Increased Beat-to-Beat Variability of T-Wave Heterogeneity Measured From Standard 12-Lead Electrocardiogram Is Associated With Sudden Cardiac Death: A Case-Control Study

Introduction

The prognostic significance of beat-to-beat variability of spatial heterogeneity of repolarization measured from standard 12-lead ECG is not well-understood.

Methods

We measured the short-term variability of repolarization parameters, such as T-wave heterogeneity in leads V4–V6 (TWH) and QT interval (QT), from five consecutive beats of previously recorded standard 12-lead ECG in 200 victims of unexpected sudden cardiac death (SCD) confirmed to be due to complicated atherosclerotic coronary artery disease (CAD) in medico-legal autopsy and 200 age- and sex-matched controls with angiographically confirmed CAD. The short-term variability of repolarization heterogeneity was defined as the standard deviation (SD) of the measured repolarization parameters. All ECGs were in sinus rhythm, and no premature ventricular contractions were included in the measured segment.

Results

TWH-SD and QT-SD were significantly higher in SCD victims than in subjects with CAD (6.9 ± 5.6 μV vs. 3.8 ± 2.6 μV, p = 1.8E-11; 8.3 ± 13.1 ms vs. 3.8 ± 7.1 ms, p = 0.00003, respectively). After adjusting in the multivariate clinical model with factors, such as diabetes, RR interval, and beta blocker medication, TWH-SD and QT-SD retained their significant power in discriminating between the victims of SCD and the patients with CAD (p = 0.00003, p = 0.006, respectively). TWH-SD outperformed QT-SD in identifying the SCD victims among the study subjects (area under the curve in the receiver operating characteristics curve 0.730 vs. 0.679, respectively).

Conclusion

Increased short-term variability of repolarization heterogeneity measured from standard 12-lead ECG is associated with SCD.

Lower ST-elevation myocardial infarction incidence during COVID-19 epidemic in Northern Europe

We compared the ST elevation myocardial infarction (STEMI) incidence during COVID-19 pandemic (March 2020) to January-February 2020 and to same time period in earlier years 2017-2019 in five Nordic-Baltic tertiary centers. During 2017-2019, there were no marked differences in STEMI incidence between January, February and March. During 2020, there was an average drop of 32% in STEMI incidence in March. The isolation measures may decrease the risk for respiratory virus infection and contribute to the lower STEMI incidence and that we might benefit from firmer suggestions on hand hygiene and social distancing during flu season at least among high-risk individuals.

Electrocardiographic Risk Markers for Heart Failure in Women Versus Men

Heart failure (HF) is one of the leading causes of hospitalization in the Western world. Women have a lower HF hospitalization rate and mortality compared with men. The role of electrocardiography as a risk marker of future HF in women is not well known. We studied association of electrocardiographic (ECG) risk factors for HF hospitalization in women from a large middle-aged general population with a long-term follow-up and compared the risk profile to men. Standard 12-lead ECG markers were analyzed from 10,864 subjects (49% women), and their predictive value for HF hospitalization was analyzed. During the follow-up (30 ± 11 years), a total of 1,743 subjects had HF hospitalization; of these, 861 were women (49%). Several baseline characteristics, such as age, body mass index, blood pressure, and history of previous cardiac disease predicted the occurrence of HF both in women and men (p <0.001 for all). After adjusting for baseline variables, ECG sign of left ventricular hypertrophy (LVH) (p <0.001), and atrial fibrillation (p <0.001) were the only baseline ECG variables that predicted future HF in women. In men, HF was predicted by fast heart rate (p = 0.008), T wave inversions (p <0.001), abnormal Q-waves (p = 0.002), and atrial fibrillation (p <0.001). Statistically significant gender interactions in prediction of HF were observed in ECG sign of LVH, inferolateral T wave inversions, and heart rate. In conclusion, ECG sign of LVH predicts future HF in middle-aged women, and T wave inversions and elevated heart rate are associated with HF hospitalization in men.

Association of Silent Myocardial Infarction and Sudden Cardiac Death

Importance

Myocardial infarction in the absence of major or unrecognized symptoms are characterized as silent (SMI). The prevalence of SMI among individuals who experience sudden cardiac death (SCD), with or without concomitant electrocardiographic (ECG) changes, has not previously been described in detail from large studies to our knowledge.

Objective

To determine the prevalence of SMI in individuals who experience SCD without a prior diagnosis of coronary artery disease (CAD) and to detect ECG abnormalities associated with SMI-associated SCD.

Design, Setting, and Participants

This case-control study compared autopsy findings, clinical characteristics, and ECG markers associated with SMI in a consecutive cohort of individuals in the Finnish Genetic Study of Arrhythmic Events (Fingesture) study population who were verified to have had SCD. The Fingesture study consists of individuals who had autopsy-verified SCD in Northern Finland between 1998 and 2017. Individuals who had SCD with CAD and evidence of SMI were regarded as having had cases; those who had SCD with CAD without SMI were considered control participants. Analyses of ECG tests were carried out by investigators blinded to the SMI data. Data analysis was completed from October 2018 through November 2018.

Main Outcomes and Measures

Silent MI was defined as a scar detected by macroscopic and microscopic evaluation of myocardium without previously diagnosed CAD. Clinical history was obtained from medical records, previously recorded ECGs, and a standardized questionnaire provided to the next of kin. The hypothesis tested was that SMI would be prevalent in the population who had had SCD with CAD, and it might be detected or suspected from findings on ECGs prior to death in many individuals.

Results

A total of 5869 individuals were included (2459 males [78.8%]; mean [SD] age, 64.9 [12.4] years). The cause of SCD was CAD in 4392 individuals (74.8%), among whom 3122 had no history of previously diagnosed CAD. Two individuals were excluded owing to incomplete autopsy information. An ECG recorded prior to SCD was available in 438 individuals. Silent MI was detected in 1322 individuals (42.4%) who experienced SCD without a clinical history of CAD. The participants with SMI were older than participants without MI scarring (mean [SD] age, 66.9 [11.1] years; 65.5 [11.6] years; P < .001) and were more often men (1102 of 1322 [83.4%] vs 1357 of 1798 [75.5%]; P < .001). Heart weight was higher in participants with SMI (mean [SD] weight, 483 [109] g vs 438 [106] g; P < .001). In participants with SMI, SCD occurred more often during physical activity (241 of 1322 [18.2%] vs 223 of 1798 [12.4%]; P < .001). A prior ECG was abnormal in 125 of the 187 individuals (66.8%) who had SCD after SMI compared with 139 of 251 (55.4%) of those who had SCD without SMI (P = .02).

Conclusions and Relevance

Many individuals who experienced SCD associated with CAD had a previously undetected MI at autopsy. Previous SMI was associated with myocardial hypertrophy and SCD during physical activity. Premortem ECGs in a subset with available data were abnormal in 67% of the individuals who had had a SCD after an SMI.

Electrocardiogram as a predictor of survival without appropriate shocks in primary prophylactic ICD patients: A retrospective multi-center study

BACKGROUND

Abnormal 12-lead electrocardiogram (ECG) can predict cardiovascular events, including sudden cardiac death. We tested the hypothesis that ECG provides useful information on guiding implantable cardioverter defibrillator (ICD) therapy into individuals with impaired left ventricular ejection fraction (LVEF).

METHODS

Retrospective data of primary prevention ICD implantations from 14 European centers were gathered. The registry included 5111 subjects of whom 1687 patients had an interpretable pre-implantation ECG available (80.0% male, 63.3 ± 11.4 years). Primary outcome was survival without appropriate ICD shocks or heart transplantation. A low-risk ECG was defined as a combination of ECG variables that were associated with the primary outcome.

RESULTS

A total of 1224 (72.6%) patients survived the follow-up (2.9 ± 1.7 years) without an ICD shock, 224 (13.3%) received an appropriate shock and 260 (15.4%) died. Low-risk ECG defined as QRS duration <120 ms, QTc interval <450 ms for men and <470 ms for women, and sinus rhythm, were met by 515 patients (30.5%). Multivariable Cox regression showed that the hazard (HR) for death, heart transplantation or appropriate shock were reduced by 42.5% in the low-risk group (HR 0.575; 95% CI 0.45-0.74; p < 0.001), compared to the high-risk group. The HR for the first appropriate shock was 42.1% lower (HR 0.58; 95% CI 0.41-0.82; p = 0.002) and the HR for death was 48.0% lower (HR 0.52; 95% CI 0.386-0.72; p < 0.001) in the low-risk group.

CONCLUSION

Sinus rhythm, QRS <120 ms and normal QTc in standard 12-lead ECG provides information about survival without appropriate ICD shocks and might improve patient selection for primary prevention ICD therapy.

P481The genetic background of sudden cardiac deaths caused by single vessel coronary artery disease and myocardial hypertrophy with fibrosis

Funding Acknowledgements

Sigrid Juselius Foundation, Finnish Foundation for Cardiovascular Research, Aarne Koskelo Foundation, The Finnish Medical Foundation

Background

Coronary artery disease (CAD) is the most common underlying cause of sudden cardiac death (SCD). Cardiac hypertrophy with varying amount of myocardial fibrosis is a common risk factor for CAD related SCD especially in young SCD victims where severity of CAD seems not to entirely explain the cause of SCD.

Purpose

The aim was to study the genetic background of hypertrophy and fibrosis among young, ischemic SCD victims with single vessel CAD.

Methods

The study population was derived from the Fingesture study consisting of all autopsy-verified sudden cardiac deaths in Northern Finland between years 1998-2017 (n = 5,869). CAD was determined to be the cause of SCD in 4,392 victims (74.8%). We carried out targeted next-generation sequencing using a panel of 174 genes associated with myocardial structure and ion channel function in 95 ischemic-SCD victims (mean [standard error] age, 63.6 [1.06] years; 88.4% males) with single-vessel CAD and cardiac hypertrophy in the absence of previously diagnosed CAD, and whose DNA passed the quality control for further analysis. Assessment for pathogenicity of detected variants was based on American College of Medical Genetics consensus guidelines.

Results

A total of 43 variants were detected in 43 of the study subjects (45.3 %). Five variants in eight subjects (8.4%) were classified as pathogenic or likely pathogenic. We observed 38 variants of uncertain significance in 39 victims (40.6 %). Variants were detected in myocardial structure protein coding genes, associated with arrhythmogenic right ventricular cardiomyopathy (13 variants), dilated cardiomyopathy (16 variants), hypertrophic cardiomyopathy (6 variants) and left ventricular non-compaction cardiomyopathy (3 variants). Five variants were detected in RYR2 associated with both cardiomyopathies and catecholaminergic polymorphic ventricular tachycardias. Seven variants were detected in multiple unrelated subjects. None of the subjects presented characteristic autopsy findings related to cardiomyopathies.

Conclusions

Variants associated with cardiomyopathies were common findings among CAD related SCD victims with single vessel disease and myocardial hypertrophy found at autopsies, suggesting that these variants may modulate the risk for fatal arrhythmias and sudden death in ischemic disease.

Automated electrocardiographic quantification of myocardial scar in patients undergoing primary prevention implantable cardioverter-defibrillator implantation: Association with mortality and subsequent appropriate and inappropriate therapies

BACKGROUND

Myocardial scarring from infarction or nonischemic fibrosis forms an arrhythmogenic substrate. The Selvester QRS score has been developed to estimate myocardial scar from the 12-lead electrocardiogram.

OBJECTIVE

We aimed to assess the value of an automated version of the Selvester QRS score for the prediction of implantable cardioverter-defibrillator (ICD) therapy and death in patients undergoing primary prevention ICD implantation.

METHODS

Unselected patients undergoing primary prevention ICD implantation were included in this retrospective, observational, multicenter study. The QRS score was calculated automatically from a digital standard preimplantation 12-lead electrocardiogram and was correlated to the occurrence of death and appropriate and inappropriate shocks during follow-up. Analyses were performed in groups defined by QRS duration < 130 ms vs ≥ 130 ms.

RESULTS

Overall, 1047 patients (872 [83%] men; median age 64 years IQR [55-71]) with ischemic (648, 62%) or nonischemic (399, 38%) cardiomyopathy were included. The median QRS duration was 123 ms (interquartile range [IQR] 111-157 ms), and the median QRS score was 5 (IQR 2-8). The QRS duration was <130 ms in 59% and ≥130 ms in 41%. During a median follow-up of 45 months (IQR 24-72 months), a QRS score of ≥5 was independently associated with a significantly higher risk of mortality (hazard ratio [HR] 1.67; 95% confidence interval [CI] 1.05-2.66; P = .031) and appropriate (HR 1.83; 95% CI 1.07-3.14; P = .028) and inappropriate (HR 2.32; 95% CI 1.04-5.17; P = .039) shocks in patients with QRS duration ≥ 130 ms. No association of the QRS score and outcome was observed in patients with QRS duration < 130 ms (P > .05).

CONCLUSION

The automatically calculated Selvester QRS score, an indicator of myocardial scar burden, predicts mortality and appropriate and inappropriate shocks in patients undergoing primary prevention ICD implantation with a prolonged QRS duration.

Physical Activity and the Risk for Sudden Cardiac Death in Patients With Coronary Artery Disease

BACKGROUND

The association between leisure-time physical activity (LTPA) and the risk of sudden cardiac death (SCD) in coronary artery disease patients is not well known. We aim to assess whether there is an association between LTPA and the risk of SCD and non-SCD in patients with coronary artery disease.

METHODS

Patients with angiographically verified coronary artery disease (n=1946) underwent a clinical evaluation, including filling in an LTPA questionnaire and extensive risk profiling at the baseline. The patients were classified into 4 groups according to LTPA: (1) inactive; (2) irregularly active; (3) active, exercise regularly 2× to 3× weekly; (4) highly active, exercise regularly ≥4× weekly. Age, sex, body mass index, left ventricular ejection fraction, type 2 diabetes mellitus, history of myocardial infarction, Canadian Cardiovascular Society grading of angina pectoris class, and exercise capacity were used as covariates in the multivariate Cox regression analysis.

RESULTS

During follow-up (median 6.3 years), 52 SCDs and 49 non-SCDs occurred. Inactive patients had increased risk for SCD compared with active patients (hazard ratio, 2.45 [95% CI, 1.01-5.98]; P<0.05). A significant LTPA×Canadian Cardiovascular Society grading of angina pectoris class interaction was observed in SCD risk (P=0.019 in highly active patients). LTPA was not associated with SCD in patients with Canadian Cardiovascular Society grading of angina pectoris class 1 (n=1107, 18 events). Among patients with Canadian Cardiovascular Society grading of angina pectoris class 2 or higher (n=839, 34 events), increased risk for SCD was encountered in highly active patients (hazard ratio, 7.46 [95% CI, 2.32-23.9]; P<0.001) and inactive patients (hazard ratio, 3.64 [95% CI, 1.16-11.5]; P<0.05) as compared to active patients. A linear association was observed between LTPA and non-SCD; those with high LTPA had the lowest risk for non-SCD.

CONCLUSIONS

Inactive coronary artery disease patients had increased risk for SCD. In subgroup analysis among symptomatic patients, the risk of SCD was increased in highly active and inactive patients compared with active patients. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01426685.

Association of non-shockable initial rhythm and psychotropic medication in sudden cardiac arrest

Background

Asystole (ASY) and pulseless electrical activity (PEA) have a poor outcome during sudden cardiac arrest (SCA). Psychotropic medication has been associated with a risk for sudden cardiac death (SCD). Our aim was to study the association of psychotropic medication with ASY/PEA during SCA.

Methods and results

A total of 659 SCA subjects were derived from the emergency data of Oulu University Hospital (2007-2012). Subjects with non-cardiac origin of SCA and over 30-minute delay to rhythm recording were excluded. Population included 222 subjects after exclusions (mean age 64 ± 14 years, 78% males). Initial rhythm was ventricular fibrillation (VF) or ventricular tachycardia (VT) in 123 (55%), ASY in 67 (30%) and PEA in 32 (14%) subjects. The delay (collapse to rhythm recording) was similar in VF/VT and ASY/PEA subjects (median 8 min [1st-3rd quartile 3-12 min] versus 10 [0-14] minutes, p = 0.780). Among VF/VT subjects underlying cardiac disease was more often ischemic compared to ASY/PEA subjects (85% versus 68%, p = 0.003). Psychotropic medication was associated with ASY/PEA rhythm (OR 3.18, 95%CI 1.40-7.23, p = 0.006) after adjustment for gender, age and underlying cardiac disease. Subsequently, antipsychotics (OR 4.27, 95%CI 1.28-14.25, p = 0.018) were more common in the ASY/PEA group. Benzodiazepines and antidepressants were not associated with ASY/PEA.

Conclusion

Psychotropic medication and especially antipsychotics are associated with non-shockable rhythm during SCA and may lower the possibility of survival from the event. This might partly explain the risk of SCD related to psychotropic medication.

Appropriate Shocks and Mortality in Patients With Versus Without Diabetes With Prophylactic Implantable Cardioverter Defibrillators

OBJECTIVE

Diabetes increases the risk of all-cause mortality and sudden cardiac death (SCD). The exact mechanisms leading to sudden death in diabetes are not well known. We compared the incidence of appropriate shocks and mortality in patients with versus without diabetes with a prophylactic implantable cardioverter defibrillator (ICD) included in the retrospective EU-CERT-ICD registry.

RESEARCH DESIGN AND METHODS AND RESULTS

A total of 3,535 patients from 12 European EU-CERT-ICD centers with a mean age of 63.7 ± 11.2 years (82% males) at the time of ICD implantation were included in the analysis. A total of 995 patients (28%) had a history of diabetes. All patients had an ICD implanted for primary SCD prevention. End points were appropriate shock and all-cause mortality. Mean follow-up time was 3.2 ± 2.3 years. Diabetes was associated with a lower risk of appropriate shocks (adjusted hazard ratio [HR] 0.77 [95% CI 0.62-0.96], P = 0.02). However, patients with diabetes had significantly higher mortality (adjusted HR 1.30 [95% CI 1.11-1.53], P = 0.001).

CONCLUSIONS

All-cause mortality is higher in patients with diabetes than in patients without diabetes with primary prophylactic ICDs. Subsequently, patients with diabetes have a lower incidence of appropriate ICD shocks, indicating that the excess mortality might not be caused primarily by ventricular tachyarrhythmias. These findings suggest a limitation of the potential of prophylactic ICD therapy to improve survival in patients with diabetes with impaired left ventricular function.

Sudden Cardiac Death in Women

BACKGROUND

Despite recent progress in profiling of risk for sudden cardiac death (SCD) and prevention and intervention of cardiac diseases, SCD remains a major cause of death. Among women, the incidence of SCD is significant, but lower than in men, particularly in the premenopausal and early postmenopausal years. Possibly, as a consequence of the difference in population burden, the mechanisms and risk markers of SCD are not as well defined for women. The aim of this study was to determine the autopsy findings and causes of death among women in a large SCD population. Additionally, we sought to classify prior ECG characteristics in male and female subjects with SCD.

METHODS

The Fingesture study has systematically collected clinical and autopsy data from subjects with SCD in Northern Finland between 1998 and 2017. The cohort consists of 5869 subjects with SCD. Previously recorded ECGs were available and analyzed in 1101 subjects (18.8% of total population; and in 25.3% of women).

RESULTS

Female subjects with SCD were significantly older than men: 70.1±13.1 years versus 63.5±11.8 years (mean ± standard deviation, P<0.001). The most frequently identified cause of death was ischemic heart disease in both sexes: 71.7% among women versus 75.7% among men, P=0.005. In contrast, women were more likely to have nonischemic cause of SCD than men (28.3% versus 24.3%, P=0.005). The prevalence of primary myocardial fibrosis was higher among women (5.2%, n=64) than in men (2.6%, n=120; P<0.001). Female subjects with SCD were more likely to have normal prior ECG tracings (22.2% versus 15.3% in men, P<0.001). A normal ECG was even more common among nonischemic female subjects with SCD (27.8% versus 16.2% in men, P=0.009). However, ECG markers of left ventricular hypertrophy, with or without repolarization abnormalities, were more common among women (8.2%; 17.9%) than in men (4.9%; 10.6%, P=0.036; P<0.001, respectively).

CONCLUSIONS

Women were considerably older at the time of SCD and more commonly had nonischemic causes. Women were also more likely to have a prior normal ECG than men, but an increased marker for SCD risk based on ECG criteria for left ventricular hypertrophy with repolarization abnormalities was more commonly observed in women.

Three-year outcomes related to coronary stenting; a registry-based real-life population study

Objectives. Developments in medication and coronary interventions have improved coronary artery disease (CAD) treatment. We studied long-term outcomes in an observational, real-life population of CAD patients undergoing percutaneous coronary intervention (PCI) depending on the presentation and the stent type used. Design and results. Register included 789 consecutive patients undergoing PCI. Follow up period was three years with primary composite outcome (MACE) of all cause -mortality, myocardial infarction and target lesion revascularization. Mean age was 65 ± 11 and 69% were male. New-generation drug-eluting stents (DES-2) were associated with lower adjusted rates of MACE (HR 0.47; 95% CI 0.29-0.77) but not mortality (HR 0.50; 95% CI 0.22-1.14) in comparison to bare-metal stents. Patients with STEMI (14.4%) or NSTEMI (13.7%) had higher crude mortality rates than those with unstable (4.5%) or stable CAD (3.1%; p < .001). The association diminished after adjustments in NSTEMI (HR 2.01; 95% CI 0.88-4.58). Among smokers 45% quitted and 36% achieved recommended cholesterol levels. Conclusions. The overall prognosis was good. Irrespective of comorbidities, NSTEMI was not associated with worse outcome than stable CAD. DES-2 was associated with lower rates of MACE than BMS without affecting mortality rate. Patients succeeded better in smoking cessation than reaching recommended cholesterol levels.

Effect of Sex and Underlying Disease on the Genetic Association of QT Interval and Sudden Cardiac Death

Background Sudden cardiac death (SCD) accounts for ≈300 000 deaths annually in the United States. Men have a higher risk of SCD and are more likely to have underlying coronary artery disease, while women are more likely to have arrhythmic events in the setting of inherited or acquired QT prolongation. Moreover, there is evidence of sex differences in the genetics of QT interval duration. Using sex- and coronary artery disease-stratified analyses, we assess differences in genetic association between longer QT interval and SCD risk. Methods and Results We examined 2282 SCD subjects and 3561 Finnish controls. The SCD subjects were stratified by underlying disease (ischemic versus nonischemic) and by sex. We used logistic regression to test for association between the top QT interval-associated single-nucleotide polymorphism, rs12143842 (in the NOS1AP locus), and SCD risk. We also performed Mendelian randomization to test for causal association of QT interval in the various subgroups. No statistically significant differences were observed between the sexes for associations with rs12143842, despite the odds ratio being higher in females across all subgroup analyses. Consistent with our hypothesis, female non-ischemics had the highest odds ratio point estimate for association between rs12143842 and SCD risk and male ischemics the lowest odds ratio point estimate (P=0.036 for difference). Similar trends were observed for the Mendelian randomization analysis. Conclusions While individual subgroup comparisons did not achieve traditional criteria for statistical significance, this study is consistent with the hypothesis that the causal association of longer QT interval on SCD risk is stronger in women and nonischemic individuals.

Predicting sudden cardiac death in a general population using an electrocardiographic risk score

OBJECTIVE

We investigated whether combining several ECG abnormalities would identify general population subjects with a high sudden cardiac death (SCD) risk.

METHODS

In a sample of 6830 participants (mean age 51.2±13.9 years; 45.5% male) in the Mini-Finland Health Survey, a general population cohort representative of the Finnish adults aged ≥30 years conducted in 1978-1980, we examined their ECGs, following subjects for 24.3±10.4 years. We analysed the association between individual ECG abnormalities and 10-year SCD risk and developed a risk score using five ECG abnormalities independently associated with SCD risk: heart rate >80 beats per minute, PR duration >220 ms, QRS duration >110 ms, left ventricular hypertrophy and T-wave inversion. We validated the score using an external general population cohort of 10 617 subjects (mean age 44.0±8.5 years; 52.7% male).

RESULTS

No ECG abnormalities were present in 4563 subjects (66.8%), while 96 subjects (1.4%) had ≥3 ECG abnormalities. After adjusting for clinical factors, the SCD risk increased progressively with each additional ECG abnormality. Subjects with ≥3 ECG abnormalities had an HR of 10.23 (95% CI 5.29 to 19.80) for SCD compared with those without abnormalities. The risk score similarly predicted SCD risk in the validation cohort, in which subjects with ≥3 ECG abnormalities had HR 10.82 (95% CI 3.23 to 36.25) for SCD compared with those without abnormalities.

CONCLUSION

The ECG risk score successfully identified general population subjects with a high SCD risk. Combining ECG risk markers may improve the risk stratification for SCD.

P6588Impact of age and sex on the long-term prognosis associated with early repolarization in the general population

Background

Early repolarization (ER) in the electrocardiogram (ECG) has been associated with increased sudden cardiac death (SCD) risk in the general population. However, controversy remains about the risk associated with ER in different population subgroups.

Purpose

We evaluated whether age and sex affect the prognostic significance of ER in general population subjects.

Methods

The study population consisted of Finnish general population subjects aged over 30 years participating in the Mini-Finland Health Survey in 1978–80. Subjects underwent extensive baseline health examinations including a resting 12-lead ECG and were followed for 24±10 years. After excluding ECGs with QRS duration >110ms, the presence of ER (J-point elevation ≥0.1 mV in ≥2 inferior/lateral leads) was assessed from the remaining 6,631 subjects. The association between ER and SCD risk was analysed in subgroups according to age (<50 years or ≥50 years) and sex by using the Cox proportional hazards model. Effect modification of ER by age group and by sex was tested using the Wald test.

Results

ER was present in 250 (15.7%) of the 1,592 male subjects aged <50 years, 117 (6.8%) of the 1,713 female subjects aged <50 years, 182 (13.4%) of the 1,362 male subjects aged ≥50 years, and 244 (12.4%) of the 1,964 female subjects aged ≥50 years. There was a significant interaction between age group and ER (p=0.011). Among subjects aged <50 years, ER was associated with SCD risk after adjusting for age, sex, blood pressure, body mass index, serum cholesterol, coronary artery disease, diabetes, and active smoking (hazard ratio [HR] 1.79; 95% confidence interval [CI] 1.09–2.92; p=0.021), whereas in subjects aged ≥50 years ER was not associated with increased risk of SCD. Particularly female subjects aged <50 years with ER had a high risk of SCD (HR 4.85; 95% CI 1.65–14.29; p=0.004) in the multivariate analysis, whereas among <50-year-old male subjects ER was not associated with SCD (p=0.024 for interaction between sex and ER).

Conclusion

Our results suggest that among adults <50 years old, and especially among <50-year-old women, ER is associated with increased SCD risk, whereas among older subjects ER is not associated with SCD. Future research should focus on identifying the factors accounting for the difference between the age groups and to improve the risk stratification in the younger female patient populations with ER.

Acknowledgement/Funding

Aarne Koskelo foundation and Paavo Ilmari Ahvenainen Foundation

P4168Ischemic sudden cardiac deaths among victims under 50 years - Characteristics and autopsy findings

Background

Sudden cardiac death (SCD) is one of the most prevalent cause of death in Western countries representing nearly 20% of total mortality. About 70–80% of SCDs are due to coronary artery disease (CAD). Especially among young victims, whose first cardiac event is often SCD, decent risk prediction and prevention strategies are sadly lacking.

Purpose

The aim of this study was to determine the characteristics and autopsy findings of ischemic sudden cardiac deaths among young victims under the age of 50 years.

Methods

The study population is derived from Fingesture study, consisting of prospectively collected consecutive victims of SCD in Northern Finland among whom post-mortem examinations were performed between years 1998–2017 (n=5,869). According to Finnish law, all unexpected deaths undergo medico-legal autopsy. All post-mortem examinations included histological examinations, as well as a toxicology investigation was carried out if needed. Information about the victims was collected from autopsy data, death certificates, medical records, standardized questionnaire to the closest family members of the victims and police reports about the conditions of the death. 10% off all SCDs occurred among victims aged under 50 years (607 victims).

Results

CAD was the most common underlying cause of SCD among young victims (265 victims, 44%), followed by obesity related (102 victims, 17%) and alcoholic cardiomyopathy (67 victims, 11%). The mean age of ischemic SCD victims was 44±4 years and they were mostly men (89%). 90% of victims had no history of CAD prior to death and 34% of these had a myocardial scar at autopsy indicating previously unrecognized MI. 26% of SCDs occurred during physical activity. Hypertrophied hearts (59%) and myocardial fibrosis (83%) were common findings among young ischemic SCD victims. 27% of victims had a history of heavy drinking and alcohol was found in toxicology investigations in 35% of victims. At least one cardiovascular risk factor (diabetes mellitus, hypertension, dyslipidemia, obesity) was present in 51% of cases.

Conclusions

CAD was the most common cause of SCD among victims under 50 years. Most ischemic SCDs among young occurred without previously diagnosed CAD, and yet severe findings were seen at autopsy.

Acknowledgement/Funding

Sigrid Juselius Foundation, Finnish Foundation for Cardiovascular Research, Aarne Koskelo Foundation

P3511Gender differences in electrocardiographic risk markers of heart failure

Background

Heart failure (HF) is one the leading causes of hospitalization in the Western world. Women have a lower rate of HF hospitalization and mortality compared to men. Role of 12-lead electrocardiography (ECG) as a risk marker of future HF in women is not well known.

Purpose

We studied the association of standard 12-lead ECG and clinical risk factors to HF hospitalization in women and in men separately from a large middle aged general population sample with a long-term follow-up.

Methods

Standard 12-lead ECG markers were analyzed from 10,864 subjects (48.8% women, N=5,215) of the prospective Mobile Clinic Study, and their predictive value for HF hospitalization was analyzed.

Results

During the follow-up (29.6±11.2 yrs.), a total of 1,743 subjects had HF hospitalization; out of these, 861 were women (49.4%). Several baseline characteristics, such as age, body mass index, blood pressure, and history of prior cardiac disease predicted the occurrence of HF both in women and men (P<0.001 for all). After adjusting for baseline variables, ECG sign of left ventricular hypertrophy (LVH) (P<0.001), and atrial fibrillation (P<0.001) were the only baseline ECG variables that predicted the future HF in women. In men, HF was predicted by fast heart rate (P=0.008), T wave inversions (P<0.001), abnormal Q waves (P=0.002), and atrial fibrillation (P<0.001). Statistically significant gender interactions in prediction of HF were observed in ECG sign of LVH (P<0.001), inferolateral T wave inversions (P=0.005), and heart rate (P=0.012).

Conclusions

ECG sign of LVH predicts future HF in middle-aged women independently, and T wave inversions and elevated heart rate are associated with HF hospitalization in men in.

Acknowledgement/Funding

Finnish Cultural Foundation, The University of Oulu Scholarship Foundation, Juho Vainio Foundation

3254Manifestations of myocardial fibrosis in the standard 12-lead electrocardiogram

Background

Myocardial fibrosis has substantial role in sudden cardiac deaths (SCD). Major challenge in preventing SCDs is early recognition of vulnerable patients with fibrotic cardiomyopathy. Our aim was to find manifestations of myocardial fibrosis in 12-lead electrocardiogram (ECG).

Methods

Study population is based on the Fingesture study, which has gathered data from 5,869 consecutive autopsied SCD victims between 1998 and 2017 in Finland. The degree of fibrosis was determined based on the histological samples taken from the heart during autopsy and was categorized into four groups; 1) no fibrosis, 2) scattered mild fibrosis, 3) moderate patchy fibrosis and 4) substantial fibrosis. We were able to collect pre-mortem 12-lead ECGs from 1,100 SCD victims. Ischemic cardiomyopathy was the cause of death in 689 cases and 411 had nonischemic cardiomyopathy at autopsy in the group where ECG was available.

Results

Mean age of the study subjects was 66±13 years and 75% were male. At least some amount of myocardial fibrosis was present in 92% of the victims. QRS duration in ECG correlated with the degree of fibrosis in autopsy as follows; 96±21ms in group 1 (n=93), 97±20ms in group 2 (n=357), 103±26ms in group 3 (n=506) and 108±27ms in group 4 (n=144; p<0.001, β=0.153). Prevalence of fragmented QRS complex was higher among victims with severe fibrosis (40% in group 1, 43% in group 2, 60% in group 3 and 65% in group 4; p<0.001). Additionally, inferolateral T-wave inversions were more common in groups with increasing amount of myocardial fibrosis (5.4% in group 1, 13.2% in group 2, 20.4% in group 3 and 31.9% in group 4; p<0.001). Associations were visible in both ischemic and nonischemic SCDs but reached statistical significance only among ischemic SCD victims. Heart rate corrected JT interval and Sokolow-Lyon index had no linear correlation with the degree of fibrosis.

Conclusions

Myocardial fibrosis was associated with QRS prolongation, T-wave inversions and QRS fragmentation among SCD victims. Fibrosis did not manifest as clearly in ECG among patients with nonischemic cardiomyopathies as among ischemic SCD victims. The results may explain the increased risk for SCD in patients with abnormal QRS complex or inverted T waves providing means for recognizing patients with underlying fibrotic cardiomyopathy.

Acknowledgement/Funding

Sigrid Juselius Foundation, Foundation of Cardiac Research, Paavo Nurmi Foundation and Paulo foundation, Finland

3056Orthogonal P wave morphology, traditional P wave indices, and the risk of atrial fibrillation in the general population

Background

A substantial portion of the risk of atrial fibrillation (AF) remains unexplained by the established risk markers. However, accurate assessment of AF risk would be beneficial, especially among stroke patients and subjects with symptoms attributable to arrhythmia.

Purpose

To study the associations of P-wave indices with AF risk in the general population.

Methods

Electrocardiograms, including orthogonal leads, of 7217 Finnish subjects aged over 30 years who took part in the baseline examinations of the Mini-Finland Health Survey in 1978–80, were digitized. P-wave duration, third-degree interatrial block (IAB), and P terminal force (PTF) were assessed manually. PTF was considered abnormal when the amplitude of the negative terminal part of the P wave in lead V1 was ≥0.1mV and duration ≥40ms. Third-degree IAB was defined as P-wave duration ≥120ms and the presence of ≥2 +/− biphasic P-waves in the inferior leads. Orthogonal P-wave morphology, which is related to left atrial breakthrough site and affected by atrial fibrosis (1 being considered benign, 2 borderline, and 3 shown to be associated with adverse events), was assessed with an automated algorithm, and ascertained manually. Subjects were followed 10 years for AF hospitalization and mortality. The risk of AF associated with P wave parameters was assessed using Cox proportional hazards models. Model discrimination improvement was quantified by the change in C index, integrated discrimination improvement (IDI), and continuous net reclassification improvement (cNRI).

Results

There were 5489 subjects (47.8% male, mean age 50.5 years) with a readable ECG, sinus rhythm, no missing data, and a predefined orthogonal P-wave morphology. Type 3 orthogonal P morphology (n=216, multivariate adjusted HR [maHR] 3.01, 95% confidence interval [CI] 1.66–5.45, p<0.001), P-wave duration ≥120ms (n=752, maHR 1.67, 95% CI 1.06–2.64, p=0.027), and third-degree IAB (n=103, maHR 3.18, 95% CI 1.66–6.13, p=0.001) were independently associated with the risk of AF in separate models. PTF did not independently predict AF. Subjects presenting with both Type 1 orthogonal P-wave morphology and P-wave duration <110ms (n=2074) were at low risk of AF (maHR 0.46, 95% CI 0.26–0.83, p=0.006) when compared to the rest of the subjects. The inclusion of variables combining orthogonal P-wave morphology and P-wave duration to a multivariate model including conventional AF risk factors improved C index from 0.815 to 0.832 (change 0.017, 95% CI 0.001–0.033), IDI was 0.012 (95% CI 0.006–0.051), and cNRI was 0.220 (95% CI 0.048–0.357).

Conclusions

P-wave indices and orthogonal P-wave morphology can be used to identify subjects at high and low risk for AF and possibly direct extensive AF screening protocols towards high-risk subjects in the general population in order to decrease the risk of cardioembolic stroke. However, more research is needed in this topic.

Acknowledgement/Funding

Finnish Medical Foundation, Onni and Hilja Tuovinen's Foundation, Orion Research Foundation, Paavo Nurmi's Foundation, Veritas Foundation