Perioperative Atrial Fibrillation and One-year Clinical Outcomes in Patients Following Major Emergency Abdominal Surgery

The prevalence and impact of perioperative atrial fibrillation (AF) during an admission for major emergency abdominal surgery are sparsely examined. Therefore, this study aimed to compare the 30-day and 1-year outcomes (AF-related hospitalization, stroke, and all-cause mortality) in patients with and without perioperative AF to their major emergency abdominal surgery. All patients without a history of AF who underwent major emergency abdominal surgery from 2000 to 2019 and discharged alive were identified using Danish nationwide registries. Patients with and without perioperative AF (defined as new-onset AF during the index hospitalization) were matched 1:4 on age, gender, year of surgery, and type of surgery. The cumulative incidences and hazard ratios of outcomes were assessed using a multivariable Cox regression analysis comparing patients with and without perioperative AF. A total of 2% of patients were diagnosed with perioperative AF. The matched cohort comprised 792 and 3,168 patients with and without perioperative AF, respectively (median age 78 years [twenty-fifth to seventy-fifth percentile 70 to 83 years]; 43% men). Cumulative incidences of AF-related hospitalizations, stroke, and mortality 1 year after discharge were 30% versus 3.4%, 3.4% versus 2.7%, and 35% versus 22% in patients with and without perioperative AF, respectively. The 30-day outcomes were similarly elevated among patients with perioperative AF. Perioperative AF during an admission for major emergency abdominal surgery was associated with higher 30-day and 1-year rates of AF-related hospitalization and mortality and similar rates of stroke. These findings suggest that perioperative AF is a prognostic marker of increased morbidity and mortality in relation to major emergency abdominal surgery and warrants further investigation.

Diuretic treatment before and after transcatheter aortic valve implantation: A Danish nationwide study

OBJECTIVES

We examined loop diuretic treatment before and 1-year after transcatheter aortic valve implantation (TAVI), as a proxy for changes in symptom severity and secondly assessed how changes in loop diuretics related to mortality risk.

BACKGROUND

Randomized clinical trials suggest that approximately one third of patients undergoing TAVI do not achieve symptom relief, but "all-comer" data are lacking.

METHODS

Using Danish nationwide registries, we identified all citizens, who underwent TAVI from 2008 to 2019 and were alive at 1-year post-discharge. Loop diuretic treatment pre-TAVI and at 1-year post-TAVI were assessed and grouped as receiving 1) no-loop diuretics; 2) low: 1-40 mg of furosemide (or equivalent bumetanide) daily; 3) intermediate: 41-120 mg of furosemide daily; or 4) high: >120 mg furosemide daily.

RESULTS

Among the 4431 patients undergoing TAVI, 2173 (49%) patients were not treated with loop diuretics at the time of TAVI, 918 (21%) had low-loop diuretics, 881 (20%) had intermediate-loop diuretics, and 459 (10%) had high-loop diuretics. At 1-year post-TAVI, 893 (20%) patients had increased, 1010 (23%) had reduced, and 2528 (57%) had unchanged loop diuretic treatment. The cumulative 5-year risk of death in patients surviving one year, was 61% (95% CI: 56.4% to 65.3%) in patients with increased and 47% (95% CI: 44.9% to 49.9%) in patients with reduced/unchanged loop diuretic treatment, respectively. In multivariable Cox proportional hazard analysis, increased loop diuretic treatment was associated with a higher risk of death compared with reduced/unchanged loop diuretic treatment (Hazard ratio: 1.4; 95% CI: 1.22 to 1.52).

CONCLUSIONS

Among patients undergoing TAVI, surviving one year, one fifth of patients had increased loop diuretic treatment, and a little over one fifth had reduced loop diuretic treatment 1-year post-procedure. In patients with increased diuretic treatment, the risk of death was higher compared to those with reduced/unchanged loop diuretic treatment.

Association between hemodialysis and patient characteristics, microbiological etiology, cardiac surgery, and mortality in patients with infective endocarditis: a nationwide study

Background

Hemodialysis and infective endocarditis are both associated with poor patient outcome. However, despite high mortality rates for each disease entity, little attention is given to patients on hemodialysis who develop infective endocarditis.

Purpose

To examine patient characteristics, microbiological etiology, cardiac surgery, and outcome among patients on hemodialysis with infective endocarditis compared with patients with infective endocarditis without hemodialysis treatment.

Methods

With Danish nationwide registries, we identified patients with infective endocarditis between 2010–2018 and linked them to microbiological data from a nationwide microbiological registry with complete blood culture data. We included patients in the hemodialysis group if they received hemodialysis treatment within 6 months prior to their first-time infective endocarditis admission. Patients not meeting this criteria were put in the non-hemodialysis group. We used Kaplan-Meier estimates for difference in mortality and Cox regression for adjusted analysis.

Results

We included 4,106 patients with infective endocarditis of which 265 (6.5%) patients were also in hemodialysis treatment (66.8% men). Patients on hemodialysis were younger (median age 66 years [IQR=54.2–74.9] vs. 72.3 years [IQR=62.3–80.4]) and had a higher burden of comorbidities including hypertension (68.7 vs. 56.9%), diabetes (47.2% vs. 18.8%), and ischemic heart disease (41.1% vs. 32.2%) compared to patients without hemodialysis treatment, all p-values <0.01. Cardiac surgery was less frequently performed in patients in the hemodialysis group than in the non-hemodialysis group (11.9% vs. 19.4%, respectively, p<0.001) and Staphylococcus aureus was more frequently the microbiological etiology of infective endocarditis in the hemodialysis group than in the non-hemodialysis group (57.0% vs. 25.3%, respectively, p<0.0001). No statistically significant difference for in-hospital mortality was found. Figure 1 shows difference in mortality between the two groups. 1- and 5-year mortality were significantly higher in the hemodialysis group than in the non-hemodialysis group (34.3% vs. 17.2% and 50.5% vs. 33.9%, respectively, p<0.00001) and in adjusted analysis hemodialysis was associated with higher 1- and 5-year mortality (hazard ratio of 2.41, 95% CI 1.85–3.13 and 2.50, 95% CI 2.05–3.05, respectively), as compared with patients in the non-hemodialysis group.

Conclusion

Patients on hemodialysis with infective endocarditis are younger, sicker and have Staphylococcus aureus as causing agent more than twice as often as patients with infective endocarditis without hemodialysis treatment. This patient group have a higher mortality and by 5 years, 75% of patients in our hemodialysis group were dead.

Funding Acknowledgement

Type of funding sources: None.

Incidence of atrial fibrillation/flutter, one-year re-admission rates, and practice patterns among patients <65 years of age: a Danish nationwide study

Background/Introduction

The general atrial fibrillation/flutter (AF) population is well explored and described, but there is sparse data on temporal changes in the incidence, AF-readmission rates, and practice patterns in patients with AF under 65 years of age from unselected cohorts.

Purpose

To investigate temporal changes, AF readmission rates, and practice patterns in patients under 65 years of age with first-time AF diagnosed between 2000–2018.

Methods

Using Danish nationwide registries, we identified patients >18 years and <65 years with a first-time AF-diagnosis from 2000–2018. The cohort was categorized according to calendar periods; 2000–2002, 2003–2006, 2007–2010, 2011–2014 and 2015–2018. Incidence rate (IR) of AF per 100,000 person years (PY), AF-readmission, and practice patterns of medical treatment, electrical cardioversion, and catheter ablation was investigated in the first year following AF-diagnosis.

Results

In this study 60,917 patients were included; 8,150 patients (13.4%) in 2000–2002, 11,898 (19.5%) in 2003–2006, 13,560 (22.3%) in 2007–2010, 14,167 (23.3%) in 2011–2014 and 13,142 (21.6%) in 2015–2018. No major differences were seen in patient characteristics according to calendar period. A stepwise increase, as seen in the Table, in the crude IR of AF per 100,000 PY was observed across calendar periods, except for 2015–2018 (Crude IR [95% CI]: 2000–2002: 78.7 [77.0; 80.4], 2003–2006: 86.3 [84.7; 87.8], 2007–2010: 97.9 [96.3; 99.6], 2011–2014: 102.3 [100.7; 104.0], 2015–2018: 93.6 [92.0; 95.2], while no difference in AF readmission was identified (AF-readmissions: 2000–2002: 32.7%, 2003–2006: 31.1%, 2007–2010: 32.2%, 2011–2014: 32.1% and 2015–2018: 31.7%), as seen in the Figure, right panel. In the first year following AF-diagnosis, the cumulative incidence of catheter ablation increased stepwise from 1.2% in 2000–2002 to 7.6% in 2015–2018 and electrical cardioversion from 2.0% in 2000–2002 to 8.7% in 2015–2018 (Figure, left panel). Treatment with oral anticoagulant therapy (OAC) increased from 28.5% in 2000–2002 to 47.8% in 2015–2018, while there was no change in treatment with rhythm or rate medication therapy.

Conclusion

From 2000–2018, we found an increase in the incidence of atrial fibrillation/flutter (AF) in patients <65 years from 78.7/100,000 person years (PY) to 93.6/100,000 PY and an increase in the use of catheter ablation, electrical cardioversion and OAC in the first year following first-time AF-diagnosis. AF readmission rates were stable over calendar periods.

Funding Acknowledgement

Type of funding sources: None.

Heart failure hospitalizations and diuretic use before and after first-time pulmonary vein isolation ablation for atrial fibrillation among patients with heart failure

Background

Small randomized clinical trials have found that patients with heart failure (HF) and atrial fibrillation (AF) randomized to an ablation strategy for AF experienced improved cardiovascular outcomes. We examined the relation in routine clinical practice.

Purpose

We aimed to assess if first-time pulmonary vein isolation ablation (PVI) for AF among patients with HF was associated with decrease in HF hospital admissions rates and furosemide dosage in the year after PVI compared with the year before.

Methods

We identified patients with HF and available left ventricular ejection fraction (LVEF) treated with a first-time PVI using the Danish Ablation Registry, and alive at 1-year follow-up. Patient comorbidities and concomitant pharmacotherapy (including furosemide dosage and HF hospital admissions) were identified utilizing Danish nationwide registries. For inclusion, patients were required to have been diagnosed with HF in an in- or outpatient setting <10 years of first-time PVI or have a LVEF at the time of PVI ≤45%. Patients were grouped according to LVEF at time of PVI: ≤35%, 36–45%, and >45%. For comparison of HF hospital admission and furosemide usage before and after PVI, McNemars test were used. Wilcox signed-rank test were used to test difference in furosemide dosage before and after PVI.

Results

We identified 668/3450 patients with HF treated with first-time PVI for AF between 2010–2017 (median age 62 years [Q1,Q3=56,69 years], 81% male, and median LVEF 45% [Q1,Q3=40,60%]). Of these, 13 patients (2%) died during one-year follow-up. Overall, 36% of patients with HF had one or more HF hospital admissions the year before PVI compared with 7% in the year after PVI (p<0.0001) (Figure 1). Patients with LVEF ≤35% had the highest proportion of HF hospital admissions the year before PVI (53%) and was reduced more than 4-fold (13%) in the year after first-time PVI, with consistent findings in all LVEF groups (Figure 1). At the time of PVI, 36% of patients with HF were treated with furosemide compared with 30% in the year after PVI (p<0.0001) (Figure 2). Moreover, we identified significant reductions in furosemide dose in the year after PVI compared with the year before (median dose 60 mg [Q1,Q3=30,80 mg] and 20 mg [Q1,Q3=0,60 mg], respectively, p=0.001). Here, reductions in furosemide requirements were consistent across LVEF subgroups.

Conclusion

Patients with HF treated with a first-time PVI strategy for AF had a 5-fold decrease in HF hospital admissions in the following year compared with the year before PVI. Among patients treated with furosemide at time of PVI, significant reductions in dose one year after PVI was identified but also significant reductions in proportion of patients requiring any furosemide at all.

Funding Acknowledgement

Type of funding sources: None.

Risk of lead explantation after first-time implantation of cardiac implantable electronic device as a function of comorbidity: a nationwide study

Background

The benefit of cardiac implantable electronic devices (CIEDs) is challenged by the risk of procedure-related complications and lead explantation. Whether patient comorbidity burden is associated with risk of lead explantation <6 months of implantation is unknown.

Purpose

We assessed the risk of lead explantation and its association with comorbidity burden within 6 months after first-time CIED implantation.

Methods

The study population comprised patients ≥18 years old with first-time CIED implantation (i.e., pacemaker [PM], implantable cardioverter defibrillator [ICD], and cardiac resynchronisation therapy with defibrillator [CRT-D] or without [CRT-P]) using Danish nationwide registries including the Danish Pacemaker and ICD registry (1 January 2000 to 30 June 2018). Patients were followed from their first-time CIED implantation and 6 months forward. Patient comorbidity burden was categorised in four groups according to the Charlson Comorbidity Index (CCI) score: 0 (none), 1–2 (mild), 3–4 (moderate), and ≥5 (severe). Multivariable cause-specific Cox regression was performed to assess risk of lead explantation according to comorbidity burden, with death as competing risk. Comorbidity burden was adjusted for sex, age, type of CIED, and body mass index categories.

Results

We identified 73,491 patients with first-time CIED implantation including 55,733 (75.8%) with PM, 11,351 (15.5%) with ICD, 2,989 (4.1%) with CRT-P, and 3,418 (4.7%) with CRT-D. In total, 1,049 (1.4%) patients underwent lead explantation. The median age of the study population was 75.1 years [25th-75th percentile 66.2–82.5 years], and 62.1% were male. Patients undergoing lead explantation had higher median CCI score, compared with those not undergoing lead explantation (2 [1–3] and 1 [0–3], respectively). The median age and distribution of sex were similar in both groups. In the multivariable Cox regression model (Figure 1), an increase in patient comorbidity burden was associated with higher hazard ratio [HR] of lead explantation, compared with CCI score 0 (CCI score 1–2: HR=1.38 [95% confidence interval [CI]: 1.12–1.69], CCI score 3–4: HR=1.61 [95% CI: 1.28–2.03], and CCI score ≥5: HR=1.60 [95% CI: 1.25–2.05]).

Conclusion

Risk of lead explantation within 6 months after first-time implantation of cardiac implantable electronic device was 1.4% and associated with higher comorbidity burden.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Independent Research Fund Denmark

Diuretic use before and after transcatheter aortic valve implantation: a nationwide study

Background

Transcatheter aortic valve implantation (TAVI) is the new standard of care in patients of older age with symptomatic severe aortic stenosis, and these patients often depend upon diuretics for symptom relief. Randomized clinical trials suggest that approximately one third of patients undergoing TAVI do not achieve symptom relief. Furthermore, some patients have more symptoms after intervention, but “real-life” data are lacking.

Purpose

We examined use of diuretic therapy before and one year after TAVI in order to identify the proportion of patients who had intensification of diuretic treatment after intervention as a proxy for more symptoms. We also examined baseline factors associated with an intensification event.

Methods

Using Danish nationwide registries, we identified all Danish citizens who underwent TAVI from January 1, 2008 to December 31, 2019 and were alive one year after the intervention. Diuretic use pre-TAVI and 1-year post-TAVI (based on prescription fillings) was divided into the following groups: 1) no use; 2) low diuretic use: 1–40 mg of furosemide (or equivalent bumetanide); 3) intermediate diuretic use: 41–120 mg of furosemide; and 4) high diuretic use: >120 mg furosemide. Diuretic intensification was defined as a change from one pre-TAVI diuretic group to a higher post-TAVI diuretic group. Factors associated with intensified diuretic treatment was examined with logistic regression. In this analysis of intensification, only patients who could potentially have an intensification event were included (i.e., no diuretic use, low diuretic use, or intermediate diuretic use groups).

Results

A total of 3,978 patients (median age 81 [interquartile range 77–85]; 54% men) undergoing TAVI were identified. Pre-TAVI, 1,279 (32%) had no diuretic use, 1,818 (46%) had low diuretic use and 881 (22%) had intermediate diuretic use. Overall, patients with pre-TAVI intermediate diuretic use had a greater burden of cardiovascular and non-cardiovascular comorbidities (higher prevalence of heart failure, atrial fibrillation, chronic kidney disease and diabetes) compared with those with no or low diuretic use. The distribution of age and sex was similar between diuretic groups. One year post-TAVI, 1,406 (35.3%) had no diuretic use, 1,635 (41.1%) had low diuretic use, 654 (16.4%) had intermediate diuretic use and 283 (7.1%) had high diuretic use (Figure 1). Overall, 1,077 (27%) patients had intensification of diuretic treatment one year after undergoing TAVI. Ischemic heart disease and chronic renal failure were associated with an intensification event (odds ratio 1.23 [95% CI 1.05–1.23] and 1.46 [95% CI 1.10–1.94], respectively).

Conclusion

Among patients undergoing TAVI not treated with high-dose diuretics at time of intervention, approximately 1 out of 4 patients had intensification of diuretic treatment one year after intervention. Ischemic heart disease and chronic renal failure were associated with intensification.

Funding Acknowledgement

Type of funding sources: None.

Severity of chronic obstructive pulmonary disease and risk of one-year mortality after first-time implantation of implantable cardioverter defibrillator: a nationwide study

Background

Current guidelines, on implantable cardioverter defibrillator (ICD), recommend implantation in patients with an expected survival beyond one year. Information on risk of all-cause mortality among ICD recipients with chronic obstructive pulmonary disease (COPD) according to severity of COPD is lacking.

Purpose

We examined the association between the severity of COPD and risk of all-cause mortality within one year after first-time ICD implantation.

Methods

We identified patients ≥18 years old undergoing first-time ICD implantation with COPD using Danish nationwide registries (1 January 2000 to 31 December 2018). All patients were eligible for one-year follow-up. We used concomitant COPD-related pharmacotherapy six months prior to ICD implantation and COPD hospitalisations one year prior to ICD implantation to determine severity of COPD from mild to very severe according to Table 1. Multivariable Cox regression was used to assess risk of one-year all-cause mortality according to severity of COPD. Severity of COPD was adjusted for sex, age, year of implantation, primary prevention, type of ICD, history of atrial fibrillation, stroke, peripheral artery disease, diabetes, cancer, chronic renal disease, and dialysis.

Results

The study population included 1,536 patients with first-time ICD and COPD. The median age was 69.5 years [25th-75th percentile 63.5–74.3 years], and the majority of patients were males (79.4%). Of these, 896 (58.3%) received an ICD for primary prevention, and 485 (31.6%) had cardiac resynchronisation therapy device with defibrillator (CRT-D). In total, 1,348 (87.8%) patients were diagnosed with heart failure. Patients were grouped according to severity of COPD from mild to very severe: Group 1 (N=666), Group 2 (N=72), Group 3 (N=149), Group 4 (N=445), and Group 5 (N=204). Overall, 154/1,536 (10.0%) ICD recipients with COPD died within one year after first-time ICD implantation. No difference in sex and comorbidities was identified according to the five groups of COPD severity. However, ICD recipients with mild intermittent COPD (Group 1) were the youngest (68.3 years [61.8–73.0 years]). According to our multivariable cox regression in Figure 1, patients with very severe COPD (Group 5) were associated with increased risk of all-cause mortality within one year after first-time ICD implantation (adjusted hazard ratio [HR] 1.90 [95% confidence interval [CI]: 1.21–2.98]), compared with mild intermittent COPD (Group 1). The most common causes of death within one year after ICD implantation were attributed to cardiovascular diseases 95/154 (61.7%), respiratory diseases 15/154 (9.7%), and endocrine disorders 12/154 (7.8%).

Conclusion

In this nationwide study, very severe chronic obstructive pulmonary disease was associated with increased risk of all-cause mortality within one year after first-time implantation of implantable cardioverter defibrillator.

Funding Acknowledgement

Type of funding sources: Foundation. Main funding source(s): Independent Research Fund Denmark

Use of non-recommended drugs in Brugada Syndrome: a Danish nationwide cohort study

Funding Acknowledgements

Type of funding sources: None.

Background

To lower the risk of sudden cardiac death, patients with Brugada Syndrome (BrS) are recommended to avoid intake of drugs known to increase the risk of arrhythmias or the development of type-1 BrS ECG. However, information on adherence to these recommendations among patients with BrS is limited.

Purpose

To examine treatment with non-recommended drugs before and after diagnosis with BrS, risk factors of treatment with these drugs, and whether treatment was associated with a higher risk of hospitalization with ventricular arrhythmias or death.

Methods

All patients diagnosed with BrS in Denmark (1995-2018) with >12 months of follow-up were identified through nationwide registries using the ICD-10 diagnosis code DI472M (PPV 95.8%). Relevant BrS risk drugs were identified and grouped as drugs to "avoid" or "preferably avoid" in agreement with the likelihood of promoting arrhythmias and type-1 BrS ECG according to brugadadrugs.org(1) (accessed August 2021). Multiple logistic regression (adjusted for sex, age, year of diagnosis, and relevant comorbidities and drugs) was performed to identify factors associated with risk drug use during follow-up.

Results

We identified 270 patients with BrS. Median age at the time of diagnosis was 46.2 years [IQR 32.6-57.6], 70.4% were male. Before the time of diagnosis, 16 patients (5.9%) were treated with a drug to "avoid" or "preferably avoid" (n=5 and n=12, respectively). During a median follow-up of 79 months, 89 patients (33%) were treated with at least one BrS risk drug after the time of diagnosis (table). A total of 22 patients with BrS (8.1%) received ≥2 different drugs at any time during follow-up. There was no significant difference in proportions of patients receiving a risk drug the year prior to diagnosis (12.2%) compared to each of the five years following diagnosis (year 1-5, respectively: 12.2%; 9.7%; 12.3%; 13.6%; 13.5% (p>0.05 for all)).

Females had an odds ratio (OR) of 2.21 [95% CI 1.21-4.03] for use of risk drugs. Also associated with a greater likelihood of risk drug use after diagnosis were having a psychiatric disease at baseline (OR=4.80 [1.72-13.41]) and any use of a risk drug within 90 days prior to diagnosis (OR=8.54 [2.13-34.31]) (figure).

During follow-up, six patients were hospitalized for ventricular arrhythmias; none had redeemed a prescription of a risk drug. In total, 12 patients died, of which five (41.7%) had redeemed a prescription of one or more risk drugs within 50 days of death.

Conclusions

1/3 patients with BrS received a risk drug at any time point after diagnosis. No change in proportions of patients treated with risk drugs was identified after time of diagnosis. 5/12 patients that died during follow-up had redeemed a prescription of one or more risk drugs within 50 days of death. Female sex, any psychiatric diagnosis, and use of a non-recommended drug before diagnosis with BrS were associated with a greater likelihood of risk drug use after diagnosis.

Clinical characteristics and lipid lowering treatment of patients initiated on proprotein convertase subtilisin-kexin type 9 inhibitors: a nationwide cohort study

OBJECTIVES

Given the novelty of proprotein convertase subtilisin-kexin type 9 inhibitors (PCSK9i), little is known regarding overall implementation or clinical characteristics among patients who initiate treatment. We aimed to assess the total number of patients initiated on PCSK9i along with a description of the clinical characteristics and lipid lowering treatment (LLT) of such patients.

SETTING

A register-based descriptive cohort study of patients receiving a PCSK9i in the time period from 01 January 2016 to 31 March 2017 using a cross linkage between three nationwide Danish registers. Information regarding PCSK9i prescriptions, patient demographics, concurrent pharmacotherapy, comorbidities and previous coronary procedures was identified.

RESULTS

Overall, 137 patients initiated treatment with PCSK9i in the study period from 11 in the first quarter of 2016 to 40 in the first quarter of 2017. The majority had a history of ischaemic heart disease (IHD) (67.9%) with ischaemic stroke and diabetes mellitus being present in 7.3% and 16.8% of patients, respectively. All patients initiated on PCSK9i had been previously prescribed statin treatment with atorvastatin and simvastatin being most frequently prescribed in 53% and 36% of patients, respectively. The majority of patients had received both statins and ezetimibe (94.9%) and approximately half of these patients had also received bile acid sequestrant (45.3%). Clinical characteristics mainly differed in patients receiving triple LLT compared with patients not receiving triple LLT in the regards of heart failure.

CONCLUSION

Patients treated with PCSK9i were rare, characterised by having IHD and had received various and intensive conventional LLT prior to PCSK9i initiation in agreement with current international guidelines.

Genetic investigation of 100 heart genes in sudden unexplained death victims in a forensic setting

In forensic medicine, one-third of the sudden deaths remain unexplained after medico-legal autopsy. A major proportion of these sudden unexplained deaths (SUD) are considered to be caused by inherited cardiac diseases. Sudden cardiac death (SCD) may be the first manifestation of these diseases. The purpose of this study was to explore the yield of next-generation sequencing of genes associated with SCD in a cohort of SUD victims. We investigated 100 genes associated with cardiac diseases in 61 young (1-50 years) SUD cases. DNA was captured with the Haloplex target enrichment system and sequenced using an Illumina MiSeq. The identified genetic variants were evaluated and classified as likely, unknown or unlikely to have a functional effect. The criteria for this classification were based on the literature, databases, conservation and prediction of the effect of the variant. We found that 21 (34%) individuals carried variants with a likely functional effect. Ten (40%) of these variants were located in genes associated with cardiomyopathies and 15 (60%) of the variants in genes associated with cardiac channelopathies. Nineteen individuals carried variants with unknown functional effect. Our findings indicate that broad genetic investigation of SUD victims increases the diagnostic outcome, and the investigation should comprise genes involved in both cardiomyopathies and cardiac channelopathies.

Next-generation sequencing of 100 candidate genes in young victims of suspected sudden cardiac death with structural abnormalities of the heart

BACKGROUND

In sudden, unexpected, non-traumatic death in young individuals, structural abnormalities of the heart are frequently identified at autopsy. However, the findings may be unspecific and cause of death may remain unclear. A significant proportion of these cases are most likely caused by inherited cardiac diseases, and the cases are categorized as sudden cardiac death (SCD). The purpose of this study was to explore the added diagnostic value of genetic testing by next-generation sequencing (NGS) of a broad gene panel, as a supplement to the traditional forensic investigation in cases with non-diagnostic structural abnormalities of the heart.

METHODS AND RESULTS

We screened 72 suspected SCD cases (<50 years) using the HaloPlex Target Enrichment System (Agilent) and NGS (Illumina MiSeq) for 100 genes previously associated with inherited cardiomyopathies and channelopathies. Fifty-two cases had non-diagnostic structural cardiac abnormalities and 20 cases, diagnosed with a cardiomyopathy post-mortem (ARVC = 14, HCM = 6), served as comparators. Fifteen (29%) of the deceased individuals with non-diagnostic findings had variants with likely functional effects based on conservation, computational prediction, allele-frequency and supportive literature. The corresponding frequency in deceased individuals with cardiomyopathies was 35% (p = 0.8).

CONCLUSION

The broad genetic screening revealed variants with likely functional effects at similar high rates, i.e. in 29 and 35% of the suspected SCD cases with non-diagnostic and diagnostic cardiac abnormalities, respectively. Although the interpretation of broad NGS screening is challenging, it can support the forensic investigation and help the cardiologist's decision to offer counselling and clinical evaluation to relatives of young SCD victims.

Genetic investigations of sudden unexpected deaths in infancy using next-generation sequencing of 100 genes associated with cardiac diseases

Sudden infant death syndrome (SIDS) is the most frequent manner of post-perinatal death among infants. One of the suggested causes of the syndrome is inherited cardiac diseases, mainly channelopathies, that can trigger arrhythmias and sudden death. The purpose of this study was to investigate cases of sudden unexpected death in infancy (SUDI) for potential causative variants in 100 cardiac-associated genes. We investigated 47 SUDI cases of which 38 had previously been screened for variants in RYR2, KCNQ1, KCNH2 and SCN5A. Using the Haloplex Target Enrichment System (Agilent) and next-generation sequencing (NGS), the coding regions of 100 genes associated with inherited channelopathies and cardiomyopathies were captured and sequenced on the Illumina MiSeq platform. Sixteen (34%) of the SUDI cases had variants with likely functional effects, based on conservation, computational prediction and allele frequency, in one or more of the genes screened. The possible effects of the variants were not verified with family or functional studies. Eight (17%) of the SUDI cases had variants in genes affecting ion channel functions. The remaining eight cases had variants in genes associated with cardiomyopathies. In total, one third of the SUDI victims in a forensic setting had variants with likely functional effect that presumably contributed to the cause of death. The results support the assumption that channelopathies are important causes of SUDI. Thus, analysis of genes associated with cardiac diseases in SUDI victims is important in the forensic setting and a valuable supplement to the clinical investigation in all cases of sudden death.