Reproducibility of autonomic cardiovascular function and hemodynamics at rest and during recovery from exercise

Smartwatches and home-based blood pressure (BP) devices have permitted easy use of heart rate variability (HRV) and BP to identify the recovery status of users after acute exercise training. The reproducibility of HRV and BP after exercise in healthy young participants is not well known. Eighteen participants (age 27 ± 6 years, female n = 8) performed test and retest aerobic exercises (cycling, 30 min, 60% of peak workload, W) and a control session in randomized order. RMSSD, high and low-frequency power of RR intervals, and BP were measured at rest and 30-60 min after interventions. The relative reproducibility was assessed by the intraclass correlation coefficient (ICC) and 95% confidence interval (95% CI). The absolute reproducibility was evaluated using the coefficient of variation (CV%). HRV indices revealed moderate-to-excellent reproducibility at rest (ICC 0.81-0.86; 95% CI 0.53-0.95) but not after exercise (ICC -0.06 to 0.60; 95% CI -1.85 to 0.85). Systolic BP had a good-to-excellent reproducibility before (ICC 0.93; 95% CI 0.81-0.98, CV% 4.2) and after exercise (ICC 0.93; 95% CI 0.81-0.97, CV% 4.2). The reproducibility of HRV indices is poor after exercise in young participants. However, the reproducibility of BP is excellent at rest and after aerobic exercise.

Prognostic significance of beat-to-beat variability of spatial heterogeneity of repolarization analyzed from a 5-minute resting electrocardiogram in coronary artery disease

BACKGROUND

Data on the prognostic significance of temporal variability of spatial heterogeneity of electrocardiographic repolarization in coronary artery disease (CAD) are limited.

OBJECTIVE

The purpose of this study was to evaluate the prognostic value of temporal variability of T-wave morphology analyzed from a 5-minute resting electrocardiogram in CAD.

METHODS

The standard deviation (SD) of T-wave morphology dispersion (TMD-SD) and the SD of total cosine R-to-T were analyzed on a beat-to-beat basis from a 5-minute period of the standard resting 12-lead electrocardiogram obtained before the clinical stress test in 1702 patients with angiographically verified CAD and well-preserved left ventricular function.

RESULTS

During an average of 8.7 ± 2.2 years of follow-up, 60 patients experienced sudden cardiac death/arrest (SCD/SCA) (3.5%), 69 patients nonsudden cardiac death (NSCD) (4.1%), and 161 patients noncardiac death (9.5%). TMD-SD was significantly higher in patients who experienced SCD/SCA than in other patients (1.72 ± 2.00 vs 1.12 ± 1.75; P = .01) and higher in patients who succumbed to NSCD than in other patients (1.57 ± 1.74 vs 1.12 ± 1.76; P = .04), but it did not differ significantly between patients who experienced noncardiac death and those without such an event (1.16 ± 1.42 vs 1.14 ± 1.79; P = .86). In the Cox multivariable hazards model, TMD-SD retained its significant association with the risk of SCD/SCA (hazard ratio 1.119; 95% confidence interval 1.015-1.233; P = .024) but not with the risk of NSCD (hazard ratio 1.089; 95% confidence interval 0.983-1.206; P = .103).

CONCLUSION

TMD-SD is independently associated with the long-term risk of SCD/SCA in patients with CAD.

Lack of Prognostic Value of T-Wave Alternans for Implantable Cardioverter-Defibrillator Benefit in Primary Prevention

BACKGROUND

New methods to identify patients who benefit from a primary prophylactic implantable cardioverter-defibrillator (ICD) are needed. T-wave alternans (TWA) has been shown to associate with arrhythmogenesis of the heart and sudden cardiac death. We hypothesized that TWA might be associated with benefit from ICD implantation in primary prevention.

METHODS AND RESULTS

In the EU-CERT-ICD (European Comparative Effectiveness Research to Assess the Use of Primary Prophylactic Implantable Cardioverter-Defibrillators) study, we prospectively enrolled 2327 candidates for primary prophylactic ICD. A 24-hour Holter monitor reading was taken from all recruited patients at enrollment. TWA was assessed from Holter monitoring using the modified moving average method. Study outcomes were all-cause death, appropriate shock, and survival benefit. TWA was assessed both as a contiguous variable and as a dichotomized variable with cutoff points <47 μV and <60 μV. The final cohort included 1734 valid T-wave alternans samples, 1211 patients with ICD, and 523 control patients with conservative treatment, with a mean follow-up time of 2.3 years. TWA ≥60 μV was a predicter for a higher all-cause death in patients with an ICD on the basis of a univariate Cox regression model (hazard ratio, 1.484 [95% CI, 1.024-2.151]; P=0.0374; concordance statistic, 0.51). In multivariable models, TWA was not prognostic of death or appropriate shocks in patients with an ICD. In addition, TWA was not prognostic of death in control patients. In a propensity score-adjusted Cox regression model, TWA was not a predictor of ICD benefit.

CONCLUSIONS

T-wave alternans is poorly prognostic in patients with a primary prophylactic ICD. Although it may be prognostic of life-threatening arrhythmias and sudden cardiac death in several patient populations, it does not seem to be useful in assessing benefit from ICD therapy in primary prevention among patients with an ejection fraction of ≤35%.

Day-of-the-week variation of sudden unexpected cardiac death

Background

There has been some controversy about the day-of-the-week (septadian) variation of unexpected sudden cardiac death (SCD).

Methods

We evaluated the incidence of unexpected SCD on different days of the week in a consecutive series of 5869 SCD victims from Northern Finland [the FINGESTURE study (Finnish Genetic Study of Arrhythmic Events)]. As it is mandatory in Finland, a medico-legal autopsy was performed on all unexpected sudden death victims. The autopsies were performed between the years 1998-2017.

Results

The mean incidence of unexpected SCD was higher at weekends (during the days from Friday to Sunday, peaking on Saturday) than during the days from Monday to Thursday (8.54 ± 0.72 vs. 7.22 ± 0.19 SCDs per day of the week per 100,000 inhabitants per year, p < 0.001). Regardless of sex or ischemic versus non-ischemic etiology of SCD, the distribution of the occurrence of SCD among the days of the week was similar compared with the whole SCD cohort.

Conclusion

The incidence of unexpected SCD was highest at weekends (during the days from Friday to Sunday, peaking on Saturday).

Lifestyle and Cardiac Structure and Function in Healthy Midlife Population

The association between lifestyle and cardiac structure and function measures, such as global longitudinal strain and diastolic function in a healthy midlife general population, is not well known. A subpopulation of the Northern Finland Birth Cohort 1966 took part in follow-up, including echocardiography (n = 1,155) at the age of 46. All antihypertensive medication users (n = 164), patients with diabetes (n = 70), subjects with any cardiac diseases (n = 24), and subjects with echocardiography abnormalities (n = 21) were excluded. Moderate to vigorous physical activity (MVPA) was recorded with a wrist-worn accelerometer over 14 days and categorized into high, moderate, and low MVPA groups. Similarly, alcohol consumption was categorized as low, moderate, and high-dose users of alcohol and smoking as nonsmokers, former, and current smokers. The total number of healthy subjects included in the study was 715 (44% males). Left ventricular mass index and left atrial end-systolic volume index were significantly higher in the high MVPA group compared with the low MVPA group (adjusted main effect p = 0.002 and p <0.001, respectively). Cardiac function did not differ among the physical activity groups. High alcohol consumption was associated with impaired global longitudinal strain and diastolic function (adjusted main effect p = 0.002 and p = 0.004, respectively) but not with any cardiac structure variables. Smoking was not associated with cardiac structure or function. In healthy middle-aged adults, MVPA was independently associated with structural changes in the heart but not with cardiac function. High alcohol consumption was associated with impaired modern cardiac function measures but not with cardiac structure.

Lower hemoglobin levels associate with higher baroreflex sensitivity and heart rate variability

The aim of this study was to cross-sectionally examine whether hemoglobin (Hb) levels within the normal variation associate with heart rate variability (HRV) measures and baroreflex sensitivity (BRS). The study population included 733 Finnish subjects of the OPERA cohort (aged 41-59 yr, 53% males, 51.7% treated for hypertension) of whom HRV was measured from a standardized 45-min period and whose Hb levels were within the Finnish reference intervals. The low Hb tertile (mean Hb, 135 g/L) had an overall healthier metabolic profile compared with the high Hb tertile (mean Hb, 152 g/L). BRS was higher in the low Hb tertile compared with the high Hb tertile (P < 0.05). R-R interval (RRi) and standard deviation (SD) of the RRi (SDNN)index were the longest in the low Hb tertile regardless of posture. Of the spectral components of HRV, HF power was the highest in the low Hb tertile regardless of posture (P < 0.05). In a stepwise logistic regression model, BRS associated negatively with Hb levels after adjusting for covariates (B = -0.160 [-0.285; -0.035]). Similar associations were observed for SDNNindex when lying down (B = -0.105 [-0.207; -0.003]) and walking (B = -0.154 [-0.224; -0.083]). For HF power negative associations with Hb levels were observed when lying down (B = -0.110 [-0.180; -0.040]), sitting (B = -0.150 [-0.221; -0.079]), and in total analysis (B = -0.124 [-0.196; -0.053]). Overall, lower Hb levels associated independently with healthier cardiac autonomic function.NEW & NOTEWORTHY Heart rate variability (HRV) and baroreflex sensitivity (BRS), which can be measured noninvasively, can predict cardiac and metabolic diseases. Our findings show that within normal variation subjects with lower hemoglobin (Hb) levels have an overall healthier HRV profile and increased cardiac parasympathetic activity in middle age, independent of age, sex, smoking status, and key metabolic covariates. These findings support our previous findings that Hb levels can be used in assessing long-term risks for cardiometabolic diseases.

Association of electrocardiographic spatial heterogeneity of repolarization and spatial heterogeneity of atrial depolarization with left ventricular fibrosis

AIMS

To evaluate the relationship between spatial heterogeneity of electrocardiographic repolarization and spatial heterogeneity of atrial depolarization with arrhythmic substrate represented by left ventricular fibrosis.

METHODS AND RESULTS

We assessed the associations of T- and P-wave morphology parameters analysed from the standard 12-lead electrocardiograms with left ventricular fibrosis in 378 victims of unexpected sudden cardiac death (SCD) who underwent medico-legal autopsy. Based on autopsy findings, the SCD victims were categorized into four different groups according to different stages of severity of left ventricular fibrosis (substantial fibrosis, moderate patchy fibrosis, scattered mild fibrosis, no fibrosis). T-wave and P-wave area dispersion (TWAd: 0.0841 ± 0.496, 0.170 ± 0.492, 0.302 ± 404, 0.296 ± 0.476, P = 0.008; PWAd: 0.574 ± 0.384, 0.561 ± 0.367, 0.654 ± 0.281, 0.717 ± 0.257, P = 0.011, respectively; low values abnormal), non-dipolar components of T-wave and P-wave morphology (T_NonDipolarABS: 0.0496 ± 0.0377, 0.0571 ± 0.0487, 0.0432 ± 0.0476, 0.0380 ± 0.0377, P = 0.027; P_NonDipolarABS: 0.0132 ± 0.0164, 0.0130 ± 0.0135, 0.0092 ± 0.0117, 0.0069 ± 0.00472, P = 0.005, respectively, high values abnormal), T-wave morphology dispersion (TMD: 45.9 ± 28.3, 40.5 ± 25.8, 35.5 ± 24.9, 33.0 ± 24.6, P = 0.030, respectively, high values abnormal), and P-wave heterogeneity (PWH: 20.0 ± 9.44, 19.7 ± 8.87, 17.9 ± 9.78, 15.4 ± 4.60, P = 0.019, respectively, high values abnormal) differed significantly between the groups with different stages of left ventricular fibrosis. After adjustment with heart weight, T_NonDipolarABS [standardized β (sβ) = 0.131, P = 0.014], PWAd (sβ = -0.161, P = 0.003), P_NonDipolarABS (sβ = 0.174, P = 0.001), and PWH (sβ = 0.128, P = 0.015) retained independent association, and TWAd (sβ = -0.091, P = 0.074) and TMD (sβ = 0.097, P = 0.063) tended to retain their association with the degree of myocardial fibrosis.

CONCLUSION

Our findings suggest that abnormal values of T- and P-wave morphology are associated with arrhythmic substrate represented by ventricular fibrosis partly explaining the mechanism behind their prognostic significance.

Use of psychotropic medication in victims of sudden cardiac death with nonischemic heart disease

BACKGROUND

Nonischemic heart disease (NIHD) is the underlying pathology in about 20% of sudden cardiac deaths (SCDs). Psychotropic medication has been reported as a risk factor for SCD among patients with coronary artery disease, but similar information concerning NIHD is scarce.

OBJECTIVES

We evaluated the use of psychotropic medication in victims of SCD due to NIHD and compared it to the general medication use in Finland.

METHOD

Study population was derived from the Finnish Genetic Study of Arrhythmic Events (Fingesture) (n = 5,869, mean age 65±12, 79% males; 1,404 victims of SCD due to NIHD, mean age 57±13, 77% males). All deaths occurred in Northern Finland during 1998-2017. All victims underwent a medico-legal autopsy. Data on use of medication was defined using post-mortem toxicology results and patient records. Subjects with neither toxicological analysis nor information of medication use available were excluded. Information on general medication use was derived from Finnish Statistics on Medicines 2018 and presented as defined daily dose/1000 inhabitants/day.

RESULTS

Psychotropic medication was used by 579 (41%) subjects with NIHD, whereas in the general population only 12% were estimated to use psychotropics. The results were similar in subgroups of psychotropic medication: 27% vs 2.3% for benzodiazepines, 19% vs 7.5% for antidepressants and 18% vs 2.2% for antipsychotics.

CONCLUSIONS

Use of psychotropic medication is common in victims of SCD due to NIHD compared to the general population.

Prognostic value of P-wave morphology in general population

AIMS

To evaluate the prognostic significance of novel P-wave morphology descriptors in general population.

METHODS AND RESULTS

Novel P-wave morphology variables were analyzed from orthogonal X-, Y-, Z-leads of the digitized electrocardiogram using a custom-made software in 6906 middle-aged subjects of the Mini-Finland Health Survey. A total of 3747 (54.3%) participants died during the follow-up period of 24.3 ± 10.4 years; 379 (5.5%) of the study population succumbed to sudden cardiac death (SCD), 928 (13.4%) to non-SCD (NSCD) and 2440 (35.3%) patients to non-cardiac death (NCD). In univariate comparisons, most of the studied P-wave morphology parameters had a significant association with all modes of death (P from <0.05 to <0.001). After relevant adjustments in the Cox multivariate hazards model, P-wave morphology dispersion (PMD) still tended to predict SCD [hazard ratio (HR): 1.006, 95% confidence interval (CI): 1.000-1.012, P = 0.05) but not NSCD (HR: 0.999, 95% CI: 0.995-1.003, P = 0.68) or NCD (HR: 0.999, 95% CI: 0.997-1.001, P = 0.44). The P-wave maximum amplitude in the lead Z (P-MaxAmp-Z) predicted SCD even after multivariate adjustments (HR: 1.010, 95% CI: 1.005-1.015, P = 0.0002) but also NSCD (HR: 1.005, 95% CI: 1.002-1.009, P = 0.0005) and NCD (HR: 1.002, 95% CI: 1.000-1.005, P = 0.03).

CONCLUSION

Abnormalities of P-wave morphology are associated with the risk of all modes of death in general population. After relevant adjustments, PMD was still closely associated with the risk of SCD but not with NSCD or NCD. P-MaxAmp-Z predicted SCD even after adjustments, however, it also retained its association with NSCD and NCD.

Causes and characteristics of unexpected sudden cardiac death in octogenarians/nonagenarians

INTRODUCTION

The risk for sudden cardiac death (SCD) increases with ageing.

METHODS

We evaluated causes and characteristics of unexpected SCD in SCD victims aged ≥ 80 years in a consecutive series of 5,869 SCD victims in Northern Finland. All the victims underwent medico-legal autopsy as medico-legal autopsy is mandatory in cases of unexpected sudden death in Finland. All the non-cardiac deaths such as pulmonary embolism and cerebral hemorrhage were excluded from the study, as were unnatural deaths such as intoxications.

RESULTS

Among SCD victims ≥ 80 years, 91.0% of SCDs were due to ischemic heart disease (IHD) determined in autopsy and 9.0% due to non-ischemic heart disease (NIHD), whereas among those < 80 years, only 72.6% of SCDs were due to IHD and 27.4% due to NIHD (P < .001). Severe fibrosis in myocardium was more common whereas heart weight and liver weight, body mass index and abdominal fat thickness, were lower among SCD victims aged ≥ 80 years than among victims aged < 80 years. In those with IHD as etiology of SCD, at least 75% stenosis in one or more major coronary vessels was more common in SCD victims aged ≥ 80 years than among victims aged < 80 years (P = .001). SCD victims 80 years or older were less likely to die during physical activity than those under 80 years old (5.6% vs. 15.9%, P < .001). Dying in sauna was more common among those ≥ 80 years than among those < 80 years (5.5% vs. 2.6%, P < .001).

CONCLUSION

In victims of unexpected SCD aged ≥ 80 years, the autopsy-based etiology of SCD was more commonly IHD than in those aged < 80 years. In SCD victims aged ≥ 80 years, severe fibrosis in myocardium, representing arrhythmic substrate, was more common than in the younger ones.

Association of atrial depolarization variability and cardiac autonomic regulation with sudden cardiac death in coronary artery disease

AIMS

To evaluate the prognostic significance of the temporal variability of P-wave morphology, specifically in relation to cardiac autonomic regulation.

METHODS AND RESULTS

We analyzed the standard deviation of P-wave residuum (PWRSD) from five consecutive beats of the standard 12-lead ECG in 1236 patients with angiographically verified coronary artery disease (CAD). We evaluated the prognostic value of PWRSD, of PWRSD and PWR in relation to the 24 h standard deviation of normal-to-normal intervals (PWRSD/SDNN and PWR/SDNN). After 8.7 ± 2.2 years of follow-up on average, 43 patients (3.5%) experienced sudden cardiac death (SCD) or were resuscitated from sudden cardiac arrest (SCA), 34 (2.8%) succumbed to non-sudden cardiac death (NSCD) and 113 (9.1%) to non-cardiac death (NCD). In the Cox regression analysis, PWRSD (≥0.002727) had a significant univariate (uv) [hazard ratio (HR): 4.27, 95% confidence interval (CI): 2.26-8.08, P = 0.000008] and multivariate (mv) (HR: 2.58, 95% CI: 1.31-5.08, P = 0.006) association with SCD/SCA but not with NSCD (uv P = 0.76, mv P = 0.33) or NCD (uv P = 0.57, mv P = 0.66). All the studied P-morphology parameters retained a significant association with the risk of SCD/SCA after relevant adjustment (mv P-values from 0.00003 to <0.05) but not with NSCD or NCD. When dichotomized PWRSD, PWR, PWRSD/SDNN, and PWR/SDNN were added to the clinical risk model for SCD/SCD, the C-index increased from 0.799 to 0.834 and integrated discrimination index and net reclassification index improved significantly (P < 0.001).

CONCLUSION

Variability of P-morphology representing temporo-spatial heterogeneity of atrial depolarization, specifically when combined with cardiac autonomic regulation, independently predicts the risk of SCD in patients with CAD.

T-wave alternans poorly prognostic in primary prophylactic ICD patients: a prospective EU-CERT-ICD study

Background

New methods to identify patients who truly benefit from primary prophylactic implantable cardioverter defibrillation (ICD) are urgently needed. T-wave alternans (TWA) represents a beat-to-beat fluctuation in the morphology of the ST-segment and T-wave. It has been shown to associate with arrhythmogenesis of heart and sudden cardiac death [1]. We hypothised that TWA might associate with benefit from ICD implantation in primary prevention.

Methods

In EU-CERT-ICD study, we prospectively enrolled 2327 primary prophylactic ICD candidates from 15 European countries. A 24-hours Holter-monitoring was taken from all recruited patients at enrolment. TWA was assessed from Holter-monitoring using MMA method with Getemed Cardioday software. To assess the benefit from ICD treatment, we used outcomes all-cause mortality, appropriate shock and survival benefit. We conducted Cox regression model, competing risk regression model and propensity score adjusted Cox regression model. TWA was assessed both as contiguous variable and with cut-off points &lt;47 μV and &lt;60 μV.

Results

Final cohort included 1,734 valid T-wave alternans samples, 1,211 patients with ICD and 523 control patients with conservative treatment, with mean follow-up time 2.3 years. TWA &lt;60 μV predicted lower all-cause mortality in ICD patients in univariate cox regression model (HR 1.484, 95% CI 1.024–2.151, p=0.0374). In multivariate models, TWA did not predict death or appropriate shocks in ICD patients. In addition, TWA did not predict death in control patients. In propensity score adjusted Cox regression model, TWA did not predict ICD benefit.

Conclusion

T-wave alternans is poorly prognostic in primary prophylactic ICD patients. Altough it may predict life-threatening arrhythmias and sudden cardiac death in several patient populations, it cannot be used in assessing benefit from implantable cardioverter defibrillator in primary prevention among patients with ejection fraction ≤35%.

Funding Acknowledgement

Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Community's 7th Framework Program FP7/2007-2013

Sex differences in prevalence of electrocardiographic and echocardiographic left ventricular hypertrophy among patients with coronary artery disease

Background

Both electrocardiographic left ventricular hypertrophy (ECG-LVH) and echocardiographic LVH (echo-LVH) are associated with higher risk of cardiovascular and sudden cardiac death. ECG-LVH seems to be partly distinct from echo-LVH as many subjects with echo-LVH do not have ECG-LVH and vice versa. The difference between sexes have not been studied earlier.

Purpose

The aim of this study was to determine sex differences in prevalence of ECG-LVH and echo-LVH among patients with coronary artery disease (CAD) and to study if ECG-LVH would have higher accuracy for echo-LVH in either of sexes.

Methods

Standard 12-lead electrocardiograms and echocardiographic measurements were studied from 1,894 subjects of ARTEMIS Study (31.8% women). Echo-LVH was determined as estimated left ventricular (LV) mass ≥201 g in men and ≥151 g in women and was categorized as mildly, moderately and severely abnormal. ECG-LVH was determined if either criteria of Sokolow-Lyon or Cornell were met.

Results

Echo-LVH was found from 1,162 of the study subjects (women 34.3%, p=0.004) and ECG-LVH only from 222 of the subjects (women 55.9%, p&lt;0.001). Of those with ECG-LVH, 82.0% had increased LV mass (p&lt;0.001), and ECG-LVH seemed to correlate slightly better to echo-LVH in women than in men (82.3% vs. 81.6%, p&lt;0.001). Of those with ECG-LVH, 47.7% had severe echo-LVH (p&lt;0.001). The prevalence of ECG-LVH was the higher the greater the LV mass was. Among men with ECG-LVH, 46.9% had severe echo-LVH (p&lt;0.001). Among women with ECG-LVH, 16.1% had mild echo-LVH (p=0.029) and 48.4% severe echo-LVH (p&lt;0.001). In addition, 18% of those with ECG-LVH did not have echo-LVH (p&lt;0.001). This proportion was slightly smaller in women than in men (17.7% vs. 18.4%, p&lt;0.001).

Only 15.7% of the subjects with echo-LVH had ECG-LVH (p&lt;0.001). This proportion was significantly higher in women than in men (25.6% vs. 10.5%, p&lt;0.001). ECG-LVH was more common finding in subjects with severe echo-LVH as 20.9% of those CAD patients had ECG-LVH (p&lt;0.001). Among women with severe echo-LVH, ECG-LVH was found in 35.3% (p&lt;0.001) whereas only in 13.7% of men with severe echo-LVH (p&lt;0.001). The prevalence of ECG-LVH seemed to be considerably higher among female CAD patients with T2DM and without prior MI as ECG-LVH was seen in 33.0% of those subjects with at least midl echo-LVH (p&lt;0.001) and 43.8% of those subjects with severe echo-LVH (p&lt;0.001). In male patients from similar subgroup and some degree of echo-LVH, ECG-LVH was seen in 6.7% (p=0.042) and with severe echo-LVH in 12.2% (p&lt;0.001) of the subjects.

Conclusions

In patients with CAD echo-LVH was often seen without signs of ECG-LVH, especially in men. Majority of the CAD patients with ECG-LVH had also echo-LVH and the prevalence on ECG-LVH was the higher the greater the LV mass was. ECG-LVH seemed to correlate better to anatomic LVH in women with CAD than in men, and the sex difference was highlighted in CAD patients with T2DM and no prior MI.

Funding Acknowledgement

Type of funding sources: None.

The Risk of Sudden Cardiac Death Associated with QRS, QTc and JTc intervals in the General Population Revision #4

BACKGROUND

QRS duration and QTc interval have been associated with sudden cardiac death (SCD), but no data is available on the significance of repolarization component (JTc interval) of QTc as an independent risk marker in the general population.

OBJECTIVE

In this study, we sought to quantify the risk of SCD associated with QRS, QTc and JTc.

METHODS

This study was conducted using data from 3 population cohorts from different eras, comprising a total of 20,058 individuals. The follow-up was limited to 10 years and age at baseline to 30-61 years. QRS duration and QT interval (Bazett's) were measured from standard 12-lead electrocardiograms at baseline. JTc interval was defined as QTc - QRS duration. Cox proportional hazard models that controlled for confounding clinical factors identified at baseline were used to estimate the relative risk of SCD.

RESULTS

During a mean period of 9.7 years, 207 SCDs occurred (1.1 per 1000 person-years). QRS duration was associated with a significantly increased risk of SCD in each cohort (pooled hazard ratio 1.030 per 1 ms increase (95% confidence interval 1.017-1.043). The QTc interval had borderline to significant associations with SCD and varied among cohorts (pooled HR 1.007, 95%CI 1.001-1.012). JTc interval as a continuous variable was not associated with SCD (pooled HR 1.001, 95%CI 0.996-1.007).

CONCLUSIONS

Prolonged QRS durations and QTc intervals are associated with an increased risk of sudden cardiac death. However, when QTc is deconstructed into QRS and JTc intervals, the repolarization component (JTc) appears to have no independent prognostic value.

Genetic Variants Associated With Sudden Cardiac Death in Victims With Single Vessel Coronary Artery Disease and Left Ventricular Hypertrophy With or Without Fibrosis

Objective: Cardiac hypertrophy with varying degrees of myocardial fibrosis is commonly associated with coronary artery disease (CAD) related sudden cardiac death (SCD), especially in young victims among whom patterns of coronary artery lesions do not entirely appear to explain the cause of SCD. Our aim was to study the genetic background of hypertrophy, with or without fibrosis, among ischemic SCD victims with single vessel CAD.

Methods: The study population was derived from the Fingesture study, consisting of all autopsy-verified SCDs in Northern Finland between the years 1998 and 2017 (n = 5,869). 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 age 63.6 ± 10.3 years; 88.4% males) with single-vessel CAD in the absence of previously diagnosed CAD and cardiac hypertrophy with or without myocardial fibrosis at autopsy.

Results: A total of 42 rare variants were detected in 43 subjects (45.3% of the study subjects). Five variants in eight subjects (8.4%) were classified as pathogenic or likely pathogenic. We observed 37 variants of uncertain significance in 39 subjects (40.6%). Variants were detected in myocardial structure protein coding genes, associated with arrhythmogenic right ventricular, dilated, hypertrophic and left ventricular non-compaction cardiomyopathies. Also, variants were detected in ryanodine receptor 2 (RYR2), a gene associated with both cardiomyopathies and catecholaminergic polymorphic ventricular tachycardias.

Conclusions: Rare variants associated with cardiomyopathies, in the absence of anatomic evidence of the specific inherited 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 SCD in ischemic disease.

Blood alcohol levels in Finnish victims of non-ischaemic sudden cardiac death

INTRODUCTION

Non-ischaemic heart disease (NIHD) is the underlying pathology in∼20% of all sudden cardiac deaths (SCDs). Heavy drinking is known to be associated with SCD due to ischaemic heart disease, but studies on association of recent alcohol consumption and SCD in patients with NIHD are scarce. We evaluated the blood alcohol levels of autopsy verified non-ischaemic SCD victims.

METHODS

Study population was derived from the Finnish Genetic Study of Arrhythmic Events (Fingesture) (n = 5869, mean age 65 ± 12, 79% males). All deaths occurred in Northern Finland during 1998-2017. All victims underwent a medico-legal autopsy. Subjects of SCD due to ischaemic heart disease were excluded.

RESULTS

A total of 1301 (mean age 57 ± 12, 78% males) victims of SCD due to NIHD were included in the study. The blood ethanol level was elevated in 543 (42%) subjects, out of which the blood alcohol level was ≥0.10%in 339 (62%) subjects and ≥0.15%in 252 (46%) subjects. Male SCD victims had alcohol in blood more frequently compared to females (45% versus 31%, p < .001).

CONCLUSION

Elevated blood alcohol level is common in SCD victims due to NIHD, especially in males. Recent alcohol consumption might contribute to the subsequent SCD in many non-ischaemic SCD victims.KEY MESSAGESElevated blood alcohol level is common in victims of sudden cardiac death due to non-ischaemic heart disease, especially in males.Recent alcohol consumption may contribute to the subsequent death in many nonischemic sudden cardiac death victims.

Q waves are the strongest electrocardiographic variable associated with primary prophylactic implantable cardioverter-defibrillator benefit: a prospective multicentre study

AIM

The association of standard 12-lead electrocardiogram (ECG) markers with benefits of the primary prophylactic implantable cardioverter-defibrillator (ICD) has not been determined in the contemporary era. We analysed traditional and novel ECG variables in a large prospective, controlled primary prophylactic ICD population to assess the predictive value of ECG in terms of ICD benefit.

METHODS AND RESULTS

Electrocardiograms from 1477 ICD patients and 700 control patients (EU-CERT-ICD; non-randomized, controlled, prospective multicentre study; ClinicalTrials.gov Identifier: NCT02064192), who met ICD implantation criteria but did not receive the device, were analysed. The primary outcome was all-cause mortality. In ICD patients, the co-primary outcome of first appropriate shock was used. Mean follow-up time was 2.4 ± 1.1 years to death and 2.3 ± 1.2 years to the first appropriate shock. Pathological Q waves were associated with decreased mortality in ICD patients [hazard ratio (HR) 0.54, 95% confidence interval (CI) 0.35-0.84; P < 0.01] and patients with pathological Q waves had significantly more benefit from ICD (HR 0.44, 95% CI 0.21-0.93; P = 0.03). QTc interval increase taken as a continuous variable was associated with both mortality and appropriate shock incidence, but commonly used cut-off values, were not statistically significantly associated with either of the outcomes.

CONCLUSION

Pathological Q waves were a strong ECG predictor of ICD benefit in primary prophylactic ICD patients. Excess mortality among Q wave patients seems to be due to arrhythmic death which can be prevented by ICD.

Prognostic significance of flat T-waves in the lateral leads in general population

BACKGROUND

Negative T-waves are associated with sudden cardiac death (SCD) risk in the general population. Whether flat T-waves also predict SCD is not known. The aim of the study was to examine the clinical characteristics and risk of SCD in general population subjects with flat T-waves.

METHODS

We examined the electrocardiograms of 6750 Finnish general population adults aged ≥30 years and classified the subjects into 3 groups: 1) negative T-waves with an amplitude ≥0.1 mV in ≥2 of the leads I, II, aVL, V4-V6, 2) negative or positive low amplitude T-waves with an amplitude <0.1 mV and the ratio of T-wave and R-wave <10% in ≥2 of the leads I, II, aVL, V4-V6, and 3) normal positive T-waves (not meeting the aforesaid criteria). The association between T-wave classification and SCD was assessed during a 10-year follow-up.

RESULTS

A total of 215 (3.2%) subjects had negative T-waves, 856 (12.7%) flat T-waves, and 5679 (84.1%) normal T-waves. Flat T-wave subjects were older and had more often cardiovascular morbidities compared to normal T-wave subjects, while negative T-wave subjects were the oldest and had most often cardiovascular morbidities. After adjusting for multiple factors, both flat T-waves (hazard ratio [HR] 1.81; 95% confidence interval [CI] 1.13-2.91) and negative T-waves (HR 3.27; 95% CI 1.85-5.78) associated with SCD.

CONCLUSIONS

Cardiovascular risk factors and disease are common among subjects with flat T-waves, but these minor T-wave abnormalities are also independently associated with increased SCD risk.

Prognostic value of heart rate variability in patients with coronary artery disease in the current treatment era

Coronary artery disease (CAD) mortality has declined substantially over the past decades thanks to advancing medical and interventional/surgical treatments; therefore, the prognostic value of the heart rate variability in CAD in the current treatment era is not well established. We evaluated the prognostic significance of baseline heart rate variability in 1,757 ARTEMIS study patients with angiographically verified CAD. During an average follow-up time of 8.7 ± 2.2 years, a total of 285 (16.2%) patients died. Of the patients, 63 (3.6%) suffered sudden cardiac death or were resuscitated from sudden cardiac arrest (SCD/SCA), 60 (3.4%) experienced non-sudden cardiac death (NSCD), and death attributable to non-cardiac causes (NCD) occurred in 162 (9.2%) patients. For every 10 ms decrease in standard deviation of normal to normal intervals the risk for SCD/SCA, NSCD and NCD increased significantly: HR 1.153 (95% CI 1.075–1.236, p<0.001), HR 1.187 (95% CI 1.102–1.278, p<0.001) and HR 1.080 (95% CI 1.037–1.125, p<0.001), respectively. The natural logarithm of the low-frequency component of the power spectrum and the short-term scaling exponent of the detrended fluctuation analysis also had significant association with all modes of death (p<0.001). After relevant adjustment, standard deviation of normal-to-normal intervals retained its association with NSCD and NCD (p<0.01), the natural logarithm of the low-frequency component of the power spectrum with all modes of death (p from <0.05 to <0.01), and the short-term scaling exponent of the detrended fluctuation analysis with SCD/SCA (p<0.05) and NCD (p<0.001). In conclusion, impairment of many measures of heart rate variability predicts mortality but is not associated with any specific mode of death in patients with stable CAD during the current treatment era, limiting the clinical applicability of heart rate variability to targeting therapy.

Orthogonal P-wave morphology, conventional P-wave indices, and the risk of atrial fibrillation in the general population using data from the Finnish Hospital Discharge Register

AIMS

Identifying subjects at high and low risk of atrial fibrillation (AF) is of interest. This study aims to assess the risk of AF associated with electrocardiographic (ECG) markers linked to atrial fibrosis: P-wave prolongation, 3rd-degree interatrial block, P-terminal force in lead V1, and orthogonal P-wave morphology.

METHODS AND RESULTS

P-wave parameters were assessed in a representative Finnish population sample aged ≥30 years (n = 7217, 46.0% male, mean age 51.4 years). Subjects (n = 5489) with a readable ECG including the orthogonal leads, sinus rhythm, and a predefined orthogonal P-wave morphology type [positive in leads X and Y and either negative (Type 1) or ± biphasic (Type 2) in lead Z; Type 3 defined as positive in lead X and ± biphasic in lead Y], were followed 10 years from the baseline examinations (performed 1978-80). Subjects discharged with AF diagnosis after any-cause hospitalization (n = 124) were defined as having developed AF. Third-degree interatrial block was defined as P-wave ≥120 ms and the presence of ≥2 ± biphasic P waves in the inferior leads. Hazard ratios (HRs) and confidence intervals (CIs) were assessed with Cox models. Third-degree interatrial block (n = 103, HR 3.18, 95% CI 1.66-6.13; P = 0.001) and Type 3 morphology (n = 216, HR 3.01, 95% CI 1.66-5.45; P < 0.001) were independently associated with the risk of hospitalization with AF. Subjects with P-wave <110 ms and Type 1 morphology (n = 2074) were at low risk (HR 0.46, 95% CI 0.26-0.83; P = 0.006), compared to the rest of the subjects.

CONCLUSION

P-wave parameters associate with the risk of hospitalization with AF.