Risk of mortality associated to chronic kidney disease in patients with complete left bundle branch block

Chronic kidney disease (CKD) is associated with cardiac conduction defects and is a strong risk factor for heart failure. Complete left bundle branch block (cLBBB), a cardiac conduction abnormality, may have an unfavorable effect on ventricular mechanical synchrony and lead to the progression of heart failure. Once heart failure develops, it seems to act together with underlying CKD in a vicious circle. Therefore, this study aimed to explore the influence of CKD in patients with cLBBB by assessing the estimated glomerular filtration rate (eGFR). We examined a hospital-based sample of 416 adult patients with cLBBB from 2010 to 2013. The eGFR was calculated using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Cox proportional hazard models were used to estimate the hazard ratio for all-cause mortality and cardiovascular mortality. A total of 416 adult patients with a mean age of 71 ± 13 years were enrolled. The median follow-up period was 3.6 years. After adjusting for clinical, electrocardiographic parameters, and medication use, cox regression analysis showed that total mortality was significantly associated with older age (Hazard Ratio (HR) = 1.03, 95% CI = 1.01-1.05, p = 0.002), presence of congestive heart failure (HR = 2.39, 95% CI = 1.63-3.49, p < 0.001), advanced CKD (HR = 2.48, 95% CI = 1.71-3.59, p < 0.001), higher HR (HR = 1.02, 95% CI = 1.01-1.03, p < 0.001) and without use of ACEI/ARB (HR = 0.59, 95% CI = 0.41-0.85, p = 0.005) were independent predictors of the total mortality. Multivariate Cox hazard regression analysis demonstrated that, in comparison to patients lacking cLBBB, the coexistence of CKD (eGFR < 60 mL/min/1.73 m2) among those with LBBB significantly heightened the risks of both total mortality (HR ratio of 5.01 vs. 2.40) and CV death (HR ratio of 61.78 vs. 14.41) even following adjustment for clinical covariates and ECG parameters. In summary, within patients exhibiting cLBBB, the presence of CKD serves as a significant risk factor for all-cause mortality.

Prevalence, Incidence and Prognostic Implications of Left Bundle Branch Block in Patients with Chronic Coronary Syndromes (From the CLARIFY Registry)

Left Bundle Branch Block (LBBB) is a frequently encountered electrical abnormality in patients with chronic (more than 3 months after myocardial infarction, or evidence of coronary artery disease with ischemia) coronary syndromes (CCS), but its prognostic significance remains unclear. We aimed to describe the prevalence, incidence and five-year outcomes of LBBB in outpatients with CCS using the CLARIFY registry. Main outcome was a composite of CV death, MI or stroke. Secondary outcomes included all cause death, hospitalization for heart failure (HF) and permanent pacemaker implantation. Among 23.544 patients with available information regarding LBBB status at baseline, 1.041 (4.4%) had LBBB at baseline and 1.015 (4.5%) patients developed a new LBBB during 5-year follow-up. In multivariate analysis, LBBB at baseline was not associated with the composite outcome of CV death, MI or stroke (HR 1.06, 95% CI [0.86 - 1.31], p = 0.67) or the risk of all-cause death (HR 1.07, 95% CI [0.87 - 1.32], p = 0.52) but was significantly associated with a higher risk of hospitalization for HF (HR 1.50, 95% CI [1.21 - 1.88], p < 0.001) and permanent pacemaker implantation (HR 2.11, 95% CI [1.45 - 3.07], p < 0.001). The main factors associated with new-onset LBBB were male sex (HR 0.8 [0.66-0.98], p = 0.028) history of atrial fibrillation (HR 1.29, 95% CI [1.01 - 1.64], p = 0.04), CABG (HR 1.27, [1.08 - 1.51], p = 0.004) and MI (HR 1.19, 95% CI [1.01 - 1.40], p = 0.034). In conclusion, in a contemporary registry of outpatients with CCS, the prevalence of LBBB was 4.4% and the additional 5-years incidence 6.2%. LBBB, in itself, was not associated with a higher risk of major adverse cardiovascular events or all cause mortality. It was however an independent predictor of risk of hospitalization for heart failure and permanent pacemaker implantation.

Intermittent left bundle branch block and acute heart failure in trastuzumab-induced cardiotoxicity

A 70-year-old woman with HER2+/ER+ breast cancer on adjuvant trastuzumab therapy without a history of cardiovascular disease presented with respiratory failure from influenza and was found to have intermittent left bundle branch block (LBBB) with new onset systolic heart failure. Her course was complicated by polymorphic ventricular tachycardia and recurrent chest pain. Significant investigations included a normal cardiac MRI and cardiac catheterisation with unobstructed coronaries. It was determined that the aetiology of her heart failure was trastuzumab-induced cardiotoxicity after comprehensive workup. This case highlights an uncommon presentation of LBBB and the steps taken to diagnose a rare cardiomyopathy.

[CME: Left Bundle Branch Block and Painful Left Bundle Branch Block Syndrome]

CME: Left Bundle Branch Block and Painful Left Bundle Branch Block Syndrome Abstract. Left bundle branch block (LBBB) is the electrocardiographic correlate of a pathologic transmission of the electrical signals in the myocardium which can lead to a dyssynchronous left ventricular activation and thus to an inefficient contraction of the ventricles. It is usually the expression of an underlying cardiopathy and represents an independent risk factor of cardiovascular mortality, therefore further examination is indicated in each case. Besides the treatment of an underlying disease, a specific therapy has been available since the introduction of cardiac resynchronization therapy (CRT). A rarer phenomenon is the painful left bundle branch block in structurally healthy hearts.

Electrocardiographic and echocardiographic features in patients with major arterial vascular disease assigned to surgical revascularization

Background: We aimed to depict the electrocardiographic and echocardiographic aspects in patients before elective major vascular surgery.Methods: We evaluated through standard 12 lead electrocardiography and transthoracic echocardiography 469 patients with asymptomatic large abdominal aortic aneurysm (AAA), 334 with critical carotid stenosis (CAS), and 238 with advanced peripheral artery disease (PAD) before surgical revascularization.Results: Patients with AAA were predominantly males (p < .001) with normal sinus rhythm (p = .026), were more affected by atrioventricular block (p = .033) and left anterior fascicular block (p < .001). They also presented larger aortic root size (p < .001) and septal hypertrophy (p = .036), in addition, atrial fibrillation was less frequent in the same group (p = .023). Patients with CAS were of older age (p < .001) with a substantial number of females (p < .001). They presented less left ventricular segmental kinetic disorders and fewer dilated ventricles (p = .004 and p < .001 respectively). Finally, those with PAD had reduced septal and posterior wall thickness (p < .01, p = .009 respectively), greater mitral and aortic annular calcification (p < .001), and were more affected by previous myocardial infarction (p < .001). The PR interval, left anterior fascicular block and aortic root size were independently associated with aneurysm, previous myocardial infarction with PAD, while smaller left ventricular end systolic volumes with carotid artery stenosis.Conclusions: Patients with AAA were mostly affected by cardiac conduction disorders, septal hypertrophy, aortic root dilation and less affected by atrial fibrillation. Patients with CAS were older with more normal sized ventricles, whereas, previous myocardial infarction was most common amongst patients with peripheral artery disease.

Implications of Left Bundle Branch Block in Takotsubo Cardiomyopathy: Propensity Match Analysis from the National Inpatient Sample

INTRODUCTION

Takotsubo cardiomyopathy (TTC), also called stress cardiomyopathy, is a transient reversible left ventricular dysfunction mimicking acute coronary syndrome (ACS). Studies have shown similar rates of in-hospital complications in TTC and myocardial infarction (MI). Left bundle branch block (LBBB) is associated with increased mortality in patients with MI; however, similar studies comparing outcomes of TTC in the presence of LBBB are lacking.

METHODS

The 2016 National Inpatient Sample (NIS) database was queried to identify all admissions with a primary discharge diagnosis of TTC. Diagnosis-specific codes were used to stratify patients based on the presence or absence of LBBB. Both population sets were paired using 1:10 propensity score matching. Multivariate logistic regression analysis was performed to compare various in-hospital outcomes among both groups.

RESULTS

Amongst 7270 admissions for TTC, 226 patients had concomitant LBBB. After performing 1:10 propensity matching, 130 patients with LBBB were compared to 1275 patients without LBBB. The presence of LBBB was associated with increased odds of cardiogenic shock (AOR = 2.2, 95% CI 1.21-3.99, p = 0.0097); ventricular arrhythmia (AOR 1.99, 95% CI 1.11-3.57, p = 0.02), acute congestive heart failure (AOR = 1.49, 95% CI 1.01-2.2, p = 0.04), and sudden cardiac arrest (AOR = 3.37, 95% CI 1.59-7.13, p = 0.0001). There was no statistical difference in all-cause in-hospital mortality, however a trend towards worsening was noted.

CONCLUSIONS

The incidence of arrhythmia and shock in patients with TTC does not correlate with the extent of myocardium involvement. The presence of LBBB in such cases can help recognize at-risk populations, and with timely intervention, life-threatening complications can be avoided. Despite limitations of the dataset and inability to establish causality, prospective studies with longer follow-up are warranted.

Effect of Left Ventricular Conduction Delay on All-Cause and Cardiovascular Mortality (from the PRECISION Trial)

The prognosis associated with prolonged intraventricular conduction on electrocardiogram (ECG) remains uncertain. We aimed to compare clinical outcomes of narrow versus prolonged intraventricular conduction on ECG stratified by QRS morphology and cardiovascular disease (CVD) status. A post-hoc analysis was performed of the randomized-control PRECISION trial. Patients with centrally adjudicated, nonpaced baseline ECGs were included. QRS duration was classified narrow (≤100 ms) versus prolonged (>100 ms) with additional categorization into left (LBBB) or right (RBBB) bundle branch block or nonspecific intraventricular conduction delay (IVCD). IVCD was subclassified if left ventricular conduction delay (LVCD) was present (L-IVCD) or absent (O-IVCD). The primary outcome was adjudicated all-cause and cardiovascular (CV) mortality. Of 24,081 patients randomized, 22,067 (92%) were included with follow-up 34 ± 13 months. Study patients were 63 ± 9 years, 64% female, 75% Caucasian, 23% with established CVD. The prevalence of QRS prolongation was 5.6% (1,240): 760 right bundle branch block (3.4%), 313 LBBB (1.4%), and 161 IVCD (0.7%), 95 subclassified L-IVCD (0.4%). After adjustment, LBBB and L-IVCD were similarly associated with increased all-cause (LBBB: 2.3 [1.4 to 3.8], p = 0.001; L-IVCD: 4.0 [2.1 to 7.9], p <0.001) and CV (LBBB: 3.6 [2.0 to 6.5], p <0.001; L-IVCD 3.6 [1.3 to 9.7], p = 0.001) mortality. The presence of LVCD (LBBB or L-IVCD) was associated with all-cause (2.8 [1.8 to 4.2], p <0.001) and CV (3.6 [2.2 to 6.1], p <0.001) mortality exceeding the observed risks of coronary artery disease, left ventricular hypertrophy, or diabetes. The LVCD hazard persisted across QRS durations (100 to 120 vs >120 ms) and CVD status. In conclusion, LVCD, whether LBBB or L-IVCD, was strongly associated with increased mortality in patients with and at-risk for CVD.

All-Cause Mortality for Life Insurance Applicants with the Presence of Bundle Branch Block

Objective.-To determine the all-cause mortality of life insurance applicants who have a bundle branch block. Background.-Bundle branch block is an electrocardiographic pattern that has variable prognostic implications. Research studies have shown that both left and right bundle branch block are associated with increased mortality among cases that have heart disease. In the general population and life insurance applicant population, the prevalence of bundle branch block is relatively low, and its effects on long-term prognosis are not as well established. Methodology.-Life insurance applicants with reported bundle branch block were extracted from data covering United States residents between October 2009 and October 2016. Information about these applicants was matched to the Social Security Death Master (SSDMF) file for deaths occurring from 2009 to 2012 and to another commercially available death source file (Other Death Source, ODS) for deaths occurring from 2009 to 2016 to determine vital status. Actual to expected (A/E) mortality ratios were calculated using the Society of Actuaries 2015 Valuation Basic Table (2015VBT), select and ultimate table (age last birthday). All expected bases were not smoker distinct. Confidence bands around these mortality ratios were calculated. The variables of interest were applicant age, gender, location of the bundle branch block, and the presence of cardiac or cardiovascular conditions. Results.-There were 258,529.85 person-years exposure for applicants with bundle branch block. Of the applicants, 57.2% had right bundle branch block. Of person-years exposure, 11.5% had a cardiac condition along with the bundle branch block, and 4.4% had an underlying cardiovascular condition. Female mortality ratios were higher than those for males, but due to the low number of deaths, this difference was not significant. Left bundle branch block mortality ratios (1.01) were 1.4 times higher than those with right (0.74). Those applicants with a cardiac condition along with their bundle branch block had between 1.6 to 1.8 times the mortality ratio depending on the bundle branch block location, and those with a cardiovascular condition had between 1.5 to 1.7 times the mortality ratio over those applicants with just bundle branch block alone. Conclusion.-The presence of bundle branch block in an insurance applicant may be associated with increased all-cause mortality. In this study, life insurance applicants overall had a mortality slightly lower than the expected mortality based on the 2015 VBT. However, applicants with bundle branch block and a cardiac or cardiovascular comorbid condition had a significantly higher mortality ratio.

Contemporary Review of Left Bundle Branch Block in the Failing Heart - Pathogenesis, Prognosis, and Therapy

Cardiac resynchronisation therapy (CRT) is a cornerstone in the contemporary management of heart failure. The most effective way of predicting response to this therapy remains electrocardiographic (ECG) criteria of electromechanical dyssynchrony. The left bundle branch block (LBBB) pattern is currently the most robust ECG criterion in predicting improvement in symptoms and reduction in mortality. However, recent studies using three-dimensional (3D) mapping and cardiac magnetic resonance imaging (CMR) have demonstrated heterogeneous left ventricular activation patterns in patients with LBBB. This has led to intense debate on the activation pattern of "true LBBB" and resulted in the proposal of stricter criteria for defining LBBB. This review will focus on the definitions and implications of LBBB in the CRT era. At a minimum, the use of stricter ECG criteria appears warranted, and adjunctive pre-implant imaging or mapping may further identify patient-specific electrophysiological patterns that determine response to CRT.

A Three-Decade Survival Analysis of Intraventricular Conduction Delay in Adults Without Ischemic Heart Disease

BACKGROUND

The prognosis of an incidental finding of intraventricular conduction delay in individuals without ischemic heart disease is debatable. Intraventricular conduction delay presents electrocardiographically as bundle branch block or nonspecific intraventricular conduction delay. We aimed to assess the long-term survival of an incidental intraventricular conduction delay finding in a cohort of individuals without ischemic heart disease, followed up for 3 decades.

METHODS

A randomized stratified cohort of the adult Israeli population underwent medical examinations and electrocardiography between 1976 and 1982. Patients with ischemic heart disease were excluded, and the cohort was followed for all-cause mortality for a median of 30.4 years. Major intraventricular conduction delay was defined as having complete bundle branch block or nonspecific intraventricular conduction delay, and minor intraventricular conduction delay was defined as having incomplete bundle branch block. Cox proportional hazard model was performed, comparing individuals by electrocardiogram finding, adjusting for demographic, clinical, and electrocardiographic variables.

RESULTS

Of 2465 subjects, 2385 (96.8%) were without intraventricular conduction delay, 38 (1.5%) had minor intraventricular conduction delay, and 42 (1.7%) had major intraventricular conduction delay. All-cause mortality rates were higher among minor and major intraventricular conduction delay groups (57.9% and 66.7%, P = .43 and P = .04, respectively) compared with no intraventricular conduction delay (52.1%). By controlling for sex, age, and body mass index, intraventricular conduction delay was not associated with all-cause mortality: hazard ratios, 0.82 (95% confidence interval, 0.52-1.25) and 1.06 (95% confidence interval, 0.72-1.54) for minor and major intraventricular conduction delay, respectively.

CONCLUSIONS

Intraventricular conduction delay was not found to be an independent risk factor for all-cause mortality in individuals without ischemic heart disease.

Ventricular conduction abnormalities as predictors of long-term survival in acute de novo and decompensated chronic heart failure

Aims

Data on the prognostic role of left and right bundle branch blocks (LBBB and RBBB), and nonspecific intraventricular conduction delay (IVCD; QRS ≥ 110 ms, no BBB) in acute heart failure (AHF) are controversial. Our aim was to investigate electrocardiographic predictors of long‐term survival in patients with de novo AHF and acutely decompensated chronic heart failure (ADCHF).

Methods and Results

We analysed the admission electrocardiogram of 982 patients from a multicenter European cohort of AHF with 3.9 years' mean follow‐up. Half (51.5%, n = 506) of the patients had de novo AHF. LBBB, and IVCD were more common in ADCHF than in de novo AHF: 17.2% vs. 8.7% (P < 0.001) and 20.6% vs. 13.2% (P = 0.001), respectively, and RBBB was almost equally common (6.9% and 8.1%; P = 0.5), respectively. Mortality during the follow‐up was higher in patients with RBBB (85.4%) and IVCD (73.7%) compared with patients with normal ventricular conduction (57.0%); P < 0.001 for both. The impact of RBBB on prognosis was prominent in de novo AHF (adjusted HR 1.93, 1.03–3.60; P = 0.04), and IVCD independently predicted death in ADCHF (adjusted HR 1.79, 1.28–2.52; P = 0.001). Both findings were pronounced in patients with reduced ejection fraction. LBBB showed no association with increased mortality in either of the subgroups. The main results were confirmed in a validation cohort of 1511 AHF patients with 5.9 years' mean follow‐up.

Conclusions

Conduction abnormalities predict long‐term survival differently in de novo AHF and ADCHF. RBBB predicts mortality in de novo AHF, and IVCD in ADCHF. LBBB has no additive predictive value in AHF requiring hospitalization.

Bundle branch blocks and the risk of mortality in the Atherosclerosis Risk in Communities study

AIMS

The main objective of our study was to evaluate the associations between different categories of bundle branch blocks (BBBs) and mortality and to consider possible impact of QRS prolongation in these associations.

METHODS

This analysis included 15 408 participants (mean age 54 years, 55.2% women, and 26.9% blacks) from the Atherosclerosis Risk in Communities study. We used Cox regression to examine associations between left BBB (LBBB), right BBB (RBBB) and indetermined type of ventricular conduction defect [intraventricular conduction defect (IVCD)] with coronary heart disease (CHD) death and all-cause mortality.

RESULTS

During a mean 21 years of follow-up, 4767 deaths occurred; of these, 728 were CHD deaths. Compared to No-BBB, LBBB and IVCD were strongly associated with increased CHD death (hazard ratios 4.11 and 3.18, respectively; P < 0.001 for both). Furthermore, compared to No-BBB with QRS duration less than 100 ms, CHD mortality risk was increased 1.33-fold for the No-BBB group with QRS duration 100-109 ms, and 1.48-fold with QRS duration 110-119 ms, 3.52-fold for pooled LBBB-IVCD group with QRS duration less than 140 ms and 4.96-fold for pooled LBBB-IVCD group with QRS duration at least 140 ms (P < 0.001). However, mortality risk was not significantly increased for lone RBBB. For all-cause mortality, trends similar to those for CHD death were observed within the BBB groups, although at lower levels of risk.

CONCLUSION

Prevalent LBBB and IVCD, but not RBBB, are associated with increased risk of CHD death and all-cause mortality. Mortality risk is further increased as the QRS duration is prolonged above 140 ms.

Ventricular conduction defects and the risk of incident heart failure in the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

We evaluated the risk of incident heart failure (HF) associated with various categories of ventricular conduction defects (VCDs) and examined the impact of QRS duration on the risk of HF.

METHODS AND RESULTS

This analysis included 14,478 participants from the Atherosclerosis Risk in Communities (ARIC) study who were free of HF at baseline. VCDs (n = 377) were categorized into right and left bundle branch blocks (RBBB and LBBB, respectively), bifascicular BBB (RBBB with fascicular block), indeterminate-type VCD (IVCD), and pooled VCD group excluding lone RBBB. During an average of 18 years' follow-up, 1,772 participants were hospitalized for incident HF. Compared with no VCD, LBBB and pooled VCD were strongly associated with increased risk of incident HF (multivariable hazard ratios 2.87 and 2.29, respectively). Compared with no VCD with QRS duration <100 ms, HF risk was 1.17-fold for the no VCD group with QRS duration 100-119 ms, 1.97-fold for the pooled VCD group with QRS duration 120-139 ms, and 3.25-fold for the pooled VCD group with QRS duration ≥140 ms. HF risk for the pooled VCD group remained significant (1.74-fold for QRS duration 120-139 ms and 2.81-fold for QRS duration ≥140 ms) in the subgroup free from cardiovascular disease at baseline. Lone RBBB was not associated with incident HF.

CONCLUSIONS

VCDs except for isolated RBBB are strong predictors of incident HF, and HF risk is further increased as the QRS duration is prolonged >140 ms.

QRS duration predicts death and hospitalization among patients with atrial fibrillation irrespective of heart failure: evidence from the AFFIRM study

AIMS

The association of QRS duration (QRSd) with morbidity and mortality is understudied in patients with atrial fibrillation (AF). We sought to assess any association of prolonged QRS with increased risk of death or hospitalization among patients with AF.

METHODS AND RESULTS

QRS duration was retrieved from the baseline electrocardiograms of patients enroled in the Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) study and divided into three categories: <90, 90-119, ≥120 ms. Cox models were applied relating the hazards of mortality and hospitalizations to QRSd. Among 3804 patients with AF, 593 died and 2305 were hospitalized. Compared with those with QRS < 90 ms, patients with QRS ≥ 120 ms, had an increased mortality [hazard ratio (HR) 1.61, 95% confidence interval (CI): 1.29-2.03, P < 0.001] and hospitalizations (HR 1.14, 95% CI: 1.07-1.34, P = 0.043) over an average follow-up of 3.5 years. Importantly, for patients with QRS 90-119 ms, mortality and hospitalization were also increased (HR 1.31, P = 0.005 and 1.11, P = 0.026, respectively). In subgroup analysis based on heart failure (HF) status (previously documented or ejection fraction <40%), mortality was increased for QRS ≥ 120 ms patients with (HR 1.87, P < 0.001) and without HF (HR 1.63, P = 0.02). In the QRS 90-119 ms group, mortality was increased (HR 1.38, P = 0.03) for those with HF, but not significantly among those without HF (HR 1.23, P = 0.14).

CONCLUSION

Among patients with AF, QRSd ≥ 120 ms was associated with a substantially increased risk for mortality (all-cause, cardiovascular, and arrhythmic) and hospitalization. Interestingly, an increased mortality was also observed among those with QRS 90-119 ms and concomitant HF.

Treatment strategies for the prevention of heart failure

With the astounding morbidity and mortality associated with heart failure (HF), preventive approaches have been explored. Controlling hypertension to prevent HF is well-established, especially with sodium restriction and thiazide-based antihypertensive therapies showing potential advantages. Control of dyslipidemia with aggressive statin therapy is particularly beneficial in preventing HF in the setting of acute coronary syndrome. The HOPE study also established the benefit of ACE inhibitors in the prevention of HF in high-risk subjects. Meanwhile old data supporting tight glycemic control in preventing HF have not been confirmed, suggesting the complexity of diabetic cardiomyopathy. Avoiding tobacco use and other known cardiotoxins are likely helpful. While there has been substantial development in identifying biomarkers predicting future development of HF, therapeutic interdiction guided by biomarker levels have yet to be established, even though it offers hope in modulating the natural history of the development of HF in at-risk individuals.

Different patterns of bundle-branch blocks and the risk of incident heart failure in the Women's Health Initiative (WHI) study

BACKGROUND

We evaluated the risk of incident heart failure (HF) associated with bundle-branch blocks (BBBs) in postmenopausal women.

METHODS AND RESULTS

Cox's regression was used to evaluate hazard ratios with 95% confidence intervals for HF among 65975 participants of the Women's Health Initiative (WHI) study during an average follow-up of 14 years. BBBs observed in 1676 women at baseline were categorized into left, right, and indetermined-type BBBs (LBBB, RBBB, and intraventricular conduction defect, respectively). Compared with women with no BBB, LBBB, and intraventricular conduction defect were strong predictors of incident HF in multivariable-adjusted risk models (hazard ratio, 3.79; confidence interval, 2.95-4.87 for LBBB and hazard ratio, 3.53; confidence interval, 2.14-5.81 for intraventricular conduction defect). RBBB was not a significant predictor of incident HF in multivariable-adjusted risk model, but the combination of RBBB and left anterior fascicular block was a strong predictor (hazard ratio, 2.96; confidence interval, 1.77-4.93). QRS duration was an independent predictor of incident HF only in LBBB, with more pronounced risk at QRS ≥ 140 ms than at <140 ms. QRS nondipolar voltage (RNDPV) was an independent predictor in both RBBB and LBBB and, in addition, in LBBB, QRS/STT angle and ST J-point depression in aVL were independent predictors.

CONCLUSIONS

LBBB, intraventricular conduction defect, and RBBB combined with left anterior fascicular block are strong predictors of incident HF in multivariable-adjusted risk models, but RBBB is not a significant predictor. QRS duration ≥ 140 ms may warrant consideration in LBBB as an indication for further diagnostic evaluation for possible therapeutic and preventive action. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00000611.

The evaluation and management of drug effects on cardiac conduction (PR and QRS intervals) in clinical development

Recent advances in electrocardiographic monitoring and waveform analysis have significantly improved the ability to detect drug-induced changes in cardiac repolarization manifested as changes in the QT/corrected QT interval. These advances have also improved the ability to detect drug-induced changes in cardiac conduction. This White Paper summarizes current opinion, reached by consensus among experts at the Cardiac Safety Research Consortium, on the assessment of electrocardiogram-based safety measurements of the PR and QRS intervals, representing atrioventricular and ventricular conduction, respectively, during drug development.

Cardiac Safety Implications of hNav1.5 Blockade and a Framework for Pre-Clinical Evaluation

The human cardiac sodium channel (hNav1.5, encoded by the SCN5A gene) is critical for action potential generation and propagation in the heart. Drug-induced sodium channel inhibition decreases the rate of cardiomyocyte depolarization and consequently conduction velocity and can have serious implications for cardiac safety. Genetic mutations in hNav1.5 have also been linked to a number of cardiac diseases. Therefore, off-target hNav1.5 inhibition may be considered a risk marker for a drug candidate. Given the potential safety implications for patients and the costs of late stage drug development, detection, and mitigation of hNav1.5 liabilities early in drug discovery and development becomes important. In this review, we describe a pre-clinical strategy to identify hNav1.5 liabilities that incorporates in vitro, in vivo, and in silico techniques and the application of this information in the integrated risk assessment at different stages of drug discovery and development.

Prognostic impact of electrocardiographic signs in patients with Type 2 diabetes and cardiovascular disease: results from the PROactive study

AIMS

Although a resting electrocardiograph is broadly applied in clinical practice for evaluating patients with Type 2 diabetes and cardiovascular disease, the independent prognostic relevance of electrocardiographic signs has not thoroughly been examined.

METHODS

Baseline 12-lead electrocardiographs available in 5231 of the 5238 participants of the PROactive trial were analysed for heart rate, heart rate corrected QT-interval, presence of atrial fibrillation/flutter, left axis deviation, right and left bundle branch block. The association of electrocardiographic signs with total mortality, the principal secondary composite endpoint (death, myocardial infarction and stroke) and serious adverse heart failure events was examined by Cox-regression analysis.

RESULTS

Two hundred and twenty-three (4.3%) patients showed atrial fibrillation/flutter, 213 (4.1%) patients had right bundle branch block, 111 (2.1%) patients had left bundle branch block and 706 (13.5%) patients had left axis deviation. Mean cQT-interval was 418 ms (± 25 ms) and mean heart rate was 72/min (± 14/min). In multivariate adjusted analyses, heart rate and cQT-interval were significantly associated with mortality, the composite secondary endpoint and heart failure, whereas right and left bundle branch blocks were significantly associated with heart failure only. Left axis deviation was associated with heart failure and atrial fibrillation/flutter was associated with mortality and heart failure in univariate but not multivariate analyses.

CONCLUSION

Easily assessable electrocardiographic signs such as heart rate, cQT-interval and bundle branch blocks were predictive for adverse outcome independently of multiple risk factor adjustment and should be considered in clinical care.