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The coronavirus disease 2019 (COVID-19) can result in a hyperinflammatory state, leading to acute respiratory distress syndrome (ARDS), myocardial injury, and thrombotic complications, among other sequelae. Statins, which are known to have anti-inflammatory and antithrombotic properties, have been studied in the setting of other viral infections, but their benefit has not been assessed in COVID-19. This is a retrospective analysis of patients admitted with COVID-19 from February 1st through May 12th, 2020 with study period ending on June 11th, 2020. Antecedent statin use was assessed using medication information available in the electronic medical record. We constructed a multivariable logistic regression model to predict the propensity of receiving statins, adjusting for baseline sociodemographic and clinical characteristics, and outpatient medications. The primary endpoint includes in-hospital mortality within 30 days. A total of 2626 patients were admitted during the study period, of whom 951 (36.2%) were antecedent statin users. Among 1296 patients (648 statin users, 648 non-statin users) identified with 1:1 propensity-score matching, statin use is significantly associated with lower odds of the primary endpoint in the propensity-matched cohort (OR 0.47, 95% CI 0.36–0.62, p, Statins, which have anti-inflammatory and antithrombotic properties, could have effects in COVID-19 patients. Here, the authors find in a retrospective analysis of patients hospitalized with COVID-19 that antecedent statin use is associated with lower inpatient mortality.

Rationale: Changing activity of cardiac Ca V 1.2 channels under basal conditions, during sympathetic activation, and in heart failure is a major determinant of cardiac physiology and pathophysiology. Although cardiac Ca V 1.2 channels are prominently upregulated via activation of PKA (protein kinase A), essential molecular details remained stubbornly enigmatic. Objective: The primary goal of this study was to determine how various factors converging at the Ca V 1.2 I-II loop interact to regulate channel activity under basal conditions, during β-adrenergic stimulation, and in heart failure. Methods and Results: We generated transgenic mice with expression of Ca V 1.2 α 1C subunits with (1) mutations ablating interaction between α 1C and β-subunits, (2) flexibility-inducing polyglycine substitutions in the I-II loop (GGG-α 1C ), or (3) introduction of the alternatively spliced 25-amino acid exon 9* mimicking a splice variant of α 1C upregulated in the hypertrophied heart. Introducing 3 glycine residues that disrupt a rigid IS6–α-interaction domain helix markedly reduced basal open probability despite intact binding of Ca V β to α 1C I-II loop and eliminated β-adrenergic agonist stimulation of Ca V 1.2 current. In contrast, introduction of the exon 9* splice variant in the α 1C I-II loop, which is increased in ventricles of patients with end-stage heart failure, increased basal open probability but did not attenuate stimulatory response to β-adrenergic agonists when reconstituted heterologously with β 2B and Rad or transgenically expressed in cardiomyocytes. Conclusions: Ca 2+ channel activity is dynamically modulated under basal conditions, during β-adrenergic stimulation, and in heart failure by mechanisms converging at the α 1C I-II loop. Ca V β binding to α 1C stabilizes an increased channel open probability gating mode by a mechanism that requires an intact rigid linker between the β-subunit binding site in the I-II loop and the channel pore. Release of Rad-mediated inhibition of Ca 2+ channel activity by β-adrenergic agonists/PKA also requires this rigid linker and β-binding to α 1C .

Activation of protein kinase A by cyclic AMP results in a multi-fold upregulation of CaV1.2 currents in the heart, as originally reported in the 1970's and 1980's. Despite considerable interest and much investment, the molecular mechanisms responsible for this signature modulation remained stubbornly elusive for over 40 years. A key manifestation of this lack of understanding is that while this regulation is readily apparent in heart cells, it has not been possible to reconstitute it in heterologous expression systems. In this review, we describe the efforts of many investigators over the past decades to identify the mechanisms responsible for the β-adrenergic mediated activation of voltage-gated Ca2+ channels in the heart and other tissues.

Increased cardiac contractility during the fight-or-flight response is caused by β-adrenergic augmentation of CaV1.2 voltage-gated calcium channels1–4. However, this augmentation persists in transgenic murine hearts expressing mutant CaV1.2 α1C and β subunits that can no longer be phosphorylated by protein kinase A—an essential downstream mediator of β-adrenergic signalling—suggesting that non-channel factors are also required. Here we identify the mechanism by which β-adrenergic agonists stimulate voltage-gated calcium channels. We express α1C or β2B subunits conjugated to ascorbate peroxidase5 in mouse hearts, and use multiplexed quantitative proteomics6,7 to track hundreds of proteins in the proximity of CaV1.2. We observe that the calcium-channel inhibitor Rad8,9, a monomeric G protein, is enriched in the CaV1.2 microenvironment but is depleted during β-adrenergic stimulation. Phosphorylation by protein kinase A of specific serine residues on Rad decreases its affinity for β subunits and relieves constitutive inhibition of CaV1.2, observed as an increase in channel open probability. Expression of Rad or its homologue Rem in HEK293T cells also imparts stimulation of CaV1.3 and CaV2.2 by protein kinase A, revealing an evolutionarily conserved mechanism that confers adrenergic modulation upon voltage-gated calcium channels. An in vivo approach to identify proteins whose enrichment near cardiac CaV1.2 channels changes upon β-adrenergic stimulation finds the G protein Rad, which is phosphorylated by protein kinase A, thereby relieving channel inhibition by Rad and causing an increased Ca2+ current.

There is growing evidence that COVID-19 can cause cardiovascular complications. However, there are limited data on the characteristics and importance of atrial arrhythmia (AA) in patients hospitalized with COVID-19. Data from 1,029 patients diagnosed with of COVID-19 and admitted to Columbia University Medical Center between March 1, 2020 and April 15, 2020 were analyzed. The diagnosis of AA was confirmed by 12 lead electrocardiographic recordings, 24-hour telemetry recordings and implantable device interrogations. Patients' history, biomarkers and hospital course were reviewed. Outcomes that were assessed were intubation, discharge and mortality. Of 1,029 patients reviewed, 82 (8%) were diagnosed with AA in whom 46 (56%) were new-onset AA 16 (20%) recurrent paroxysmal and 20 (24%) were chronic persistent AA. Sixty-five percent of the patients diagnosed with AA (n=53) died. Patients diagnosed with AA had significantly higher mortality compared with those without AA (65% vs 21%; p < 0.001). Predictors of mortality were older age (Odds Ratio (OR)=1.12, [95% Confidence Interval (CI), 1.04 to 1.22]); male gender (OR=6.4 [95% CI, 1.3 to 32]); azithromycin use (OR=13.4 [95% CI, 2.14 to 84]); and higher D-dimer levels (OR=2.8 [95% CI, 1.1 to 7.3]). In conclusion, patients diagnosed with AA had 3.1 times significant increase in mortality rate versus patients without diagnosis of AA in COVID-19 patients. Older age, male gender, azithromycin use and higher baseline D-dimer levels were predictors of mortality.

Background: D-Dimer values may be elevated in hyperinflammatory or prothrombotic states and are frequently measured in patients with coronavirus disease 2019 (COVID-19). Many institutional algorithms and ongoing studies suggest using D-Dimer cutoffs to initiate anticoagulation. The relationship between D-Dimer levels and deep venous thrombosis (DVT) has not been extensively studied specifically in patients with COVID-19. Methods: We retrospectively studied patients hospitalized at our institution between 2/1/20-5/19/20 for COVID-19 who underwent lower extremity venous doppler imaging. After stratifying by presence of DVT, baseline characteristics, vital signs, and laboratory values were assessed. We assessed the association between peak D-Dimer levels and diagnosis of DVT during admission. Upper limit D-Dimer value for the hospital’s laboratory assay was >20 mg/dL. Results: Of the 2677 patients admitted, 514 underwent lower extremity imaging, out of whom 186 (36.2%) were diagnosed with DVT. Other than history of cancer, which was more common in patients with a diagnosis of DVT (14.7% vs. 6.3%, p Conclusions: In this analysis of patients hospitalized with COVID-19, DVT was frequently diagnosed in patients who underwent imaging. There was considerable overlap of peak D-Dimer values in patients with and without documented DVT. As such, elevation in D-Dimer values alone should not prompt routine initiation of therapeutic anticoagulation in COVID-19 patients. Data from prospective clinical trials and registries regarding optimal antithrombotic practices in this patient population is needed.

Changing activity of cardiac CaThe primary goal of this study was to determine how various factors converging at the CaWe generated transgenic mice with expression of CaCa

Introduction: There is growing evidence that COVID-19 can cause cardiovascular complications. However, there are limited data on the characteristics and importance of atrial arrhythmia (AA) in patients hospitalized with COVID-19. Methods: Data from 1029 patients diagnosed with of COVID-19 and admitted to Columbia University Medical Center between March 1st and April 15th 2020 were analyzed. The diagnosis of AA was confirmed by 12 lead electrocardiographic recordings, 24-hour telemetry recordings and implantable device interrogations. Patients’ history, biomarkers and hospital course were reviewed. Outcomes of death, intubation and discharge were assessed. Results: Of 1029 patients, 82 (8%) were diagnosed with AA. Out of the 82 patients with AA. Of the AA patients, new-onset AA was seen in 46 (56%) patients, recurrent paroxysmal and chronic persistent were diagnosed in 16 (20%) and 20 (24%) individuals, respectively. Sixty-five percent of the patients diagnosed with AA (n=53) died. Patients diagnosed with AA had significantly higher mortality compared to those without AA (65% vs. 21%; p < 0.001). Predictors of mortality were older age (Odds Ratio (OR) =1.12, [95% Confidence Interval (CI), 1.04 to 1.22]); male gender (OR=6.4 [95% CI, 1.3 to 32]); azithromycin use (OR=13.4 [95% CI, 2.14 to 84]); and higher D-dimer levels (OR=2.8 [95% CI, 1.1 to7.3]). Conclusions: Patients diagnosed with AA had 3.1 times significant increase in mortality rate versus patients without diagnosis of AA in COVID-19 patients. Older age, male gender, azithromycin use and higher baseline D-dimer levels were predictors of mortality.

The identification of a gain-of-function mutation in CACNA1C as the cause of Timothy Syndrome (TS), a rare disorder characterized by cardiac arrhythmias and syndactyly, highlighted unexpected roles for the L-type voltage-gated Ca2+ channel CaV1.2 in nonexcitable cells. How abnormal Ca2+ influx through CaV1.2 underlies phenotypes such as the accompanying syndactyly or craniofacial abnormalities in the majority of affected individuals is not readily explained by established CaV1.2 roles. Here, we show that CaV1.2 is expressed in the first and second pharyngeal arches within the subset of cells that give rise to jaw primordia. Gain-of-function and loss-of-function studies in mouse, in concert with knockdown/rescue and pharmacological approaches in zebrafish, demonstrated that Ca2+ influx through CaV1.2 regulates jaw development. Cranial neural crest migration was unaffected by CaV1.2 knockdown, suggesting a role for CaV1.2 later in development. Focusing on the mandible, we observed that cellular hypertrophy and hyperplasia depended upon Ca2+ signals through CaV1.2, including those that activated the calcineurin signaling pathway. Together, these results provide new insights into the role of voltage-gated Ca2+ channels in nonexcitable cells during development.

Mutations in CACNA1C that increase current through the CaV1.2 L-type Ca2+ channel underlie rare forms of long QT syndrome (LQTS), and Timothy syndrome (TS). We identified a variant in CACNA1C in a male child of Filipino descent with arrhythmias and extracardiac features by candidate gene sequencing and performed functional expression studies to electrophysiologically characterize the effects of the variant on CaV1.2 channels. As a baby, the subject developed seizures and displayed developmental delays at 30 months of age. At age 5 years, he displayed a QTc of 520 ms and experienced recurrent VT. Physical exam at 17 years of age was notable for microcephaly, short stature, lower extremity weakness and atrophy with hyperreflexia, spastic diplegia, multiple dental caries and episodes of rhabdomyolysis. Candidate gene sequencing identified a G>C transversion at position 5731 of CACNA1C (rs374528680) predicting a glycine>arginine substitution at residue 1911 (p.G1911R) of CaV1.2. The allele frequency of this variant is 0.01 in Malays, but absent in 984 Caucasian alleles and in the 1000 genomes project. In electrophysiological analyses, the variant decreased voltage-dependent inactivation, thus causing a gain of function of CaV1.2. We also observed a negative shift of V1/2 of activation and positive shift of V1/2 of channel inactivation, resulting in an increase of the window current. Together, these suggest a gain-of-function effect on CaV1.2 and suggest increased susceptibility for arrhythmias in certain clinical settings. The p.G1911R variant was also identified in a case of sudden unexplained infant death (SUID), for which an increasing number of clinical observations have demonstrated can be associated with arrhythmogenic mutations in cardiac ion channels. In summary, the combined effects of the CACNA1C variant to diminish voltage-dependent inactivation of CaV1.2 and increase window current expand our appreciation of mechanisms by which a gain of function of CaV1.2 can contribute to QT prolongation. Published version

Rationale : Fibroblast growth factor (FGF) homologous factors (FHFs; FGF11–14) are intracellular modulators of voltage-gated Na + channels, but their cellular distribution in cardiomyocytes indicated that they performed other functions. Objective : We aimed to uncover novel roles for FHFs in cardiomyocytes, starting with a proteomic approach to identify novel interacting proteins. Methods and Results : Affinity purification of FGF13 from rodent ventricular lysates followed by mass spectroscopy revealed an interaction with junctophilin-2, a protein that organizes the close apposition of the L-type Ca 2+ channel Ca V 1.2 and the ryanodine receptor 2 in the dyad. Immunocytochemical analysis revealed that overall T-tubule structure and localization of ryanodine receptor 2 were unaffected by FGF13 knockdown in adult ventricular cardiomyocytes but localization of Ca V 1.2 was affected. FGF13 knockdown decreased Ca V 1.2 current density and reduced the amount of Ca V 1.2 at the surface as a result of aberrant localization of the channels. Ca V 1.2 current density and channel localization were rescued by expression of an shRNA-insensitive FGF13, indicating a specific role for FGF13. Consistent with these newly discovered effects on Ca V 1.2, we demonstrated that FGF13 also regulated Ca 2+ -induced Ca 2+ release, indicated by a smaller Ca 2+ transient after FGF13 knockdown. Furthermore, FGF13 knockdown caused a profound decrease in the cardiac action potential half-width. Conclusions : This study demonstrates that FHFs not only are potent modulators of voltage-gated Na + channels but also affect Ca 2+ channels and their function. We predict that FHF loss-of-function mutations would adversely affect currents through both Na + and Ca 2+ channels, suggesting that FHFs may be arrhythmogenic loci, leading to arrhythmias through a novel, dual-ion channel mechanism.

Background Less than 30% of the cases of Brugada syndrome (BrS) have an identified genetic cause. Of the known BrS-susceptibility genes, loss-of-function mutations in SCN5A or CACNA1C and their auxiliary subunits are most common. On the basis of the recent demonstration that fibroblast growth factor (FGF) homologous factors (FHFs; FGF11–FGF14) regulate cardiac Na + and Ca 2+ channel currents, we hypothesized that FHFs are candidate BrS loci. Objective The goal of this study was to test whether FGF12 is a candidate BrS locus. Methods We used quantitative polymerase chain reaction to identify the major FHF expressed in the human ventricle and then queried a phenotype-positive, genotype-negative BrS biorepository for FHF mutations associated with BrS. We queried the effects of an identified mutant with biochemical analyses combined with electrophysiological assessment. We designed a novel rat ventricular cardiomyocyte system in which we swapped the endogenous FHF with the identified mutant and defined its effects on multiple ionic currents in their native milieu and on the cardiac action potential. Results We identified FGF12 as the major FHF expressed in the human ventricle. In 102 individuals in the biorepository, we identified a single missense mutation in FGF12-B (Q7R-FGF12). The mutant reduced binding to the Na V 1.5 C terminus, but not to junctophilin-2. In adult rat cardiac myocytes, Q7R-FGF12, but not wild-type FGF12, reduced Na + channel current density and availability without affecting Ca 2+ channel function. Furthermore, the mutant, but not wild-type FGF12, reduced action potential amplitude, which is consistent with a mutant-induced loss of Na + channel function. Conclusions These multilevel investigations strongly suggest that Q7R-FGF12 is a disease-associated BrS mutation. Moreover, these data suggest for the first time that FHF effects on Na + and Ca 2+ channels are separable. Most significantly, this study establishes a new method to analyze effects of human arrhythmogenic mutations on cardiac ionic currents.

The four fibroblast growth factor homologous factors (FHFs, FGF11–FGF14) are intracellular proteins that bind and modulate voltage-gated sodium channels (VGSCs). While FHFs have been well studied in neurons and implicated in neurologic disease, their role in cardiomyocytes was unclear until recently. In this review, we discuss the expression profile and function of FHFs in mouse and rat ventricular cardiomyocytes. Recent data show that FGF13 is the predominant FHF in the murine heart, directly binds the cardiac VGSC α subunit, and is essential for normal cardiac conduction. FHF loss-of-function mutations may be unrecognized causes of cardiac arrhythmias, such as Long QT and Brugada syndromes.

Rationale: Fibroblast growth factor homologous factors (FHFs), a subfamily of fibroblast growth factors (FGFs) that are incapable of functioning as growth factors, are intracellular modulators of Na + channels and have been linked to neurodegenerative diseases. Although certain FHFs have been found in embryonic heart, they have not been reported in adult heart, and they have not been shown to regulate endogenous cardiac Na + channels or to participate in cardiac pathophysiology. Objective: We tested whether FHFs regulate Na + channels in murine heart. Methods and Results: We demonstrated that isoforms of FGF13 are the predominant FHFs in adult mouse ventricular myocytes. FGF13 binds directly to, and colocalizes with, the Na V 1.5 Na + channel in the sarcolemma of adult mouse ventricular myocytes. Knockdown of FGF13 in adult mouse ventricular myocytes revealed a loss of function of Na V 1.5-reduced Na + current density, decreased Na + channel availability, and slowed Na V 1.5-reduced Na + current recovery from inactivation. Cell surface biotinylation experiments showed ≈45% reduction in Na V 1.5 protein at the sarcolemma after FGF13 knockdown, whereas no changes in whole-cell Na V 1.5 protein or in mRNA level were observed. Optical imaging in neonatal rat ventricular myocyte monolayers demonstrated slowed conduction velocity and a reduced maximum capture rate after FGF13 knockdown. Conclusion: These findings show that FHFs are potent regulators of Na + channels in adult ventricular myocytes and suggest that loss-of-function mutations in FHFs may underlie a similar set of cardiac arrhythmias and cardiomyopathies that result from Na V 1.5 loss-of-function mutations.

The four members of the intracellular Fibroblast Growth Factor (iFGF) subfamily, FGF11-14, regulate voltage-gated sodium (Nav) channels. A missense mutation in FGF14 causes spinocerebellar ataxia 27, thought to be due to Nav channel dysfunction. iFGFs are expressed in the heart, but whether they regulate cardiac Nav channels is not known. Using quantitative real-time RT-PCR, we identified that FGF13 isoforms are the dominant iFGFs in adult mouse heart. Using whole cell patch-clamp configuration, we determined a functional link between FGF13 and Nav1.5. We found that the FGF13 isoforms, FGF13S, FGF13U, and FGF13VY differentially modulate Nav1.5 current density when transiently co-expressed in HEK293 cells. Steady-state activation was not altered. In contrast, steady-state availability was significantly shifted towards the depolarizing direction by each of the FGF13 isoforms. Most strikingly, FGF13S induced a dramatic slowing of recovery from inactivation. Co-immunoprecipitation showed that FGF13 interacted with Nav1.5 in cardiomyocytes. Using a pull down assay, we found that FGF13 directly interacted with C-terminus of Nav1.5. Immunostaining showed that FGF13 co-localized with Nav1.5 on sarcolemma. Some FGF13 is present in subcellular regions devoid of Nav1.5, suggesting other roles than sodium channel modulation. FGF13 knockdown by adenoviral infection with shRNA in adult mice cardiomyocytes affected sodium current density and steady-state availability. FGF13 knockdown in a neonatal rat cardiomyocyte monolayer reduced cardiac impulse conduction and the velocity of the action potential upstroke. These data are the first report of FGF13 as regulator of Nav1.5 in heart and suggest that FGF13 isoform-specific regulation of cardiac Nav channels plays important physiological and pathophysiological roles.

Background Timothy syndrome (TS) is a rare congenital long QT syndrome (LQTS) associated with extracardiac manifestations including craniofacial dysmorphia and dental abnormalities. The locus for TS is CACNA1C , which encodes the Ca V 1.2 L-type Ca 2+ channel, for which canonical mutations lead to a decrease in voltage-dependent inactivation (VDI). However, a recent report of a patient with LQTS in isolation and a CACNA1C mutation that did not affect VDI raised the question whether altered VDI is necessary for extracardiac phenotypes. In a patient with a maternally inherited microdeletion with a chromosomal translocation who presented with LQTS and associated ventricular tachyarrhythmias (Figure A), a subset of TS phenotypes, and a skeletal myopathy not readily explained by the translocation, we sought to identify a causative mutation for the TS phenotypes. Methods A candidate gene approach identified a mutation in CACNA1C that was absent in the mother. We performed electrophysiologic studies on the mutant and characterized CACNA1C expression in skeletal muscle with a mouse CACNA1C reporter line. Results We identified a glycine to arginine mutation at position 1911 (G1911R) in Ca V 1.2. Functional studies revealed that G1911R increased Ca V 1.2 channel availability (Figures B and C) and decreased VDI (Figure D). The CACNA1C reporter mouse showed no Ca V 1.2 expression in skeletal muscle. Conclusions We describe a CACNA1C mutation that leads to a subset of TS phenotypes. In the context of a recently described CACNA1C mutation that does not affect VDI in an LQTS patient without extracardiac phenotypes, these data suggest that the extracardiac phenotypes seen in TS require effects on VDI.