P6562The relationship between serum potassium concentrations and electrocardiographic characteristics in 163,547 individuals from primary care

Aims

Potassium disturbances are common and associated with increased morbidity and mortality, even in patients without prior cardiovascular disease. We examined six electrocardiographic (ECG) measures and their association to serum potassium levels.

Methods and results

From the Copenhagen General Practitioners' Laboratory, we identified 163,547 individuals aged ≥16 years with a first available ECG and a concomitant serum potassium measurement during 2001–2011. Restricted cubic splines curves showed a non-linear relationship between potassium and the Fridericia corrected QT (QTcF) interval, T-wave amplitude, morphology combination score (MCS), PR interval, P-wave amplitude and duration. Therefore, potassium was stratified in two intervals K: 2.0–4.1 mmol/L and 4.2–6.0 mmol/L for further analyses. Within the low potassium range, we observed: QTcF was 12.5 ms longer for each mmol/L decrease in potassium (p<0.0001); T-wave amplitude was 55.1 μV lower for each mmol/L decrease in potassium (p<0.0001); and MCS was 0.09 higher per mmol/L decrease in potassium (p<0.001). Moreover, P-wave duration and PR interval were prolonged by 3.1 and 3.3 ms for each mmol/L decrease in potassium (p<0.0001), respectively. Within the lowest potassium range (2.0–4.1 mmol/L) P-wave amplitude was 10.7 μV higher for each mmol/L decrease in potassium (p<0.0001). Within the high potassium range associations with the above-mentioned ECG parameters were much weaker.

Restricted cubic splines on adjusted lin

Conclusion

The association of potassium with six commonly measured ECG parameters was non-linear. Strong associations between ECG abnormalities and potassium were seen among individuals with lower potassium levels (≤4.1 mmol/L).

Acknowledgement/Funding

None

Next-generation sequencing of 34 genes in sudden unexplained death victims in forensics and in patients with channelopathic cardiac diseases

Sudden cardiac death (SCD) is responsible for a large proportion of sudden deaths in young individuals. In forensic medicine, many cases remain unexplained after routine postmortem autopsy and conventional investigations. These cases are called sudden unexplained deaths (SUD). Genetic testing has been suggested useful in forensic medicine, although in general with a significantly lower success rate compared to the clinical setting. The purpose of the study was to estimate the frequency of pathogenic variants in the genes most frequently associated with SCD in SUD cases and compare the frequency to that in patients with inherited cardiac channelopathies. Fifteen forensic SUD cases and 29 patients with channelopathies were investigated. DNA from 34 of the genes most frequently associated with SCD were captured using NimbleGen SeqCap EZ library build and were sequenced with next-generation sequencing (NGS) on an Illumina MiSeq. Likely pathogenic variants were identified in three out of 15 (20%) forensic SUD cases compared to 12 out of 29 (41%) patients with channelopathies. The difference was not statistically significant (p = 0.1). Additionally, two larger deletions of entire exons were identified in two of the patients (7%). The frequency of likely pathogenic variants was >2-fold higher in the clinical setting as compared to SUD cases. However, the demonstration of likely pathogenic variants in three out of 15 forensic SUD cases indicates that NGS investigations will contribute to the clinical investigations. Hence, this has the potential to increase the diagnostic rate significantly in the forensic as well as in the clinical setting.

High prevalence of genetic variants previously associated with Brugada syndrome in new exome data

More than 300 variants in 12 genes have been associated with Brugada syndrome (BrS) which has a prevalence ranging between 1:2000 and 1:100,000. Until recently, there has been little knowledge regarding the distribution of genetic variations in the general population. This problem was partly solved, when exome data from the NHLI GO Exome Sequencing Project (ESP) was published. In this study, we aimed to report the prevalence of previously BrS-associated variants in the ESP population. We performed a search in ESP for variants previously associated with BrS. In addition, four variants in ESP were genotyped in a second Danish control population (n = 536) with available electrocardiograms. In ESP, we identified 38 of 355 (10%) variants, distributed on 272 heterozygote carriers and two homozygote carriers. The genes investigated were on average screened in 6258 individuals. This corresponds to a surprisingly high genotype prevalence of 1:23 (274:6258). Genotyping the four common ESP-derived variants CACNA2D1 S709N, SCN5A F2004L, CACNB2 S143F, and CACNB2 T450I in the Danish controls, we found a genotype prevalence comparable with that found in ESP. We suggest that exome data are used in research, as an additive tool to predict the pathogenicity of variants in patients suspected for BrS.

A nationwide, retrospective analysis of symptoms, comorbidities, medical care and autopsy findings in cases of fatal pulmonary embolism in younger patients

OBJECTIVE

Our objective was to provide a comprehensive description of fatal pulmonary embolism (PE) in younger persons. Specifically, we recorded information on symptoms, comorbidity, medical contact, if this had been required, and subsequent autopsy findings.

METHODS

We reviewed all death certificates from persons aged 0-35 years who had died between 1 January 2000 and 31 December 2006, and retrospectively identified all cases of fatal PE. Additional information was retrieved from the National Patient Registry, autopsy reports, and clinical charts.

RESULTS

Sixty-one cases of fatal PE were included; 38% of these were in males. The median age was 29 years. The predominant symptoms were dyspnea, syncope, leg pains, and chest pains. Sixty-three per cent of patients reportedly experienced symptoms for days, weeks, or months. More than half of the patients had sought medical care, and at the time of medical evaluation the majority of the patients were not hemodynamically compromised. In 21% cases, the correct diagnosis was reached before death; however, in only 5% of cases was this accomplished before clinical deterioration. Furthermore, clinical history and subsequent postmortem examinations showed that approximately half of younger persons dying from PE were otherwise healthy, and in no case was occult cancer diagnosed.

CONCLUSIONS

Our data show that a substantial proportion of younger victims of fatal PE had experienced symptoms for an extended period of time. Furthermore, the correct diagnosis remained elusive in the majority of cases, even though approximately half of the subjects had sought medical evaluation for symptoms that, in retrospect, were most likely caused by a venothrombotic event.