Arrhythmogenic or dilated or desmoplakin cardiomyopathy? A challenging case managed by our multidisciplinary cardiogenetic team.

Arrhythmogenic cardiomyopathy (ACM), characterized by fibro or fibrofatty infiltration of the myocardium with a predominant arrhythmic presentation, is a genetically mediated cause of sudden cardiac death in the young and athletic individuals. We report a case of a severe form of biventricular ACM in a middle-aged man with a family history of cardiomyopathy-related young death. The proband was identified to harbor two novel mutations in the DES and DOLK genes and was managed comprehensively with a multidisciplinary team approach. This report reinforces the need for a dedicated cardiovascular genetics program as well as a population-specific genetic database in developing countries.

Channelopathies - emerging trends in the management of inherited arrhythmias.

In spite of their relative rarity, inheritable arrhythmias have come to the forefront as a group of potentially fatal but preventable cause of sudden cardiac death in children and (young) adults. Comprehensive management of inherited arrhythmias includes diagnosing and treating the proband and identifying and protecting affected family members. This has been made possible by the vast advances in the field of molecular biology enabling better understanding of the genetic underpinnings of some of these disease groups, namely congenital long QT syndrome, catecholaminergic polymorphic ventricular tachycardia and Brugada syndrome. The ensuing knowledge of the genotype-phenotype correlations enables us to risk-stratify, prognosticate and treat based on the genetic test results. The various diagnostic modalities currently available to us, including clinical tools and genetic technologies, have to be applied judiciously in order to promptly identify those affected and to spare the emotional burden of a potentially lethal disease in the unaffected individuals. The therapeutic armamentarium of inherited arrhythmias includes pharmacological agents, device therapies and surgical interventions. A treatment strategy keeping in mind the risk profile of the patients, the local availability of drugs and the expertise of the treating personnel is proving effective. While opportunities for research are numerous in this expanding field of medicine, there is also tremendous scope for incorporating the emerging trends in managing patients and families with inherited arrhythmias in the Indian subcontinent.

Results of comprehensive genetic testing in patients presenting to a multidisciplinary inherited heart disease clinic in India.

OBJECTIVES: This study aims to analyze the results of comprehensive genetic testing in patients presenting to a dedicated multidisciplinary inherited heart disease clinic in India. METHODS: All patients presenting to our clinic from August 2017 to October 2023 with a suspected inherited heart disease and consenting for genetic testing were included. The probands were grouped into familial cardiomyopathies namely hypertrophic cardiomyopathy (HCM), dilated cardiomyopathy (DCM), arrhythmogenic cardiomyopathy (ACM) and peripartum cardiomyopathy (PPCM), channelopathies namely congenital long QT syndrome (LQTS) and Brugada syndrome (BrS), and heritable connective tissue disorder namely Marfan Syndrome (MFS). Next generation sequencing (NGS) was used, and pre-test and post-test counseling were provided to probands and cascade screening offered to relatives. RESULTS: Mean age of the subjects (n = 77; 48 probands, 29 relatives) was 43 ± 18 years, 68 % male and 44 % symptomatic, with 36 HCM, 3 DCM, 3 ACM, 1 PPCM, 3 LQTS, 1 BrS and 1 MFS probands. The diagnostic yield of NGS-based genetic testing was 31 %; variants of uncertain significance (VUS) were identified in 54 %; and 15 % were genotype-negative. Twenty-nine relatives from 18 families with HCM (n = 12), DCM (n = 3), ACM (n = 2) and MFS (n = 1) underwent genetic testing. The genotype positive probands/relatives and VUS carriers with strong disease phenotype and/or high risk variant were advised periodic follow-up; the remaining probands/relatives were discharged from further clinical surveillance. CONCLUSIONS: Genetic testing guides treatment and follow-up of patients with inherited heart diseases and should be carried out in dedicated multidisciplinary clinics with expertise for counseling and cascade screening of family members.

Mutation location effect on severity of phenotype during exercise testing in type 1 long-QT syndrome: impact of transmembrane and C-loop location.

BACKGROUND: Targeted mutation site-specific differences have correlated C-loop missense mutations with worse outcomes and increased benefit of beta-blockers in LQT1. This observation has implicated the C-loop region as being mechanistically important in the altered response to sympathetic stimulation known to put patients with LQT1 at risk of syncope and sudden cardiac death. OBJECTIVE: The objective of this study was to determine if there is mutation site-specific response to sympathetic stimulation and beta-blockers using exercise testing. METHODS: This study is a retrospective review of LQT1 patients undergoing exercise testing at 3 academic referral centers. RESULTS: A total of 123 patients (age 28 ± 17 years, 59 male) were studied including 34 patients (28%) with C-loop mutations. There were no significant differences in supine, standing, peak exercise and 1-minute recovery QTc duration between patients with C-loop mutations and patients with alternate mutation sites. In 37 patients that underwent testing on and off beta-blockers, beta-blocker use was associated with a significant reduction in supine, standing and peak exercise QTc. This difference was not seen in the small group of patients (7/37) with C-loop mutations. There was no difference in QTc at 1 and 4 minutes into recovery. CONCLUSIONS: Genetically confirmed LQT1 patients in this study cohort with C-loop mutations did not demonstrate the expected increase in QTc in response to exercise, or resultant response to beta-blocker. The apparent increased risk of cardiac events associated with C-loop mutation sites and the marked benefit received from beta-blocker therapy are not reflected by exercise-mediated effects on QTc in this study population.

Derivation and validation of a simple exercise-based algorithm for prediction of genetic testing in relatives of LQTS probands.

BACKGROUND: Genetic testing can diagnose long-QT syndrome (LQTS) in asymptomatic relatives of patients with an identified mutation; however, it is costly and subject to availability. The accuracy of a simple algorithm that incorporates resting and exercise ECG parameters for screening LQTS in asymptomatic relatives was evaluated, with genetic testing as the gold standard. METHODS AND RESULTS: Asymptomatic first-degree relatives of genetically characterized probands were recruited from 5 centers. QT intervals were measured at rest, during exercise, and during recovery. Receiver operating characteristics were used to establish optimal cutoffs. An algorithm for identifying LQTS carriers was developed in a derivation cohort and validated in an independent cohort. The derivation cohort consisted of 69 relatives (28 with LQT1, 20 with LQT2, and 21 noncarriers). Mean age was 35±18 years, and resting corrected QT interval (QTc) was 466±39 ms. Abnormal resting QTc (females ≥480 ms; males ≥470 ms) was 100% specific for gene carrier status, but was observed in only 48% of patients; however, mutations were observed in 68% and 42% of patients with a borderline or normal resting QTc, respectively. Among these patients, 4-minute recovery QTc ≥445 ms correctly restratified 22 of 25 patients as having LQTS and 19 of 21 patients as being noncarriers. The combination of resting and 4-minute recovery QTc in a screening algorithm yielded a sensitivity of 0.94 and specificity of 0.90 for detecting LQTS carriers. When applied to the validation cohort (n=152; 58 with LQT1, 61 with LQT2, and 33 noncarriers; QTc=443±47 ms), sensitivity was 0.92 and specificity was 0.82. CONCLUSIONS: A simple algorithm that incorporates resting and exercise-recovery QTc is useful in identifying LQTS in asymptomatic relatives.

Continued exploration of biphenylsulfonamide scaffold as a platform for aggrecanase-1 inhibition.

Design, synthesis and structure-activity relationship of a series of biphenylsulfonamido-3-methylbutanoic acid based aggrecanase-1 inhibitors are described. In addition to robust aggrecanase-1 inhibition, these compounds also exhibit potent MMP-13 activity. In cell-based cartilage explants assay compound 48 produced 87% inhibition of proteoglycan degradation at 10 µg/mL. Good pharmacokinetic properties were demonstrated by 46 with a half-life of 6h and bioavailability of 23%.

Contemporary indications and therapeutic implications for digoxin use.

Heart failure (HF) is a leading cause of morbidity and mortality. Appropriate medical therapy using angiotensin converting enzyme inhibitors and beta-blockers improves outcomes in HF, whereas the role of digoxin is still not clearly defined. Digoxin is currently recommended for patients with HF who are symptomatic despite standard therapy and for controlling the ventricular rate in atrial fibrillation. Digoxin is a time-tested drug that accounts for 20 million drug prescriptions annually in the United States. It has favorable hemodynamic effects for patients with HF and atrial tachyarrhythmias. We conducted a systematic literature search for the current indications for digoxin. Despite extensive research and safety data, the literature suggests that digoxin is underused in clinical settings. Citing the literature where available, our review highlights the various clinical settings where digoxin is indicated. Despite difficulties with designing prospective studies in acute HF settings and lack of outcomes data, we believe that digoxin will continue to serve an important role in optimizing care in certain acute and chronic cardiac conditions.

Tenascin-C induces inflammatory mediators and matrix degradation in osteoarthritic cartilage.

BACKGROUND: Tenascin-C (TN-C) is an extracellular matrix glycoprotein that is involved in tissue injury and repair processes. We analyzed TN-C expression in normal and osteoarthritic (OA) human cartilage, and evaluated its capacity to induce inflammatory and catabolic mediators in chondrocytes in vitro. The effect of TN-C on proteoglycan loss from articular cartilage in culture was also assessed. METHODS: TN-C in culture media, cartilage extracts, and synovial fluid of human and animal joints was quantified using a sandwich ELISA and/or analyzed by Western immunoblotting. mRNA expression of TN-C and aggrecanases were analyzed by Taqman assays. Human and bovine primary chondrocytes and/or explant culture systems were utilized to study TN-C induced inflammatory or catabolic mediators and proteoglycan loss. Total proteoglycan and aggrecanase -generated ARG-aggrecan fragments were quantified in human and rat synovial fluids by ELISA. RESULTS: TN-C protein and mRNA expression were significantly upregulated in OA cartilage with a concomitant elevation of TN-C levels in the synovial fluid of OA patients. IL-1 enhanced TN-C expression in articular cartilage. Addition of TN-C induced IL-6, PGE2, and nitrate release and upregulated ADAMTS4 mRNA in cultured primary human and bovine chondrocytes. TN-C treatment resulted in an increased loss of proteoglycan from cartilage explants in culture. A correlation was observed between TN-C and aggrecanase generated ARG-aggrecan fragment levels in the synovial fluid of human OA joints and in the lavage of rat joints that underwent surgical induction of OA. CONCLUSIONS: TN-C expression in the knee cartilage and TN-C levels measured in the synovial fluid are significantly enhanced in OA patients. Our findings suggest that the elevated levels of TN-C could induce inflammatory mediators and promote matrix degradation in OA joints.

A robust multiplexed assay to quantify C1-inhibitor, C1q, and C4 proteins for in vitro diagnosis of hereditary angioedema from dried blood spot.

Hereditary angioedema (HAE) is a rare genetic disease caused by deficiency or dysfunction of C1 esterase inhibitor (C1-INH). Plasma C1-INH activity and concentrations of C1-INH and complement components 1q and 4 (C1q, C4) are critical to the HAE diagnosis. We describe a novel multiplexed assay to simultaneously measure C1-INH, C1q, and C4 levels in dried blood spot (DBS) of HAE patients. The blood proteins were extracted from 3 mm punches of DBS samples and were subsequently digested by trypsin. The signature peptide derived from each protein was quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Analyte-depleted blood was generated as a surrogate matrix for the preparation of calibration curves to overcome the interference of endogenous proteins, and the assay reproducibility was further monitored by assessing the signal of plasma transferrin as a house-keeping protein. The assay was fully validated following regulatory guideline, with a quantification range of 12.5-800 µg/mL for C1-INH and C4 and 3.13-200 µg/mL for C1q. The precision and accuracy ranged from 3.3%-9.8% and -8.2%-12.6%, respectively. All the patient samples exhibited C1-INH levels lower than normal range except the Type II patient and the C4 and C1q concentrations were as expected. Results from the DBS-based LC-MS assay were highly correlated with the ELISA data measured in plasma of the same subjects. The method described here offers unique advantages such as less invasive sampling, minimal blood processing, and easy transportation and sample storage, allowing, for the first time, C1-INH, C4, and C1q levels to be simultaneously determined in a drop of dried blood.

The role of the epinephrine test in the diagnosis and management of children suspected of having congenital long QT syndrome.

The epinephrine test has been shown to be a powerful tool to predict the genotype of congenital long QT syndrome (LQTS). The aim of this study was to evaluate its role in the diagnosis and management of LQTS in children. The test (using the Shimizu protocol) was conducted in patients with some evidence of LQTS but in whom clinical and management decisions were challenging (n = 41, age 9.6 +/- 3.9 years, 19 female). LQT1, LQT2, and negative responses to epinephrine were obtained in 16, 5, and 20 subjects, respectively. LQTS gene positivity was obtained in two subjects. Beta-blocker therapy was started in all subjects with a positive epinephrine response (n = 21) and in some negative responders because of their strong LQTS phenotype (n = 10). No therapy was given to the subset with less convincing features of LQTS who had also responded negatively to epinephrine (n = 10). Follow-up for 3.0 +/- 2 years was uneventful in both management groups. Due to the discordance with genotyping, the epinephrine test cannot be used to diagnose genotype-positive LQTS but when used in combination with phenotype assessment and genetic screening, it could enable better management decisions.

Considerations for prenatal counselling of patients with cardiac rhabdomyomas based on their cardiac and neurologic outcomes.

Cardiac rhabdomyomas are benign cardiac tumours with few cardiac complications, but with a known association to tuberous sclerosis that affects the neurologic outcome of the patients. We have analysed the long-term cardiac and neurological outcomes of patients with cardiac rhabdomyomas in order to allow comprehensive prenatal counselling, basing our findings on the records of all patients seen prenatally and postnatally with an echocardiographic diagnosis of cardiac rhabdomyoma encountered from August, 1982, to September, 2007. We analysed factors such as the number and the location of the tumours to establish their association with a diagnosis of tuberous sclerosis, predicting the cardiac and neurologic outcomes for the patients.Cardiac complications include arrhythmias, obstruction of the ventricular outflow tracts, and secondary cardiogenic shock. Arrhythmias were encountered most often during the neonatal period, with supraventricular tachycardia being the commonest rhythm disturbance identified. No specific dimension or location of the cardiac rhabdomyomas predicted the disturbances of rhythm.The importance of the diagnosis of tuberous sclerosis is exemplified by the neurodevelopmental complications, with four-fifths of the patients showing epilepsy, and two-thirds having delayed development. The presence of multiple cardiac tumours suggested a higher risk of being affected by tuberous sclerosis. The tumours generally regress after birth, and cardiac-related problems are rare after the perinatal period. Tuberous sclerosis and the associated neurodevelopmental complications dominate the clinical picture, and should form an important aspect of the prenatal counselling of parents.

Prevalence of cardiovascular health risk behaviors in college-going women in a major metropolis in India.

There is an increasing incidence of cardiovascular disease (CVD) in Indian men and women of younger ages but research related to CVD risk behaviors in college-going women in India is limited. A cross-sectional questionnaire-based survey conducted among 554 students from two women's colleges in Chennai showed that there was an alarmingly high prevalence of unhealthy diet and inadequate exercise, a moderately high prevalence of psychosocial risk and a low prevalence of tobacco use and alcohol consumption. It is imperative to increase awareness and provide targeted interventions to help our young women adopt a heart-healthy lifestyle.

A multicentre retrospective study on quality and outcomes of cardiac rehabilitation programs in India.

Cardiac rehabilitation (CR) programs in India are comprehensive in nature, consist of multidisciplinary teams and demonstrate significant improvement in various clinical parameters. However, there is a disparity in patient evaluation, risk assessment, data collection and documentation. CR programs in India need to be streamlined to meet the quality indicators outlined by the international guideline recommendations.

A first of its kind quantitative functional C1-esterase inhibitor lateral flow assay for hereditary angioedema point-of-care diagnostic testing.

Hereditary Angioedema (HAE) is a rare, autosomal dominant disease caused by mutations in SERPING1 gene leading to dysfunction/deficiency of C1-esterase inhibitor (C1-INH) protein and subsequent dysregulation of the contact system and bradykinin overproduction. As functional C1-INH (fC1-INH) levels are reduced in HAE types I and II (HAE-I/II), a specific, sensitive and accessible rapid diagnostic method to quantitate fC1-INH is crucial in diagnosing HAE-I/II. Previously, we developed/validated methods to detect fC1-INH levels in human plasma based on functional binding to C1s or FXIIa for C1-INH-based therapies. Quantitative fC1-INH immunoassay methods were converted to the Lateral flow assay (LFA) platform after identifying the best reagent/s pair. The assay was developed and optimized as a first of its kind LFA method for quantifying fC1-INH in human plasma to aid HAE point-of-care diagnosis. Receiver operating characteristic analysis was performed using normal control and HAE subject plasma samples to calculate area-under-curve and a cut-off point to distinguish normal versus HAE subject samples. LFA data was correlated with the conventional diagnostic assay for fC1-INH in HAE plasma samples and profiles matched for individual subjects. Here, we demonstrate a proof-of-concept for the quantitative fC1-INH LFA using normal and HAE plasma samples. We propose that the method could be used as a point-of-care test to diagnose HAE in a variety of settings, such as, a hospital or physician's office, at home or in an ambulance.

Parallel comparison of three methodologies for measuring functional C1-inhibitor in Hereditary angioedema patients.

Hereditary angioedema (HAE) types I and II are characterized by functional C1 inhibitor (fC1-INH) deficiency which results in bradykinin overproduction. Sensitive, specific and robust methods to quantitate fC1-INH in human samples are required for diagnosing HAE and/or to measure pharmacodynamic activity of C1-INH drugs in clinical studies. To date, three methods have been reported in literature to measure fC1-INH: conventional chromogenic assay measuring residual C1-esterase activity, and immunoassays based on functional binding to either activated complement C1s or Factor XIIa/kallikrein. We used three qualified/validated fit-for purpose methods to quantitate fC1-INH in human plasma and to conduct a parallel comparison for diagnostic purposes and as a read-out for pharmacodynamic activity. Sensitivity and specificity were determined from the Receiver Operator Characteristics (ROC) curve analysis of the three fC1-INH methods through testing of fifty healthy control vs. HAE plasma samples. fC1-INH profile of fifteen HAE subjects, who underwent different treatment regimen in a cross-over Shire C1-INH clinical study, was analyzed in these three methods in parallel. A correlation analysis performed between these methods using data generated from clinical samples showed that profiles obtained from different fC1-INH methods matched for individual HAE subjects. Our findings suggest that functional binding immunoassay methods serve as reliable alternates for conventional chromogenic method to quantitate fC1-INH in human plasma samples with a better dynamic range of detection and ease of use. Of the two immunoassays used in this study, FXIIa-binding method gave better sensitivity, specificity, and correlation to the chromogenic method as a diagnostic method to distinguish HAE samples from healthy controls.

A novel functional C1 inhibitor activity assay in dried blood spot for diagnosis of Hereditary angioedema.

BACKGROUND: Hereditary angioedema (HAE) is a rare genetic disease caused by deficiency or dysfunction of C1 esterase inhibitor (C1-INH). Timely and accurate diagnosis is an ongoing challenge. Measurement of plasma C1-INH activity is currently the critical standard test. We describe a novel and highly robust point-of-care assay to quantify C1-INH activity in dried blood spot (DBS). METHODS: C1-INH was extracted from 3 mm punches of DBS samples and incubated with excess amount of C1 esterase (C1s). The mixture was subsequentially incubated with C1s substrate, followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) quantitation of the enzyme reaction product. RESULTS: The assay was validated within a quantification range from 100 to 1500 mU/mL. The intra-day precision and accuracy ranged from 4.0% to 11.6% and -11.1% to -2.1%, and the inter-day precision and accuracy were 8.1-13.1% and -10.3% to 0.9%, respectively. Normal C1-INH activity (n = 103) ranged from 311 to 1090 mU/mL, whereas 23 out of 24 HAE patients exhibited C1-INH activity lower than 100 mU/mL. CONCLUSION: DBS specimen collection for measurement of functional C1-INH activity in a physician's office is straightforward and not limited by logistic considerations and therefore, appropriate for the diagnosis of HAE in high throughput diagnostic laboratories.

Fibrosterol sulfates from the Philippine sponge Lissodendoryx (Acanthodoryx) fibrosa: sterol dimers that inhibit PKCzeta.

Three new sulfated sterol dimers, fibrosterol sulfates A-C (1-3), have been isolated from the sponge Lissodendoryx (Acanthodoryx) fibrosa, collected in the Philippines. The structures were assigned on the basis of extensive 1D and 2D NMR studies as well as analysis by HRESIMS. Compounds 1 and 2 inhibited PKCzeta with IC(50) values of 16.4 and 5.6 microM, respectively.

3,4-Disubstituted benzofuran P1' MMP-13 inhibitors: optimization of selectivity and reduction of protein binding.

Potent 3,4-disubstituted benzofuran P1' MMP-13 inhibitors have been prepared. Selectivity over MMP-2 was achieved through a substituent at the C4 position of the benzofuran P1' moiety of the molecule. By replacing a backbone benzene with a pyridine and valine with threonine, compounds (e.g., 44) with greatly reduced plasma protein binding were also obtained.

Implantable cardioverter defibrillator as a bridge to recovery in an infant with cardiac rhabdomyoma.

Multiple cardiac rhabdomyomas in an infant presented with recurrent life-threatening ventricular arrhythmias refractory to medical treatment and necessitating the placement of an implantable cardioverter defibrillator (ICD). The device functioned effectively as a bridge to recovery during a 2-year follow-up period, when the tumor showed spontaneous regression, along with an almost complete resolution of the ventricular arrhythmias. We conclude that childhood cardiac rhabdomyomas causing severe drug-refractory ventricular arrhythmias can be managed by ICD therapy.