Canagliflozin reduces proteinuria by targeting hyperinsulinaemia in diabetes patients with heart failure: A post hoc analysis of the CANDLE trial.

AIM: To investigate factors associated with proteinuria regression in patients with type 2 diabetes mellitus (T2DM) treated with canagliflozin. MATERIALS AND METHODS: This study was a post hoc analysis of the CANDLE trial (UMIN000017669), which compared the effect of 24 weeks of treatment with canagliflozin or glimepiride for changes in N-terminal pro-brain natriuretic peptide in patients with T2DM and chronic heart failure (CHF). Factors associated with regression of proteinuria at 24 weeks were evaluated with multivariate logistic models. RESULTS: The rate of regression of proteinuria was higher (28/102, 27.5% vs. 12/112, 10.7%), and that of progression was lower (9/102, 8.8% vs. 26/112, 23.2%), in the canagliflozin versus the glimepiride group (P = .0001). There were no differences in the change in the estimated glomerular filtration rate category between groups. Insulin level, homeostatic model assessment of ß-cell function, homeostatic model assessment for insulin resistance and estimated plasma volume were decreased at 24 weeks in the regression subclass but not in the progression subclass, suggesting that regression of proteinuria is associated with the declines in these values in the canagliflozin group. Higher insulin level at baseline was solely associated with proteinuria regression in the multivariate logistic regression model (baseline insulin, as per a 1-mlU/L increase, odds ratio 1.24 [1.05-1.47], P = .011). CONCLUSIONS: In patients with T2DM and CHF, regression of proteinuria with canagliflozin treatment was associated with the pretreatment insulin level. These results may provide clinicians with novel mechanistic insights into the beneficial effects of canagliflozin on renal outcomes and may warrant discussion for selecting preferred patient profiles, including pretreatment insulin levels.

Efficacy and safety of atrial fibrillation ablation in heart failure patients with left ventricular ejection fraction less than 50.

INTRODUCTION: The efficacy of catheter ablation in patients with low cardiac function has been previously reported; however, only a few studies have included mid-range ejection fraction (mrEF). This study aimed to evaluate the efficacy and safety of atrial fibrillation (AF) ablation in patients with left ventricular ejection fraction (LVEF) < 50%. METHODS: This study retrospectively analyzed 79 patients (reduced ejection fraction [rEF]/mrEF, 38/41; paroxysmal/persistent, 37/42; heart failure hospitalizations within one year before ablation, 36 [45.6%]) who underwent the first ablation procedure at our hospital from April 2017 to December 2021. Radiofrequency ablation and cryoablation were performed for 69 and 10 patients, respectively. RESULTS: Complications included pacemaker implantation for postoperative sick sinus syndrome in one patient and inguinal hematoma in one patient. Regarding efficacy, there were significant postoperative improvements in echocardiographic data, blood test values, and diuretic use. After a mean follow-up of 60 months, 86.1% patients had no AF recurrence. There were 9 heart failure hospitalizations (11.4%) and 5 all-cause deaths (6.3%); no significant differences were found between the rEF and mrEF groups. No significant predictors of AF recurrence were found in preoperative patient characteristics. CONCLUSION: AF ablation in patients with LVEF <50% significantly improved cardiac and renal functions with few complications, resulting in a high non-recurrence rate and reduced heart failure.

Efficacy of isoproterenol in the evaluation of dormant conduction and arrhythmogenic foci identification in atrial fibrillation ablation.

BACKGROUND: Catheter ablation for atrial fibrillation (AF) is an established therapy. However, postoperative recurrence is a serious issue caused by the reconduction of the isolated pulmonary veins (PV) and the onset of non-PV foci. The objectives of this study were to elucidate dormant conduction, confirm PV arrhythmia substrate, induce non-PV foci after PV isolation, and assess the acute efficacy of high dose isoproterenol (ISP) when administered in addition to adenosine. METHODS: The study consisted of 100 patients with drug-refractory AF (paroxysmal and persistent) who underwent ablation therapy (either radio-frequency or cryoballoon ablation) as the first-line of therapy at our hospital. All patients first underwent PV isolation (PVI) and were administered adenosine followed by ISP (6 µg × 5 min). The effects were observed, and the therapeutic strategy was evaluated. RESULTS: Persistent dormant conduction due to ISP administration was observed in 13 patients. In over half of the patients, arrhythmia substrates were identified in the PV. Ten patients presented with persistent PV firing. The ablation of non-PV foci was additionally performed in 23 patients. CONCLUSIONS: We found that dormant conduction, as a result of ISP administration, is persistent and ISP is useful when performing an ablation. In addition, ISP administration is useful for the identification of PV arrhythmia substrates and induction of non-PV foci. However, the effectiveness of ISP may be partially due to the complementary effect of adenosine, and, therefore, a combination of the two drugs seems preferable.

Rationale and Design of the Multicenter Trial on Japan Working Group on the Effects of Angiotensin Receptor Blockers Selection (Azilsartan vs. Candesartan) on Diastolic Function in the Patients Suffering from Heart Failure with Preserved Ejection Fraction: J-TASTE Trial.

BACKGROUND: Previous studies suggest that the pathophysiology of heart failure with preserved ejection fraction (HFpEF) is characterized not only by high ventricular stiffness, but also by vascular stiffness. Azilsartan has higher vascular affinity compared with other angiotensin II receptor blockers (ARBs), which were proven to have no beneficial effects on clinical outcomes in patients with HFpEF in earlier clinical trials. We aimed to test the hypothesis that azilsartan may improve left ventricular diastolic function in HFpEF patients with hypertension in this trial. METHODS: The Effects of Angiotensin Receptor Blockers on Diastolic Function in Patients Suffering from Heart Failure with Preserved Ejection Fraction: J-TASTE trial is a multicenter, randomized, open-labeled, and assessor(s)-blinded, active controlled using candesartan, parallel-group clinical trial, to compare changes in left ventricular (LV) diastolic dysfunction between HFpEF patients with hypertension who have received candesartan or azilsartan for 48 weeks. The primary endpoint is the change in early diastolic wave height/early diastolic mitral annulus velocity (E/e') assessed by echocardiography from the baseline to the end of the study (48 weeks). A total of 190 patients will be recruited into the study. CONCLUSIONS: The design of the J-TASTE trial will provide data on whether differences between the effects of the two tested drugs on LV diastolic function exist in HFpEF patients with hypertension and will improve understanding of the pathophysiological role of vascular stiffness on diastolic function.

Enhancement of Warfarin Anticoagulant Reaction in Patients with Repeated Oral Tolvaptan Administration.

The pharmacokinetics and pharmacodynamics of warfarin remained unaffected by tolvaptan during clinical trials. However, tolvaptan prolonged the prothrombin time-international normalized ratio (PT-INR) level of patients with cardiovascular disease taking warfarin. Tolvaptan was prescribed to 576 patients from December 2010 to December 2015. Of these patients, 37 underwent anticoagulant therapy. We investigated PT-INR fluctuation immediately before tolvaptan therapy was initiated. PT-INR remained unchanged in the control group and in groups administered with less than 7.5 mg/d tolvaptan, whereas it was significantly increased (p=0.03) in the group administered with more than 7.5 mg/d tolvaptan. This result indicates the possibility that tolvaptan affects the pharmacodynamics of warfarin in vivo. However, further research is necessary to clarify the mechanism of this phenomenon.

The Effect of Sitagliptin on Carotid Artery Atherosclerosis in Type 2 Diabetes: The PROLOGUE Randomized Controlled Trial.

BACKGROUND: Experimental studies have suggested that dipeptidyl peptidase-4 (DPP-4) inhibitors provide cardiovascular protective effects. We performed a randomized study to evaluate the effects of sitagliptin added on to the conventional therapy compared with conventional therapy alone (diet, exercise, and/or drugs, except for incretin-related agents) on the intima-media thickness (IMT) of the carotid artery, a surrogate marker for the evaluation of atherosclerotic cardiovascular disease, in people with type 2 diabetes mellitus (T2DM). METHODS AND FINDINGS: We used a multicenter PROBE (prospective, randomized, open label, blinded endpoint) design. Individuals aged ≥30 y with T2DM (6.2% ≤ HbA1c < 9.4%) were randomly allocated to receive either sitagliptin (25 to 100 mg/d) or conventional therapy. Carotid ultrasound was performed at participating medical centers, and all parameters were measured in a core laboratory. Of the 463 enrolled participants with T2DM, 442 were included in the primary analysis (sitagliptin group, 222; conventional therapy group, 220). Estimated mean (± standard error) common carotid artery IMT at 24 mo of follow-up in the sitagliptin and conventional therapy groups was 0.827 ± 0.007 mm and 0.837 ± 0.007 mm, respectively, with a mean difference of -0.009 mm (97.2% CI -0.028 to 0.011, p = 0.309). HbA1c level at 24 mo was significantly lower with sitagliptin than with conventional therapy (6.56% ± 0.05% versus 6.72% ± 0.05%, p = 0.008; group mean difference -0.159, 95% CI -0.278 to -0.041). Episodes of serious hypoglycemia were recorded only in the conventional therapy group, and the rate of other adverse events was not different between the two groups. As it was not a placebo-controlled trial and carotid IMT was measured as a surrogate marker of atherosclerosis, there were some limitations of interpretation. CONCLUSIONS: In the PROLOGUE study, there was no evidence that treatment with sitagliptin had an additional effect on the progression of carotid IMT in participants with T2DM beyond that achieved with conventional treatment. TRIAL REGISTRATION: University Hospital Medical Information Network Clinical Trials Registry UMIN000004490.

A Randomized Controlled Study of Finerenone vs. Eplerenone in Japanese Patients With Worsening Chronic Heart Failure and Diabetes and/or Chronic Kidney Disease.

BACKGROUND: Finerenone, a nonsteroidal mineralocorticoid receptor antagonist, was evaluated in Japanese patients with heart failure (HF) with reduced ejection fraction and chronic kidney disease and/or diabetes mellitus. METHODS AND RESULTS: ARTS-HF Japan was a randomized, double-blind, phase 2b study. Patients (n=72) received oral, once-daily (o.d.) finerenone (2.5, 5, 7.5, 10 or 15 mg, up-titrated to 5, 10, 15, 20, or 20 mg, respectively, on day 30) or eplerenone (25 mg every other day, increased to 25 mg o.d. on day 30, and 50 mg on day 60) for 90 days. The primary endpoint was the proportion of individuals with a decrease of >30% in plasma NT-proBNP at day 90. Safety endpoints included the incidence of hyperkalemia. Decreases in NT-proBNP occurred in 23.1% of patients in the eplerenone group and 15.4%, 23.1%, 45.5%, 27.3% and 45.5% in the 2.5→5 mg, 5→10 mg, 7.5→15 mg, 10→20 mg and 15→20 mg finerenone groups, respectively (all P=NS). Mean changes in serum potassium levels were similar between groups. CONCLUSIONS: Because of the small sample size, limited conclusions can be drawn. Considering the results of ARTS-HF and that finerenone was well tolerated in Japanese patients in ARTS-HF Japan, the safety and efficacy of finerenone should be further explored in a large outcomes trial including Japanese patients. (Circ J 2016; 80: 1113-1122).

Distribution of Anti-Factor Xa Activity in Patients on Edoxaban Therapy for Non-Valvular Atrial Fibrillation.

BACKGROUND: The distribution of anti-factor Xa activity (AXA) values in non-valvular atrial fibrillation (NVAF) patients on edoxaban therapy has not been fully elucidated. METHODS AND RESULTS: The steady-state trough and peak AXA values were measured in 66 NVAF patients. The trough AXA value did not differ significantly between the 60-mg and the 30-mg OD groups (0.17±0.13 IU/ml vs. 0.12±0.11 IU/ml, respectively; P=0.17). Similarly, the peak AXA value did not differ significantly between the 2 groups (1.45±0.81 IU/ml vs. 1.25±0.48 IU/ml, respectively; P=0.26). CONCLUSIONS: Recommended dosing should be followed for sufficient efficacy of edoxaban. (Circ J 2016; 80: 745-747).

Measurement of Anti-Factor Xa Activity in Patients on Apixaban for Non-Valvular Atrial Fibrillation.

BACKGROUND: Chromogenic anti-factor Xa activity (AXA) assay is reported to be the most appropriate method to measure the pharmacodynamics of apixaban, but the distribution of AXA in non-valvular atrial fibrillation (NVAF) patients on apixaban therapy has not been fully elucidated. METHODS AND RESULTS: Steady-state trough and peak AXA were measured in 124 NVAF patients taking apixaban. In 25 patients, baseline, first peak, and trough AXA were also examined, and were 0.01±0.02 IU/ml, 0.83±0.43 IU/ml, and 0.34±0.17 IU/ml, respectively. First trough AXA was significantly lower than steady-state trough AXA, although it was significantly higher than baseline (P<0.0001). Similarly, first peak AXA was significantly lower than steady-state peak AXA (P<0.0001). In 124 patients, steady-state peak AXA was significantly higher in the 5-mg b.i.d. group than in the 2.5-mg b.i.d. group (2.05±0.73 IU/ml vs. 1.51±0.65 IU/ml, respectively; P<0.001), although there was no significant difference in trough AXA. Other than dose, age and serum creatinine were significantly related to both trough and peak AXA. CONCLUSIONS: The distribution of AXA in Japanese NVAF patients on apixaban therapy in daily clinical practice both in the acute and steady-state phase was measured. In patients taking apixaban, measurement of AXA clearly showed the pharmacodynamic profile of this drug.

Multicenter, Randomized, Double-Blinded, Placebo-Controlled Phase II Study of Serelaxin in Japanese Patients With Acute Heart Failure.

BACKGROUND: Serelaxin, a recombinant form of human relaxin-2, is in development for treating acute heart failure (AHF) and a Phase II study in Japanese AHF patients was conducted. METHODS AND RESULTS: A randomized, double-blind, placebo-controlled study of serelaxin at 10 and 30 µg·kg(-1)·day(-1)continuous intravenous infusion for up to 48 h, added to standard care for Japanese AHF patients. Primary endpoints were adverse events (AEs) through Day 5, serious AEs (SAEs) through Day 14, and serelaxin pharmacokinetics. Secondary endpoints included changes in systolic blood pressure (SBP) and cardiorenal biomarkers. A total of 46 patients received the study drug and were followed for 60 days. The observed AE profile was comparable between the groups, with no AEs of concern. Dose-dependent increase in the serum concentration of serelaxin was observed across the 2 dose rates of serelaxin. A greater reduction in SBP was observed with serelaxin 30 µg·kg(-1)·day(-1)vs. placebo (-7.7 [-16.4, 1.0] mmHg). A greater reduction in NT-proBNP was noted with serelaxin (-50.8% and -54.9% for 10 and 30 µg·kg(-1)·day(-1), respectively at Day 2). CONCLUSIONS: Serelaxin was well tolerated in this study with Japanese AHF patients, with no AEs of concern and favorable beneficial trends on efficacy. These findings support further evaluation of serelaxin 30 µg·kg(-1)·day(-1)in this patient population.

Long-term effects of tolvaptan in patients requiring recurrent hospitalization for heart failure.

Although reports suggest that tolvaptan does not reduce survival or subsequent hospitalization rates in heart failure patients, its continuous use has shown good outcomes in some patients who cannot be effectively managed with high doses of loop diuretics. Therefore, we investigated the association of patient characteristics and continued tolvaptan use in heart failure patients with changes in the frequency and annual duration of patient hospitalization due to heart failure. We carefully reviewed the medical records of patients hospitalized due to heart failure who began tolvaptan therapy and continued with outpatient treatment between December 2010 and November 2013 (tolvaptan group); patients hospitalized for heart failure between May 2008 and March 2009 served as controls. We set the reference dates as the start of tolvaptan therapy (tolvaptan group) or as the date of admission (control group). The changes in hospitalization frequency and total hospitalization time due to heart failure, before and after the reference dates, were not significantly different between the tolvaptan and control groups. In the tolvaptan group, a high estimated glomerular filtration rate was a predictor of decreased hospitalization. Continuous tolvaptan use did not decrease hospitalization duration in all heart failure patients, but good renal function was predictive of a good response.

Impact of HIF prolyl hydroxylase inhibitors in heart failure patients with renal anemia.

OBJECTIVE: Hypoxia-inducible factor prolyl hydroxylase (HIF-PH) inhibitors are a new class of anti-anemia agents. We retrospectively evaluated the safety and efficacy of HIF-PH inhibitors in patients with heart failure (HF) complicated by anemia associated with chronic kidney disase. HIF-PH inhibitor treatment was initiated in 32 patients with chronic HF complicated by renal anemia and were followed up for 3 months. RESULTS: Hematocrit and hemoglobin levels markedly improved 3 months after HIF-PH inhibitor treatment. However, levels of NT-proBNP, which is an indicator of HF, did not decrease considerably. Based on the rate of change in NT-proBNP, we divided the patients into "responder" and "non-responder" groups. The results showed that considerably more patients had a ferritin level of less than 100 ng/mL in the non-responder group at baseline. There were substantially more patients with TSAT of less than 20% in the non-responder group at 1 month after HIF-PH inhibitor treatment. The cut-off values to maximize the predictive power of ferritin level at baseline and TSAT value at 1 month after treatment were 41.8 ng/ml and 20.75. HIF-PH inhibitor treatment can be expected to be effective for improving both anemia and HF if ferritin≥41.8 ng/ml at baseline or TSAT≥20.75 at 1 month after treatment.

Treatment of sirolimus-eluting stent restenosis: additional stent, balloon angioplasty, and coronary artery bypass graft.

OBJECTIVE: Sirolimus-eluting stent (SES) has shown a significant efficacy in reducing restenosis after percutaneous coronary interventions. However, an increase in total number of SES use along with targeting more complex lesions generated a large number of SES restenosis. This study aimed to investigate the clinical and angiographic outcomes of different revascularization strategies for SES restenosis. METHODS AND RESULTS: A total of 176 lesions in 149 patients were included in the study. Fifteen patients underwent coronary artery bypass graft surgery (CABG group) and the remaining patients were treated with percutaneous coronary intervention (PCI). Stent reimplantation was performed in 88 patients (Stent group), whereas 46 patients received balloon therapy (Balloon group). Among 176 lesions, major cardiac adverse event (MACE) occurred in 41 lesions (23.3%) during a median follow-up of 310 days (interquartile range: 146-517 days). The Kaplan-Meier method with a log-rank test revealed no significant difference in MACE rates between the three groups (6%, 25%, 26%, p = 0.13; CABG group, Stent group, Balloon group, respectively). However, when the Balloon group and Stent group were combined together as a PCI group, PCI group had a significantly higher rate of MACE compared with the CABG group (p = 0.04). In addition, angiographic restenosis was significantly less prevalent in the CABG group when compared with the other two groups (8%, 57%, 46%, p = 0.006; CABG group, Stent group, Balloon group, respectively). CONCLUSIONS: CABG surgery for patients with SES restenosis is associated with the better clinical outcomes as well as better angiographic outcomes when compared with that of PCI.

Efficacy of azilsartan on left ventricular diastolic dysfunction compared with candesartan: J-TASTE randomized controlled trial.

Characterized by ventricular and vascular stiffness, heart failure with preserved ejection fraction (HFpEF) has led to high morbidity and mortality. As azilsartan is an angiotensin receptor blocker with the highest myocardial and vascular affinities, azilsartan may improve the left ventricular (LV) diastolic function in patients with hypertension and either HFpEF or HF with mildly reduced ejection fraction (HFmrEF) more than candesartan. In this randomized, open-label trial, we randomly assigned 193 hypertensive patients with HF and LV ejection fraction ≥ 45% to 20 mg of azilsartan (n = 95) or 8 mg of candesartan (n = 98), once daily for 48 weeks. After the initiation of treatment, changes in the doses of the study drugs were permitted based on the patient's conditions, including blood pressure (median dose at 48 weeks: azilsartan 20.0 mg/day, candesartan 8.0 mg/day). The primary endpoint was the baseline-adjusted change in the ratio of peak early diastolic transmitral flow velocity (E) to early diastolic mitral annular velocity (e') (E/e'). Adjusted least-squares mean (LSM) change in E/e' was - 0.8 (95% confidence interval [CI] - 1.49 to - 0.04) in the azilsartan group and 0.2 (95% CI - 0.49 to 0.94) in the candesartan group, providing the LSM differences of - 1.0 (95% CI - 2.01 to 0.03, P = 0.057). The median change in left atrial volume index was - 2.7 mL/m2 with azilsartan vs 1.4 mL/m2 with candesartan (P = 0.091). The frequency of adverse events related to hypotension and hyperkalemia did not differ between the groups. The current study did not provide strong evidence that azilsartan improves LV diastolic dysfunction, and further confirmatory study is required.

Evaluation of arrhythmogenic foci using a novel automated detection algorithm and isoproterenol in persistent atrial fibrillation.

PURPOSE: The CARTOFINDER mapping system analyzes activation patterns using unipolar potentials during atrial fibrillation (AF), where isoproterenol (ISP) is conventionally used to induce non-pulmonary vein (PV) foci and confirm PV arrhythmogenicity. In 20 patients with persistent AF who underwent ablation at our hospital, arrhythmogenic foci were evaluated using both these methods. METHODS: Before pulmonary vein isolation (PVI), PV and left atrium (LA) were analyzed during AF using CARTOFINDER, and the isolation line was determined based on the results. After PVI, ISP was loaded after return of sinus rhythm and confirmation of the presence of arrhythmogenic foci. The activation site in LA was ablated at the discretion of the surgeon. RESULTS: Focal activation sites detected by CARTOFINDER correlated with the arrhythmogenic foci induced by ISP in the PVs. The results also showed that a greater number of focal activation sites in the PVs correlated to an increased response to ISP administration. In one patient, it was observed that the focal activation site identified in the PV also coincided with the site of the origin of automaticity induced by ISP after PVI. CONCLUSION: CARTOFINDER and ISP both reliably determined the presence of arrhythmogenic foci in PV, in patients with persistent AF. Knowledge of the nature of arrhythmogenic foci in non-PV is considered to be a topic for future studies, and further data collection is required.

Contrast-enhanced computed tomography for optimizing the outcomes of pulmonary vein isolation with cryoablation -the role of isolation of PVs including carina.

PURPOSE: Compared with conventional pulmonary vein isolation (PVI) with radiofrequency ablation, PVI with cryoballoon is an easier and shorter procedure without reconnection, particularly in the superior pulmonary vein. However, the durability of the cryoballoon may be reduced due to anatomical factors and the position of the pulmonary vein (PV). Further, inadequate isolation of the carina leads to recurrence of atrial fibrillation (AF). We aimed to determine whether using contrast-enhanced computed tomography (CT) for patient selection improves the early success rate and prevents the recurrence of AF in PVI with cryoballoon. METHODS: We evaluated patients who underwent ablation for paroxysmal atrial fibrillation in our hospital between July 2019 and November 2020. After excluding patients with contraindications for cryoablation, 50 patients were selected through visual inspection of the results of preoperative contrast-enhanced CT. A treatment plan was established, and the clinical course and outcomes were followed up. RESULTS: Of the 200 PVs of the 50 patients, only 8 PVs (4%) were incompletely isolated with a single cryoablation. Six of the eight PVs were successfully isolated with additional cryoablation. Only 2 patients (4%) underwent additional PVI with radiofrequency ablation. Four patients had AF recurrence within a mean follow-up period of 14.3 ± 5.1 months. The rate of sinus rhythm maintenance was 92%. PV reconnection was observed in 2 patients. None of the patients had postoperative atrial flutter. CONCLUSIONS: Selecting patients for cryoablation according to contrast-enhanced CT findings made the procedure easier to perform, leading to improved early success rates and clinical course.

Isolated bilateral external iliac artery dissections with emotional stress.

We present a patient with isolated bilateral external iliac artery dissections associated with emotional stress. The diagnosis should be kept in mind in young, fit patients presenting lower back pain occurring subsequent to emotional stress.

A case of accessory pathway mapped with ultra-high-resolution mapping led to a coronary sinus diverticulum.

Ultra-high-resolution mapping is useful in the ablation of accessory pathways. However, in patients with accessory pathways in the coronary sinus (CS) diverticulum, treatment with endocardial ablation may be challenging. Patients suspected of having subepicardial accessory pathways may require the examination of the venous anomaly using CS angiography.

Secondary Cardiac Lymphoma Presenting as Sick Sinus Syndrome and Atrial Fibrillation Which Required Leadless Pacemaker Implantation.

Cardiac involvement of malignant lymphoma is relatively common, although such a phenomenon has subclinical manifestations that are difficult to detect. We herein describe a patient with atrial fibrillation and sick sinus syndrome as the main symptoms. Computed tomography showed a mass in the right atrium extending into the superior vena cava (SVC). We implanted the patient with a leadless pacemaker. Transvenous biopsy revealed a diffuse large B-cell lymphoma. The patient was treated successfully with chemotherapy including rituximab. This case suggested that cardiac lymphoma may cause sick sinus syndrome, and leadless pacemaker implantation is a safe treatment option in patients with partial SVC obstruction.