Insight from the microelectrodes in case of two different types of premature ventricular contractions originating from left ventricular summit.

Premature ventricular contraction (PVC) is usually eliminated in the earliest activation site based on the conventional electrode of ablation catheter. However, the large size electrode may contain far-field potential. The QDOT MICRO ablation catheter has three micro electrodes with 0.33 mm electrode length, in addition to the conventional electrode with 3.5 mm electrode length. The micro electrodes can reflect only near-field potential. A 78-year-old with symptomatic frequent PVCs underwent catheter ablation. PVC-1 showed good pace-mapping in distal great cardiac vein (GCV). The local bipolar electrograms in the conventional electrode of ablation catheter preceded the PVC-QRS onset by 32 ms in distal GCV and 13 ms in left coronary cusp (LCC), but those in the micro electrodes preceded only by 13 ms both in distal GCV and LCC. PVC-1 was eliminated by radiofrequency (RF) application, not in distal GCV, but in LCC. PVC-2 showed good pace-mapping in LCC. The local bipolar electrograms in both the conventional electrode and the micro electrodes of ablation catheter preceded the PVC-QRS onset by 32 ms in LCC. PVC-2 was eliminated by RF application in LCC. Comparing the local electrograms of micro electrodes and the conventional electrodes may be important for identifying depth of the origin of PVCs.

Concomitant Mitral Regurgitation in Severe Aortic Stenosis　- Insights From the CURRENT AS Registry-2.

BACKGROUND: Data on concomitant mitral regurgitation (MR) in patients with severe aortic stenosis (AS) are scarce.Methods and Results: We investigated the risk of concomitant MR in patients with severe AS in the CURRENT AS Registry-2 according to initial treatment strategy (transcatheter aortic valve implantation [TAVI], surgical aortic valve replacement [SAVR], or conservative). Among 3,365 patients with severe AS, 384 (11.4%) had moderate/severe MR (TAVI: n=126/1,148; SAVR: n=68/591; conservative: n=190/1,626). The cumulative 3-year incidence for death or heart failure (HF) hospitalization was significantly higher in the moderate/severe than no/mild MR group in the entire population (54.6% vs. 34.3%, respectively; P<0.001) and for each treatment strategy (TAVI: 45.0% vs. 31.8% [P=0.006]; SAVR: 31.9% vs. 18.7% [P<0.001]; conservative: 67.8% vs. 41.6% [P<0.001]). The higher adjusted risk of moderate/severe MR relative to no/mild MR for death or HF hospitalization was not significant in the entire population (hazard ratio [HR] 1.15; 95% confidence interval [CI] 0.95-1.39; P=0.15); however, the risk was significant in the SAVR (HR 1.92; 95% CI 1.04-3.56; P=0.04) and conservative (HR 1.30; 95% CI 1.02-1.67; P=0.04) groups, but not in the TAVI group (HR 1.03; 95% CI 0.70-1.52; P=0.86), despite no significant interaction (Pinteraction=0.37). CONCLUSIONS: Moderate/severe MR was associated with a higher risk for death or HF hospitalization in the initial SAVR and conservative strategies, while the association was less pronounced in the initial TAVI strategy.

Optimal Intravascular Ultrasound-Guided Percutaneous Coronary Intervention in Patients With Multivessel Disease and Diabetes.

There is a scarcity of data on clinical outcomes after intravascular ultrasound (IVUS)-guided percutaneous coronary intervention (PCI) in patients with multivessel disease and diabetes. OPTIVUS-Complex PCI study multivessel cohort was a prospective multicenter single-arm trial enrolling 1021 patients who underwent multivessel PCI including left anterior descending coronary artery using IVUS aiming to meet the prespecified OPTIVUS criteria for optimal stent expansion. We compared the clinical outcomes between those patients with and without diabetes. The primary endpoint was a composite of death, myocardial infarction, stroke, or any coronary revascularization. There were 560 patients (54.8%) with diabetes, and 461 patients (45.2%) without diabetes. Mean age was not different between the 2 groups (70.9±9.7 years versus 71.7±10.4 years, P=0.17). Patients with diabetes more often had chronic kidney disease and complex coronary artery disease as indicated by the greater total number of stents and longer total stent length. The rate of meeting OPTIVUS criteria was not different between the 2 groups (61.2% vs. 60.7%, P=0.83). The cumulative 1-year incidence of the primary endpoint was not different between the 2 groups (10.8% versus 9.8%, log-rank P=0.65). After adjusting confounders, the risk of diabetes relative to non-diabetes remained insignificant for the primary endpoint (HR, 0.97; 95%CI, 0.65-1.44; P=0.88). In conclusion, in patients who underwent multivessel IVUS-guided PCI, and were managed with contemporary clinical practice, patients with diabetes had similar 1-year outcomes compared with patients without diabetes.

Subclass phenotypes in patients with unprovoked venous thromboembolisms using a latent class analysis.

BACKGROUND: Patients with unprovoked venous thromboembolisms (VTEs) can be sub-classified based on the different phenotypes using a latent class analysis (LCA), which might be useful for selecting individual management strategies. METHODS: In the COMMAND VTE Registry-2 database enrolling 5197 VTE patients, the current derivation cohort consisted of 1556 patients with unprovoked VTEs. We conducted clustering with an LCA, and the patients were classified into subgroups with the highest probability. We compared the clinical characteristics and outcomes among the developed subgroups. RESULTS: This LCA model proposed 3 subgroups based on 8 clinically relevant variables, and classified 592, 813, and 151 patients as Class I, II, and III, respectively. Based on the clinical features, we named Class I the younger, Class II the older with a few comorbidities, and Class III the older with many comorbidities. The cumulative 3-year anticoagulation discontinuation rate was highest in the older with many comorbidities (Class III) (39.9 %, 36.1 %, and 48.4 %, P = 0.02). There was no significant difference in the cumulative 5-year incidence of recurrent VTEs among the 3 classes (12.8 %, 11.1 %, and 4.0 % P = 0.20), whereas the cumulative 5-year incidence of major bleeding was significantly higher in the older with many comorbidities (Class III) (7.8 %, 12.7 %, and 17.8 %, P = 0.04). CONCLUSION: The current LCA revealed that patients with unprovoked VTEs could be sub-classified into further phenotypes depending on the patient characteristics. Each subclass phenotype could have different clinical outcomes risks especially a bleeding risk, which could have a potential benefit when considering the individual anticoagulation strategies. CLINICAL TRIAL REGISTRATION: URL: http://www.umin.ac.jp/ctr/index.htm COMMAND VTE Registry-2: Unique identifier, UMIN000044816 COMMAND VTE Registry: Unique identifier, UMIN000021132.

Medium-chain triglyceride-specific appetite is regulated by the ß-oxidation of medium-chain fatty acids in the liver.

Most studies on fat appetite have focused on long-chain triglycerides (LCTs) due to their obesogenic properties. Medium-chain triglycerides (MCTs), conversely, exhibit antiobesogenic effects; however, the regulation of MCT intake remains elusive. Here, we demonstrate that mice can distinguish between MCTs and LCTs, and the specific appetite for MCTs is governed by hepatic ß-oxidation. We generated liver-specific medium-chain acyl-CoA dehydrogenase (MCAD)-deficient (MCADL-/-) mice and analyzed their preference for MCT and LCT solutions using glyceryl trioctanoate (C8-TG), glyceryl tridecanoate (C10-TG), corn oil, and lard oil in two-bottle choice tests conducted over 8 days. In addition, we used lick microstructure analyses to evaluate the palatability and appetite for MCT and LCT solutions. Finally, we measured the expression levels of genes associated with fat ingestion (Galanin, Qrfp, and Nmu) in the hypothalamus 2 h after oral gavage of fat. Compared with control mice, MCADL-/- mice exhibited a significantly reduced preference for MCT solutions, with no alteration in the preference for LCTs. Lick analysis revealed that MCADL-/- mice displayed a significantly decreased appetite for MCT solutions only while the palatability of both MCT and LCT solutions remained unaffected. Hypothalamic Galanin expression in control mice was elevated by oral gavage of C8-TG but not by LCTs, and this response was abrogated in MCADL-/- mice. In summary, our data suggest that hepatic ß-oxidation is required for MCT-specific appetite but not for LCT-specific appetite. The induction of hypothalamic galanin upon MCT ingestion, dependent on hepatic ß-oxidation, could be involved in the regulation of MCT-specific appetite.NEW & NOTEWORTHY Whether and how medium-chain triglyceride (MCT) intake is regulated remains unknown. Here, we showed that mice can discriminate between MCTs and LCTs. Hepatic ß-oxidation participates in MCT-specific appetite, and hypothalamic galanin may be one of the factors that regulate MCT intake. Because of the antiobesity effects of MCTs, studying MCT-specific appetite may help combat obesity by promoting the intake of MCTs instead of LCTs.

Potential treatment option of rivaroxaban for breastfeeding women: A case series.

The use of direct oral anticoagulants (DOACs) in breastfeeding women is currently challenging due to limited safety data for breastfeeding infants, and there have been no previous studies on the drug concentration in breastfeeding infants. We treated 2 patients (one case was twin pregnancy) with venous thromboembolisms in breastfeeding women administered rivaroxaban at our institution. Blood samples from the mothers and breastmilk samples were collected at time 0 and 2 h after the rivaroxaban administration, breastfeeding was conducted 2 h after the rivaroxaban administration, and blood samples from the infants were collected 2 h after breastfeeding (4 h after maternal rivaroxaban administration). The milk-to-plasma (M:P) ratios were 0.27 in Case 1 and 0.32 in Case 2. The estimated relative infant dose (RID) was 0.82 % in Case 1 Children 1 and 2, and 1.27 % in Case 2. The rivaroxaban concentration in the infant plasma was below the lower limit of quantification in all infants. In addition, even in the high-exposure case simulation based on 5 days of breastfeeding in Case 2, the infant plasma concentration level was below the lower limit of quantification. At 3 months of follow-up, breastfeeding was continued, and all infants grew and developed without any health problems including bleeding events. The current case series showed that there were no pharmacokinetic or clinical concerns for breastfeeding women or breastfed infants, and provides support for rivaroxaban as a safe treatment option for these patients.

Edoxaban for 12 Versus 3 Months in Cancer-associated Isolated Distal Deep Vein Thrombosis According to Different Doses: Insights from the ONCO DVT study.

BACKGROUND: The ONCO DVT study revealed the superiority of 12-month relative to 3-month edoxaban treatment for cancer-associated isolated distal deep vein thrombosis (DVT) regarding the thrombotic risk. METHODS: In this pre-specified subgroup analysis of the ONCO DVT study, we stratified the patients into those with a standard edoxaban dose (60 mg/day; N=151) and those with a reduced edoxaban dose (30 mg/day; N=450) and evaluated the clinical outcomes for the 12-month and 3-month treatments. RESULTS: The cumulative 12-month incidence of symptomatic recurrent venous thromboembolism was lower in the 12-month than 3-month group for both the 60 mg (1.3% vs. 11.6%, P=0.02; odds ratio [OR], 0.12; 95% CI, 0.01-0.97) and 30 mg (1.1% vs. 7.6%, P=0.002; OR, 0.14; 95% CI, 0.03-0.60) edoxaban subgroups, which was consistent across the edoxaban doses without a significant interaction (P =0.90). The 12-month cumulative incidence of major bleeding was higher in the 12-month group than 3-month group for the 60 mg edoxaban subgroup (14.3% vs. 4.4%, P=0.046; OR, 3.61; 95% CI, 0.97-13.52), whereas it did not significantly differ between the two groups for the 30 mg edoxaban subgroup (8.7% vs. 8.6%, P=0.89; OR, 0.97; 95% CI, 0.49-1.91), signaling there was a potential interaction (P=0.07). CONCLUSIONS: A 12-month edoxaban regimen for cancer-associated isolated distal DVT was consistently superior to a 3-month regimen, across the edoxaban doses for the thrombotic risk. However, caution was suggested for the standard dose of edoxaban due to the potential for an increased risk of bleeding with prolonged anticoagulation therapy.

CRISPR-Cas9-guided amplification-free genomic diagnosis for familial hypercholesterolemia using nanopore sequencing.

Familial hypercholesterolemia is an inherited disorder that remains underdiagnosed. Conventional genetic testing methods such as next-generation sequencing (NGS) or target PCR are based on the amplification process. Due to the efficiency limits of polymerase and ligase enzymes, these methods usually target short regions and do not detect large mutations straightforwardly. This study combined the long-read nanopore sequencing and CRISPR-Cas9 system to sequence the target DNA molecules without amplification. We originally designed and optimized the CRISPR-RNA panel to target the low-density lipoprotein receptor gene (LDLR) and proprotein convertase subtilisin/kexin type 9 gene (PCSK9) from human genomic DNA followed by nanopore sequencing. The average coverages for LDLR and PCSK9 were 106× and 420×, versus 1.2× for the background genome. Among them, continuous reads were 52x and 307x, respectively, and spanned the entire length of LDLR and PCSK9. We identified pathogenic mutations in both coding and splicing donor regions in LDLR. We also detected an 11,029 bp large deletion in another case. Furthermore, using continuous long reads generated from the benchmark experiment, we demonstrated how a false-positive 670 bp deletion caused by PCR amplification errors was easily eliminated.

Atrial fibrillation-induced cardiomyopathy presenting with bilateral intermittent claudication associated with intracardiac thrombi.

Systemic thromboembolism associated with atrial fibrillation (AF) is usually caused by thrombi in the left atrial appendage and acute onset. We experienced an unusual case of a woman in her 60s who presented to the outpatient district having bilateral intermittent claudication for more than 1 month, which turned out to be multiple thromboembolism from asymptomatic AF with tachycardia. She was also complicated with non-ischaemic dilated cardiomyopathy with reduced ejection fraction, consistent with arrhythmia-induced cardiomyopathy (AiCM), along with left atrial and left ventricular thrombi and thromboembolism in multiple organs. Rate control with beta-blockers was not effective. With the administration of amiodarone after adequate anticoagulation therapy, she returned to sinus rhythm, and the ejection fraction was restored. This case is instructive in that AiCM with AF can cause thrombosis in the left ventricle, and the patient may present with worsening intermittent claudication as a result of systemic embolism.

Subclinical myocardial damage after anthracycline chemotherapy in Japanese patients with breast cancer.

BACKGROUND: Data on the incidence, timing, and severity of myocardial damage after anthracycline-based chemotherapy (AC) in Japanese patients with breast cancer are limited. METHOD: We evaluated cancer therapy-related cardiac dysfunction (CTRCD) in Japanese women with breast cancer (n = 51) after the first AC according to the definitions of the 2022 European Society of Cardiology onco-cardiology guideline, including assessment of high-sensitivity troponin I (TnI) and B-type natriuretic peptide (BNP) levels. RESULTS: CTRCD was detected in 67 % of the patients (3.9 %, 7.8 %, 9.8 %, 43 %, 37 %, 22 %, 20 %, and 9.8 % of patients at 1 week and 1, 2, 3, 6, 9, 12, and 15 months post-AC, respectively) without significant left ventricular ejection fraction reduction (<50 %) and heart failure. Elevated TnI levels (>26 pg/mL) were found in 43 % of patients, and elevated BNP levels (≥35 pg/mL) were observed in 22 % of patients during the follow-up period. CONCLUSIONS: Approximately two-thirds of the Japanese patients in this study experienced CTRCD, which was frequently observed at 3 or 6 months post-AC. However, all patients with CTRCD were diagnosed with mild asymptomatic CTRCD. Although, these patients were diagnosed with mild asymptomatic CTRCD, careful long-term follow-up will be required.

Sustained activation of NF-κB through constitutively active IKKß leads to senescence bypass in murine dermal fibroblasts.

Although the transcription factor nuclear factor κB (NF-κB) plays a central role in the regulation of senescence-associated secretory phenotype (SASP) acquisition, our understanding of the involvement of NF-κB in the induction of cellular senescence is limited. Here, we show that activation of the canonical NF-κB pathway suppresses senescence in murine dermal fibroblasts. IκB kinase ß (IKKß)-depleted dermal fibroblasts showed ineffective NF-κB activation and underwent senescence more rapidly than control cells when cultured under 20% oxygen conditions, as indicated by senescence-associated ß-galactosidase (SA-ß-gal) staining and p16INK4a mRNA levels. Conversely, the expression of constitutively active IKKß (IKKß-CA) was sufficient to drive senescence bypass. Notably, the expression of a degradation-resistant form of inhibitor of κB (IκB), which inhibits NF-κB nuclear translocation, abolished senescence bypass, suggesting that the inhibitory effect of IKKß-CA on senescence is largely mediated by NF-κB. We also found that IKKß-CA expression suppressed the derepression of INK4/Arf genes and counteracted the senescence-associated loss of Ezh2, a catalytic subunit of the Polycomb repressive complex 2 (PRC2). Moreover, pharmacological inhibition of Ezh2 abolished IKKß-CA-induced senescence bypass. We propose that NF-κB plays a suppressive role in the induction of stress-induced senescence through sustaining Ezh2 expression.

Cobalt protoporphyrin promotes heme oxygenase 1 expression and ameliorates cardiac dysfunction in long-term fasting mice.

BACKGROUND: The association between malnutrition and cardiac dysfunction has been reported. Heme oxygenase (HO)-1 played protective roles in the animals functioning as a myocardial infarction, heart failure, or cardiomyopathy model. We hypothesized that the administration of HO-1 inducer, cobalt protoporphyrin (CoPP) reduces oxidative stress and ameliorates cardiac systolic dysfunction in long-term fasting mice. METHODS: C57BL/6 J mice were classified into three groups: fed mice (fed group), 48-h fasting mice with a single intraperitoneal injection of the corresponding vehicle (fasting group), and 48-h fasting mice with a single intraperitoneal injection of 5 mg/kg CoPP (CoPP group). RESULTS: The fasting group showed a significant increase in heme and 4-hydroxy-2-nonenal (4HNE) protein in the heart tissue, and reduced left ventricular ejection fraction (LVEF) when compared with the fed group. The CoPP group showed significantly increased protein levels of nuclear factor-erythroid 2-related factor 2 and HO-1, and increased mRNA expression levels of HO-1, peroxisome proliferator-activated receptor gamma coactivator 1-alpha, forkhead box protein O1, sirtuin-1, cyclooxygenase 2, and superoxide dismutase 2, and reduced levels of heme and 4HNE protein when compared with the fasting group. LVEF were significantly higher in the CoPP group than in the fasting group. CONCLUSIONS: Administration of CoPP reduced heme accumulation and oxidative stress, and ameliorated cardiac systolic dysfunction in long-term fasting mice. This study suggests that heme accumulation may be associated with impaired cardiac function induced by long-term fasting and that HO-1 may be a key factor or therapeutic target.

Home Treatment for Active Cancer Patients With Low-Risk Pulmonary Embolism　- A Predetermined Companion Report From the ONCO PE Trial.

BACKGROUND: Patients with appropriately selected low-risk pulmonary embolism (PE) can be treated at home, although it has been controversial whether applies to patients with cancer, who are considered not to be at low risk.Methods and Results: The current predetermined companion report from the ONCO PE trial evaluated the 3-month clinical outcomes of patients with home treatment and those with in-hospital treatment. The ONCO PE trial was a multicenter, randomized clinical trial among 32 institutions in Japan investigating the optimal duration of rivaroxaban treatment in cancer-associated PE patients with a score of 1 using the simplified version of the Pulmonary Embolism Severity Index (sPESI). Among 178 study patients, there were 66 (37%) in the home treatment group and 112 (63%) in the in-hospital treatment group. The primary endpoint of a composite of PE-related death, recurrent venous thromboembolism (VTE) and major bleeding occurred in 3 patients (4.6% [0.0-9.6%]) in the home treatment group and in 2 patients (1.8% [0.0-4.3%]) in the in-hospital treatment group. In the home treatment group, there were no cases of PE-related death or recurrent VTE, but major bleeding occurred in 3 patients (4.6% [0.0-9.6%]), and 2 patients (3.0% [0.0-7.2%]) required hospitalization due to bleeding events. CONCLUSIONS: Active cancer patients with PE of sPESI score=1 could be potential candidates for home treatment.

Radiofrequency Catheter Ablation for Atrial Fibrillation Patients on Hemodialysis (From the Kansai Plus Atrial Fibrillation Registry)　- Clinical Impact of Early Recurrence.

BACKGROUND: Catheter ablation (CA) for atrial fibrillation (AF) in patients on hemodialysis (HD) is reported to have a high risk of late recurrence (LR). However, the relationship between early recurrence (ER) within a 90-day blanking period after CA in AF patients and LR in HD patients remains unclear.Methods and Results: Of the 5,010 patients in the Kansai Plus Atrial Fibrillation Registry, 5,009 were included in the present study. Of these patients, 4,942 were not on HD (non-HD group) and 67 were on HD (HD group). HD was an independent risk factor for LR after the initial CA (adjusted hazard ratio 1.6; 95% confidence interval 1.1-2.2; P=0.01). In patients with ER, the rate of sinus rhythm maintenance at 3 years after the initial CA was significantly lower in the HD than non-HD group (11.4% vs. 35.4%, respectively; log-rank P=0.004). However, in patients without ER, there was no significant difference in the rate of sinus rhythm maintenance at 3 years between the HD and non-HD groups (67.7% vs. 74.5%, respectively; log-rank P=0.62). CONCLUSIONS: ER in HD patients was a strong risk factor for LR. However, even HD patients could expect a good outcome without ER after the initial CA.

Aspirin-free strategy for percutaneous coronary intervention in acute coronary syndrome based on the subtypes of acute coronary syndrome and high bleeding risk: the STOPDAPT-3 trial.

BACKGROUND AND AIMS: High bleeding risk (HBR) and acute coronary syndrome (ACS) subtypes are critical in determining bleeding and cardiovascular event risk after percutaneous coronary intervention (PCI). METHODS: In 4476 ACS patients enrolled in the STOPDAPT-3, where the no-aspirin and dual antiplatelet therapy (DAPT) strategies after PCI were randomly compared, the pre-specified subgroup analyses were conducted based on HBR/non-HBR and ST-segment elevation myocardial infarction (STEMI)/non-ST-segment elevation ACS (NSTE-ACS). The co-primary bleeding endpoint was BARC type 3 or 5, and the co-primary cardiovascular endpoint was a composite of cardiovascular death, myocardial infarction, definite stent thrombosis, or ischemic stroke at 1 month. RESULTS: Irrespective of the subgroups, the effect of no-aspirin compared with DAPT was not significant for the bleeding endpoint (HBR [N = 1803]: 7.27% and 7.91%, HR 0.91, 95%CI 0.65-1.28; non-HBR [N = 2673]: 3.40% and 3.65%, HR 0.93, 95%CI 0.62-1.39; Pinteraction = 0.94; STEMI [N = 2553]: 6.58% and 6.56%, HR 1.00, 95% CI 0.74-1.35; NSTE-ACS [N = 1923]: 2.94% and 3.64%, HR 0.80, 95%CI 0.49-1.32; Pinteraction = 0.45), and for the cardiovascular endpoint (HBR: 7.87% and 5.75%, HR 1.39, 95%CI 0.97-1.99; non-HBR: 2.56% and 2.67%, HR 0.96, 95%CI 0.60-1.53; Pinteraction = 0.22; STEMI: 6.07% and 5.46%, HR 1.11, 95%CI 0.81-1.54; NSTE-ACS: 3.03% and 1.71%, HR 1.78, 95%CI 0.97-3.27; Pinteraction = 0.18). CONCLUSIONS: In patients with ACS undergoing PCI, the no-aspirin strategy compared to the DAPT strategy failed to reduce major bleeding events irrespective of HBR and ACS subtypes. The numerical excess risk of the no-aspirin strategy relative to the DAPT strategy for cardiovascular events was observed in patients with HBR and in patients with NSTE-ACS.

KUS121, a VCP modulator, has an ameliorating effect on acute and chronic heart failure without calcium loading via maintenance of intracellular ATP levels.

AIMS: As heart failure (HF) progresses, ATP levels in myocardial cells decrease, and myocardial contractility also decreases. Inotropic drugs improve myocardial contractility but increase ATP consumption, leading to poor prognosis. Kyoto University Substance 121 (KUS121) is known to selectively inhibit the ATPase activity of valosin-containing protein, maintain cellular ATP levels, and manifest cytoprotective effects in several pathological conditions. The aim of this study is to determine the therapeutic effect of KUS121 on HF models. METHODS AND RESULTS: Cultured cell, mouse, and canine models of HF were used to examine the therapeutic effects of KUS121. The mechanism of action of KUS121 was also examined. Administration of KUS121 to a transverse aortic constriction (TAC)-induced mouse model of HF rapidly improved the left ventricular ejection fraction and improved the creatine phosphate/ATP ratio. In a canine model of high frequency-paced HF, administration of KUS121 also improved left ventricular contractility and decreased left ventricular end-diastolic pressure without increasing the heart rate. Long-term administration of KUS121 to a TAC-induced mouse model of HF suppressed cardiac hypertrophy and fibrosis. In H9C2 cells, KUS121 reduced ER stress. Finally, in experiments using primary cultured cardiomyocytes, KUS121 improved contractility and diastolic capacity without changing peak Ca2+ levels or contraction time. These effects were not accompanied by an increase in cyclic adenosine monophosphate or phosphorylation of phospholamban and ryanodine receptors. CONCLUSIONS: KUS121 ameliorated HF by a mechanism totally different from that of conventional catecholamines. We propose that KUS121 is a promising new option for the treatment of HF.