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.

Prevalence and 11-Year Incidence of Cataract and Cataract Surgery and the Effects of Socio-Demographic and Lifestyle Factors

Purpose

To assess the impact of cataract in ageing population by evaluating the prevalence, incidence, and background factors of cataract and cataract surgery.

Patients and Methods

Two health examination surveys representing Finnish population in 2000 and 2011 included 7380 and 5930 participants aged 30 years or older with cataract status known. An 11-year follow-up included 4840 persons who participated in both the surveys. The data include information on physician-made diagnoses, socio-demographic factors, and lifestyle factors based on self-reported assessment. Cataract diagnoses and surgeries recorded in the Finnish Care Register for Health Care were linked to the survey data. Cataract patients were compared to those without cataract using logistic regression. Differences in cataract surgery age were evaluated using linear regression. Univariable and multivariable models were included.

Results

During 2000–2011, the prevalence of cataract increased from 8.8% to 13.6% and cataract surgery from 5.7% to 8.9% in a representative sample of the Finnish adult population. Cataract and cataract surgery were associated with age, smoking, and high alcohol consumption. Cataract was also associated with female gender and low income in 2000, but this association declined during the 11 years. Smoking and high alcohol consumption were associated with younger surgery age.

Conclusion

The prevalence of cataract and cataract surgery is increasing with the ageing of the population. The increase in cataract surgery is likely also reflecting the improvements in eye care. The possibility to equally use health-care services throughout a country can reduce the impact of socio-demographic status. Healthy lifestyle delays the development of cataract, whereas smoking and high alcohol consumption are associated with earlier cataract development. Therefore, the availability of cataract services and promotion of healthy lifestyle will be the key to prevent the detrimental effects of cataract on patients and the society in countries where the population is rapidly ageing.

Improving health-related quality of life in glaucoma during 11 years and its association with vision loss and treatment of the disease

PURPOSE

To evaluate the impact of glaucoma on health-related quality of life (HRQoL) and mental health in the ageing population of Finland.

METHODS

Altogether 7380 and 5774 Finnish individuals aged 30 years and older with known eye disease status were studied in 2000 and 2011, respectively, in two population-based surveys, including an 11-year follow-up of 4683 participants. Data on HRQoL (EQ-5D-3L, 15D), depression (BDI), psychological distress (GHQ-12) and eye disease diagnoses were obtained from self-reported assessments. Information on glaucoma was complemented with the medication, diagnosis and eye surgery data obtained from the Finnish Health Registries. Distance visual acuity was assessed using the Snellen eye chart test. In logistic regression analyses, data were corrected for age, gender and the most common comorbidities.

RESULTS

Glaucoma patients with verified diagnosis (n = 192 in 2000, n = 202 in 2011) and individuals with self-suspected glaucoma (n = 100 in 2000, n = 41 in 2011) showed a significant decrease in their HRQoL. Glaucoma was also associated with worsened overall mental health based on BDI and GHQ-12 results. Visual impairment associated with glaucoma is the major determinant of the reduced HRQoL and mental health. Neither glaucoma medication nor glaucoma surgery affected these parameters. The impact of glaucoma on HRQoL and mental health diminished between 2000 and 2011 in a cross-sectional setting. The newly diagnosed glaucoma during the 11-year follow-up had a minimal effect on them.

CONCLUSION

Glaucoma patients show reduced HRQoL and mental health, which is associated with vision loss regardless of the awareness or treatment of the disease. However, this effect seems to be diminishing over time, and the newly diagnosed glaucoma did not show a significant effect on either HRQoL or mental health.

Prevalence and 11-year incidence of common eye diseases and their relation to health-related quality of life, mental health, and visual impairment

Purpose

To study the prevalence and incidence of the most common eye diseases and their relation to health-related quality of life (HRQoL), depression, psychological distress, and visual impairment in the aging population of Finland.

Methods

Our study was based on two nationwide health surveys conducted in 2000 and 2011. Eye disease status data were obtained from 7379 and 5710 individuals aged 30 + years, of whom 4620 partook in both time points. Both surveys included identical indicators of HRQoL (EuroQol-5 Dimension [EQ-5D], 15D), depression (Beck Depression Inventory [BDI]), psychological distress (General Health Questionnaire-12 [GHQ-12]), visual acuity, and self-reported eye diseases. We assessed the impact of known eye diseases on these factors, adjusted for age, gender, and co-morbidities.

Results

Prevalence of self-reported eye diseases was 3.1/2.7% for glaucoma, 8.1/11.4% for cataract, and 3.4/3.8% for retinal degeneration in 2000 and 2011, and the average incidence between 2000 and 2011 was 22, 109, and 35 /year/10,000 individuals, respectively. These eye diseases were associated with a significant decrease in EQ-5D and 15D index scores in both time points. BDI and GHQ-12 scores were also worsened, with some variation between different eye diseases. Impaired vision was, however, the strongest determinant of declined HRQoL. During the 11-year follow-up the effect of eye diseases on HRQoL and mental health diminished.

Conclusion

Declined HRQoL associated with eye diseases is more related to impaired vision than the awareness of the disease itself, and this declining effect diminished during the follow-up. Therefore, information directed to the public on the risks and prevention of blindness can and should be strengthened to prevent the deleterious effects of visual impairment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s11136-021-02817-1.

The ability of an electrocardiogram to predict fatal and non-fatal cardiac events in asymptomatic middle-aged subjects

INTRODUCTION

The long-term prognostic value of a standard 12-lead electrocardiogram (ECG) for predicting cardiac events in apparently healthy middle-aged subjects is not well defined.

MATERIALS AND METHODS

A total of 9511 middle-aged subjects (mean age 43 ± 8.2 years, 52% males) without a known cardiac disease and with a follow-up 40 years were included in the study. Fatal and non-fatal cardiac events were collected from the national registries. The predictive value of ECG was separately analyzed for 10 and 30 years. Major ECG abnormalities were classified according to the Minnesota code.

RESULTS

Subjects with major ECG abnormalities (N = 1131) had an increased risk of cardiac death after 10-years (adjusted hazard ratio [HR] 1.7; 95% confidence interval [95% CI], 1.1-2.5, p = 0.009) and 30-years of follow-up (HR 1.3, 95% CI, 1.1-1.5, p < 0.001). Model discrimination measured with the C-index showed only a minor improvement with the inclusion of ECG abnormalities: 0.851 versus 0.853 and 0.742 versus 0.743 for 10- and 30-year follow-up, respectively. ECG did not predict non-fatal cardiac events after 10-years or 30-years of follow-up.

DISCUSSION

Major ECG abnormalities are associated with an increased risk of short and long-term cardiac mortality in middle-aged subjects. However, the improvement in discrimination between subjects with and without fatal cardiac events was marginal with abnormal ECG.

KEY MESSAGES

Abnormalities observed on 12-lead electrocardiogram are shown to have prognostic significance for cardiac events in elderly subjects without known cardiac disease. Our results suggest that ECG abnormalities increase the risk of fatal cardiac events also in middle-aged healthy subjects.

Diabetes, glucose tolerance, and the risk of sudden cardiac death

BACKGROUND

Diabetes predisposes to sudden cardiac death (SCD). However, it is uncertain whether greater proportion of cardiac deaths are sudden among diabetes patients than other subjects. It is also unclear whether the risk of SCD is pronounced already early in the course of the disease. The relationship of impaired glucose tolerance (IGT) and SCD is scarcely documented.

METHODS

A general population cohort of 10594 middle-aged subjects (mean age 44 years, 52.6 % male, follow-up duration 35-41 years) was divided into diabetes patients (n = 82), subjects with IGT (n = 3806, plasma glucose ≥9.58 mmol/l in one-hour glucose tolerance test), and controls (n = 6706).

RESULTS

Diabetes patients had an increased risk of SCD after adjustment confounders (hazard ratio 2.62, 95 % confidence interval 1.46-4.70, p = 0.001) but risk for non-sudden cardiac death was similarly increased and the proportion of SCD of cardiac deaths was not increased. The SCD risk persisted after exclusion of subjects with baseline cardiac disease or non-fatal cardiac events during the follow-up. Subjects with IGT were at increased risk for SCD (univariate hazard ratio 1.51; 95 % confidence interval 1.31-1.74; p < 0.001) and also for non-sudden cardiac deaths and non-fatal cardiac events but adjustments for other risk factors attenuated these effects.

CONCLUSIONS

Diabetes was associated with increased risk of SCD but also the risk of non-sudden cardiac death was similarly increased. The proportion of cardiac deaths being sudden in subjects with diabetes was not increased. The higher SCD risk in diabetes patients was independent of known cardiac disease at baseline or occurrence of non-fatal cardiac event during the follow-up.

Body Mass Index as a Predictor of Sudden Cardiac Death and Usefulness of the Electrocardiogram for Risk Stratification

Evidence of the role of body mass index (BMI) as a risk factor for sudden cardiac death (SCD) is conflicting, and how electrocardiographic (ECG) SCD risk markers perform in subjects with different BMIs is not known. In this study, a general population cohort consisting of 10,543 middle-aged subjects (mean age 44 years, 52.7% men) was divided into groups of lean (BMI <20, n = 374), normal weight (BMI 20.0 to 24.9, n = 4,334), overweight (BMI 25.0 to 29.9, n = 4,390), and obese (BMI >30, n = 1,445) subjects. Cox proportional hazards models adjusted for confounders were used to assess the risk for SCD associated with BMI and the risk for SCD associated with ECG abnormalities in subjects with different BMIs. The overweight and obese subjects were at increased risk for SCD (hazard ratios [95% CIs] were 1.33 [1.13 to 1.56], p = 0.001 and 1.79 [1.44 to 2.23], p <0.001 for overweight and obese subjects, respectively). The risk of non-SCD had a similar relation with BMI as SCD. Hazard ratios associated with ECG abnormalities were 3.03, 1.75, 1.74, and 1.34 in groups of lean, normal weight, overweight, and obese subjects, respectively, but no statistical significance was reached in the obese. ECG abnormalities improved integrated discrimination indexes and continuous net reclassification indexes statistically significantly only in the normal weight group. In conclusion, the overweight and obese are at increased risk for SCD but also for non-SCD, and ECG abnormalities are associated with increased risk of SCD also in normal weight subjects presenting with less traditional cardiovascular risk factors.

Early repolarization as a predictor of arrhythmic and nonarrhythmic cardiac events in middle-aged subjects

BACKGROUND

Early repolarization (ER) in the inferior/lateral leads predicts mortality, but whether ER is a specific sign of increased risk for arrhythmic events is not known.

OBJECTIVE

The purpose of this study was to study the association of ER and arrhythmic events and nonarrhythmic morbidity and mortality.

METHODS

We assessed the prognostic significance of ER in a community-based general population of 10,846 middle-aged subjects (mean age 44 ± 8 years). The end-points were sustained ventricular tachycardia or resuscitated ventricular fibrillation (VT-VF), arrhythmic death, nonarrhythmic cardiac death, new-onset atrial fibrillation (AF), hospitalization for congestive heart failure, or coronary artery disease during mean follow-up of 30 ± 11 years. ER was defined as ≥0.1-mV elevation of J point in either inferior or lateral leads.

RESULTS

After including all risk factors of cardiac mortality and morbidity in Cox regression analysis, inferior ER (prevalence 3.5%) predicted VF-VT events (n = 108 [1.0%]) with a hazard ratio (HR) of 2.2 (95% confidence interval [CI] 1.1-4.5, P = .03) but not nonarrhythmic cardiac death (n = 1235 [12.2%]), AF (n = 1659 [15.2%]), congestive heart failure (n = 1752 [16.1%]), or coronary artery disease (n = 3592 [32.9%]) (P = NS for all). Inferior ER predicted arrhythmic death in cases without other QRS complex abnormalities (multivariate HR 1.68, 95 % CI 1.10-2.58, P = .02) but not in those with ER and other coexisting abnormalities in QRS morphology (HR 1.30, 95% CI 0.86-1.96, P = .22).

CONCLUSION

ER in the inferior leads, especially in cases without other QRS complex abnormalities, predicts the occurrence of VT-VF but not nonarrhythmic cardiac events, suggesting that ER is a specific sign of increased vulnerability to ventricular tachyarrhythmias.

Prevalence and prognostic significance of T-wave inversions in right precordial leads of a 12-lead electrocardiogram in the middle-aged subjects

BACKGROUND

T-wave inversion in right precordial leads V(1) to V(3) is a relatively common finding in a 12-lead ECG of children and adolescents and is infrequently found also in healthy adults. However, this ECG pattern can also be the first presentation of arrhythmogenic right ventricular cardiomyopathy. The prevalence and prognostic significance of T-wave inversions in the middle-aged general population are not well known.

METHODS AND RESULTS

We evaluated 12-lead ECGs of 10 899 Finnish middle-aged subjects (52% men, mean age 44 ± 8.5 years) recorded between 1966 and 1972 for the presence of inverted T waves and followed the subjects for 30 ± 11 years. Primary end points were all-cause mortality, cardiac mortality, and arrhythmic death. T-wave inversions in right precordial leads V(1) to V(3) were present in 54 (0.5%) of the subjects. In addition, 76 (0.7%) of the subjects had inverted T waves present only in leads other than V(1) to V(3). Right precordial T-wave inversions did not predict increased mortality (not significant for all end points). However, inverted T waves in leads other than V(1) to V(3) were associated with an increased risk of cardiac and arrhythmic death (P<0.001 for both).

CONCLUSIONS

T-wave inversions in right precordial leads are relatively rare in the general population, and are not associated with adverse outcome. Increased mortality risk associated with inverted T waves in other leads may reflect the presence of an underlying structural heart disease.

Intraventricular Conduction Delay in a Standard 12-Lead Electrocardiogram as a Predictor of Mortality in the General Population

Background—

Prolonged duration of QRS complex in a 12-lead ECG is associated with adverse prognosis in patients with cardiac disease, but its significance is not well established in the general population. In particular, there is a paucity of data on the prognostic significance of nonspecific intraventricular conduction delay in apparently healthy subjects.

Methods and Results—

We evaluated the 12-lead ECGs of 10 899 Finnish middle-aged subjects from the general population (52% of whom were men; mean age 44±8.5 years) between 1966 and 1972 and followed them for 30±11 years. Primary end points were all-cause mortality, cardiac mortality, and arrhythmic death. Prolonged QRS duration was defined as QRS ≥110 ms and intraventricular conduction delay as QRS ≥110 ms, without the criteria of complete or incomplete bundle-branch block. QRS duration ≥110 ms was present in 1.3% (n=147) and intraventricular conduction delay in 0.6% (n=67) of the subjects. Prolonged QRS duration predicted all-cause mortality (multivariate-adjusted relative risk [RR] 1.48; 95% confidence interval [CI] 1.22–1.81; P <0.001), cardiac mortality (RR 1.94; CI 1.44–2.63; P <0.001), and sudden arrhythmic death (RR 2.14; CI 1.38–3.33; P =0.002). Subjects with intraventricular conduction delay had increased all-cause mortality (RR 2.01; CI 1.52–2.66; P <0.001), increased cardiac mortality (RR 2.53; CI 1.64–3.90; P <0.001), and an elevated risk of arrhythmic death (RR 3.11; CI 1.74–5.54; P =0.001). Left bundle-branch block also weakly predicted arrhythmic death ( P =0.04), but right bundle-branch block was not associated with increased mortality.

Conclusions—

Prolonged QRS duration in a standard 12-lead ECG is associated with increased mortality in a general population, with intraventricular conduction delay being most strongly associated with an increased risk of arrhythmic death.

Early repolarization: electrocardiographic phenotypes associated with favorable long-term outcome

BACKGROUND

Early repolarization (ER) in inferior/lateral leads of standard ECGs increases the risk of arrhythmic death. We tested the hypothesis that variations in the ST-segment characteristics after the ER waveforms may have prognostic importance.

METHODS AND RESULTS

ST segments after ER were classified as horizontal/descending or rapidly ascending/upsloping on the basis of observations from 2 independent samples of young healthy athletes from Finland (n=62) and the United States (n=503), where ascending type was the dominant and common form of ER. Early repolarization was present in 27/62 (44%) of the Finnish athletes and 151/503 (30%) of the US athletes, and all but 1 of the Finnish (96%) and 91/107 (85%) of US athletes had an ascending/upsloping ST variant after ER. Subsequently, ECGs from a general population of 10 864 middle-aged subjects were analyzed to assess the prognostic modulation of ER-associated risk by ST-segment variations. Subjects with ER ≥0.1 mV and horizontal/descending ST variant (n=412) had an increased hazard ratio of arrhythmic death (relative risk 1.43; 95% confidence interval 1.05 to 1.94). When modeled for higher amplitude ER (>0.2 mV) in inferior leads and horizontal/descending ST-segment variant, the hazard ratio of arrhythmic death increased to 3.14 (95% confidence interval 1.56 to 6.30). However, in subjects with ascending ST variant, the relative risk for arrhythmic death was not increased (0.89; 95% confidence interval 0.52 to 1.55).

CONCLUSIONS

ST-segment morphology variants associated with ER separates subjects with and without an increased risk of arrhythmic death in middle-aged subjects. Rapidly ascending ST segments after the J-point, the dominant ST pattern in healthy athletes, seems to be a benign variant of ER.

Long-term outcome associated with early repolarization on electrocardiography

BACKGROUND

Early repolarization, which is characterized by an elevation of the QRS-ST junction (J point) in leads other than V(1) through V(3) on 12-lead electrocardiography, has been associated with vulnerability to ventricular fibrillation, but little is known about the prognostic significance of this pattern in the general population.

METHODS

We assessed the prevalence and prognostic significance of early repolarization on 12-lead electrocardiography in a community-based general population of 10,864 middle-aged subjects (mean [+/-SD] age, 44+/-8 years). The primary end point was death from cardiac causes, and secondary end points were death from any cause and death from arrhythmia during a mean follow-up of 30+/-11 years. Early repolarization was stratified according to the degree of J-point elevation (> or = 0.1 mV or > 0.2 mV) in either inferior or lateral leads.

RESULTS

The early-repolarization pattern of 0.1 mV or more was present in 630 subjects (5.8%): 384 (3.5%) in inferior leads and 262 (2.4%) in lateral leads, with elevations in both leads in 16 subjects (0.1%). J-point elevation of at least 0.1 mV in inferior leads was associated with an increased risk of death from cardiac causes (adjusted relative risk, 1.28; 95% confidence interval [CI], 1.04 to 1.59; P=0.03); 36 subjects (0.3%) with J-point elevation of more than 0.2 mV in inferior leads had a markedly elevated risk of death from cardiac causes (adjusted relative risk, 2.98; 95% CI, 1.85 to 4.92; P<0.001) and from arrhythmia (adjusted relative risk, 2.92; 95% CI, 1.45 to 5.89; P=0.01). Other electrocardiographic risk markers, such as a prolonged QT interval corrected for heart rate (P=0.03) and left ventricular hypertrophy (P=0.004), were weaker predictors of the primary end point.

CONCLUSIONS

An early-repolarization pattern in the inferior leads of a standard electrocardiogram is associated with an increased risk of death from cardiac causes in middle-aged subjects.