Diagnosis and Management of Cardiac Sarcoidosis: A Scientific Statement From the American Heart Association.

Cardiac sarcoidosis is an infiltrative cardiomyopathy that results from granulomatous inflammation of the myocardium and may present with high-grade conduction disease, ventricular arrhythmias, and right or left ventricular dysfunction. Over the past several decades, the prevalence of cardiac sarcoidosis has increased. Definitive histological confirmation is often not possible, so clinicians frequently face uncertainty about the accuracy of diagnosis. Hence, the likelihood of cardiac sarcoidosis should be thought of as a continuum (definite, highly probable, probable, possible, low probability, unlikely) rather than in a binary fashion. Treatment should be initiated in individuals with clinical manifestations and active inflammation in a tiered approach, with corticosteroids as first-line treatment. The lack of randomized clinical trials in cardiac sarcoidosis has led to treatment decisions based on cohort studies and consensus opinions, with substantial variation observed across centers. This scientific statement is intended to guide clinical practice and to facilitate management conformity by providing a framework for the diagnosis and management of cardiac sarcoidosis.

The HFSA Advanced Heart Failure and Transplant Cardiology Fellowship Consensus Conference.

There is waning interest among cardiology trainees in pursuing an Advanced Heart Failure/Transplant Cardiology (AHFTC) fellowship as evidenced by fewer applicants in the National Resident Matching Program match to this specialty. This trend has generated considerable attention across the heart failure community. In response, the Heart Failure Society of America convened the AHFTC Fellowship Task Force with a charge to develop strategies to increase the value proposition of an AHFTC fellowship. Subsequently, the HFSA sponsored the AHFTC Fellowship Consensus Conference April 26-27, 2023. Before the conference, interviews of 44 expert stakeholders diverse across geography, site of practice (traditional academic medical center or other centers), specialty/area of expertise, sex, and stage of career were conducted virtually. Based on these interviews, potential solutions to address the declining interest in AHFTC fellowship were categorized into five themes: (1) alternative training pathways, (2) regulatory and compensation, (3) educational improvements, (4) exposure and marketing for pipeline development, and (5) quality of life and mental health. These themes provided structure to the deliberations of the AHFTC Fellowship Consensus Conference. The recommendations from the Consensus Conference were subsequently presented to the HFSA Board of Directors to inform strategic plans and interventions. The HFSA Board of Directors later reviewed and approved submission of this document. The purpose of this communication is to provide the HF community with an update summarizing the processes used and concepts that emerged from the work of the HFSA AHFTC Fellowship Task Force and Consensus Conference.

Cardiovascular Burden of the V142I Transthyretin Variant.

Importance: Individual cohort studies concur that the amyloidogenic V142I variant of the transthyretin (TTR) gene, present in 3% to 4% of US Black individuals, increases heart failure (HF) and mortality risk. Precisely defining carrier risk across relevant clinical outcomes and estimating population burden of disease are important given established and emerging targeted treatments. Objectives: To better define the natural history of disease in carriers across mid to late life, assess variant modifiers, and estimate cardiovascular burden to the US population. Design, Setting, and Participants: A total of 23 338 self-reported Black participants initially free from HF were included in 4 large observational studies across the US (mean [SD], 15.5 [8.2] years of follow-up). Data analysis was performed between May 2023 and February 2024. Exposure: V142I carrier status (n = 754, 3.2%). Main Outcomes and Measures: Hospitalizations for HF (including subtypes of reduced and preserved ejection fraction) and all-cause mortality. Outcomes were analyzed by generating 10-year hazard ratios for each age between 50 and 90 years. Using actuarial methods, mean survival by carrier status was estimated and applied to the 2022 US population using US Census data. Results: Among the 23 338 participants, the mean (SD) age at baseline was 62 (9) years and 76.7% were women. Ten-year carrier risk increased for HF hospitalization by age 63 years, predominantly driven by HF with reduced ejection fraction, and 10-year all-cause mortality risk increased by age 72 years. Only age (but not sex or other select variables) modified risk with the variant, with estimated reductions in longevity ranging from 1.9 years (95% CI, 0.6-3.1) at age 50 to 2.8 years (95% CI, 2.0-3.6) at age 81. Based on these data, 435 851 estimated US Black carriers between ages 50 and 95 years are projected to cumulatively lose 957 505 years of life (95% CI, 534 475-1 380 535) due to the variant. Conclusions and Relevance: Among self-reported Black individuals, male and female V142I carriers faced similar and substantial risk for HF hospitalization, predominantly with reduced ejection fraction, and death, with steep age-dependent penetrance. Delineating the individual contributions of, and complex interplay among, the V142I variant, ancestry, the social construct of race, and biological or social determinants of health to cardiovascular disease merits further investigation.

Development of cardiometabolic risk factors following endocrine therapy in women with breast cancer.

PURPOSE: Studies comparing the effect of aromatase inhibitor (AI) and tamoxifen use on cardiovascular disease (CVD) risk factors in hormone receptor-positive breast cancer (BC) survivors report conflicting results. We examined associations of endocrine therapy use with incident diabetes, dyslipidemia, and hypertension. METHODS: The Pathways Heart Study examines cancer treatment exposures with CVD-related outcomes in Kaiser Permanente Northern California members with BC. Electronic health records provided sociodemographic and health characteristics, BC treatment, and CVD risk factor data. Hazard ratios (HR) and 95% confidence intervals (CI) of incident diabetes, dyslipidemia, and hypertension in hormone receptor-positive BC survivors using AIs or tamoxifen compared with survivors not using endocrine therapy were estimated using Cox proportional hazards regression models adjusted for known confounders. RESULTS: In 8985 BC survivors, mean baseline age and follow-up time was 63.3 and 7.8 years, respectively; 83.6% were postmenopausal. By treatment, 77.0% used AIs, 19.6% used tamoxifen, and 16.0% used neither. Postmenopausal women who used tamoxifen had an increased rate (HR 1.43, 95% CI 1.06-1.92) of developing hypertension relative to those who did not use endocrine therapy. Tamoxifen use was not associated with incident diabetes, dyslipidemia, or hypertension in premenopausal BC survivors. Postmenopausal AI users had higher hazard rates of developing diabetes (HR 1.37, 95% CI 1.05-1.80), dyslipidemia (HR 1.58, 95% CI 1.29-1.92), and hypertension (HR 1.50, 95% CI 1.24-1.82) compared with non-endocrine therapy users. CONCLUSION: Hormone receptor-positive BC survivors treated with AIs may have higher rates of developing diabetes, dyslipidemia, and hypertension over an average 7.8 years post-diagnosis.

Diagonal Interactions between Glutamate and Arginine Analogs with Varying Side-Chain Lengths in a ß-Hairpin.

Cross-strand interactions are important for the stability of ß-sheet structures. Accordingly, cross-strand diagonal interactions between glutamate and arginine analogs with varying side-chain lengths were studied in a series of ß-hairpin peptides. The peptides were analyzed by homonuclear two-dimensional nuclear magnetic resonance methods. The fraction folded population and folding free energy of the peptides were derived from the chemical shift data. The fraction folded population trends could be rationalized using the strand propensity of the constituting residues, which was not the case for the peptides with lysine analogs, highlighting the difference between the arginine analogs and lysine analogs. Double-mutant cycle analysis was used to derive the diagonal ion-pairing interaction energetics. The most stabilizing diagonal cross-strand interaction was between the shortest residues (i.e., Asp2-Agp9), most likely due to the least side-chain conformational penalty for ion-pair formation. The diagonal interaction energetics in this study involving the arginine analogs appears to be consistent with and extend beyond our understanding of diagonal ion-pairing interactions involving lysine analogs. The results should be useful for designing ß-strand-containing molecules to affect biological processes such as amyloid formation and protein-protein interactions.

Recognition, Prevention, and Management of Arrhythmias and Autonomic Disorders in Cardio-Oncology: A Scientific Statement From the American Heart Association.

With the advent of novel cancer therapeutics and improved screening, more patients are surviving a cancer diagnosis or living longer with advanced disease. Many of these treatments have associated cardiovascular toxicities that can manifest in both an acute and a delayed fashion. Arrhythmias are an increasingly identified complication with unique management challenges in the cancer population. The purpose of this scientific statement is to summarize the current state of knowledge regarding arrhythmia identification and treatment in patients with cancer. Atrial tachyarrhythmias, particularly atrial fibrillation, are most common, but ventricular arrhythmias, including those related to treatment-induced QT prolongation, and bradyarrhythmias can also occur. Despite increased recognition, dedicated prospective studies evaluating true incidence are lacking. Moreover, few studies have addressed appropriate prevention and treatment strategies. As such, this scientific statement serves to mobilize the cardio-oncology, electrophysiology, and oncology communities to develop clinical and scientific collaborations that will improve the care of patients with cancer who have arrhythmias.

Risk of heart failure with preserved versus reduced ejection fraction in women with breast cancer.

PURPOSE: While clinical heart failure (HF) is recognized as an adverse effect from breast cancer (BC) treatment, sparse data exist on specific HF phenotypes in affected BC survivors. We examined risk of HF by left ventricular ejection fraction (LVEF) status in women with a history of BC. METHODS: 14,804 women diagnosed with all stages of invasive BC from 2005 to 2013 and with no history of HF were matched 1:5 to 74,034 women without BC on birth year, race, and ethnicity. LVEF values were extracted from echocardiography studies within 30 days before through 90 days after the HF clinical encounter. HF was stratified into HF with preserved ejection fraction (HFpEF, LVEF ≥ 45%) and HF with reduced ejection fraction (HFrEF, LVEF < 45%). Cumulative incidence rates (CIRs) were estimated with competing risk of overall death. Hazard ratios (HR) were calculated by multivariable Cox proportional hazards regression. RESULTS: Mean time to HF diagnosis was 5.31 years (range 0.03-13.03) in cases and 5.25 years (range 0.01-12.94) in controls. 10-year CIRs were 1.2% and 0.9% for overall HF, 0.8% and 0.7% for HFpEF, and 0.4% and 0.2% for HFrEF in cases and controls, respectively. In fully adjusted models, an overall significant increased risk of HF in cases versus controls was observed (HR: 1.31, 95% CI 1.14, 1.51). The increased risk was seen for both HFrEF (HR: 1.59, 95% CI 1.22, 2.08) and HFpEF (HR: 1.22; 95% CI 1.03, 1.45). CONCLUSION: BC survivors experienced higher risk of HF compared with women without BC, and the risk persisted across LVEF phenotypes. Systematic cardio-oncology surveillance should be considered to mitigate this risk in BC patients.

The shock team: a multidisciplinary approach to early patient phenotyping and appropriate care escalation in cardiogenic shock.

PURPOSE OF REVIEW: Cardiogenic shock (CS) is a highly morbid condition with mortality remaining greater than 30% despite improved pathophysiologic understanding and access to mechanical circulatory support (MCS). In response, shock teams modeled on successful multidisciplinary care structures for other diseases are being implemented nationwide. RECENT FINDINGS: Primary data supporting a benefit of shock team implementation on patient outcomes are relatively limited and entirely observational. Four single-center before-and-after studies and one multicenter registry study have demonstrated improved outcomes in patients with CS, potentially driven by increased pulmonary artery catheter (PAC) utilization and earlier (and more appropriate) initiation of MCS. Shock teams are also supported by a growing body of literature recognizing the independent benefit of the interventions they seek to implement, including patient phenotyping with PAC use and an algorithmic approach to CS care. Though debated, MCS is also highly likely to improve CS outcomes when applied appropriately, which further supports a multidisciplinary shock team approach to patient and device selection. SUMMARY: Shock teams likely improve patient outcomes by facilitating early patient phenotyping and appropriate intervention. Institutions should strongly consider adopting a multidisciplinary shock team approach to CS care, though additional data supporting these interventions are needed.

Cardiotoxicity as an adverse effect of immunomodulatory drugs and proteasome inhibitors in multiple myeloma: A network meta-analysis of randomized clinical trials.

We aim to determine the cumulative and comparative risk of cardiovascular events associated with different Immunomodulatory Drugs (iMiDs) and Proteasome Inhibitor (PIs) in Multiple Myeloma (MM) patients through pairwise and network meta-analysis. Electronic searches were conducted using Ovid MEDLINE, EMBASE, CINAHL, Web of Science, and Clinical Trial Registry (Clinical Trials.gov) up to May 2021. Phase 3 randomized clinical trials (RCTs) reporting cardiotoxicity in MM patients (newly diagnoses and/or relapsed) treated with iMiD and/or PI. Studies, where iMiD or PI was used alongside the chemotherapy versus placebo or no additional drugs (control) in the other arm were included. The primary outcome was the presence of cardiotoxicity after follow-up. Pairwise meta-analysis and network meta-analysis were performed using the frequentist's approach to estimate the odds ratio (OR). Twenty RCTs with 10,373 MM patients were included in this analysis. Eleven studies compared iMiDs with control, seven studies compared PIs with control, and two studies compared bortezomib against carfilzomib. CTACE high-grade (≥grade 3) cardiotoxic events were increased with iMiDs compared to their control counterpart (OR 2.05; 95% CI 1.30-3.26). Similar high-grade cardiotoxicity was also noted more frequently with PI use when compared to the control group (OR 1.67; 95% CI 1.17-2.40). Among the PIs, carfilzomib was associated with a maximum risk of cardiotoxicity (OR 2.68; 95% CI 1.63-4.40). There was no evidence of publication bias among studies. iMiDs and PIs, particularly carfilzomib, appear to be associated with increased risk of high-grade cardiovascular events in MM patients.

Cardiometabolic Consequences of Targeted Anticancer Therapies.

ABSTRACT: Cardiometabolic disease (CMD) is the most common preventable cause of death in the world. A number of components are included in the spectrum of CMD, such as metabolic syndrome/obesity, hyperglycemia/diabetes, dyslipidemia, and hypertension, which are independently associated with cardiovascular disease risk. These conditions often occur together, and patients with cancer frequently undergo treatments that can generate or worsen CMD. This review highlights and presents mechanistic and epidemiological evidence regarding CMD in 4 categories of anticancer medications, namely, mTOR/PI3K-Akt inhibitors, multitargeted tyrosine kinase inhibitor, immune checkpoint inhibitor therapy, and endocrine therapy. Patients taking these medications need careful monitoring during therapy. There is a role for cardio-oncology and onco-primary care specialists in optimally managing patients at risk to mitigate CMD during treatment with these and other investigational anticancer medications.

The Effects of Charged Amino Acid Side-Chain Length on Diagonal Cross-Strand Interactions between Carboxylate- and Ammonium-Containing Residues in a ß-Hairpin.

The ß-sheet is one of the common protein secondary structures, and the aberrant aggregation of ß-sheets is implicated in various neurodegenerative diseases. Cross-strand interactions are an important determinant of ß-sheet stability. Accordingly, both diagonal and lateral cross-strand interactions have been studied. Surprisingly, diagonal cross-strand ion-pairing interactions have yet to be investigated. Herein, we present a systematic study on the effects of charged amino acid side-chain length on a diagonal ion-pairing interaction between carboxylate- and ammonium-containing residues in a ß-hairpin. To this end, 2D-NMR was used to investigate the conformation of the peptides. The fraction folded population and the folding free energy were derived from the chemical shift data. The fraction folded population for these peptides with potential diagonal ion pairs was mostly lower compared to the corresponding peptide with a potential lateral ion pair. The diagonal ion-pairing interaction energy was derived using double mutant cycle analysis. The Asp2-Dab9 (Asp: one methylene; Dab: two methylenes) interaction was the most stabilizing (-0.79 ± 0.14 kcal/mol), most likely representing an optimal balance between the entropic penalty to enable the ion-pairing interaction and the number of side-chain conformations that can accommodate the interaction. These results should be useful for designing ß-sheet containing molecular entities for various applications.

Training and Career Development in Cardio-Oncology Translational and Implementation Science.

Cardiovascular disease is a leading cause of death in cancer survivors, after recurrence of the primary tumor or occurrence of a secondary malignancy. Consequently, the interdisciplinary field of cardio-oncology has grown rapidly in recent years to address the cardiovascular care needs of this unique population through clinical care and research initiatives. Here, the authors discuss the ideal infrastructure for training and career development in cardio-oncology translational and implementation science and emphasize the importance of the multidisciplinary cardiovascular team for both research and patient care. Cardio-oncology training opportunities in general cardiology, hematology/oncology, and specialized cardio-oncology clinical and research fellowships are also considered.

Insertion of Pro-Hyp-Gly provides 2 kcal mol-1 stability but attenuates the specific assembly of ABC heterotrimeric collagen triple helices.

Collagen is a major structural component of the extracellular matrix and connective tissue. The key structural feature of collagen is the collagen triple helix, with a Xaa-Yaa-Gly (glycine) repeating pattern. The most frequently occurring triplet is Pro (proline)-Hyp (hydroxyproline)-Gly. The reversible thermal folding and unfolding of a series of heterotrimeric collagen triple helices with varying number of Pro-Hyp-Gly triplets were monitored by circular dichroism spectroscopy to determine the unfolding thermodynamic parameters Tm (midpoint transition temperature), ΔHTm (unfolding enthalpy), and ΔGunfold (unfolding free energy). The Tm and ΔGunfold of the heterotrimeric collagen triple helices increased with increasing number of Pro-Hyp-Gly triplets. The ΔGunfold increased by 2.0 ± 0.2 kcal mol-1 upon inserting one Pro-Hyp-Gly triplet into all three chains. The Tm difference between the most stable ABC combination and the second most stable BCC combination decreased with increasing number of Pro-Hyp-Gly triplets, even though the ΔGunfold difference remained the same. These results should be useful for tuning the stability of collagen triple helical peptides for hydrogel formation, recognition of denatured collagen triple helices as diagnostics and therapeutics, and targeted drug delivery.

Longer charged amino acids favor ß-strand formation in hairpin peptides.

Interactions between charged amino acids significantly influence the structure and function of proteins. The encoded charged amino acids Asp, Glu, Arg, and Lys have different number of hydrophobic methylenes linking the backbone to the charged functionality. It remains to be fully understood how does this difference in the number of methylenes affect protein structure stability. Protein secondary structures are the fundamental three-dimensional building blocks of protein structures. ß-Sheet structures are particularly interesting, because these structures have been associated with a number of protein misfolding diseases. Herein, we report the effect of charged amino acid side chain length at two ß-strand positions individually on the stability of a ß-hairpin. The charged amino acids include side chains with a carboxylate, an ammonium, or a guanidinium group. The experimental peptides, fully folded reference peptides, and fully unfolded reference peptides were synthesized by solid phase peptide synthesis and analyzed by 2D NMR methods including TOCSY, DQF-COSY, and ROESY. Sequence specific assignments were performed for all peptides. The chemical shift data were used to derive the fraction folded population and the folding free energy for the experimental peptides. Results showed that the fraction folded population increased with increasing charged amino acid side chain length. These results should be useful for developing functional peptides that adopt the ß-conformation.

The Role and Impact of Social Media in Cardio-oncology During the COVID-19 Pandemic.

PURPOSE OF REVIEW: To give an overview of the role of social media (SoMe) in cardio-oncology during the COVID-19 pandemic. RECENT FINDINGS: SoMe has been critical in fostering education, outreach, awareness, collaboration, dissemination of information, and advocacy in cardio-oncology. This has become increasingly evident during the COVID-19 pandemic, during which SoMe has helped share best practices, community, and research focused on the impact of COVID-19 in cardiology and hematology/oncology, with cardio-oncology at the interface of these two subspecialty fields. A strength of SoMe is the ability to amplify a message in real-time, globally, with minimal investment of resources. This has been particularly beneficial for the emerging field of cardio-hematology/cardio-oncology, a field focused on the interplay of cancer and cardiovascular disease. SoMe field especially during the COVID-19 pandemic. We illustrate how social media has supported innovation (including telemedicine), amplification of healthcare workers' voice, and illumination of pre-existing and continued health disparities within the field of cardio-oncology during the pandemic.

When cardiomyopathy, cancer, and COVID-19 collide: A case report.

Malignancy has historically prohibited solid organ transplant; however, patients with effectively treated, favorable-risk cancers should not necessarily be eliminated as transplant candidates. These cases require careful review by a multidisciplinary team. Here, we report the case of a woman with end-stage heart failure undergoing heart transplant evaluation during the COVID pandemic who was found to have early-stage, hormone receptor-positive breast cancer. Given her favorable cancer-related prognosis, a multidisciplinary committee recommended lumpectomy, accelerated partial breast irradiation, and adjuvant aromatase inhibitor therapy for definitive treatment to allow for consideration of orthotopic heart transplant.

Impact of malignancy on In-hospital mortality, stratified by the cause of admission: An analysis of 67 million patients from the National Inpatient Sample.

OBJECTIVE: To describe the patient characteristics and the reason for admission of patients with malignancy by malignancy, and to study mortality rates for the different causes of admissions among the different types of cancer. PATIENTS AND METHODS: Using the nationwide Inpatient Sampling (2015-2017) we examined the cause of admission and associated in-hospital mortality, stratified by presence and type of malignancy. Multivariable logistic regression models were used to examine the association between in-hospital mortality and malignancy sites for different primary admission causes. RESULTS: Out of 67 819 693 inpatient admissions, 8.8% had malignancy. Amongst those with malignancy, haematological malignancy was the most common (20.2%). The most common cause of admission amongst all cancers were malignancy-related admissions, where up to 57% of all colorectal admissions were malignancy-related. The most common non-malignancy cause of admission was infectious causes, which were most frequent among patients with haematological malignancy (18.4%). Patients with malignancy had higher crude mortality rates (5.7% vs 1.9%). Mortality rates were highest among patients with lung cancer (8.7%). Among all admissions, the adjusted rates of mortality were higher for patients with lung (OR 3.65, 95% CI [3.59-3.71]), breast (OR 2.06, 95% CI [1.99-2.13]), haematological (OR 1.79, 95% CI [1.76-1.82]) and colorectal (OR 1.71, 95% CI [1.66-1.76]) malignancies compared with patients with no malignancy. CONCLUSION: Our work highlights the need to consider the burden of cancer on our hospital services and consider how the prognostic impact of different types of admissions may relate to the type of cancer diagnosis and understand whether these differences relate to disparities in clinical care/treatments.

Trends in cardiovascular mortality of cancer patients in the US over two decades 1999-2019.

BACKGROUND: Cancer is the second most common cause of death globally after cardiovascular disease, and cancer patients are at an increased risk of CV death. This recognition has led to publication of cardio-oncological guidelines and to the widespread adoption of dedicated cardio-oncology services in many institutes. However, it is unclear whether there has been a change in the incidence of CV death in cancer patients. METHODS AND RESULTS: Using Centers for Disease Control and Prevention Wide-Ranging, Online Data for Epidemiologic Research (CDC WONDER) Multiple Cause of Death dataset, we determined national trends in age-standardised mortality rates attributed to cardiovascular diseases in patients with and without cancer, from 1999 to 2019, stratified by cancer type, age, gender, race, and place of residence (state and urbanisation status). Among more than 17.8 million cardiovascular deaths in the United States, 13.6% were patients with a concomitant cancer diagnosis. During the study period, among patients with cancer, the age-adjusted mortality rate dropped by 52% (vs 38% in patients with no cancer). In cancer patients, age-adjusted mortality rate dropped more significantly among patients with gastrointestinal, breast, and prostate malignancy than among patients with haematological malignancy (59%-63% vs. 41%). Similar reduction was observed in both genders (53%-54%), but more prominent reduction was observed in older patients and in those living in metro areas. CONCLUSIONS: Our findings emphasise the role of multidisciplinary management of cancer patients. Widespread adoption of cardio oncology services have the potential to impact the inherent risk of increased CV mortality in both cancer patients and survivors.

How to Manage Mitral Stenosis Due to Mitral Annular Calcification.

PURPOSE OF REVIEW: Mitral annular calcification (MAC) is associated with cardiovascular comorbidities and events and in the presence of mitral stenosis (MS) represents a high-risk cohort with limited treatment options. Emerging hybrid, minimally invasive, and transcatheter therapies that use circumferential MAC as an anchor for mitral valve replacement are emerging, but none are consistently associated with ideal outcomes. RECENT FINDINGS: In patients with MAC and nonrheumatic calcific mitral stenosis who are severely symptomatic, mitral intervention may be indicated. Surgical decalcification and replacement of the mitral valve remains the conventional therapy. Surgical techniques to avoid decalcification are being described including a left atrium to left ventricular apex graft conduit. Transcatheter balloon-expandable valves designed for the aortic valve have been implanted in the mitral position in MAC with a surgical direct transatrial transcatheter approach or transseptal transcatheter approach. Left ventricular outflow tract (LVOT) obstruction remains prevalent and associated with increased mortality. Direct transatrial approach allows for surgical resection of the anterior leaflet to mitigate this risk, and percutaneous therapies to lacerate the anterior leaflet or to ablate the basal septum are being developed. Cardiac computed tomography has emerged as a requisite for patient selection and procedural planning and has powerful predictive value for LVOT obstruction and valve embolization in valve-in-MAC. Novel transcatheter valves designed specifically for the mitral space are being studied in patients with MAC. MAC with mitral stenosis remains a challenging disease. Advances in technique, technology, and imaging may create new and reproducible treatment options with low procedural mortality for this challenging disease entity.

Swapping the Positions in a Cross-Strand Lateral Ion-Pairing Interaction between Ammonium- and Carboxylate-Containing Residues in a ß-Hairpin.

Cross-strand lateral ion-pairing interactions are important for antiparallel ß-sheet stability. Statistical studies suggested that swapping the position of cross-strand lateral residues should not significantly affect the interaction. Herein, we swapped the position of ammonium- and carboxylate-containing residues with different side-chain lengths in a cross-strand lateral ion-pairing interaction in a ß-hairpin. The peptides were analyzed by 2D-NMR. The fraction folded population and folding free energy were derived from the chemical shift data. The ion-pairing interaction energy was derived using double mutant cycle analysis. The general trends for the fraction folded population and interaction energetics remained similar upon swapping the position of the interacting charged residues. The most stabilizing cross-strand interactions were between short residues, similar to the unswapped study. However, the fraction folded populations for most of the swapped peptides were higher compared to the corresponding unswapped peptides. Furthermore, subtle differences in the ion-pairing interaction energy upon swapping were observed, most likely due to the "unleveled" relative positioning of the interacting residues created by the inherent right-handed twist of the structure. These results should be useful for developing functional peptides that rely on lateral ion-pairing interactions across antiparallel ß-strands.