Incidence of heart failure in relation to QRS duration during antihypertensive therapy: the LIFE study

Incident left bundle branch block predicts cardiovascular events and death in hypertensive patients with left ventricular hypertrophy. The LIFE Study

Aim: Whether incident left bundle branch block (LBBB) is associated with increased cardiovascular (CV) morbidity and mortality in treated hypertensive patients with left ventricular hypertrophy (LVH) is unknown. Thus, the present study aimed to examine CV outcomes of incident LBBB in treated hypertensive patients with LVH. Methods: In the Losartan Intervention For Endpoint reduction in hypertension (LIFE) study, 9,193 hypertensive patients with LVH on screening electrocardiogram (ECG) were randomized to losartan or atenolol based treatment. Participants (n = 8,567) did not have LBBB (Minnesota code 7.1) on baseline ECG. Cox regression models controlling for significant covariates assessed independent associations of incident LBBB with CV events and all-cause mortality during 4.8 years mean follow-up. Results: Annual follow-up ECGs identified 295 patients (3.4%) with incident LBBB associated with male gender (P < 0.05), older age, higher Cornell voltage (both P < 0.005) and history of diabetes, isolated systolic hypertension and prevalent CV disease. When adjusted for the history of previous CV disease, diabetes, isolated systolic hypertension, the Framingham risk score, ECG-LVH and randomized study treatment, Cox regression models showed that incident LBBB predicted higher risk of the composite endpoint CV death, myocardial infarction and stroke [hazard ratio (HR) 1.9, 95% confidence intervals (CIs) 1.3–2.9, P < 0.001], CV death (HR 3.0, 95% CIs 1.84–5.0, P < 0.001), heart failure (HR 3.6, 95% CIs 1.9–6.6, P < 0.001) and all-cause mortality (HR 3.0, 95% CIs 2.0–4.3, P < 0.001). Conclusions: These data suggest that among hypertensive patients with ECG-LVH receiving aggressive antihypertensive therapy, incident LBBB independently predicts increased risk of subsequent CV events including congestive heart failure and CV and all-cause mortality (ClinicalTrials.gov identifier: NCT00338260).

Prevalence and long-term prognostic implications of prolonged QRS duration in left ventricular hypertrophy: a population-based observational cohort study

OBJECTIVES

ECG left ventricular hypertrophy (ECG-LVH) has been associated with left ventricular dysfunction and adverse prognosis, but little is known about the prevalence and prognostic significance of different levels of QRS duration in the presence of ECG-LVH in a general population.

DESIGN

Population-based observational prospective cohort study.

PARTICIPANTS

Nationally representative random cluster of Finnish adult population.

METHODS

We assessed the prevalence and long-term (median 15.9 years) prognostic significance of QRS duration in ECG-LVH, and compared the risk to individuals without ECG-LVH in a predominantly middle-aged random sample of 6033 Finnish subjects aged over 30 years (mean age 52.2, SD 14.6 years), who participated in a health examination including a 12-lead ECG.

MAIN OUTCOME MEASURES

Cardiovascular and all-cause mortality, incidence of heart failure (HF).

RESULTS

ECG-LVH was present in 1337 (22.2%) subjects; 403 of these (30.1%) had QRS duration ≥100 ms and 100 (7.5%) had ≥110 ms. The increased risk of mortality in ECG-LVH became evident after a QRS threshold of ≥100 ms. After controlling for known clinical risk factors, QRS 100-109 ms was associated with increased cardiovascular (HR 1.38, 95% CI 1.01 to 1.88, p=0.045) and QRS≥110 ms with cardiovascular (1.74, 95% CI 1.07 to 2.82, p=0.025) and all-cause mortality (1.52, 95% CI 1.02 to 2.25, p=0.039) in ECG-LVH. The risk of new-onset HF was two-fold in subjects with QRS 100-109 ms and threefold in subjects with QRS ≥110 ms, even after adjustment for incident myocardial infarction within the follow-up. When the prognosis was compared with subjects without ECG-LVH, subjects with ECG-LVH but QRS duration <100 ms displayed similar mortality rates with or without ECG-LVH but higher rates of incident HF.

CONCLUSIONS

In ECG-LVH, the risk of excess mortality and new-onset HF markedly increases with longer QRS duration, but even QRS duration within normal limits in ECG-LVH carried a risk of HF compared with the risk in individuals without ECG-LVH.

Layer-specific dyssynchrony and its relationship to the change of left ventricular function in hypertensive patients

Left ventricular (LV) remodeling in systemic arterial hypertension causes electrical conduction delay and impairs synchronous contraction, which may contribute to the development of heart failure. This study aimed to assess the change of LV mechanics in hypertension by layer-specific dyssynchrony. One hundred and twenty-one patients with primary hypertension and LV ejection fraction >50 % (mean age, 62 ± 10 years) and 31 normotensive controls (mean age, 63 ± 9 years) were prospectively included. Layer-specific dyssynchrony index (DI) was defined as standard deviation of time interval (TI) from the onset of Q wave to peak longitudinal strain obtained from 18 segments in each endocardial, myocardial, and epicardial layer. The global TI between the onset of Q wave to peak global longitudinal strain in each layer was obtained and the time difference (TD) of global TI between layers was calculated. DIs were significantly different in three layers (P < 0.001 in both groups), and were significantly greater in hypertensive patients than in controls except epicardial DI. End diastolic filling pressure and LV global longitudinal strain were related with endocardial DI. TD between endocardium and myocardium was greater in hypertensive patients than in controls (P = 0.001). Layer-specific DI revealed delayed contraction in each layer and between layers in hypertensive patients, which were apparent in endocardium and between endocardium and myocardium. Increased layer-specific DIs were associated with subclinical LV dysfunction, although LV ejection fraction was preserved. These may be helpful to understand layer-specific mechanical property of LV myocardium and for early detection of subclinical impairment of myocardial function.

Sequencing of SCN5A identifies rare and common variants associated with cardiac conduction: Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium

BACKGROUND

The cardiac sodium channel SCN5A regulates atrioventricular and ventricular conduction. Genetic variants in this gene are associated with PR and QRS intervals. We sought to characterize further the contribution of rare and common coding variation in SCN5A to cardiac conduction.

METHODS AND RESULTS

In Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium Targeted Sequencing Study, we performed targeted exonic sequencing of SCN5A (n=3699, European ancestry individuals) and identified 4 common (minor allele frequency >1%) and 157 rare variants. Common and rare SCN5A coding variants were examined for association with PR and QRS intervals through meta-analysis of European ancestry participants from CHARGE, National Heart, Lung, and Blood Institute's Exome Sequencing Project (n=607), and the UK10K (n=1275) and by examining Exome Sequencing Project African ancestry participants (n=972). Rare coding SCN5A variants in aggregate were associated with PR interval in European and African ancestry participants (P=1.3×10(-3)). Three common variants were associated with PR and QRS interval duration among European ancestry participants and one among African ancestry participants. These included 2 well-known missense variants: rs1805124 (H558R) was associated with PR and QRS shortening in European ancestry participants (P=6.25×10(-4) and P=5.2×10(-3), respectively) and rs7626962 (S1102Y) was associated with PR shortening in those of African ancestry (P=2.82×10(-3)). Among European ancestry participants, 2 novel synonymous variants, rs1805126 and rs6599230, were associated with cardiac conduction. Our top signal, rs1805126 was associated with PR and QRS lengthening (P=3.35×10(-7) and P=2.69×10(-4), respectively) and rs6599230 was associated with PR shortening (P=2.67×10(-5)).

CONCLUSIONS

By sequencing SCN5A, we identified novel common and rare coding variants associated with cardiac conduction.

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.

Association of QRS duration with left ventricular structure and function and risk of heart failure in middle-aged and older adults: the Multi-Ethnic Study of Atherosclerosis (MESA)

AIMS

Prolonged QRS duration (QRSd) on the electrocardiogram (ECG) has been associated with cardiac structural and functional abnormalities by echocardiography and an increased risk of heart failure (HF). Data are sparse on these relationships in middle-aged and elderly individuals free of baseline cardiovascular disease with respect to cardiac magnetic resonance imaging (MRI). We sought to determine whether QRSd is associated with incident HF and measures of cardiac structure and function by cardiac MRI.

METHODS AND RESULTS

We analysed baseline ECGs in the Multi-Ethnic Study of Atherosclerosis (MESA) to determine whether QRSd >100 ms was associated with incident HF. We adjusted for demographic and clinical risk factors, as well as MRI measures of left ventricular (LV) structure and function. Among 4591 eligible participants (51% women; 39% white; mean age 61 years), 75 developed incident HF over a mean follow-up of 7.1 years. QRSd >100 ms was significantly associated with MRI measures of cardiac structure and function, as well as incident HF, even after adjustment for demographic covariates [hazard ratio (HR) 2.10, 95% confidence interval (CI) 1.29-3.42; P = 0.003] and clinical risk factors (HR 1.86, 95% CI 1.14-3.03; P = 0.01). With further adjustment for individual LV structural measures, findings were attenuated to non-significance. Separate adjustment for LV functional measures yielded only mild attenuation.

CONCLUSION

In middle-aged and older adults without cardiovascular disease, a QRSd >100 ms was significantly associated with incident HF. After adjustment for LV structural measures, the association was attenuated to non-significance, suggesting that prolonged QRSd is potentially a useful marker of LV structure that may predispose to HF risk.

Impact of antihypertensive treatment on left ventricular systolic dyssynchrony in treatment-naïve hypertensive patients

Dyssynchrony is common in asymptomatic patients with hypertension. We sought to investigate the impact of antihypertensive treatment on dyssynchrony in patients with hypertension. A total of sixty patients who had uncomplicated hypertension that had never been treated (treatment-naïve hypertensive patients) underwent echocardiographic evaluations of left ventricular (LV) dyssynchrony at baseline and after a 6-month treatment with antihypertensive drugs. The measured parameters were as follows: (1) the s.d. of 12 LV-segment time-to-peak systolic velocities (Ts-SD12), and (2) the maximal difference between peak systolic velocities of any 2 of the 12 segments (Ts-Max). Patients with Ts-SD12 ≥ 33 ms or Ts-Max ≥ 100 ms were regarded as having LV systolic dyssynchrony. Patients with systolic dyssynchrony (group 1, n = 29) and without systolic dyssynchrony (group 2, n = 31) were compared. Among the patients in group 1, antihypertensive treatment significantly improved LV systolic dyssynchrony (ΔTs-SD12, -13.1 ms; P<0.001 and ΔTs-Max, -34.0 ms; P = 0.003), whereas it did not demonstrate additional benefit among group 2 patients. The change in LV systolic dyssynchrony was significantly associated with changes in the mean annulus E' velocity, mean annulus S' velocity and mean annulus E'/A' ratio, but not with changes in blood pressure and LV mass index. It is likely that chronic antihypertensive treatment could reverse the LV systolic dyssynchrony and simultaneously improve subclinical systolic and diastolic function in patients with hypertension and LV systolic dyssynchrony.

Effect of changing heart rate during treatment of hypertension on incidence of heart failure

An elevated heart rate (HR) at rest at baseline is associated with an increased risk of incident heart failure (HF) and with greater cardiovascular event rates in patients with chronic HF. However, despite the high attributable risk of hypertension for HF, whether the in-treatment HR predicts incident HF in patients with treated hypertension has not been evaluated. The HR was evaluated on annual electrocardiograms from 9,024 patients with hypertension without HF who were treated with losartan- or atenolol-based regimens. During a mean follow-up of 4.7 ± 1.1 years, HF developed in 285 patients (3.2%). On multivariate Cox analyses adjusted for randomized treatment, the baseline risk factors for HF, baseline and in-treatment blood pressure, QRS duration, and electrocardiographic left ventricular hypertrophy, a greater in-treatment HR predicted a 45% greater adjusted risk of new HF for every 10-beats/min increase in the HR (95% confidence interval [CI] 34% to 57%) or a 159% greater risk of HF in patients with the persistence or development of a HR of ≥84 beats/min (95% CI 88% to 257%). In contrast, with adjustment for the same covariates, the baseline HR as a continuous variable was a significantly less powerful predictor of new HF (hazard ratio 1.15 per 10 beats/min, 95% CI 1.03 to 1.28) and a baseline HR of ≥84 beats/min did not predict new HF (hazard ratio 1.00, 95% CI 0.63 to 1.58). In conclusion, a greater in-treatment HR on the serial electrocardiograms predicts a greater risk of incident HF during antihypertensive treatment, independent of the covariates, in patients with hypertension with electrocardiographic left ventricular hypertrophy. These findings support serial HR assessment to improve the risk stratification of patients with hypertension.

Factors associated with development of prolonged QRS duration over 20 years in healthy young adults: the Coronary Artery Risk Development in Young Adults study

BACKGROUND

Data describing factors associated with the development of a prolonged QRS duration (QRSd) from young adulthood to middle age are sparse.

METHODS

We analyzed 12-lead electrocardiograms (ECGs) from the Coronary Artery Risk Development in Young Adults study over 20 years. We performed logistic regression to examine the associations of baseline (year 0) or average (years 0-20) risk factors with incident prolonged QRSd (QRS >100 milliseconds).

RESULTS

We included 2537 participants (57.2% women, 44.7% black; mean age, 25 years); 292 (11.5%) developed incident QRSd greater than 100 milliseconds by year 20. In univariate analyses, baseline covariates associated with incident QRSd prolongation included white race, male sex, ECG-left ventricular mass index, and baseline QRSd. Similar results were observed after multivariable adjustment.

CONCLUSION

We found no long-term associations of modifiable risk factors with incident QRSd >100 milliseconds. Men, whites, and those with higher ECG-left ventricular mass index and QRSd in young adulthood are at an increased risk for incident prolonged QRSd by middle age.

Racial differences in incident heart failure during antihypertensive therapy

BACKGROUND

Blacks have a higher prevalence of heart failure (HF) than nonblacks, possibly reflecting a greater burden of HF risk factors, including hypertension. Although HF incidence is significantly higher in blacks during long-term follow-up of young adults, the relationship of incident HF to race in hypertensive patients undergoing treatment is unclear.

METHODS AND RESULTS

Incident HF was evaluated in 497 black and 8199 nonblack hypertensive patients with no history of HF randomly assigned to losartan- or atenolol-based treatment. During 4.7±1.1 years mean follow-up, HF hospitalization occurred in 265 patients (3.0%); 5-year HF incidence was significantly greater in black than nonblack patients (7.0 versus 3.1%, P<0.001). In Cox multivariate analyses adjusting for randomized treatment, age, sex, the presence of the strain pattern on the baseline ECG, and other HF risk factors treated as standard covariates, and for incident myocardial infarction, in-treatment QRS duration, diastolic and systolic pressure, Cornell product, and Sokolow-Lyon voltage criteria for left ventricular hypertrophy (LVH) treated as time-varying covariates, black race remained associated with a 130% increased risk of developing new HF (hazard ratio 2.30, 95% confidence interval 1.24 to 4.28).

CONCLUSIONS

Incident HF is substantially more common among black than nonblack hypertensive patients. The increased risk of developing new HF in blacks persists after adjusting for the higher prevalence of HF risk factors in blacks, for treatment effects and in-treatment blood pressure, and for the known predictive value of the ECG strain pattern and in-treatment ECG LVH and QRS duration for incident HF in this population. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00338260.