Role of the electrocardiogram in identifying the patient at increased risk for sudden death

Develop and Apply Electrocardiography-Based Risk Score to Identify Community-Based Elderly Individuals at High-Risk of Mortality

With an aging world population, risk stratification of community-based, elderly population is required for primary prevention. This study proposes a combined score developed using electrocardiographic (ECG) parameters and determines its long-term prognostic value for predicting risk of cardiovascular mortality. A cohort-study, conducted from December 2008 to April 2019, enrolled 5,380 subjects in Taiwan, who were examined, using three-serial-12-lead ECGs, and their health/demographic information were recorded. To understand the predictive effects of ECG parameters on overall-survival, Cox hazard regression analysis were performed. The mean age at enrollment was 69.04 ± 8.14 years, and 47.4% were males. ECG abnormalities, LVH [hazard ratio (HR) = 1.39, 95% confidence intervals (CI) = (1.16–1.67), P = 0.0003], QTc [HR = 1.31, CI = (1.07–1.61), P = 0.007] and PR interval [HR = 1.40, CI = (1.01–1.95), P = 0.04], were significantly associated with primary outcome all-cause death. Furthermore, LVH [HR = 2.37, CI = (1.48–3.79), P = 0.0003] was significantly associated with cardiovascular death, while PR interval [HR = 2.63, CI = (1.24– 5.57), P = 0.01] with unexplained death. ECG abnormality (EA) score was defined based on the number of abnormal ECG parameters for each patient, which was used to divide all patients into sub-groups. Competing risk survival analysis using EA score were performed by using the Gray's test, which reported that high-risk EA groups showed significantly higher cumulative incidence for all three outcomes. Prognostic models using the EA score as predictor were developed and a 10-fold cross validation design was adopted to conduct calibration and discrimination analysis, to establish the efficacy of the proposed models. Overall, ECG model could successfully predict people, susceptible to all three death outcomes (P < 0.05), with high efficacy. Statistically significant (P < 0.001) improvement of the c-indices further demonstrated the robustness of the prediction model with ECG parameters, as opposed to a traditional model with no EA predictor. The EA score is highly associated with increased risk of mortality in elderly population and may be successfully used in clinical practice.

Incidence of and risk factors for bundle branch block in adults older than 40 years

BACKGROUND

In the general population, the incidence of bundle branch block (BBB) is relatively low, and its effects on long-term prognosis have not been established. Previous studies on the incidence and correlation of BBB to clinical factors have produced conflicting results. However, the incidence of BBB was strongly related to age. This study aimed to describe the incidence of and risk factors for BBB in Korea.

METHODS

In this study, 14,540 adults (male 6,573/female 7,967) > or = 40 years old received screening tests for general health between April and December 2000. Participants answered questionnaires and underwent examinations, which included blood pressure, electrocardiogram (ECG), total cholesterol and fasting glucose. The data analysis was performed using SPSS 10.0 for windows.

RESULTS

The incidences of complete right bundle branch block (CRBBB) were 1.5 and 2.9% in people older than 40 and 65 years, respectively. Approximately 38.0% of individuals with CRBBB were older than 65 years. The incidence of CRBBB was higher in men than women at all age groups was highest in those aged 75-79 years. Males, advancing age (> or = 65 years), hypertension and diabetes mellitus (DM) were associated with an increased risk of CRBBB. The incidences of complete left bundle branch block (LBBB) and bifascicular bundle branch block (BBBB) were 0.1 and 0.08% and 0.3 and 0.2% in those older than 40 and 65 years, respectively. Approximately 71.4 and 58.3% of individuals with LBBB and BBBB, respectively, were older than 65 years. Advancing age and cardiac disease were associated with an increased risk of LBBB. Advancing age was associated with an increased risk of BBBB. The most potent risk factor for BBB in this study was advancing age.

CONCLUSION

The incidences of BBB were 1.7 and 3.4% in those older than 40 and 65 years respectively. Bundle branch block correlates strongly with age, and is common in the older ages groups. These findings support the theory that bundle branch block is a marker of slowly progressing degenerative diseases.

Window to the heart: the value of a native and paced QRS duration. Current perspective and review

Given the technological advances and reliance upon expensive testing for guiding therapy, it is surprising how an inexpensive, low tech electrocardiogram can provide a wealth of information pertaining to the underlying cardiovascular status of a patient. In this article we review the changes in hemodynamics, prognosis and guidance of therapeutic options associated with a prolonged QRS duration.

Complete bundle branch block as an independent predictor of all-cause mortality: report of 7,073 patients referred for nuclear exercise testing

PURPOSE

Complete left bundle branch block is a well-established independent risk factor for mortality, but the prognostic importance of right bundle branch block is unclear. We determined whether left and right bundle branch block was associated with all-cause mortality risk after adjustment for potential confounders, including clinical, exercise, and nuclear scintigraphic variables.

SUBJECTS AND METHODS

We studied 7,073 adults who were referred for symptom-limited nuclear exercise testing. Patients with heart failure or pacemakers were excluded. The presence or absence of bundle branch block was determined from resting electrocardiograms. The main outcome measure was all-cause mortality during a mean of 6.7 years of follow-up.

RESULTS

One hundred ninety patients (3%) had complete right bundle branch block, and 150 (2%) had complete left bundle branch block. There were 825 deaths (12%). Mortality was greater in patients with complete right bundle branch block (24% [46 of 190]) or left bundle branch block (24% [36 of 150]) than in those without these findings (11% [779 of 6,883 and 789 of 6,923, respectively]; both P <0.0001). After adjustment for potential confounders, right bundle branch block was as strong an independent predictor of mortality (hazard ratio [HR] 1.5; 95% confidence interval [CI]: 1.1 to 2.1; P = 0.007) as left bundle branch block (HR 1.5; 95% CI: 1.0 to 2.0; P = 0.017). Incomplete right bundle branch block was not associated with mortality.

CONCLUSION

Complete right and left bundle branch block are independent predictors of all-cause mortality risk even after adjustment for exercise capacity, nuclear perfusion defects, and other risk factors.

First- or second-degree atrioventricular block as a risk factor in idiopathic dilated cardiomyopathy

To evaluate the significance of clinical, hemodynamic and electrocardiographic risk factors in idiopathic dilated cardiomyopathy 94 patients were followed prospectively for 49 +/- 37 months. During follow-up, 30 patients died, 13 died suddenly, 13 died of congestive heart failure and 4 of other causes. Follow-up was completed in 85 patients, and overall cardiac mortality was 31%. Univariate analysis revealed left ventricular ejection fraction among 20 variables as the major indicator of risk of both cardiac death of all causes and sudden cardiac death separately. Multivariate overall analysis determined 3 independent risk factors in the following order for all causes of cardiac death: Ventricular pairs > 40/24 hours (RR 7.2, p < 0.0001), left ventricular ejection fraction < or = 35% (RR 6.5, p < 0.001) and first- or second-degree atrioventricular (AV) block (RR 3.1, p < 0.05). In the subset of patients with ejection fraction < or = 35% ventricular pairs > 40 per 24 hours (RR 10.7, p < 0.001), AV block (RR 3.9, p < 0.05), and the missing administration of vasodilators (RR 3.3, p < 0.05) were the most important. The chief risk factors for sudden cardiac death were age (RR 7.4, p < 0.01) and AV block (RR 4.6, p < 0.05) by adjustment for age, and ejection fraction < or = 35% (RR 7.1, p < 0.01) and AV block (RR 4.2, p < 0.05) if not adjusted for age. A differentiation into 4 risk groups was attempted. The additional independent prognostic importance of AV block was shown, especially in combination with reduced ejection fraction or a high incidence of ventricular pairs.(ABSTRACT TRUNCATED AT 250 WORDS)

Medical costs of coronary artery disease in the United States

A model has been developed to determine the cost of coronary artery disease (CAD) based on the 5 primary events identified in the Framingham Study: acute myocardial infarction, angina pectoris, unstable angina pectoris, sudden death and nonsudden death. The costs for diagnostic and therapeutic service for patients with CAD were linked to medical decision algorithms outlining the diagnosis and management of patients with CAD. Because CAD is a changing illness not represented by a single event, the algorithm tracked patients for 5 years after the time of diagnosis, or until death, to develop average cost estimates. The estimated 5-year costs (in 1986 United States dollars) of the 5 CAD events were: acute myocardial infarction $51,211, angina pectoris $24,980, unstable angina pectoris $40,581, sudden death $9,078 and nonsudden death $19,697. The costs of major CAD surgical procedures were also calculated because of their impact on health care costs for patients with CAD. These include: coronary artery bypass surgery per case over 5 years $32,465, and angioplasty per case over 5 years $26,916. The high cost of CAD reflects the improved technology and more effective and expensive therapies now available.

Transseptal left heart catheterisation in infants, children, and young adults

Over a 5 yr period, from October 1983 to September 1988, transseptal left heart catheterisation, using Mullins long-sheath technique, was performed in 217 infants, children, and young adults, with various forms of congenital or acquired heart disease. The mean age was 50 +/- 45 months, (range 1 mo to 21 yr). The procedure was successful in 215 (99%) patients. Pericardial puncture occurred in three patients (1.4%), though without tamponade or sequelae. There was no mortality or morbidity. Transseptal left heart catheterisation is a safe procedure for studying the left side of the heart. In addition, and of increasing importance, it allows the performance of interventional procedures on the left side of the heart and avoids the use of retrograde catheterisation through the femoral arteries.

Risk factor profiles of patients with sudden cardiac death and death from other cardiac causes: a report from the Coronary Artery Surgery Study (CASS)

Identification of patients at risk of sudden death is essential if optimal preventive treatment strategies are to be developed. In the Coronary Artery Surgery Study (CASS) Registry, 19,946 patients were analyzed to characterize baseline clinical, hemodynamic and angiographic features of patients dying from sudden cardiac death and to compare them with features of patients dying from other cardiac causes, of those dying from noncardiac causes and of survivors. Of the 11,843 medically treated patients, 1,621 died during a mean follow-up period of 5.0 years: death was sudden in 557 (34%), nonsudden but cardiac in 813 (50%) and noncardiac in 251 (16%). In 8,103 surgically treated patients, 824 deaths occurred during a mean follow-up period of 5.1 years: death was sudden in 204 (25%), nonsudden but cardiac in 390 (47%) and noncardiac in 230 (28%). In general, the patients (both medically and surgically treated) who died of cardiac causes, either suddenly or nonsuddenly, were similar to each other but significantly different from patients who either survived or died of noncardiac causes. Although patients with an increased risk of any type of cardiac death could be identified, there were no measures of angiographic or hemodynamic characteristics that were significantly different between patients with sudden cardiac death and those with nonsudden cardiac death. Identification of patients at high risk for sudden cardiac death will require approaches in addition to clinical, angiographic and hemodynamic assessment, such as electrophysiologic assessment or monitoring techniques to identify triggering mechanisms.

The electrocardiogram in prediction of sudden death: Framingham Study experience

The influence of ECG abnormalities on the incidence of sudden cardiac death is examined in the Framingham Study cohort and is compared with the effect of known cardiovascular risk factors. Although many individual ECG abnormalities are associated with SD, multiple regression analysis, including non-ECG variables, leaves fewer independently related ECG sudden death risk factors: ECG-MI and IVB in those with overt CHD, LVH and tachycardia in all men and in women without CHD, and nonspecific ST-T abnormalities only in men. VPBs appear to be without an independent influence. Inclusion of ECG variables in the predictive model for SD has little effect on identifying those at risk for sudden unexpected death, but it improves substantially the predictive value in persons with known CHD.