Electrocardiographic and clinical predictors separating atherosclerotic sudden cardiac death from incident coronary heart disease

Lifestyle habits associated with cardiac conduction disease

AIMS

Cardiac conduction disease can lead to syncope, heart failure, and death. The only available therapy is pacemaker implantation, with no established prevention strategies. Research to identify modifiable risk factors has been scant.

METHODS AND RESULTS

Data from the Cardiovascular Health Study, a population-based cohort study of adults ≥ 65 years with annual 12-lead electrocardiograms obtained over 10 years, were utilized to examine relationships between baseline characteristics, including lifestyle habits, and conduction disease. Of 5050 participants (mean age 73 ± 6 years; 52% women), prevalent conduction disease included 257 with first-degree atrioventricular block, 99 with left anterior fascicular block, 9 with left posterior fascicular block, 193 with right bundle branch block (BBB), 76 with left BBB, and 102 with intraventricular block at baseline. After multivariable adjustment, older age, male sex, a larger body mass index, hypertension, and coronary heart disease were associated with a higher prevalence of conduction disease, whereas White race and more physical activity were associated with a lower prevalence. Over a median follow-up on 7 (interquartile range 1-9) years, 1036 developed incident conduction disease. Older age, male sex, a larger BMI, and diabetes were each associated with incident conduction disease. Of lifestyle habits, more physical activity (hazard ratio 0.91, 95% confidence interval 0.84-0.98, P = 0.017) was associated with a reduced risk, while smoking and alcohol did not exhibit a significant association.

CONCLUSION

While some difficult to control comorbidities were associated with conduction disease as expected, a readily modifiable lifestyle factor, physical activity, was associated with a lower risk.

Prolongation of the heart rate-corrected QT interval is associated with cardiovascular diseases: Systematic review and meta-analysis

BACKGROUND

Conflicting findings have described the association between prolonged heart rate-corrected QT interval (QTc) and cardiovascular disease.

AIMS

To identify articles investigating the association between QTc and cardiovascular disease morbidity and mortality, and to summarize the available evidence for the general and type 2 diabetes populations.

METHODS

A systematic search was performed in PubMed and Embase in May 2022 to identify studies that investigated the association between QTc prolongation and cardiovascular disease in both the general and type 2 diabetes populations. Screening, full-text assessment, data extraction and risk of bias assessment were performed independently by two reviewers. Effect estimates were pooled across studies using random-effect models.

RESULTS

Of the 59 studies included, 36 qualified for meta-analysis. Meta-analysis of the general population studies showed a significant association for: overall cardiovascular disease (fatal and non-fatal) (hazard ratio [HR] 1.68, 95% confidence interval [CI] 1.33-2.12; I²=69%); coronary heart disease (fatal and non-fatal) in women (HR 1.27, 95% CI 1.08-1.50; I²=38%; coronary heart disease (fatal and non-fatal) in men (HR 2.07, 95% CI 1.26-3.39; I²=78%); stroke (HR 1.59, 95% CI 1.29-1.96; I²=45%); sudden cardiac death (HR 1.60, 95% CI 1.14-2.25; I²=68%); and atrial fibrillation (HR 1.55, 95% CI 1.31-1.83; I²=0.0%). No significant association was found for cardiovascular disease in the type 2 diabetes population.

CONCLUSION

QTc prolongation was associated with risk of cardiovascular disease in the general population, but not in the type 2 diabetes population.

Prediction of Sudden Cardiac Death Manifesting With Documented Ventricular Fibrillation or Pulseless Ventricular Tachycardia

OBJECTIVES

This study aimed to develop a novel clinical prediction algorithm for avertable sudden cardiac death.

BACKGROUND

Sudden cardiac death manifests as ventricular fibrillation (VF)/ ventricular tachycardia (VT) potentially treatable with defibrillation, or nonshockable rhythms (pulseless electrical activity/asystole) with low likelihood of survival. There are no available clinical risk scores for targeted prediction of VF/VT.

METHODS

Subjects with out-of-hospital sudden cardiac arrest presenting with documented VF or pulseless VT (33% of total cases) were ascertained prospectively from the Portland, Oregon, metro area with population ≈1 million residents (n = 1,374, 2002-2019). Comparisons of lifetime clinical records were conducted with a control group (n = 1,600) with ≈70% coronary disease prevalence. Prediction models were constructed from a training dataset using backwards stepwise logistic regression and applied to an internal validation dataset. Receiver operating characteristic curves (C statistic) were used to evaluate model discrimination. External validation was performed in a separate, geographically distinct population (Ventura County, California, population ≈850,000, 2015-2020).

RESULTS

A clinical algorithm (VFRisk) constructed with 13 clinical, electrocardiogram, and echocardiographic variables had very good discrimination in the training dataset (C statistic = 0.808; [95% CI: 0.774-0.842]) and was successfully validated in internal (C statistic = 0.776 [95% CI: 0.725-0.827]) and external (C statistic = 0.782 [95% CI: 0.718-0.846]) datasets. The algorithm substantially outperformed the left ventricular ejection fraction (LVEF) ≤35% (C statistic = 0.638) and performed well across the LVEF spectrum.

CONCLUSIONS

An algorithm for prediction of sudden cardiac arrest manifesting with VF/VT was successfully constructed using widely available clinical and noninvasive markers. These findings have potential to enhance primary prevention, especially in patients with mid-range or preserved LVEF.

Higher Serum Urate Levels Are Associated With an Increased Risk for Sudden Cardiac Death

OBJECTIVE

To determine the association of serum urate (SU) levels with sudden cardiac death and incident coronary heart disease (CHD), separately, among adults without a history of CHD.

METHODS

We conducted a case-cohort analysis of Black and White participants aged ≥ 45 years enrolled in the REason for Geographic And Racial Differences in Stroke (REGARDS) study without a history of CHD at baseline between 2003 and 2007. Participants were followed for sudden cardiac death or incident CHD (i.e., myocardial infarction [MI] or death from CHD excluding sudden cardiac death) through December 31, 2013. Baseline SU was measured in a random sample of participants (n = 840) and among participants who experienced sudden cardiac death (n = 235) or incident CHD (n = 851) during follow-up.

RESULTS

Participants with higher SU levels were older and more likely to be male or Black. The crude HR (95% CI) per 1 mg/dL higher SU level was 1.26 (1.14-1.40) for sudden cardiac death and 1.17 (1.09-1.26) for incident CHD. After adjustment for age, sex, race, and cardiovascular risk factors, the HR (95% CI) per 1 mg/dL higher SU level was 1.19 (1.03-1.37) for sudden cardiac death and 1.05 (0.96-1.15) for incident CHD. HRs for sudden cardiac death were numerically higher among participants aged 45-64 vs ≥ 65 years, without vs with diabetes, and among those of White vs Black race, although P values for effect modification were all ≥ 0.05.

CONCLUSION

Higher SU levels were associated with an increased risk for sudden cardiac death but not with incident CHD.

Early Detection of Sudden Cardiac Death by Using Ensemble Empirical Mode Decomposition-Based Entropy and Classical Linear Features From Heart Rate Variability Signals

Sudden cardiac death (SCD), which can deprive a person of life within minutes, is a destructive heart abnormality. Thus, providing early warning information for patients at risk of SCD, especially those outside hospitals, is essential. In this study, we investigated the performances of ensemble empirical mode decomposition (EEMD)-based entropy features on SCD identification. EEMD-based entropy features were obtained by using the following technology: (1) EEMD was performed on HRV beats to decompose them into intrinsic mode functions (IMFs), (2) five entropy parameters, namely Rényi entropy (RenEn), fuzzy entropy (FuEn), dispersion Entropy (DisEn), improved multiscale permutation entropy (IMPE), and Renyi distribution entropy(RdisEn), were computed from the first four IMFs obtained, which were named EEMD-based entropy features. Additionally, an automated scheme combining EEMD-based entropy and classical linear (time and frequency domains) features was proposed with the intention of detecting SCD early by analyzing 14 min (at seven successive intervals of 2 min) heart rate variability (HRV) in signals from a normal population and subjects at risk of SCD. Firstly, EEMD-based entropy and classical linear measurements were extracted from HRV beats, and then the integrated measurements were ranked by various methodologies, i.e., t-test, entropy, receiver-operating characteristics (ROC), Wilcoxon, and Bhattacharyya. Finally, these ranked features were fed into a k-Nearest Neighbor algorithm for classification. Compared with several state-of-the-art methods, the proposed scheme firstly predicted subjects at risk of SCD up to 14 min earlier with an accuracy of 96.1%, a sensitivity of 97.5%, and a specificity of 94.4% 14 min before SCD onset. The simulation results exhibited that EEMD-based entropy estimators showed significant difference between SCD patients and normal individuals and outperformed the classical linear estimators in SCD detection, the EEMD-based FuEn and IMPE indexes were particularly useful assessments for identification of patients at risk of SCD and can be used as novel indices to reveal the disorders of rhythm variations of the autonomic nervous system when affected by SCD.

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.

Associations between QT interval subcomponents, HIV serostatus, and inflammation

Background

The total QT interval comprises both ventricular depolarization and repolarization currents. Understanding how HIV serostatus and other risk factors influence specific QT interval subcomponents could improve our mechanistic understanding of arrhythmias.

Methods

Twelve‐lead electrocardiograms (ECGs) were acquired in 774 HIV‐infected (HIV+) and 652 HIV‐uninfected (HIV−) men from the Multicenter AIDS Cohort Study. Individual QT subcomponent intervals were analyzed: R‐onset to R‐peak, R‐peak to R‐end, JT segment, T‐onset to T‐peak, and T‐peak to T‐end. Using multivariable linear regressions, we investigated associations between HIV serostatus and covariates, including serum concentrations of inflammatory biomarkers such as interleukin‐6 (IL‐6), and each QT subcomponent.

Results

After adjustment for demographics and risk factors, HIV+ versus HIV− men differed only in repolarization phase durations with longer T‐onset to T‐peak by 2.3 ms (95% CI 0–4.5, p < .05) and T‐peak to T‐end by 1.6 ms (95% CI 0.3–2.9, p < .05). Adjusting for inflammation attenuated the strength and significance of the relationship between HIV serostatus and repolarization. The highest tertile of IL‐6 was associated with a 7.3 ms (95% CI 3.2–11.5, p < .01) longer T‐onset to T‐peak. Age, race, body mass index, alcohol use, and left ventricular hypertrophy were each associated with up to 2.2–12.5 ms longer T‐wave subcomponents.

Conclusions

HIV seropositivity, in combination with additional risk factors including increased systemic inflammation, is associated with longer T‐wave subcomponents. These findings could suggest mechanisms by which the ventricular repolarization phase is lengthened and thereby contribute to increased arrhythmic risk in men living with HIV.

Relation of the CHA2DS2-VASc Score to Risk of Thrombotic and Embolic Stroke in Community-Dwelling Individuals Without Atrial Fibrillation (From The Atherosclerosis Risk in Communities [ARIC] Study)

Recent hospital-based cohort studies found the CHA₂DS₂-VASc score to be associated with ischemic stroke in individuals without atrial fibrillation (AF). Our aim was to determine the distribution of embolic and thrombotic strokes and association with the CHA₂DS₂-VASc score, among community-dwelling individuals without AF. We included participants from the Atherosclerosis Risk in Communities (ARIC) Study who attended visit 4 (1996 to 1998) and had no previous AF, stroke, or anticoagulant use (n = 10,671). During follow-up through 2008, incident AF cases (n = 760) and participants who started warfarin were censored. Incident AF was ascertained from study electrocardiograms and hospital discharge diagnosis codes, and stroke was physician-adjudicated. After 10 years of follow-up, 280 ischemic strokes were identified, of which 146 were thrombotic and 57 embolic. The hazard ratios (95% confidence intervals [CI]) for thrombotic stroke were 1 (reference), 1.71 (1.13 to 2.59), 2.92 (1.91 to 4.45), 3.22 (1.70 to 6.11), and 1.25 (0.17 to 9.09), with CHA₂DS₂-VASc scores of 0 to 1, 2, 3, 4, and ≥5, respectively. The hazard ratios (95% CI) for embolic stroke were 1 (ref), 4.91 (2.10 to 11.5), 7.07 (2.93 to 17.0), 14.8 (5.50 to 39.6), and 15.2 (3.16 to 73.3), with CHA₂DS₂-VASc scores of 0 to 1, 2, 3, 4, and ≥5, respectively. A receiver-operating characteristic model had a C-statistic of 0.65 for ischemic stroke, 0.61 for thrombotic stroke, and 0.71 for embolic stroke. In conclusion, in community-dwelling individuals without AF, the CHA₂DS₂-VASc score can assess ischemic stroke risk and has good discriminatory capacity for embolic stroke.

Development of algorithms for identifying fatal cardiovascular disease in Medicare claims

BACKGROUND

Cause of death is often not available in administrative claims data.

OBJECTIVE

To develop claims-based algorithms to identify deaths due to fatal cardiovascular disease (CVD; ie, fatal coronary heart disease [CHD] or stroke), CHD, and stroke.

METHODS

Reasons for Geographic and Racial Differences in Stroke (REGARDS) study data were linked with Medicare claims to develop the algorithms. Events adjudicated by REGARDS study investigators were used as the gold standard. Stepwise selection was used to choose predictors from Medicare data for inclusion in the algorithms. C-index, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were used to assess algorithm performance. Net reclassification index (NRI) was used to compare the algorithms with an approach of classifying all deaths within 28 days following hospitalization for myocardial infarction and stroke to be fatal CVD.

RESULTS

Data from 2,685 REGARDS participants with linkage to Medicare, who died between 2003 and 2013, were analyzed. The C-index for discriminating fatal CVD from other causes of death was 0.87. Using a cut-point that provided the closest observed-to-predicted number of fatal CVD events, the sensitivity was 0.64, specificity 0.90, PPV 0.65, and NPV 0.90. The algorithms resulted in positive NRIs compared with using deaths within 28 days following hospitalization for myocardial infarction and stroke. Claims-based algorithms for discriminating fatal CHD and fatal stroke performed similarly to fatal CVD.

CONCLUSION

The claims-based algorithms developed to discriminate fatal CVD events from other causes of death performed better than the method of using hospital discharge diagnosis codes.

Electrical risk score beyond the left ventricular ejection fraction: prediction of sudden cardiac death in the Oregon Sudden Unexpected Death Study and the Atherosclerosis Risk in Communities Study

Aims

There is an urgent need to extend sudden cardiac death (SCD) risk stratification beyond the left ventricular ejection fraction (LVEF). We evaluated whether a cumulative electrocardiogram (ECG) risk score would improve identification of individuals at high risk of SCD.

Methods and results

In the community-based Oregon Sudden Unexpected Death Study (catchment population ∼1 million), 522 SCD cases with archived 12-lead ECG available (65.3 ± 14.5 years, 66% male) were compared with 736 geographical controls to assess the incremental value of multiple ECG parameters in SCD prediction. Heart rate, LV hypertrophy, QRS transition zone, QRS-T angle, QTc, and Tpeak-to-Tend interval remained significant in the final model, which was externally validated in the Atherosclerosis Risk in Communities (ARIC) Study. Sixteen percent of cases and 3% of controls had ≥4 abnormal ECG markers. After adjusting for clinical factors and LVEF, increasing ECG risk score was associated with progressively greater odds of SCD. Overall, subjects with ≥4 ECG abnormalities had an odds ratio (OR) of 21.2 for SCD [95% confidence interval (CI) 9.4-47.7; P < 0.001]. In the LVEF >35% subgroup, the OR was 26.1 (95% CI 9.9-68.5; P < 0.001). The ECG risk score increased the C-statistic from 0.625 to 0.753 (P < 0.001), with net reclassification improvement of 0.319 (P < 0.001). In the ARIC cohort validation, risk of SCD associated with ≥4 ECG abnormalities remained significant after multivariable adjustment (hazard ratio 4.84; 95% CI 2.34-9.99; P < 0.001; C-statistic improvement 0.759-0.774; P = 0.019).

Conclusion

This novel cumulative ECG risk score was independently associated with SCD and was particularly effective for LVEF >35% where risk stratification is currently unavailable. These findings warrant further evaluation in prospective clinical investigations.

Predictors of sudden cardiac death in atrial fibrillation: The Atherosclerosis Risk in Communities (ARIC) study

We previously reported that incident atrial fibrillation (AF) is associated with an increased risk of sudden cardiac death (SCD) in the general population. We now aimed to identify predictors of SCD in persons with AF from the Atherosclerosis Risk in Communities (ARIC) study, a community-based cohort study. We included all participants who attended visit 1 (1987-89) and had no prior AF (n = 14,836). Incident AF was identified from study electrocardiograms and hospitalization discharge codes through 2012. SCD was physician-adjudicated. We used cause-specific Cox proportional hazards models, followed by stepwise selection (backwards elimination, removing all variables with p>0.10) to identify predictors of SCD in participants with AF. AF occurred in 2321 (15.6%) participants (age 45-64 years, 58% male, 18% black). Over a median of 3.3 years, SCD occurred in 110 of those with AF (4.7%). Predictors of SCD in AF included higher age, body mass index (BMI), coronary heart disease, hypertension, diabetes, current smoker, left ventricular hypertrophy, increased heart rate, and decreased albumin. Predictors associated only with SCD and not other cardiovascular (CV) death included increased BMI (HR per 5-unit increase, 1.15, 95% CI, 0.97-1.36, p = 0.10), increased heart rate (HR per SD increase, 1.18, 95% CI 0.99-1.41, p = 0.07), and low albumin (HR per SD decrease 1.23, 95% CI 1.02-1.48, p = 0.03). In the ARIC study, predictors of SCD in AF that are not associated with non-sudden CV death included increased BMI, increased heart rate, and low albumin. Further research to confirm these findings in larger community-based cohorts and to elucidate the underlying mechanisms to facilitate prevention is warranted.

Association Between QT-Interval Components and Sudden Cardiac Death: The ARIC Study (Atherosclerosis Risk in Communities)

BACKGROUND

Several reports have demonstrated that prolongation of the QT interval is associated with sudden cardiac death (SCD). However, it is unknown whether any of the components within the QT interval are responsible for its association with SCD.

METHODS AND RESULTS

We examined the association of the individual QT-interval components (R-wave onset to R-peak, R-peak to R-wave end, ST-segment, T-wave onset to T-peak, and T-peak to T-wave end) with SCD in 12 241 participants (54±5.7 years; 26% black; 55% women) from the ARIC study (Atherosclerosis Risk in Communities). The QT interval and its components were measured at baseline (1987-1989) from 12-lead ECGs. SCD cases were adjudicated by a group of physicians through December 31, 2012. During a median follow-up of 23.6 years, a total of 346 cases of SCD were identified. Although prolongation of the QT interval was associated with a 49% increased risk of SCD (hazard ratio, 1.49; 95% confidence interval, 1.01-2.18), only the T-wave onset to T-peak component (per 1-SD increase: hazard ratio, 1.19; 95% confidence interval, 1.06-1.34) was associated with SCD and not any of the other components in separate models. When all of the QT-interval components were included in the same model, T-wave onset to T-peak remained the strongest predictor of SCD (per 1-SD increase: hazard ratio, 1.21; 95% confidence interval, 1.06-1.37).

CONCLUSIONS

The risk of SCD with the QT interval is driven by prolongation of the T-wave onset to T-peak component. This suggests that shifting the focus from the overall QT interval to its individual components will refine SCD prediction in the community.

Black-White Differences in Incident Fatal, Nonfatal, and Total Coronary Heart Disease

BACKGROUND

Blacks have higher coronary heart disease (CHD) mortality compared with whites. However, a previous study suggests that nonfatal CHD risk may be lower for black versus white men.

METHODS

We compared fatal and nonfatal CHD incidence and CHD case-fatality among blacks and whites in the Atherosclerosis Risk in Communities study (ARIC), the Cardiovascular Health Study (CHS), and the Reasons for Geographic and Racial Differences in Stroke study (REGARDS) by sex. Participants 45 to 64 years of age in ARIC (men=6479, women=8488) and REGARDS (men=5296, women=7822), and ≥65 years of age in CHS (men=1836, women=2790) and REGARDS (men=3381, women=4112), all without a history of CHD, were analyzed. Fatal and nonfatal CHD incidence was assessed from baseline (ARIC=1987-1989, CHS=1989-1990, REGARDS=2003-2007) through up to 11 years of follow-up.

RESULTS

Age-adjusted hazard ratios comparing black versus white men 45 to 64 years of age in ARIC and REGARDS were 2.09 (95% confidence interval, 1.42-3.06) and 2.11 (1.32-3.38), respectively, for fatal CHD, and 0.82 (0.64-1.05) and 0.94 (0.69-1.28), respectively, for nonfatal CHD. After adjustment for social determinants of health and cardiovascular risk factors, hazard ratios in ARIC and REGARDS were 1.19 (95% confidence interval, 0.74-1.92) and 1.09 (0.62-1.93), respectively, for fatal CHD, and 0.64 (0.47-0.86) and 0.67 (0.48-0.95), respectively, for nonfatal CHD. Similar patterns were present among men ≥65 years of age in CHS and REGARDS. Among women 45 to 64 years of age in ARIC and REGARDS, age-adjusted hazard ratios comparing blacks versus whites were 2.61 (95% confidence interval, 1.57-4.34) and 1.79 (1.06-3.03), respectively, for fatal CHD, and 1.47 (1.13-1.91) and 1.29 (0.91-1.83), respectively, for nonfatal CHD. After multivariable adjustment, hazard ratios in ARIC and REGARDS were 0.67 (95% confidence interval, 0.36-1.24) and 1.00 (0.54-1.85), respectively, for fatal CHD, and 0.70 (0.51-0.97) and 0.70 (0.46-1.06), respectively, for nonfatal CHD. Racial differences in CHD incidence were attenuated among older women. CHD case fatality was higher among black versus white men and women, and the difference remained similar after multivariable adjustment.

CONCLUSIONS

After accounting for social determinants of health and risk factors, black men and women have similar risk for fatal CHD compared with white men and women, respectively. However, the risk for nonfatal CHD is consistently lower for black versus white men and women.

Distinguishing between those dying suddenly or not suddenly from coronary heart disease: long-term prospective results from the Northwick Park Heart Study

AIM

To establish whether ECG findings are associated with subsequent risk of sudden death from coronary heart disease (CHD).

METHODS AND RESULTS

Potential risk factors for CHD were measured at entry to the first Northwick Park Heart Study of 2167 men. ECG findings were coded as high or low risk for CHD according to definitions in the Minnesota code. Sudden or non-sudden deaths were defined as occurring in less than or more than 24 hours, respectively. The only factor independently associated with sudden death among the 262 men dying of CHD was high-risk ECG. Of 184 sudden CHD deaths, 34 men (18.5%) had had high-risk ECGs at entry to the study compared with 5 (6.4%) of 78 men who experienced non-sudden deaths (adjusted OR 3.94 (95% CI 1.33 to 11.67)) (p=0.006). Findings were also compared among all 2167 men, where high-risk ECGs were again associated with sudden death. T-wave changes were the main abnormalities associated with a high risk of sudden death.

CONCLUSIONS

In a group of men who had not previously experienced major episodes of CHD but who subsequently died from it, there was strong evidence that high-risk ECG changes, mainly T-wave abnormalities, differentiated between those who later died sudden deaths and those who survived for >24 hours.

Serum Potassium, Mortality, and Kidney Outcomes in the Atherosclerosis Risk in Communities Study

OBJECTIVES

To investigate the association between serum potassium, mortality, and kidney outcomes in the general population and whether potassium-altering medications modify these associations.

PATIENTS AND METHODS

We studied 15,539 adults in the Atherosclerosis Risk in Communities Study. Cox proportional hazard regression was used to investigate the association of serum potassium at baseline (1987-1989), evaluated categorically (hypokalemia, <3.5 mmol/L; normokalemia, ≥3.5 and <5.5 mmol/L; hyperkalemia, ≥5.5 mmol/L) and continuously using linear spline terms (knots at 3.5 and 5.5 mmol/L), with mortality, sudden cardiac death, incident chronic kidney disease, and end-stage renal disease. The end date of follow-up for all outcomes was December 31, 2012. We also evaluated whether classes of potassium-altering medications modified the association between serum potassium and adverse outcomes.

RESULTS

Overall, 413 (2.7%) of the participants had hypokalemia and 321 (2.1%) had hyperkalemia. In a fully adjusted model, hyperkalemia was significantly associated with mortality (hazard ratio, 1.24; 95% CI, 1.04-1.49) but not sudden cardiac death, chronic kidney disease, or end-stage renal disease. Hypokalemia as a categorical variable was not associated with any outcome; however, associations of hypokalemia with all-cause mortality and kidney outcomes were observed among those who were not taking potassium-wasting diuretics (all P for interaction, <.001).

CONCLUSIONS

Higher values of serum potassium were associated with a higher risk of mortality in the general population. Lower levels of potassium were associated with adverse kidney outcomes and mortality among participants not taking potassium-wasting diuretics.

Development and Validation of a Sudden Cardiac Death Prediction Model for the General Population

BACKGROUND

Most sudden cardiac death (SCD) events occur in the general population among persons who do not have any prior history of clinical heart disease. We sought to develop a predictive model of SCD among US adults.

METHODS

We evaluated a series of demographic, clinical, laboratory, electrocardiographic, and echocardiographic measures in participants in the ARIC study (Atherosclerosis Risk in Communities) (n=13 677) and the CHS (Cardiovascular Health Study) (n=4207) who were free of baseline cardiovascular disease. Our initial objective was to derive a SCD prediction model using the ARIC cohort and validate it in CHS. Independent risk factors for SCD were first identified in the ARIC cohort to derive a 10-year risk model of SCD. We compared the prediction of SCD with non-SCD and all-cause mortality in both the derivation and validation cohorts. Furthermore, we evaluated whether the SCD prediction equation was better at predicting SCD than the 2013 American College of Cardiology/American Heart Association Cardiovascular Disease Pooled Cohort risk equation.

RESULTS

There were a total of 345 adjudicated SCD events in our analyses, and the 12 independent risk factors in the ARIC study included age, male sex, black race, current smoking, systolic blood pressure, use of antihypertensive medication, diabetes mellitus, serum potassium, serum albumin, high-density lipoprotein, estimated glomerular filtration rate, and QTc interval. During a 10-year follow-up period, a model combining these risk factors showed good to excellent discrimination for SCD risk (c-statistic 0.820 in ARIC and 0.745 in CHS). The SCD prediction model was slightly better in predicting SCD than the 2013 American College of Cardiology/American Heart Association Pooled Cohort risk equations (c-statistic 0.808 in ARIC and 0.743 in CHS). Only the SCD prediction model, however, demonstrated similar and accurate prediction for SCD using both the original, uncalibrated score and the recalibrated equation. Finally, in the echocardiographic subcohort, a left ventricular ejection fraction <50% was present in only 1.1% of participants and did not enhance SCD prediction.

CONCLUSIONS

Our study is the first to derive and validate a generalizable risk score that provides well-calibrated, absolute risk estimates across different risk strata in an adult population of white and black participants without a clinical diagnosis of cardiovascular disease.

Adiposity throughout adulthood and risk of sudden cardiac death in women

BACKGROUND

Sudden cardiac death (SCD) is often the first manifestation of coronary heart disease (CHD) among women. Data regarding BMI and risk of SCD are limited and conflicting.

OBJECTIVES

We examined the association of BMI repeatedly measured over 32 years and BMI during early and mid-adulthood with risk of SCD in the Nurses' Health Study.

METHODS

We prospectively followed 72,484 women free of chronic disease from 1980-2012. We ascertained adult height, current weight, and weight at age 18 at baseline and updated weight biennially. The primary endpoint was SCD (n=445).

RESULTS

When updated biennially, higher BMI was associated with greater SCD risk after adjusting for confounders (p, linear trend: <0.001). Compared to a BMI of 21.0-22.9, the multivariate RR (95%CI) of SCD was 1.46 (1.05, 2.04) for BMI 25.0-29.9, 1.46 (1.00, 2.13) for BMI 30.0-34.9 and 2.18 (1.44, 3.28) for BMI ≥35.0. Among women with a BMI ≥35.0, SCD remained elevated even after adjustment for interim development of CHD and other mediators (RR: 1.72; 95%CI: 1.13, 2.60). In contrast, the association between BMI and fatal CHD risk was completely attenuated after adjustment for mediators. The magnitude of the association between BMI and SCD was greater when BMI was assessed at baseline or at age 18, at which time SCD risk remained significantly elevated at BMI≥30 after adjustment for mediators.

CONCLUSIONS

Higher BMI was associated with greater risk of SCD, particularly when assessed earlier in adulthood. Strategies to maintain a healthy weight throughout adulthood may minimize SCD incidence.

Electrocardiographic Predictors of Cardiovascular Mortality

Cardiovascular diseases are the main causes of mortality. Sudden cardiac death may also appear in athletes, due to underlying congenital or inherited cardiac abnormalities. The electrocardiogram is used in clinical practice and clinical trials, as a valid, reliable, accessible, inexpensive method. The aim of the present paper was to review electrocardiographic (ECG) signs associated with cardiovascular mortality and the mechanisms underlying those associations, providing a brief description of the main studies in this area, and consider their implication for clinical practice in the general population and athletes. The main ECG parameters associated with cardiovascular mortality in the present paper are the P wave (duration, interatrial block, and deep terminal negativity of the P wave in V1), prolonged QT and Tpeak-Tend intervals, QRS duration and fragmentation, bundle branch block, ST segment depression and elevation, T waves (inverted, T wave axes), spatial angles between QRS and T vectors, premature ventricular contractions, and ECG hypertrophy criteria.

Beneficial clinical effects of grape seed proanthocyanidin extract on the progression of carotid atherosclerotic plaques

BACKGROUND

Atherosclerotic plaques indicate the occurrence of ischemia events and it is a difficult task for clinical physicians. Grape seed proanthocyanidin extract (GSPE) has been reported to exert an antiatherogenic effect by inducing regression of atherosclerotic plaques in animal experimental studies. In this study, the antiatherogenic effect of GSPE has been investigated in clinical use.

METHODS

Consecutive 287 patients diagnosed with asymptomatic carotid plaques or abnormal plaque free carotid intima-media thickness (CIMT) were randomly assigned to the GSPE group (n = 146) or control group (n = 141). The patients in the GSPE group received GSPE 200 mg per day orally, while patients in the control group were only enrolled in a lifestyle intervention program. Carotid ultrasound examination was performed at baseline and 6, 12, 24 months during follow-up. Mean maximum CIMT (MMCIMT), plaque score, echogenicity of plaques and ischemic vascular events were recorded.

RESULTS

As anticipated, after treatment, GSPE resulted in significant reduction in MMCIMT progression (4.2% decrease after six months, 4.9% decrease after 12 months and 5.8% decrease after 24 months) and plaque score (10.9% decrease after six months, 24.1% decrease after 12 months and 33.1% decrease after 24 months) for the primary outcome, while MMCIMT and plaque score were stable and even increased with the time going on in control group. The number of plaques and unstable plaques also decreased after treatment of GSPE. Furthermore, the carotid plaque can disappear after treatment with GSPE. The incidence rate for transitory ischemic attack (TIA), arterial revascularization procedure, and hospital readmission for unstable angina in GSPE group were statistically significant lower (P = 0.02, 0.08, 0.002, respectively) compared with the control group.

CONCLUSIONS

GSPE inhibited the progression of MMCIMT and reduced carotid plaque size in GSPE treated patients, and with extended treatment, the superior efficacy on MMCIMT and carotid plaque occurred. Furthermore, the GSPE group showed lower rates of clinical vascular events.

Increased prevalence of ECG markers for sudden cardiac arrest in refractory epilepsy

BACKGROUND AND AIM

People with epilepsy are at increased risk of sudden cardiac arrest (SCA) due to ECG-confirmed ventricular tachycardia/fibrillation, as seen in a community-based study. We aimed to determine whether ECG-risk markers of SCA are more prevalent in people with epilepsy.

METHODS

In a cross-sectional, retrospective study, we analysed the ECG recordings of 185 people with refractory epilepsy and 178 controls without epilepsy. Data on epilepsy characteristics, cardiac comorbidity, and drug use were collected, and general ECG variables (heart rate (HR), PQ and QRS intervals) assessed. We analysed ECGs for three markers of SCA risk: severe QTc prolongation (male >450 ms, female >470 ms), Brugada ECG pattern, and early repolarisation pattern (ERP). Multivariate regression models were used to analyse differences between groups, and to identify associated clinical and epilepsy-related characteristics.

RESULTS

People with epilepsy had higher HR (71 vs 62 bpm, p<0.001) and a longer PQ interval (162.8 vs 152.6 ms, p=0.001). Severe QTc prolongation and ERP were more prevalent in people with epilepsy (QTc prolongation: 5% vs 0%; p=0.002; ERP: 34% vs 13%, p<0.001), while the Brugada ECG pattern was equally frequent in both groups (2% vs 1%, p>0.999). After adjustment for covariates, epilepsy remained associated with ERP (ORadj 2.4, 95% CI 1.1 to 5.5) and severe QTc prolongation (ORadj 9.9, 95% CI 1.1 to 1317.7).

CONCLUSIONS

ERP and severe QTc prolongation appear to be more prevalent in people with refractory epilepsy. Future studies must determine whether this contributes to increased SCA risk in people with epilepsy.

Beat-to-beat spatiotemporal variability in the T vector is associated with sudden cardiac death in participants without left ventricular hypertrophy: the Atherosclerosis Risk in Communities (ARIC) Study

Background

Despite advances in prevention and treatment of cardiovascular disease, sudden cardiac death (SCD) remains a clinical challenge. Risk stratification in the general population is needed.

Methods and Results

Beat‐to‐beat spatiotemporal variability in the T vector was measured as the mean angle between consecutive T‐wave vectors (mean TT′ angle) on standard 12‐lead ECGs in 14 024 participants in the Atherosclerosis Risk in Communities (ARIC) study. Subjects with left ventricular hypertrophy, atrial arrhythmias, frequent ectopy, ventricular pacing, or QRS duration ≥120 ms were excluded. The mean spatial TT′ angle was 5.21±3.55°. During a median of 14 years of follow‐up, 235 SCDs occurred (1.24 per 1000 person‐years). After adjustment for demographics, coronary heart disease risk factors, and known ECG markers for SCD, mean TT′ angle was independently associated with SCD (hazard ratio 1.089; 95% CI 1.044 to 1.137; P<0.0001). A mean TT′ angle >90th percentile (>9.57°) was associated with a 2‐fold increase in the hazard for SCD (hazard ratio 2.01; 95% CI 1.28 to 3.16; P=0.002). In a subgroup of patients with T‐vector amplitude ≥0.2 mV, the association with SCD was almost twice as strong (hazard ratio 3.92; 95% CI 1.91 to 8.05; P<0.0001). A significant interaction between mean TT′ angle and age was found: TT′ angle was associated with SCD in participants aged <55 years (hazard ratio 1.096; 95% CI 0.043 to 1.152; P<0.0001) but not in participants aged ≥55 years (P_interaction=0.009).

Conclusions

In a large, prospective, community‐based cohort of left ventricular hypertrophy–free participants, increased beat‐to‐beat spatiotemporal variability in the T vector, as assessed by increasing TT′ angle, was associated with SCD.

Electrocardiographic deep terminal negativity of the P wave in V(1) and risk of sudden cardiac death: the Atherosclerosis Risk in Communities (ARIC) study

Background

Identifying individuals at risk for sudden cardiac death (SCD) is of critical importance. Electrocardiographic (ECG) deep terminal negativity of P wave in V₁ (DTNPV1), a marker of left atrial abnormality, has been associated with increased risk of all‐cause and cardiovascular mortality. We hypothesized that DTNPV1 is associated with increased risk of sudden cardiac death (SCD).

Methods and Results

This analysis included 15 375 participants (54.1±5.8 years, 45% men, 73% whites) from the Atherosclerosis Risk in Communities (ARIC) study. DTNPV1 was defined from the resting 12‐lead ECG as presence of biphasic P wave (positive/negative) in V₁ with the amplitude of the terminal negative phase >100 μV, or one small box on ECG scale. After a median of 14 years of follow‐up, 311 cases of SCD occurred. In unadjusted Cox regression, DTNPV1 was associated with an 8‐fold increased risk of SCD (HR 8.21; [95%CI 5.27 to 12.79]). Stratified by race and study center, and adjusted for age, sex, coronary heart disease (CHD), and ECG risk factors, as well as atrial fibrillation (AF), stroke, CHD, and heart failure (HF) as time‐updated variables, the risk of SCD associated with DTNPV1 remained significant (2.49, [1.51–4.10]). DTNPV1 improved reclassification: additional 3.4% of individuals were appropriately reclassified into a higher SCD risk group, as compared with traditional CHD risk factors alone. In fully adjusted models DTNPV1 was associated with increased risk of non‐fatal events: AF (5.02[3.23–7.80]), CHD (2.24[1.43–3.53]), HF (1.90[1.19–3.04]), and trended towards increased risk of stroke (1.88[0.99–3.57]).

Conclusion

DTNPV1 is predictive of SCD suggesting its potential utility in risk stratification in the general population.

Risk stratification for sudden cardiac death: current status and challenges for the future

Sudden cardiac death (SCD) remains a daunting problem. It is a major public health issue for several reasons: from its prevalence (20% of total mortality in the industrialized world) to the devastating psycho-social impact on society and on the families of victims often still in their prime, and it represents a challenge for medicine, and especially for cardiology. This text summarizes the discussions and opinions of a group of investigators with a long-standing interest in this field. We addressed the occurrence of SCD in individuals apparently healthy, in patients with heart disease and mild or severe cardiac dysfunction, and in those with genetically based arrhythmic diseases. Recognizing the need for more accurate registries of the global and regional distribution of SCD in these different categories, we focused on the assessment of risk for SCD in these four groups, looking at the significance of alterations in cardiac function, of signs of electrical instability identified by ECG abnormalities or by autonomic tests, and of the progressive impact of genetic screening. Special attention was given to the identification of areas of research more or less likely to provide useful information, and thereby more or less suitable for the investment of time and of research funds.

Abnormal electrocardiographic QRS transition zone and risk of mortality in individuals free of cardiovascular disease

AIMS

We examined the prognostic significance of abnormal electrocardiographic QRS transition zone (clockwise and counterclockwise horizontal rotations) in individuals free of cardiovascular disease (CVD).

METHODS AND RESULTS

A total of 5541 adults (age 53 ± 10.4 years, 54% women, 24% non-Hispanic black, 25% Hispanic) without CVD or any major electrocardiogram (ECG) abnormalities from the US Third National Health and Nutrition Examination Survey were included in this analysis. Clockwise and counterclockwise horizontal rotations were defined from standard 12-lead ECG using Minnesota ECG Classification. Mortality and cause of death were assessed through 2006. At baseline, 282 participants had clockwise rotation and 3500 had counterclockwise rotation. During a median follow of 14.6 years, 1229 deaths occurred of which 415 were due to CVD. In multivariable-adjusted Cox proportional hazard analysis and compared with normal rotation, clockwise rotation was significantly associated with increased risk of all-cause mortality {hazard ratio (HR) [95% confidence interval (CI)]: 1.43 (1.15-1.78); P = 0.002} and CVD mortality [HR (95% CI): 1.61 (1.09, 2.37) P = 0.016]. In contrast, counterclockwise rotation was associated with significantly lower risk of all-cause mortality [HR (95% CI): 0.86 (0.76, 0.97); P = 0.017] and non-significant association with CVD mortality [HR (95% CI): 1.07 (0.86, 1.33); P = 0.549]. These results were consistent in subgroup analysis stratified by age, sex, and race.

CONCLUSION

In a diverse community-based population free of CVD and compared with normal rotation, clockwise rotation was associated with increased risk of all-cause and CVD mortality while counterclockwise rotation was associated with lower risk of all-cause mortality and non-significant association with CVD mortality. These findings call for attention to these often neglected ECG markers, and probably call for revising the current definition of normal rotation.

Pentoxifylline alleviates cardiac ischemia and dysfunction following experimental angina in insulin resistance

We have previously shown that pentoxifylline (PTX) protects from vascular complications associated with insulin resistance (IR). Here, we investigated the protective effect of PTX against cardiac ischemia and dysfunction following experimental angina in IR. IR, along with its accompanying cardiac dysfunction, was induced in rats by a high-fructose (10% in drinking water) high-fat diet for 12 weeks. PTX was administered daily (30 mg⋅kg(-1)) during the last 4 weeks of the study. Experimental angina was induced by isoproterenol (10 µg⋅kg(-1)) administered by intravenous injection. Both before (baseline) and after the experimental angina, cardiac contractility was assessed by continuous recording in anesthetized rats via a microtip catheter inserted in the left ventricle, and cardiac conductivity was determined by a surface electrocardiograph. Serum glucose, insulin, tumor necrosis factor-α (TNFα), and adiponectin levels and lipid profile were also determined. Feeding the rats a high-fructose high-fat diet produced IR, as evidenced by significant hyperinsulinemia and hyperglycemia, and PTX administration did not affect this IR. When subjected to experimental angina, IR hearts were less resistant to the ischemia following induction of angina (reflected by the large ST height depression) compared with controls, and PTX completely prevented the excessive ST height depression in IR animals. In addition, left ventricular pressure development was largely attenuated during and after induction of angina in IR animals compared with controls. PTX administration prevented the excessive attenuation in ventricular pressure development in IR animals. IR was associated with elevated levels of the inflammatory cytokine TNFα, whereas PTX treatment elevated the serum level of the anti-inflammatory cytokine adiponectin. PTX alleviates cardiac ischemia and dysfunction following experimental angina in IR directly through inhibition of the low-grade inflammation that accompanies IR.

Investigation on cardiovascular risk prediction using physiological parameters

Cardiovascular disease (CVD) is the leading cause of death worldwide. Early prediction of CVD is urgently important for timely prevention and treatment. Incorporation or modification of new risk factors that have an additional independent prognostic value of existing prediction models is widely used for improving the performance of the prediction models. This paper is to investigate the physiological parameters that are used as risk factors for the prediction of cardiovascular events, as well as summarizing the current status on the medical devices for physiological tests and discuss the potential implications for promoting CVD prevention and treatment in the future. The results show that measures extracted from blood pressure, electrocardiogram, arterial stiffness, ankle-brachial blood pressure index (ABI), and blood glucose carry valuable information for the prediction of both long-term and near-term cardiovascular risk. However, the predictive values should be further validated by more comprehensive measures. Meanwhile, advancing unobtrusive technologies and wireless communication technologies allow on-site detection of the physiological information remotely in an out-of-hospital setting in real-time. In addition with computer modeling technologies and information fusion. It may allow for personalized, quantitative, and real-time assessment of sudden CVD events.

Cardiomyocyte injury assessed by a highly sensitive troponin assay and sudden cardiac death in the community: the Cardiovascular Health Study

OBJECTIVES

This study sought to determine the association between markers of cardiomyocyte injury in ambulatory subjects and sudden cardiac death (SCD).

BACKGROUND

The pathophysiology of SCD is complex but is believed to be associated with an abnormal cardiac substrate in most cases. The association between biomarkers of cardiomyocyte injury in ambulatory subjects and SCD has not been investigated.

METHODS

Levels of cardiac troponin T, a biomarker of cardiomyocyte injury, were measured by a highly sensitive assay (hsTnT) in 4,431 ambulatory participants in the Cardiovascular Health Study, a longitudinal community-based prospective cohort study. Serial measures were obtained in 3,089 subjects. All deaths, including SCD, were adjudicated by a central events committee.

RESULTS

Over a median follow-up of 13.1 years, 246 participants had SCD. Baseline levels of hsTnT were significantly associated with SCD (hazard ratio [HR] for +1 log(hsTnT): 2.04, 95% confidence interval [CI]: 1.78 to 2.34]. This association persisted in covariate-adjusted Cox analyses accounting for baseline risk factors (HR: 1.30, 95% CI: 1.05 to 1.62), as well as for incident heart failure and myocardial infarction (HR: 1.26, 95% CI: 1.01 to 1.57). The population was also categorized into 3 groups based on baseline hsTnT levels and SCD risk [fully adjusted HR: 1.89 vs. 1.55 vs. 1 (reference group) for hsTnT ≥12.10 vs. 5.01 to 12.09 vs. ≤ 5.00 pg/ml, respectively; p trend = 0.005]. On serial measurements, change in hsTnT levels was also associated with SCD risk (fully adjusted HR for +1 pg/ml per year increase from baseline: 1.03, 95% CI: 1.01 to 1.06).

CONCLUSIONS

The findings suggest an association between cardiomyocyte injury in ambulatory subjects and SCD risk beyond that of traditional risk factors.

Electrocardiogram as a screening tool in the general population: a strategic review

Sudden cardiac death (SCD) is a major public health concern, accounting for 400,000 deaths in the US each year. Clinical and autopsy studies have consistently demonstrated a predominant, common pathophysiology in Western populations, showing that the most common electrophysiological mechanism of SCD is ventricular fibrillation, and the most common pathologic substrate is coronary heart disease (CHD). In about half of SCD cases, death is the first clinical manifestation of CHD. Yet risk factors of SCD early in the natural history of conditions predisposing SCD have not been fully identified, and SCD risk stratification strategy in the general population has not been developed. ECG is an easily available, non-expensive and non-invasive tool, which carries valuable information on electrophysiological properties of the heart. However, traditional analysis of ECG includes very limited assessment of the arrhythmogenic substrate. In this review rationale for development of ECG SCD risk score for screening in the general population is discussed.

Almanac 2013: cardiac arrhythmias and pacing

Important advances have been made in the past few years in the fields of clinical cardiac electrophysiology and pacing. Researchers and clinicians have a greater understanding of the pathophysiological mechanisms underlying atrial fibrillation (AF), which has transpired into improved methods of detection, risk stratification, and treatments. The introduction of novel oral anticoagulants has provided clinicians with alternative options in managing patients with AF at moderate to high thromboembolic risk and further data has been emerging on the use of catheter ablation for the treatment of symptomatic AF. Another area of intense research in the field of cardiac arrhythmias and pacing is in the use of cardiac resynchronisation therapy (CRT) for the treatment of patients with heart failure. Following the publication of major landmark randomised controlled trials reporting that CRT confers a survival advantage in patients with severe heart failure and improves symptoms, many subsequent studies have been performed to further refine the selection of patients for CRT and determine the clinical characteristics associated with a favourable response. The field of sudden cardiac death and implantable cardioverter defibrillators also continues to be actively researched, with important new epidemiological and clinical data emerging on improved methods for patient selection, risk stratification, and management. This review covers the major recent advances in these areas related to cardiac arrhythmias and pacing.

Atrial fibrillation and the risk of sudden cardiac death: the atherosclerosis risk in communities study and cardiovascular health study

BACKGROUND

It is unknown whether atrial fibrillation (AF) is associated with an increased risk of sudden cardiac death (SCD) in the general population. This association was examined in 2 population-based cohorts.

METHODS

In the Atherosclerosis Risk in Communities (ARIC) Study, we analyzed data from 15 439 participants (baseline age, 45-64 years; 55.2% women; and 26.6% black) from baseline (1987-1989) through December 31, 2001. In the Cardiovascular Health Study (CHS), we analyzed data from 5479 participants (baseline age, ≥65 years; 58.2% women; and 15.4% black) from baseline (first cohort, 1989-1990; second cohort, 1992-1993) through December 31, 2006. The main outcome was physician-adjudicated SCD, defined as death from a sudden, pulseless condition presumed to be due to a ventricular tachyarrhythmia. The secondary outcome was non-SCD (NSCD), defined as coronary heart disease death not meeting SCD criteria. We used Cox proportional hazards models to assess the association between AF and SCD/NSCD, adjusting for baseline demographic and cardiovascular risk factors.

RESULTS

In the ARIC Study, 894 AF, 269 SCD, and 233 NSCD events occurred during follow-up (median, 13.1 years). The crude incidence rates of SCD were 2.89 per 1000 person-years (with AF) and 1.30 per 1000 person-years (without AF). The multivariable hazard ratios (HRs) (95% CIs) of AF for SCD and NSCD were 3.26 (2.17-4.91) and 2.43 (1.60-3.71), respectively. In the CHS, 1458 AF, 292 SCD, and 581 NSCD events occurred during follow-up (median, 13.1 years). The crude incidence rates of SCD were 12.00 per 1000 person-years (with AF) and 3.82 per 1000 person-years (without AF). The multivariable HRs (95% CIs) of AF for SCD and NSCD were 2.14 (1.60-2.87) and 3.10 (2.58-3.72), respectively. The meta-analyzed HRs (95% CIs) of AF for SCD and NSCD were 2.47 (1.95-3.13) and 2.98 (2.52-3.53), respectively.

CONCLUSIONS

Incident AF is associated with an increased risk of SCD and NSCD in the general population. Additional research to identify predictors of SCD in patients with AF is warranted.

Association of race and sex with risk of incident acute coronary heart disease events

CONTEXT

It is unknown whether long-standing disparities in incidence of coronary heart disease (CHD) among US blacks and whites persist.

OBJECTIVE

To examine incident CHD by black and white race and by sex.

DESIGN, SETTING, AND PARTICIPANTS

Prospective cohort study of 24,443 participants without CHD at baseline from the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort, who resided in the continental United States and were enrolled between 2003 and 2007 with follow-up through December 31, 2009.

MAIN OUTCOME MEASURE

Expert-adjudicated total (fatal and nonfatal) CHD, fatal CHD, and nonfatal CHD (definite or probable myocardial infarction [MI]; very small non-ST-elevation MI [NSTEMI] had peak troponin level <0.5 μg/L).

RESULTS

Over a mean (SD) of 4.2 (1.5) years of follow-up, 659 incident CHD events occurred (153 in black men, 138 in black women, 254 in white men, and 114 in white women). Among men, the age-standardized incidence rate per 1000 person-years for total CHD was 9.0 (95% CI, 7.5-10.8) for blacks vs 8.1 (95% CI, 6.9-9.4) for whites; fatal CHD: 4.0 (95% CI, 2.9-5.3) vs 1.9 (95% CI, 1.4-2.6), respectively; and nonfatal CHD: 4.9 (95% CI, 3.8-6.2) vs 6.2 (95% CI, 5.2-7.4). Among women, the age-standardized incidence rate per 1000 person-years for total CHD was 5.0 (95% CI, 4.2-6.1) for blacks vs 3.4 (95% CI, 2.8-4.2) for whites; fatal CHD: 2.0 (95% CI, 1.5-2.7) vs 1.0 (95% CI, 0.7-1.5), respectively; and nonfatal CHD: 2.8 (95% CI, 2.2-3.7) vs 2.2 (95% CI, 1.7-2.9). Age- and region-adjusted hazard ratios for fatal CHD among blacks vs whites was near 2.0 for both men and women and became statistically nonsignificant after multivariable adjustment. The multivariable-adjusted hazard ratio for incident nonfatal CHD for blacks vs whites was 0.68 (95% CI, 0.51-0.91) for men and 0.81 (95% CI, 0.58-1.15) for women. Of the 444 nonfatal CHD events, 139 participants (31.3%) had very small NSTEMIs.

CONCLUSIONS

The higher risk of fatal CHD among blacks compared with whites was associated with cardiovascular disease risk factor burden. These relationships may differ by sex.