Association between natriuretic peptides and C-reactive protein with frailty in heart failure: a systematic review and meta-analysis

BACKGROUND

Heart failure (HF) and frailty are accompanied by a bidirectional relationship, sharing common risk factors including elevated levels of natriuretic peptides and inflammation. The aim of this study was to compare biomarkers associated with poor clinical outcomes, that is, plasma brain natriuretic peptide (BNP), N-terminal-pro B-type natriuretic peptide (NT-proBNP), and C-reactive protein (CRP) in patients with HF and frailty vs. patients with HF without frailty.

METHODS

From inception until July 2023, PubMed, Scopus, Web of Science, and Cochrane Library a systematic literature search was conducted. To evaluate whether frailty is linked with greater levels of BNP, NT-proBNP, and CRP, a meta-analysis using a random-effects model was used to calculate the pooled effects (CRD42023446607).

RESULTS

Fifty-three studies were included in this systematic review and meta-analysis. Patients with HF and frailty displayed significantly higher levels of BNP (k = 11; SMD: 0.53, 95%CI 0.30-0.76, I2 = 86%, P < 0.01), NT-proBNP (k = 23; SMD: 0.33, 95%CI 0.25-0.40, I2 = 72%, P < 0.01), and CRP (k = 8; SMD: 0.30, 95%CI 0.12-0.48, I2 = 62%, P < 0.01) vs. patients with HF without frailty. Using meta-regression, body mass index (BMI) and age were deemed potential moderators of these findings.

CONCLUSIONS

Frailty in HF is linked to increased concentrations of BNP, NT-proBNP, and CRP, which have been epidemiologically associated with adverse outcomes. The increased risk of NYHA III/IV classification further emphasizes the clinical impact of frailty in this population.

In symptomatic AF, catheter ablation vs. medical therapy reduced depression and anxiety symptoms at 12 mo

SOURCE CITATION

Al-Kaisey AM, Parameswaran R, Bryant C, et al. Atrial fibrillation catheter ablation vs medical therapy and psychological distress: a randomized clinical trial. JAMA. 2023;330:925-933. 37698564.

Association between the atrial tachyarrhythmia recurrence period and long-term major adverse clinical events following catheter ablation for atrial fibrillation

Background

We previously demonstrated the clinical events in patients who underwent catheter ablation (CA) for atrial fibrillation (AF). Data on the association between the period of atrial tachyarrhythmia (ATA) recurrence after CA and long-term major adverse clinical events (MACE) remain unclear. In this study, we evaluated this issue in patients with systolic impairment (left ventricular ejection fraction < 50%) and heart failure with preserved ejection fraction (HFpEF).

Methods

We retrospectively collected data from 81 patients with systolic impairment and 83 patients with HFpEF who underwent CA for AF at our institution (median follow-up: 4.9 [3.6, 6.6] years). In each group, we compared the cumulative incidence of long-term MACE (since 1 year after CA) between patients with and without ATA recurrence at three follow-up periods (3, 6 months, and 1 year after index CA). We evaluated the period of recurrence, which was the most beneficial predictor of MACE among the periods.

Results

In the systolic impairment group, the cumulative long-term MACE incidence was significantly higher in patients with ATA recurrence than in those without it within 6 months and 1 year (P = 0.04 and P = 0.01, respectively). Recurrence within 1 year showed the highest feasibility for predicting long-term MACE (area under the curve with 95% confidence interval [CI]:0.73 [0.61-0.84]). However, there was no difference in the incidence of MACE between patients with and without recurrence in a group with HFpEF in each period.

Conclusion

ATA recurrence within 1 year could predict long-term MACE in patients with systolic impairment, but not in patients with HFpEF.

Incidence of Mid-Term Prognostic Events in Patients With Acute Coronary Syndrome During the Late 2010s in 2 Tertiary Hospitals in a Rural Area of Japan - A Temporal Comparison

Background: Data on the incidence of mid-term prognostic events in patients who developed acute coronary syndrome (ACS) in the late 2010s are scarce. Methods and Results: We retrospectively included and collected data for 889 patients with ACS (ST-elevation myocardial infarction [STEMI]/non-ST-elevation ACS [NSTE-ACS]) discharged alive from 2 tertiary hospitals in Izumo City, in rural Japan, between August 2009 and July 2018. Patients were divided into 3 time groups (T1: August 2009-July 2012; T2: August 2012-July 2015; T3: August 2015-July 2018). The cumulative incidence of major adverse cardiovascular events (MACE; comprising all-cause death, recurrent ACS, and stroke), major bleeding, and heart failure hospitalization within 2 years of discharge was compared among the 3 groups. The incidence of freedom from MACE was significantly higher in the T3 group than in the T1 and T2 groups (93 [95% confidence interval {CI} 90-96%] vs. 86% [95% CI 83-90] and 89% [95% CI 90-96], respectively; P=0.03). There was a tendency for a higher incidence of STEMI among patients in T3 (P=0.057). The incidence of NSTE-ACS was comparable among the 3 groups (P=0.31), as was the incidence of major bleeding and hospitalization for heart failure. Conclusions: The incidence of mid-term MACE in patients who developed ACS during the late 2010 s (2015-2018) was lower than that in prior periods (2009-2015).

RyR2-targeting therapy prevents left ventricular remodeling and ventricular tachycardia in post-infarction heart failure

BACKGROUND

Dantrolene binds to the Leu⁶⁰¹-Cys⁶²⁰ region of the N-terminal domain of cardiac ryanodine receptor (RyR2), which corresponds to the Leu⁵⁹⁰-Cys⁶⁰⁹ region of the skeletal ryanodine receptor, and suppresses diastolic Ca²⁺ leakage through RyR2.

OBJECTIVE

We investigated whether the chronic administration of dantrolene prevented left ventricular (LV) remodeling and ventricular tachycardia (VT) after myocardial infarction (MI) by the same mechanism with the mutation V3599K of RyR2, which indicated that the inhibition of diastolic Ca²⁺ leakage occurred by enhancing the binding affinity of calmodulin (CaM) to RyR2.

METHODS AND RESULTS

A left anterior descending coronary artery ligation MI model was developed in mice. Wild-type (WT) were divided into four groups: sham-operated mice (WT-Sham), sham-operated mice treated with dantrolene (WT-Sham-DAN), MI mice (WT-MI), and MI mice treated with dantrolene (WT-MI-DAN). Homozygous V3599K RyR2 knock-in (KI) mice were divided into two groups: sham-operated mice (KI-Sham) and MI mice (KI-MI). The mice were followed for 12 weeks. Survival was significantly higher in the WT-MI-DAN (73%) and KI-MI groups (70%) than the WT-MI group (40%). Echocardiography, pathological tissue, and epinephrine-induced VT studies showed that LV remodeling and VT were prevented in the WT-MI-DAN and KI-MI groups compared to the WT-MI group. An increase in diastolic Ca²⁺ spark frequency and a decrease in the binding affinity of CaM to the RyR2 were observed at 12 weeks after MI in the WT-MI group, although significant improvements in these values were observed in the WT-MI-DAN and KI-MI groups.

CONCLUSIONS

Pharmacological or genetic stabilization of RyR2 tetrameric structure improves survival after MI by suppressing LV remodeling and proarrhythmia.

Long-term events following catheter-ablation for atrial fibrillation in heart failure with preserved ejection fraction

AIMS

Data regarding prognostic events following catheter ablation (CA) for atrial fibrillation (AF) in patients with heart failure with preserved ejection fraction (HFpEF) are scarce. We conducted this study to compare the incidence of major adverse clinical events (MACE) following CA for AF between patients with HFpEF and those with systolic heart failure (HF).

METHODS AND RESULTS

This single-centre observational study included 142 patients with HF who underwent CA for AF (median follow-up: 4.0 [2.6, 6.3] years). The patients were grouped based on the presence of HFpEF (n = 84) and systolic HF (left ventricular ejection fraction <50%, n = 58). We compared the cumulative incidence and incidence rate of MACE, comprising all-cause death, unplanned cardiovascular hospitalization (CVH), and HF hospitalization (HFH) between both groups and the number of HFH before and after CA in each group. Multivariate analysis was performed to identify the predictors of MACE in patients with HFpEF. The incidence of MACE was comparable between the groups (following the first procedure: HFpEF: 23%, 4.7/100 person-years, vs. systolic HF: 28%, 6.6/100 person-years, P = 0.18; last procedure: 20%, 4.8/100 person-years, vs. 24%, 6.9/100 person-years, P = 0.21). Although the incidence of HFH was lower in patients with HFpEF than in those with systolic HF (first procedure: 14%, 2.9/100 person-years, vs. 24%, 5.7/100 person-years, P = 0.07; last procedure: 11%, 2.5/100 person-years, vs. 24%, 6.9/100 person-years, P = 0.01), the incidence of CVH was higher (first procedure: 8%, 1.7/100 person-years, vs. 5%, 1.2/100 person-years, P = 0.74; last procedure: 6%, 1.4/100 person-years, vs. 2%, 0.5/100 person-years, P = 0.4). The number of HFH significantly decreased in both groups after CA (HFpEF: 1 hospitalization [the first and third quartiles: 0, 1] in pre-CA, vs. 0 hospitalizations [0, 0] in post-CA, P < 0.0001; systolic HF: 1 hospitalization [0, 1], vs. 0 hospitalizations [0, 0], P < 0.005). The proportion of HFH among total clinical events was significantly smaller in patients with HFpEF than in those with systolic HF (following the first procedure: 56% vs. 88%, P < 0.005; last procedure: 52% vs. 92%, P < 0.005).

CONCLUSIONS

CA for AF could be beneficial for patients with HFpEF, similar to those with systolic HF. However, clinical events other than HFH should be considered cautiously in such patients.

The Differential Prognostic Impact of Long-Duration Atrial High-Rate Episodes Detected by Cardiac Implantable Electronic Devices between Patients with and without a History of Atrial Fibrillation

Long-duration atrial high-rate episodes (AHREs) monitored using cardiac implantable electronic devices (CIEDs) can predict long-term major adverse cardiovascular events (MACEs). This study aimed to compare the impact of long-duration AHRE on MACE development between patients with and without a history of atrial fibrillation (AF). This single-center observational study included 132 CIED-implanted patients with AHREs detected via remote monitoring. The population was dichotomized into groups: with (n = 69) and without (n = 63) AF. In each group, cumulative incidences of MACEs comprising all-cause deaths, heart failure hospitalizations, strokes, and acute coronary syndromes were compared between patients with AHRE durations of ≥24 h and <24 h. Multivariate analysis was performed to identify predictors of MACEs among patients without AF. MACE incidence was significantly higher in patients with AHRE ≥24 h than in those with <24 h in the group without AF (92% vs. 30%, p = 0.005). MACE incidence did not significantly differ between AHRE ≥24 h and <24 h in the group with AF (54% vs. 26%, p = 0.44). After a multivariate adjustment, AHRE duration of ≥24 h emerged as the only independent predictor of MACEs among patients without AF (p = 0.03). In conclusion, a long-duration AHRE was prognostic in patients without a history of AF but not in patients with a history of AHREs.

Impact of Atrial Tachyarrhythmia Recurrence on the Development of Long-Term Adverse Clinical Events Following Catheter Ablation in Patients With Atrial Fibrillation With Systolic Impairment: A Single-Center Observational Study

Background

Catheter ablation can improve long‐term prognosis of patients with atrial fibrillation with systolic impairment. However, atrial tachyarrhythmia (ATA) recurrence increases during long‐term follow‐up. We aimed to investigate the impact of ATA recurrence on the development of long‐term adverse clinical events following catheter ablation for atrial fibrillation and to identify predictors for the development of adverse clinical events.

Methods and Results

This single‐center observational study included 75 patients with systolic impairment (left ventricular ejection fraction <50%) who underwent the first catheter ablation procedure for atrial fibrillation at our institution (median follow‐up period: 3.5 [range: 2.4–4.7] years). We compared the cumulative incidence of adverse clinical events (all‐cause death, heart failure hospitalization, stroke, or acute myocardial infarction) between the groups with and without ATA recurrence following the first and last procedures. Multivariable analyses were performed to identify predictors for developing adverse clinical events. Twenty‐one patients (28%) developed adverse clinical events at a median of 2.2 (range: 0.64–2.8) years following the first procedure. The proportion of freedom from adverse clinical events following the first procedure was significantly lower in the ATA recurrence group than in the nonrecurrence group (41% [n=40] versus 95% [n=35], P<0.0005); the proportion following the last procedure also showed a similar tendency (35% [n=26] versus 57% [n=49], P<0.0001). ATA recurrence emerged as an independent predictor for adverse clinical events following both procedures after multivariable adjustment.

Conclusions

ATA recurrence following catheter ablation procedure could predict adverse clinical events in patients with atrial fibrillation with systolic impairment.

Enhanced oxidative stress and presence of ventricular aneurysm for risk prediction in cardiac sarcoidosis

Objective

Sudden cardiac death (SCD) is the major cause of death in cardiac sarcoidosis (CS). We aimed to identify the prognostic markers for sustained ventricular tachycardia (sVT) and SCD in patients with CS.

Methods

We performed a prospective observational cohort study for patients with CS diagnosed according to the Japanese or Heart Rhythm Society guidelines between June 2008 and March 2020 in our hospital. The primary endpoint was a composite of the first sVT and SCD. The levels of urinary 8-hydroxy-2′-deoxyguanosine (U-8-OHdG), a marker of oxidative DNA damage that reflects the inflammatory activity of CS, other biomarkers, and indices of cardiac function and renal function were measured on admission.

Results

Eighty-nine consecutive patients with CS were enrolled; 28 patients with no abnormal ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) accumulation in the heart were excluded and 61 patients with abnormal ¹⁸F-FDG accumulation were followed up for a median of 46 months (IQR: 20–84). During the follow-up period, 15 of 61 patients showed sVT (n=12) or SCD (n=3). A Cox proportional hazard model showed that U-8-OHdG concentration and presence of ventricular aneurysm (VA) were independent predictors of first sVT/SCD. The cut-off U-8-OHdG concentration for predicting first sVT/SCD was 14.9 ng/mg·Cr. Patients with U-8-OHdG concentration ≥14.9 ng/mg·Cr and VA showed a significantly increased risk of sVT/SCD.

Conclusions

U-8-OHdG and presence of VA were powerful predictors of first sVT/SCD in patients with CS, facilitating the stratification of cardiac events and providing relevant information about the substrates of ventricular tachycardia.

An impact of superior vena cava isolation in non-paroxysmal atrial fibrillation patients with low voltage areas

BACKGROUND

This study aimed to investigate the correlation between left atrial low-voltage areas (LVAs) and an arrhythmogenic superior vena cava (SVC) and the impact on the efficacy of an empiric SVC isolation (SVCI) along with a pulmonary vein isolation (PVI) of non-paroxysmal atrial fibrillation (non-PAF) with or without LVAs.

METHODS

We retrospectively enrolled 153 consecutive patients with non-PAF who underwent a PVI alone (n = 51) or empiric PVI plus an SVCI (n = 102). Left atrial voltage maps were constructed during sinus rhythm to identify the LVAs (<0.5 mV). An arrhythmogenic SVC was defined as firing from the SVC and an SVC associated with the maintenance of AF-like rapid SVC activity.

RESULTS

An arrhythmogenic SVC and LVAs were identified in 28% and 65% of patients with a PVI alone and 36% and 73% of patients with a PVI plus SVCI, respectively (P = .275 and P = .353). In the multivariate analysis a female gender, higher pulmonary artery systolic pressure (PAPs), and arrhythmogenic SVC were associated with the presence of LVAs. In the PVI plus SVCI strategy, there was no significant difference in the atrial tachyarrhythmia/AF-free survival between the patients with and without LVAs after initial and multiple sessions (50% vs. 61%; P = .386, 73% vs. 79%; P = .530), however, differences were observed in the PVI alone group (27% vs. 61%; P = .018, 49% vs. 78%; P = .046).

CONCLUSIONS

The presence of LVAs was associated with an arrhythmogenic SVC. An SVCI may have the potential to compensate for an impaired outcome after a PVI in non-PAF patients with LVAs.

Association Between Atrial High-Rate Episodes and Ischemic/Major Bleeding Events in Patients With a Cardiac Implantable Electronic Device - A 10-Year, Single-Center Historical Cohort Study

BACKGROUND

An association between atrial high-rate episode (AHRE) and stroke has been reported, although data for the Asian population are limited. This study aimed to investigate the role of AHRE in ischemic and major bleeding events in patients who underwent a cardiac implantable electronic device (CIED) procedure.Methods and Results:This single-center historical cohort study included 710 patients (age: 78±11 years, 374 women) who underwent a CIED-related procedure between October 2009 and September 2019 at Shimane Prefectural Central Hospital (median follow-up period: 4.5 [2.5, 7] years, 3439 person-years). Based on the maximum AHRE burden, patients were divided into: (1) <6 min; (2) ≥6 min to 24-h; and (3) ≥24-h groups. The cumulative incidence of ischemic (ischemic stroke, systemic embolism, and transient ischemic attack) and major bleeding (≥3 Bleeding Academic Research Consortium bleeding criteria) events after the procedure were compared. Uni- and multivariate analyses were performed to identify factors associated with these events. The incidence of both events increased with the rising AHRE burden, being significantly higher in the ≥24-h group than in the <6 min group. Multivariate analysis found age ≥85 years to be the only independent factor associated with both events.

CONCLUSIONS

Longer AHRE duration is associated with a high number of major bleeding and ischemic events. Monitoring these bleeding risks is mandatory when clinicians are considering anticoagulation therapy for such patients.

Incidence and Demographic Trends for Acute Coronary Syndrome in a Non-Epidemic Area During the Coronavirus Disease Pandemic in Japan - A 2-Institutional Observational Study

Background: We investigated the incidence of acute coronary syndrome (ACS) in a non-epidemic area of coronavirus disease-2019 (COVID-19) in Japan.

Methods and Results: This observational study included consecutive patients admitted for ACS at 2 tertiary hospitals in Izumo City during the pandemic in Japan (n=42, March–July 2020). Although the monthly ACS incidence was comparable, the proportions of delayed admissions and high Killip class (III/IV) were significantly higher in this population than in historical cohorts (n=197, 2015–2019).

Conclusions: Our findings stress the importance of encouraging patients with ACS-related symptoms to visit medical services promptly, especially in non-epidemic areas.

Successful ablation of biatrial tachycardia with preserved electrical activation of left atrial appendage by unidirectional connection via Bachmann’s bundle: A case report

A 57-year-old man underwent his seventh ablation session for atrial tachycardia (AT). His previous ablations involved several regions of the right atrium (RA) and left atrium (LA). The AT was characterized as biatrial tachycardia with a circuit involving the mitral annulus and septal RA. The AT was terminated by ablation through the insertion site of Bachmann’s bundle (BB) in both atria. After 3 months, the patient underwent his eighth ablation session because of AT recurrence. Activation maps showed that the connection from the RA to LA and vice versa was maintained via BB and the coronary sinus, respectively. The ablation target to interrupt the AT circuit was the mitral isthmus (MI), not BB, because BB supplied the electrical activation of the left atrial appendage (LAA) via a unidirectional electrical connection from the RA to LA. Ablation attempts from within the coronary sinus were performed to target the epicardial connection in the MI and led to complete blockage of the connection from the LA to RA. Otherwise, the connection from the RA to LA was preserved via BB. The patient was free of symptoms and anti-arrhythmic drugs at the 4-month follow-up. However, he had a high risk of electrical isolation of the LAA because extensive ablations had been performed; the strategy of targeting the MI contributed to the balance between preserving the electrical activation of the LAA and treating the biatrial tachycardia. Verification of the connective pathway between the two atria might be helpful to determine the optimal target.

Detection of Active Inflammation Status Around Ventricular Aneurysms in Patients With Cardiac Sarcoidosis

BACKGROUND

Little is known about the pattern of isotope accumulation in the heart on ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography in patients with cardiac sarcoidosis (CS) complicated by ventricular aneurysm (VA).Methods and Results:We prospectively enrolled 82 consecutive patients with CS; 54 patients with active CS (presence of abnormal ¹⁸F-FDG accumulation in the heart) were subdivided into VA (n=17) and non-VA groups (n=37). Strong ¹⁸F-FDG accumulation surrounding the VA and its disappearance in the VA center was observed in all patients with VA, probably because of scar formation at the VA. Peak standardized uptake value was higher around the VA than in the VA center (5.1±2.1 vs. 2.2±0.6, P=0.0003) and the VA center had no ¹⁸F-FDG accumulation (VA center: 2.2±0.6 vs. control area: 2.1±0.6, P=0.37). On the other hand, in non-VA patients with LV wall thinning (n=28), ¹⁸F-FDG accumulation was significantly high, even in the area of LV wall thinning (LV wall thinning area: 3.1±0.8 vs. control area: 2.0±0.6, P=0.00002).

CONCLUSIONS

A pattern of strong ¹⁸F-FDG accumulation surrounding the VA and its disappearance in the VA center might be characteristic in patients with CS complicated by VA. Careful attention to FDG uptake would further elucidate CS pathophysiology and aid in the early treatment of VA.

Addition of a β1-Blocker to Milrinone Treatment Improves Cardiac Function in Patients with Acute Heart Failure and Rapid Atrial Fibrillation

BACKGROUND

Tachycardia worsens cardiac performance in acute decompensated heart failure (ADHF). We investigated whether heart rate (HR) optimization by landiolol, an ultra-short-acting β1-selective blocker, in combination with milrinone improved cardiac function in patients with ADHF and rapid atrial fibrillation (AF).

METHODS AND RESULTS

We enrolled9 ADHF patients (New York Heart Association classification IV; HR, 138 ± 18 bpm; left ventricular [LV] ejection fraction, 28 ± 8%; cardiac index [CI], 2.1 ± 0.3 L/min-1/m-2; pulmonary capillary wedge pressure [PCWP], 24 ± 3 mm Hg), whose HRs could not be reduced using standard treatments, including diuretics, vasodilators, and milrinone. Landiolol (1.5-6.0 µg/kg-1/min-1, intravenous) was added to milrinone treatment to study its effect on hemodynamics. The addition of landiolol (1.5 µg/kg-1/min-1) significantly reduced HR by 11% without changing systolic blood pressure (BP) and resulted in a significant decrease in PCWP and a significant increase in stroke volume index (SVI), suggesting that HR reduction restores incomplete LV relaxation. Administration of more than 3.0 µg/kg-1/min-1 of landiolol decreased BP, CI, and SVI.

CONCLUSION

The addition of landiolol at doses of <3.0 µg/kg/min to milrinone improved cardiac function in decompensated chronic heart failure with rapid atrial fibrillation by selectively reducing HR.

Nuclear translocation of calmodulin in pathological cardiac hypertrophy originates from ryanodine receptor bound calmodulin

In cardiac myocytes Calmodulin (CaM) bound to the ryanodine receptor (RyR2) constitutes a large pool of total myocyte CaM, but the CaM-RyR2 affinity is reduced in pathological conditions. Knock-in mice expressing RyR2 unable to bind CaM also developed hypertrophy and early death. However, it is unknown whether CaM released from this RyR2-bound pool participates in pathological cardiac hypertrophy. We found that angiotensin II (AngII) or phenylephrine (PE) both cause CaM to dissociate from the RyR2 and translocate to the nucleus. To test whether this nuclear CaM accumulation depends on CaM released from RyR2, we enhanced CaM-RyR2 binding affinity (with dantrolene), or caused CaM dissociation from RyR2 (using suramin). Dantrolene dramatically reduced AngII- and PE-induced nuclear CaM accumulation. Conversely, suramin enhanced nuclear CaM accumulation. This is consistent with nuclear CaM accumulation coming largely from the CaM-RyR2 pool. CaM lacks a nuclear localization signal (NLS), but G-protein coupled receptor kinase 5 (GRK5) binds CaM, has a NLS and translocates like CaM in response to AngII or PE. Suramin also promoted GRK5 nuclear import, and caused nuclear export of histone deacetylase 5 (HDAC5). Dantrolene prevented these effects. After 2-8 weeks of pressure overload (TAC) CaM binding to RyR2 was reduced, nuclear CaM and GRK5 were both elevated and there was enhanced nuclear export of HDAC5. Stress (acute AngII or TAC) causes CaM dissociation from RyR2 and translocation to the nucleus with GRK5 with parallel HDAC5 nuclear export. Thus CaM dissociation from RyR2 may be an important step in driving pathological hypertrophic gene transcription.

Mutation-linked, excessively tight interaction between the calmodulin binding domain and the C-terminal domain of the cardiac ryanodine receptor as a novel cause of catecholaminergic polymorphic ventricular tachycardia

BACKGROUND

Ryanodine receptor (RyR2) is known to be a causal gene of catecholaminergic polymorphic ventricular tachycardia (CPVT), an important inherited disease. Some of the human CPVT-associated mutations have been found in a domain (4026-4172) that has EF hand motifs, the so-called calmodulin (CaM)-like domain (CaMLD).

OBJECTIVE

The purpose of this study was to investigate the underlying mechanism by which CPVT is induced by a mutation at CaMLD.

METHODS

A new N4103K/+ knock-in (KI) mice model was generated.

RESULTS

Sustained ventricular tachycardia was frequently observed after infusion of caffeine plus epinephrine in KI mice. Endogenous CaM bound to RyR2 decreased even at baseline in isolated KI cardiomyocytes. Ca²⁺ spark frequency (CaSpF) was much higher in KI cells than in wild-type cells. Addition of GSH-CaM (higher affinity CaM to RyR2) significantly decreased CaSpF. In response to isoproterenol, spontaneous Ca²⁺ transient (SCaT) was frequently observed in intact KI cells. Incorporation of GSH-CaM into intact KI cells using a protein delivery kit decreased SCaT significantly. An assay using a quartz crystal microbalance technique revealed that mutated CaMLD peptide showed higher binding affinity to CaM binding domain (CaMBD) peptide.

CONCLUSION

In the N4103K mutant, CaM binding affinity to RyR2 was significantly reduced regardless of beta-adrenergic stimulation. We found that this was caused by an abnormally tight interaction between CaMBD and mutated CaM-like domain (N4103K-CaMBD). Thus, CaMBD-CaMLD interaction may be a novel therapeutic target for treatment of lethal arrhythmia.

Recombinant Atrial Natriuretic Peptide Prevents Aberrant Ca2+ Leakage through the Ryanodine Receptor by Suppressing Mitochondrial Reactive Oxygen Species Production Induced by Isoproterenol in Failing Cardiomyocytes

Catecholamines induce intracellular reactive oxygen species (ROS), thus enhancing diastolic Ca²⁺ leakage through the ryanodine receptor during heart failure (HF). However, little is known regarding the effect of atrial natriuretic peptide (ANP) on ROS generation and Ca²⁺ handling in failing cardiomyocytes. The aim of the present study was to clarify the mechanism by which an exogenous ANP exerts cardioprotective effects during HF. Cardiomyocytes were isolated from the left ventricles of a canine tachycardia-induced HF model and sham-operated vehicle controls. The degree of mitochondrial oxidized DNA was evaluated by double immunohistochemical (IHC) staining using an anti-VDAC antibody for the mitochondria and an anti-8-hydroxy-2′-deoxyguanosine antibody for oxidized DNA. The effect of ANP on ROS was investigated using 2,7-dichlorofluorescin diacetate, diastolic Ca²⁺ sparks assessed by confocal microscopy using Fluo 4-AM, and the survival rate of myocytes after 48 h. The double IHC study revealed that isoproterenol (ISO) markedly increased oxidized DNA in the mitochondria in HF and that the ISO-induced DNA damage was markedly inhibited by the co-presence of ANP. ROS production and Ca²⁺ spark frequency (CaSF) were increased in HF compared to normal controls, and were further increased in the presence of ISO. Notably, ANP significantly suppressed both ISO-induced ROS and CaSF without changing sarcoplasmic reticulum Ca²⁺ content in HF (p<0.01, respectively). The survival rate after 48 h in HF was significantly decreased in the presence of ISO compared with baseline (p<0.01), whereas it was significantly improved by the co-presence of ANP (p<0.01). Together, our results suggest that ANP strongly suppresses ISO-induced mitochondrial ROS generation, which might correct aberrant diastolic Ca²⁺ sparks, eventually contributing to the improvement of cardiomyocyte survival in HF.

Successful cryoballoon pulmonary vein isolation in a patient with situs inversus and dextrocardia

A 79-year-old man with situs inversus and dextrocardia underwent catheter ablation of symptomatic paroxysmal atrial fibrillation. Pulmonary vein isolation (PVI), using second-generation cryoballoon under Ensite NavX system guidance, was performed successfully in a reverse manner, which required short procedure and fluoroscopy times, as required in a PVI performed on a normal heart without any complications. Cryoballoon-based PVI under Ensite NavX guidance was feasible and safe to achieve a favorable outcome in this patient with abnormal anatomy.

An oxidative stress biomarker, urinary 8-hydroxy-2'-deoxyguanosine, predicts cardiovascular-related death after steroid therapy for patients with active cardiac sarcoidosis

BACKGROUND

We investigated whether urinary 8-hydroxy-2'-deoxyguanosine (U-8-OHdG), a marker of oxidative DNA damage, is a prognosticator of cardiovascular-related death in patients with cardiac sarcoidosis (CS).

METHODS AND RESULTS

In this prospective study, 30 consecutive patients were divided into the active CS (n=20) and non-active CS (n=10) groups, based on abnormal isotope accumulation in the heart on (18)F-fluorodeoxyglucose positron-emission tomography/computed tomography ((18)F-FDG PET/CT) imaging. Nineteen patients in the active CS group underwent corticosteroid therapy. Before corticosteroid therapy initiation, U-8-OHdG, brain natriuretic peptide (BNP), other biomarkers, and indices of cardiac function were measured. Patients were followed-up for a median of 48months. The primary endpoint was the incidence of cardiovascular-related death. During the follow-up period, in the corticosteroid-treated active CS group, 7 of 19 patients experienced cardiovascular-related death. By contrast, in the non-active CS group, 1 of 10 patients died from cardiovascular-related causes. Univariate and multivariate analyses showed that U-8-OHdG and BNP were independent predictors for cardiovascular-related death. The cut-off values for predicting cardiovascular death in corticosteroid-treated patients with active CS were 19.1ng/mg·Cr and 209pg/mL for U-8-OHdG and BNP, respectively. Patients with a U-8-OHdG concentration ≥19.1ng/mg·Cr or a BNP concentration ≥209pg/mL had a significantly higher cardiovascular-related death risk, but U-8-OHdG had better predictive value compared with BNP.

CONCLUSION

These findings suggested that U-8-OHdG was a powerful predictor of cardiovascular-related death in patients with CS, suggesting that active CS patients with elevated U-8-OHdG levels might be resistant to corticosteroid therapy.

A low-dose β1-blocker in combination with milrinone improves intracellular Ca2+ handling in failing cardiomyocytes by inhibition of milrinone-induced diastolic Ca2+ leakage from the sarcoplasmic reticulum

OBJECTIVES

The purpose of this study was to investigate whether adding a low-dose β1-blocker to milrinone improves cardiac function in failing cardiomyocytes and the underlying cardioprotective mechanism.

BACKGROUND

The molecular mechanism underlying how the combination of low-dose β1-blocker and milrinone affects intracellular Ca(2+) handling in heart failure remains unclear.

METHODS

We investigated the effect of milrinone plus landiolol on intracellular Ca(2+) transient (CaT), cell shortening (CS), the frequency of diastolic Ca(2+) sparks (CaSF), and sarcoplasmic reticulum Ca(2+) concentration ({Ca(2+)}SR) in normal and failing canine cardiomyocytes and used immunoblotting to determine the phosphorylation level of ryanodine receptor (RyR2) and phospholamban (PLB).

RESULTS

In failing cardiomyocytes, CaSF significantly increased, and peak CaT and CS markedly decreased compared with normal myocytes. Administration of milrinone alone slightly increased peak CaT and CS, while CaSF greatly increased with a slight increase in {Ca(2+)}SR. Co-administration of β1-blocker landiolol to failing cardiomyocytes at a dose that does not inhibit cardiomyocyte function significantly decreased CaSF with a further increase in {Ca(2+)}SR, and peak CaT and CS improved compared with milrinone alone. Landiolol suppressed the hyperphosphorylation of RyR2 (Ser2808) in failing cardiomyocytes but had no effect on levels of phosphorylated PLB (Ser16 and Thr17). Low-dose landiolol significantly inhibited the alternans of CaT and CS under a fixed pacing rate (0.5 Hz) in failing cardiomyocytes.

CONCLUSION

A low-dose β1-blocker in combination with milrinone improved cardiac function in failing cardiomyocytes, apparently by inhibiting the phosphorylation of RyR2, not PLB, and subsequent diastolic Ca(2+) leak.