same visual perspective. This new technology allows for enhanced team communication, improved visual guidance, and more efficient navigation. The purpose of this review is to describe the EFF imaging technology, current uses of EFF imaging in congenital and structural heart disease, and future directions that will enhance this unique imaging technology to guide interventional procedures.

The acute effects of edge-to-edge percutaneous mitral valve repair on the shape and size of the mitral annulus and its relation to mitral regurgitation.

BACKGROUND: The effects of edge-to-edge percutaneous mitral valve repair on the shape and size of the mitral annulus and its relation to mitral regurgitation (MR) have not been well characterized. We evaluated acute changes in mitral annular shape and dimensions, and their effect on MR severity, in patients with functional and degenerative MR following MitraClip® . METHODS: Patients that underwent MitraClip® between January 2013 and May 2016 at our institution were retrospectively reviewed. EXCLUSIONS: inadequate images, prior mitral valve repair, and rapid atrial fibrillation. Intra-procedure TEE 3D images acquired prior to and after implantation of MitraClip® were analyzed using software to model the mitral valve apparatus. RESULTS: Of seventy-eight patients that underwent MitraClip® procedure, 60 were eligible. Mean age was 78.3 ± 11 years. Severe MR (4+) was present in 37 patients, moderately/severe MR (3+) in 23. All patients achieved MR reduction to ≤2. 3D annular circumference, bicommissural diameter, and anteroposterior diameter had a significant size reduction after MitraClip® . None of the mitral annular measures had significantly different mean change between the large and small MR change groups at the 0.05 significance level. CONCLUSIONS: In patients with functional or degenerative MR, the MitraClip® significantly affect mitral annular dimensions; however, these changes do not correlate with the immediate MR reduction.

Structural and Functional Phenotyping of the Failing Heart: Is the Left Ventricular Ejection Fraction Obsolete?

Diagnosis, prognosis, treatment, and development of new therapies for diseases or syndromes depend on a reliable means of identifying phenotypes associated with distinct predictive probabilities for these various objectives. Left ventricular ejection fraction (LVEF) provides the current basis for combined functional and structural phenotyping in heart failure by classifying patients as those with heart failure with reduced ejection fraction (HFrEF) and those with heart failure with preserved ejection fraction (HFpEF). Recently the utility of LVEF as the major phenotypic determinant of heart failure has been challenged based on its load dependency and measurement variability. We review the history of the development and adoption of LVEF as a critical measurement of LV function and structure and demonstrate that, in chronic heart failure, load dependency is not an important practical issue, and we provide hemodynamic and molecular biomarker evidence that LVEF is superior or equal to more unwieldy methods of identifying phenotypes of ventricular remodeling. We conclude that, because it reliably measures both left ventricular function and structure, LVEF remains the best current method of assessing pathologic remodeling in heart failure in both individual clinical and multicenter group settings. Because of the present and future importance of left ventricular phenotyping in heart failure, LVEF should be measured by using the most accurate technology and methodologic refinements available, and improved characterization methods should continue to be sought.

Myocardial microRNAs associated with reverse remodeling in human heart failure.

BACKGROUND: In dilated cardiomyopathies (DCMs) changes in expression of protein-coding genes are associated with reverse remodeling, and these changes can be regulated by microRNAs (miRs). We tested the general hypothesis that dynamic changes in myocardial miR expression are predictive of ß-blocker-associated reverse remodeling. METHODS: Forty-three idiopathic DCM patients (mean left ventricular ejection fraction 0.24 ± 0.09) were treated with ß-blockers. Serial ventriculography and endomyocardial biopsies were performed at baseline, and after 3 and 12 months of treatment. Changes in RT-PCR (candidate miRs) or array-measured miRs were compared based on the presence (R) or absence (NR) of a reverse-remodeling response, and a miR-mRNA-function pathway analysis (PA) was performed. RESULTS: At 3 months, 2 candidate miRs were selectively changed in Rs, decreases in miR-208a-3p and miR-591. PA revealed changes in miR-mRNA interactions predictive of decreased apoptosis and myocardial cell death. At 12 months, 5 miRs exhibited selective changes in Rs (decreases in miR-208a-3p, -208b-3p, 21-5p, and 199a-5p; increase in miR-1-3p). PA predicted decreases in apoptosis, cardiac myocyte cell death, hypertrophy, and heart failure, with increases in contractile and overall cardiac functions. CONCLUSIONS: In DCMs, myocardial miRs predict the time-dependent reverse-remodeling response to ß-blocker treatment, and likely regulate the expression of remodeling-associated miRs. TRIAL REGISTRATION: ClinicalTrials.gov NCT01798992. FUNDING: NIH 2R01 HL48013, 1R01 HL71118 (Bristow, PI); sponsored research agreements from Glaxo-SmithKline and AstraZeneca (Bristow, PI); NIH P20 HL101435 (Lowes, Port multi-PD/PI); sponsored research agreement from Miragen Therapeutics (Port, PI).

Enhanced Radiofrequency Ablation With Magnetically Directed Metallic Nanoparticles.

BACKGROUND: Remote heating of metal located near a radiofrequency ablation source has been previously demonstrated. Therefore, ablation of cardiac tissue treated with metallic nanoparticles may improve local radiofrequency heating and lead to larger ablation lesions. We sought to evaluate the effect of magnetic nanoparticles on tissue sensitivity to radiofrequency energy. METHODS AND RESULTS: Ablation was performed using an ablation catheter positioned with 10 g of force over prepared ex vivo specimens. Tissue temperatures were measured and lesion volumes were acquired. An in vivo porcine thigh model was used to study systemically delivered magnetically guided iron oxide (FeO) nanoparticles during radiofrequency application. Magnetic resonance imaging and histological staining of ablated tissue were subsequently performed as a part of ablation lesion analysis. Ablation of ex vivo myocardial tissue treated with metallic nanoparticles resulted in significantly larger lesions with greater impedance changes and evidence of increased thermal conductivity within the tissue. Magnet-guided localization of FeO nanoparticles within porcine thigh preps was demonstrated by magnetic resonance imaging and iron staining. Irrigated ablation in the regions with greater FeO, after FeO infusion and magnetic guidance, created larger lesions without a greater incidence of steam pops. CONCLUSIONS: Metal nanoparticle infiltration resulted in significantly larger ablation lesions with altered electric and thermal conductivity. In vivo magnetic guidance of FeO nanoparticles allowed for facilitated radiofrequency ablation without direct infiltration into the targeted tissue. Further research is needed to assess the clinical applicability of this ablation strategy using metallic nanoparticles for the treatment of cardiac arrhythmias.

The adrenergic system in pulmonary arterial hypertension: bench to bedside (2013 Grover Conference series).

In heart failure with reduced left ventricular ejection fraction (HFrEF), adrenergic activation is a key compensatory mechanism that is a major contributor to progressive ventricular remodeling and worsening of heart failure. Targeting the increased adrenergic activation with ß-adrenergic receptor blocking agents has led to the development of arguably the single most effective drug therapy for HFrEF. The pressure-overloaded and ultimately remodeled/failing right ventricle (RV) in pulmonary arterial hypertension (PAH) is also adrenergically activated, which raises the issue of whether an antiadrenergic strategy could be effectively employed in this setting. Anecdotal experience suggests that it will be challenging to administer an antiadrenergic treatment such as a ß-blocking agent to patients with established moderate-severe PAH. However, the same types of data and commentary were prevalent early in the development of ß-blockade for HFrEF treatment. In addition, in HFrEF approaches have been developed for delivering ß-blocker therapy to patients who have extremely advanced heart failure, and these general principles could be applied to RV failure in PAH. This review examines the role played by adrenergic activation in the RV faced with PAH, contrasts PAH-RV remodeling with left ventricle remodeling in settings of sustained increases in afterload, and suggests a possible approach for safely delivering an antiadrenergic treatment to patients with RV dysfunction due to moderate-severe PAH.

Tropheryma whipplei Endocarditis: A Two-patient Case Series.

BACKGROUND: Whipple endocarditis is caused by Tropheryma whipplei and is a well-described complication of Whipple's disease. Limited and small case series have been published regarding the presentation, diagnosis, and clinical course of this disease. METHODS/RESULTS: We describe 2 cases of patients with T. whipplei endocarditis, one of which underwent a successful heart transplant. CONCLUSION: In both cases of Whipple's endocarditis, there was a subacute prodromal phase followed by an acute rapid decompensation with severe destruction of the aortic valve, heart failure, and embolism. Because the diagnosis of T. whipplei endocarditis is typically not made until pathological examination of tissue, clinicians must have a high suspicion for it in the absence of other offending organisms, especially among middle-aged white males with sub-acute symptoms and embolic complications.

Therapeutic Molecular Phenotype of ß-Blocker-Associated Reverse-Remodeling in Nonischemic Dilated Cardiomyopathy.

BACKGROUND: When ß-blockers produce reverse-remodeling in idiopathic dilated cardiomyopathy, they partially reverse changes in fetal-adult/contractile protein, natriuretic peptide, SR-Ca(2+)-ATPase gene program constituents. The objective of the current study was to further test the hypothesis that reverse-remodeling is associated with favorable changes in myocardial gene expression by measuring additional contractile, signaling, and metabolic genes that exhibit a fetal/adult expression predominance, are thyroid hormone-responsive, and are regulated by ß1-adrenergic receptor signaling. A secondary objective was to identify which of these putative regulatory networks is most closely associated with observed changes. METHODS AND RESULTS: Forty-seven patients with idiopathic dilated cardiomyopathy (left ventricular ejection fraction, 0.24±0.09) were randomized to the adrenergic-receptor blockers metoprolol (ß1-selective), metoprolol+doxazosin (ß1/α1), or carvedilol (ß1/ß2/α1). Serial radionuclide ventriculography and endomyocardial biopsies were performed at baseline, 3, and 12 months. Expression of 50 mRNA gene products was measured by quantitative polymerase chain reaction. Thirty-one patients achieved left ventricular ejection fraction reverse-remodeling response defined as improvement by ≥0.08 at 12 months or by ≥0.05 at 3 months (Δ left ventricular ejection fraction, 0.21±0.10). Changes in gene expression in responders versus nonresponders were decreases in NPPA and NPPB and increases in MYH6, ATP2A2, PLN, RYR2, ADRA1A, ADRB1, MYL3, PDFKM, PDHX, and CPT1B. All except PDHX involved increase in adult or decrease in fetal cardiac genes, but 100% were concordant with changes predicted by inhibition of ß1-adrenergic signaling. CONCLUSIONS: In addition to known gene expression changes, additional calcium-handling, sarcomeric, adrenergic signaling, and metabolic genes were associated with reverse-remodeling. The pattern suggests a fetal-adult paradigm but may be because of reversal of gene expression controlled by a ß1-adrenergic receptor gene network. CLINICAL TRIAL REGISTRATION: URL: www.clinicaltrials.gov. Unique Identifier: NCT01798992.

Gadolinium Augmentation of Myocardial Tissue Heating During Radiofrequency Ablation.

OBJECTIVES: This study hypothesized that a metal already commonly used in medical procedures, gadolinium (Gd), will augment radiofrequency (RF) thermal injury and affect cardiac ablation lesions. BACKGROUND: Enhancement of RF ablation using metallic particles has been proposed for ablation of tumors. METHODS: A series of ablation lesions were delivered at variable power using an ex vivo model. Tissue temperatures and lesion characteristics were analyzed. Ablation in a porcine in vivo model after direct needle injection of the myocardium with Gd or after systemic administration of Gd encased in heat sensitive liposomes was also performed and compared to control values. RESULTS: Ablation after Gd infiltration of myocardial tissue resulted in significantly larger lesions at both low- and high-power settings. Larger impedance changes were observed during ablation of Gd-treated myocardium. In vivo ablation using a force-sensing irrigated tip catheter resulted in enhanced lesion sizes after Gd injection without a higher incidence of steam pops or perforation. Systemic administration of liposomal Gd with local release by RF heating did not result in larger ablation sizes. CONCLUSIONS: Gd can be used to enhance RF ablation lesions. In both ex vivo studies with a 4-mm ablation catheter under power control and in vivo findings with an irrigated tip catheter, ablation of myocardium infiltrated with Gd resulted in larger lesions, with altered RF electrical and thermal characteristics. More research is needed to refine the potential for Gd facilitation of RF ablation. The use of systemic heat-sensitive liposomes containing Gd with targeted release by RF heating did not affect lesion size.