Long-term outcomes of 265,737 patients hospitalised with atrial fibrillation and atrial flutter from 2008 to 2015

Background

Atrial fibrillation/atrial flutter (AF/AFL) hospitalisations are common, however, little is known about the long-term outcomes of these episodes.

Objective

To examine the incidence of mortality, all-cause and cause-specific re-hospitalisations at up to 8 years after a hospitalisation for AF/AFL.

Methods

Unique patients hospitalised with a primary diagnosis of AF/AFL from 2008–2015 were identified using nation-wide hospitalisation data from Australia and New Zealand. All-cause mortality was the primary outcome. Secondary endpoints included all-cause and cause-specific re-hospitalisations. Results were reported as incident rate per 100 patient-years.

Results

We included 265,737 patients (mean age 69.9±13.9y, female 45.2%, elective 28.7%). The median length of stay was 1 day (Interquartile range [IQR] 0–4 days) and the median CHA2DS2-VASc score was 2 (IQR 1–2). During the index hospitalisation, 9,837 (3.7%) patients underwent catheter or surgical ablation and 52,634 (19.8%) underwent cardioversion. During the median follow-up time of 3.4 years (range 0–8.0 years), 53,669 patients died (incident rate of 5.7/100 patient-years) with a survival probability gradually decreasing from 92.8% (95% CI 92.7–92.9%) at 1-year to 65.4% (95% CI 64.9–65.8%) at 8-years post-discharge (Table 1 and Figure 1). All-cause re-hospitalisations occurred in 210,118 patients (incident rate of 22.2/100 patient-years) with a rehospitalisation-free survival probability of 7.1% (95% CI 6.9—7.3%) at the end of follow-up. Unplanned re-hospitalisations occurred more frequently than planned episodes (incident rate of 17.2 vs. 16.6/100 patient-years respectively). AF/AFL accounted for 25.1% of all-cause re-hospitalisations (incident rate of 8.9/100 patient-years) and the probability of freedom from re-hospitalisations for AF/AFL was 55.4% (95% CI 55.0–55.8%) at 8-years. Incident rates of re-hospitalisations for catheter ablation (1.5/100 patient-years), stroke (1.6/100 patient-years), heart failure (2.7/100 patient-years), and acute myocardial infarction (1.0/100 patient-years) were low. In subgroup analyses, worse survival was observed in female patients, older age groups, patients with comorbid heart failure, hypertension, diabetes, and those who did not undergo ablation during the index hospitalisation.

Conclusion

Nearly two-thirds of patients were surviving by 8-years following an AF/AFL hospitalisation with a low rate of re-hospitalisations for stroke, heart failure, and myocardial infarction. However, re-hospitalisations for recurrent atrial arrhythmia were common. Efforts to reduce re-hospitalisations, especially unplanned encounters, are required to improve patient outcomes.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): National Heart Foundation of Australia

Trends in complications and mortality following catheter ablation of atrial fibrillation: results from 22,582 ablations in Australia and New Zealand from 2010 to 2015

Background

Recent studies from the United States report rising rates of in-hospital complications and mortality following catheter ablation of atrial fibrillation (AF) but whether such a trend is observed in other populations is uncertain.

Purpose

To examine the trends in complications and mortality following AF ablations up to 30 days after discharge in Australia and New Zealand (ANZ) using nationwide data.

Methods

All patients ≥18y undergoing catheter ablation of AF from 2010–2015 were identified using hospitalisation data from all public and most private hospitals in ANZ. The primary endpoint was one or more procedural complications during the hospital stay or within 30 days of discharge. The secondary endpoints were mortality and other specific complications. Unadjusted trend was evaluated using Cochran-Armitage test while that of complications, adjusting for differences in other characteristics, was evaluated using multivariate logistic regression with the year of ablation modelled as a continuous variable. Results are reported as odd ratios (OR) and 95% confidence intervals (CI).

Results

A total of 22,582 AF ablations were included (mean age 62.2±11.6y, 29.1% female, 94.4% elective procedures). The number of ablations increased by 26.4% during the study period (3,097 in 2010 to 3,915 in 2015). Rates of heart failure (8.98% to 10.09%, p for trend=0.010), diabetes (4.52% to 12.46%, p<0.001), chronic kidney disease (2.36% to 4.29%, p<0.001) significantly increased over time but that of hypertension decreased (15.27% to 12.29%, p<0.001). The incidence of overall complications (6.55% in 2010 to 6.67% in 2015, OR 0.99, 95% CI 0.96–1.03) was unchanged during the study period (Figure 1A). When individual complications were considered, mortality rate was low with no statistically significant change with time (0.19% to 0.15%, OR 1.03, 95% CI 0.84–1.28) (Figure 1A) while the rate of acute kidney injury (0.23% to 0.51%, OR 1.17, 95% CI 1.02–1.34) increased and that of venous thromboembolism (0.16% to 0.0%, OR 0.71, 95% CI 0.54–0.94) decreased (Figure 1B). Though the incidence of any bleeding (4.49% to 3.98%, OR 0.97, 95% CI 0.93–1.01) was unchanged, that of major bleeding requiring blood transfusion (0.97% to 0.64%, OR 0.87, 95% CI 0.79–0.96) declined significantly (Figure 1B). No significant trend was observed in other complications or when in-hospital (5.13% to 5.21%, OR 1.00, 95% CI 0.97–1.04) and post-discharge (1.55% to 1.63%, OR 0.97, 95% CI 0.91–1.03) complications were separately evaluated.

Conclusions

Though more patients with heart failure, diabetes and chronic kidney disease underwent catheter ablation of AF over time in ANZ, the overall complication rate was unchanged with a significant decrease in the incidences of major bleeding and venous thromboembolism. However, rate of acute kidney injury nearly doubled, and this could be a potential target for efforts to further improve procedural safety.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): The National Heart Foundation of Australia

Differences between public and private hospitals in complications following catheter ablation of atrial fibrillation: a cohort study in Australia

Background

Comparing outcomes of care between public and private hospitals is critical to inform patients and improve care quality.

Purpose

To compare complication rates following catheter ablation of atrial fibrillation (AF) up to 30-days post discharge between public and private hospitals.

Methods

We included patients ≥18 years who underwent AF ablation in the Australian states of New South Wales, Queensland, Victoria, and Western Australia from 2010–2015. The primary outcome was the occurrence of any complication up to 30-days after discharge. The association between provider type and the risk of complications was examined using logistic regression with inverse probability of treatment weighting (IPTW) propensity scores to account for differences in measured confounders. The minimum strength of association required for an unmeasured confounder to nullify any observed association was estimated using the E value.

Results

We identified 18,074 AF ablations during the study period (mean age 62.3±11.4y, 28.8% female, 78.4% performed in private hospitals). Patients ablated at public hospitals were younger (59.3 vs. 63.1y, p<0.001) but had higher rates of heart failure (10.3% vs. 7.7%, p<0.001), diabetes (10.9% vs. 7.9%, p<0.001), chronic kidney disease (4.9% vs. 2.2%, p<0.001), and chronic lung diseases (4.2% vs. 3.6%, p=0.046) than those at private hospitals. The unadjusted rate of complications was higher in publics hospitals compared with private ones (7.59% vs. 5.26%, p<0.001). After IPTW, there was good covariate balance with a median standardised difference of 0.006 (range 0.0–0.032) and the adjusted difference in procedural complication rates between two sectors remained significant (OR=1.46, 95% CI 1.24–1.73). The difference was mainly driven by an elevated risk of complications requiring cardiac surgery (OR=3.85, 95% CI 1.35–10.98), acute kidney injury (OR=2.95, 95% CI 1.12–7.74), cardiorespiratory failure (OR=2.69, 95% CI 1.19–6.04), postprocedural infection (OR=2.50, 95% CI 1.28–4.86), and bleeding (OR=1.26, 95% CI 1.02–1.56) (Figure 1). The disparity in the complication rates persisted when in-hospital (OR=1.41, 95% CI 1.16–1.70) and post-discharge (OR=1.52, 95% CI 1.12–2.07) complications were analysed separately. The E value was 1.79, suggesting that the disparity might plausibly be explained by unmeasured confounders.

Conclusion

AF ablation at a public hospital was associated with a 46% higher risk of complications compared with ablation at a private hospital, mainly driven by a higher risk of complications requiring cardiac surgery, acute kidney injury, cardiorespiratory failure, infections, and bleeding. The disparity could be due to differences in care quality between two sectors or explained by unmeasured confounders such as higher procedural complexity in public hospitals.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): The National Heart Foundation of Australia

Long-term clinical outcomes of troponin-positive chest pain and unobstructed coronary arteries assessed by cardiovascular magnetic resonance imaging

Background and introduction

Troponin-positive chest pain with unobstructed coronary arteries is a distinct entity with different pathophysiological causes. We have previously reported on the incremental diagnostic capability of cardiovascular magnetic resonance (CMR) in this cohort. However, there is paucity of literature on the long-term clinical outcomes of these patients assessed with CMR.

Objectives

Using the unique cohort of patients previously studied, we sought to assess the long-term clinical outcomes in patients with troponin-positive chest pain and unobstructed coronary arteries, as graded by their acute CMR presentation.

Methods

A total of 122 consecutive patients with troponin-positive chest pain and unobstructed coronary arteries undergoing CMR assessment during the acute admission (2010–2014) were studied. The primary endpoint was major adverse cardiac event (MACE), defined as a composite of all-cause mortality and cardiovascular readmissions (heart failure, acute myocardial infarction [AMI], atrial or ventricular arrhythmia and stroke). Patients were grouped into 4 categories based on their initial CMR findings: AMI, acute myocarditis, Takotsubo cardiomyopathy and normal CMR.

Results

The mean age of the study cohort was 55.6±16.5 years and 56.5% were women. CMR (performed at a median of 6 days from presentation) provided a diagnosis in 87% of the patients (38% myocarditis, 28% Takotsubo cardiomyopathy and 21% AMI). Patients with a diagnosis of AMI were prescribed guideline recommended medical therapy. Over a median follow-up of 2524 days (6.9 years), 32 (26.2%) patients experienced a MACE. The all-cause mortality was 2.5%. The most common indication for cardiovascular readmissions in this cohort was heart failure (12.3%) and AMI (9%). In multivariate analysis, a CMR diagnosis of AMI (hazard ratio = 2.6; 95% confidence interval = 1.2, 5.7; p=0.019) and peak troponin (hazard ratio = 1.0003; 95% confidence interval = 1.00003, 1.0006; p=0.028) were significantly associated with MACE after adjusting for age and gender. In addition, CMR diagnosis of AMI was significantly associated with a lower event-free survival rate compared with a diagnosis of non-AMI (adjusted hazard ratio = 2.57, p=0.019) (Figure).

Conclusions

The long-term prognosis of patients with troponin-positive chest pain and unobstructed coronary arteries is not benign. CMR diagnosis of AMI is a significant predictor of MACE even in the absence of significant coronary artery obstruction and despite guideline recommended post AMI therapy.

Figure 1

Funding Acknowledgement

Type of funding source: None

Seasonality of birth patterns in an Australian cohort of patients with biopsy-confirmed idiopathic inflammatory myopathy

Environmental exposures in the foetal period may predispose to autoimmunity. Aim of this study is to investigate whether seasonality in birth patterns exists in idiopathic inflammatory myopathies (IIM). We used Stata (StataCorp USA, version 13.0) and the user-written routine command 'circsummarise' to assess birth seasonality among South Australian patients with histologically confirmed IIM subsequent to 1980 using their date of birth. There was no evidence for a seasonal birth pattern among IIM patients overall (n = 568), however there were some ethnic variances in birth patterns among non-Caucasian patients. There was evidence for birth seasonality among both Aboriginal (mean = 7 July, Rayleigh P = 0.04) and Asian patients (mean = 12 August, Rayleigh P-value = 0.038). Non-Caucasians born in the third quarter of the calendar year may have an increased risk of developing IIM. Large international studies of IIM patients of diverse ethnicity are required to clarify the role of perinatal exposures in disease susceptibility.

Successful treatment of post-transplant lymphoproliferative disorder in autologous blood stem cell transplant recipients

We report three cases of post-transplant lymphoproliferative disorder (PTLD) in the context of autologous stem cell transplantation (ASCT) for multiple myeloma (MM) and non-Hodgkin's lymphoma. The first two cases received ASCT for MM, one with a CD34-selected autograft and the other with an unmanipulated autograft. Both these cases of PTLD achieved a complete response following treatment with IVIG, gancyclovir, solumedrol and interferon (IFN). The third case received ASCT with an unmanipulated autograft for relapsed angioimmunoblastic lymphoma. He also achieved a complete response but only after rituximab was added to IVIG, gancyclovir, solumedrol and IFN. None of these patients experienced a relapse of their PTLD with follow-up ranging from 1.5 to 5 years. These cases highlight the importance of considering PTLD in the differential diagnosis of lymphadenopathy and fever post ASCT. They also demonstrate the possibility of durable complete remission of post-ASCT PTLD following antiviral and immune modulating therapy.

Identification of a novel HLA-B*07 allele--HLA-B*0726

We describe here, the identification of a novel HLA-B*07 allele named HLA-B*0726. This allele was found in a Caucasian individual serologically typed as HLA-B7, B35. Novel DNA probe patterns for the HLA-B*07 allele were found using HLA-B specific reverse sequence-specific oligonucleotide probe (SSOP) and sequence-specific primer (SSP) typing. DNA sequencing demonstrated the presence of a new HLA-B*07 sequence variant encoding a single nucleotide substitution from a G to a T at nucleotide 539 in exon 3. This results in an amino acid substitution from arginine to leucine at residue 156 in exon 3.

Regulation of leukocyte adhesion to heart by the tripeptides feG and feG(NH2)

The role of the D-isomeric form of the salivary gland tripeptide FEG (feG) and its carboxyl-amidated derivative, feG(NH2), in regulating leukocyte adherence to nonfixed atrial slices from Sprague-Dawley rats was examined under static conditions. Optimal binding of the leukocytes was seen if the leukocytes were treated with platelet activating factor (PAF; 10(-9)M). The increased adherence of PAF-treated peripheral blood leukocytes was totally inhibited by both feG and feG(NH2) (10-9M), as well as by antibodies against CD18 and CD49d. In contrast, the binding of peritoneal leukocytes was blocked only by CD49d antibody. Circulating leukocytes obtained from lipopolysaccharide (LPS) treated (2 mg/kg ip) rats did not bind to atrial slices obtained from normal hearts, but readily bound to atrial slices obtained from LPS-treated rats. This leukocyte binding was inhibited by in vivo feG treatment (100 microg/kg ip, 24 h before harvest) or by treating the isolated cells with feG (10(-9)M). The amidated peptide feG(NH2) reduced neutrophil accumulation in the atrium elicited by ip injection of LPS, whereas feG was ineffective. The reduction in neutrophil infiltration into the myocardium by feG(NH2) and the prevention of leukocyte interaction with myocytes seen with both feG and feG(NH2) probably results in hindered leukocyte migration in the inflamed heart, resulting in less tissue damage. The inhibition by these tripeptides on neutrophil adhesion to myocytes suggests that salivary glands hormones regulate the severity of cardiac inflammation.