The incidence and risk factors for new onset atrial fibrillation in the PROSPER study

Electrocardiographic Predictors of Atrial Fibrillation

BACKGROUND

Atrial fibrillation (AF) is the most common pathological arrhythmia, and its complications lead to significant morbidity and mortality. However, patients with AF can often go undetected, especially if they are asymptomatic or have a low burden of paroxysms. Identification of those at high risk of AF development may help refine screening and management strategies.

METHODS

PubMed and Embase databases were systematically searched for studies looking at electrocardiographic predictors of AF from inception to August 2021.

RESULTS

A total of 115 studies were reported which examined a combination of atrial and ventricular parameters that could be electrocardiographic predictors of AF. Atrial predictors include conduction parameters, such as the PR interval, p-wave index and dispersion, and partial interatrial or advanced interatrial block, or morphological parameters, such as p-wave axis, amplitude and terminal force. Ventricular predictors include abnormalities in QRS amplitude, morphology or duration, QT interval duration, r-wave progression and ST segment, i.e., t-wave abnormalities.

CONCLUSIONS

There has been significant interest in electrocardiographic prediction of AF, especially in populations at high risk of atrial AF, such as those with an embolic stroke of undetermined source. This review highlights the breadth of possible predictive parameters, and possible pathological bases for the predictive role of each parameter are proposed.

Latest incidence and electrocardiographic predictors of atrial fibrillation: a prospective study from China

BACKGROUND

China bears the biggest atrial fibrillation (AF) burden in the world. However, little is known about the incidence and predictors of AF. This study aimed to investigate the current incidence of AF and its electrocardiographic (ECG) predictors in general community individuals aged over 60 years in China.

METHODS

This was a prospective cohort study, recruiting subjects who were aged over 60 years and underwent annual health checkups from April to July 2015 in four community health centers in Songjiang District, Shanghai, China. The subjects were then followed up from 2015 to 2019 annually. Data on sociodemographic characteristics, medical history, and the resting 12-lead ECG were collected. Kaplan-Meier curve was used for showing the trends in AF incidence and calculating the predictors of AF. Associations of ECG abnormalities and AF incidence were examined using Cox proportional hazard models.

RESULTS

This study recruited 18,738 subjects, and 351 (1.87%) developed AF. The overall incidence rate of AF was 5.2/1000 person-years during an observation period of 67,704 person-years. Multivariable Cox regression analysis indicated age (hazard ratio [HR], 1.07; 95% confidence interval [CI]: 1.06-1.09; P < 0.001), male (HR, 1.30; 95% CI: 1.05-1.62; P = 0.018), a history of hypertension (HR, 1.55; 95% CI: 1.23-1.95; P < 0.001), a history of cardiac diseases (HR, 3.23; 95% CI: 2.34-4.45; P < 0.001), atrial premature complex (APC) (HR, 2.82; 95% CI: 2.17-3.68; P < 0.001), atrial flutter (HR, 18.68; 95% CI: 7.37-47.31; P < 0.001), junctional premature complex (JPC) (HR, 3.57; 95% CI: 1.59-8.02; P = 0.002), junctional rhythm (HR, 18.24; 95% CI: 5.83-57.07; P < 0.001), ventricular premature complex (VPC) (HR, 1.76; 95% CI: 1.13-2.75, P = 0.012), short PR interval (HR, 5.49; 95% CI: 1.36-22.19; P = 0.017), right atrial enlargement (HR, 6.22; 95% CI: 1.54-25.14; P = 0.010), and pacing rhythm (HR, 3.99; 95% CI: 1.57-10.14; P = 0.004) were independently associated with the incidence of AF.

CONCLUSIONS

The present incidence of AF was 5.2/1000 person-years in the studied population aged over 60 years in China. Among various ECG abnormalities, only APC, atrial flutter, JPC, junctional rhythm, short PR interval, VPC, right atrial enlargement, and pacing rhythm were independently associated with AF incidence.

Value of baseline characteristics in the risk prediction of atrial fibrillation

Introduction

Atrial fibrillation (AF) is prone to heart failure and stroke. Early management can effectively reduce the stroke rate and mortality. Current clinical guidelines screen high-risk individuals based solely on age, while this study aims to explore the possibility of other AF risk predictors.

Methods

A total of 18,738 elderly people (aged over 60 years old) in Chinese communities were enrolled in this study. The baseline characteristics were mainly based on the diagnosis results of electrocardiogram (ECG) machine during follow up, accompanied by some auxiliary physical examination basic data. After the analysis of both independent and combined baseline characteristics, AF risk predictors were obtained and prioritized according to the results. Independent characteristics were studied from three aspects: Chi-square test, Mann-Whitney U test and Cox univariate regression analysis. Combined characteristics were studied from two aspects: machine learning models and Cox multivariate regression analysis, and the former was combined with recursive feature elimination method and voting decision.

Results

The resulted optimal combination of risk predictors included age, atrial premature beats, atrial flutter, left ventricular hypertrophy, hypertension and heart disease.

Conclusion

Patients diagnosed by short-time ECG machines with the occurrence of the above events had a higher probability of AF episodes, who are suggested to be included in the focus of long-term ECG monitoring or increased screening density. The incidence of risk predictors in different age ranges of AF patients suggests differences in age-specific patient management. This can help improve the detection rate of AF, standardize the management of patients, and slow down the progression of AF.

The Atrium in Atrial Fibrillation - A Clinical Review on How to Manage Atrial Fibrotic Substrates

Atrial fibrillation (AF) is the most common sustained arrhythmia in the population and is associated with a significant clinical and economic burden. Rigorous assessment of the presence and degree of an atrial arrhythmic substrate is essential for determining treatment options, predicting long-term success after catheter ablation, and as a substrate critical in the pathophysiology of atrial thrombogenesis. Catheter ablation of AF has developed into an essential rhythm-control strategy. Nowadays is one of the most common cardiac ablation procedures performed worldwide, with its success inversely related to the extent of atrial structural disease. Although atrial substrate evaluation remains complex, several diagnostic resources allow for a more comprehensive assessment and quantification of the extent of left atrial structural remodeling and the presence of atrial fibrosis. In this review, we summarize the current knowledge on the pathophysiology, etiology, and electrophysiological aspects of atrial substrates promoting the development of AF. We also describe the risk factors for its development and how to diagnose its presence using imaging, electrocardiograms, and electroanatomic voltage mapping. Finally, we discuss recent data regarding fibrosis biomarkers that could help diagnose atrial fibrotic substrates.

The Association Between Left Ventricular Hypertrophy and the Occurrence and Prognosis of Atrial Fibrillation: A Meta-Analysis

Aims: The aim of this study was to perform a meta-analysis of studies of the association of left ventricular hypertrophy (LVH) and atrial fibrillation (AF), especially the predictive and prognostic role of LVH.

Methods and Results: We searched Medline, Embase, and the Cochrane Library from inception through 10 April 2020. A total of 16 cohorts (133,091 individuals) were included. Compared with the normal subjects, patients with LVH were more susceptible to AF (RR = 1.46, 95% CI, 1.32–1.60). In patients with AF and LVH, there was a higher risk of all-cause mortality during 3.95 years (RR = 1.60, 95% CI, 1.42–1.79), and these patients were more likely to progress to persistent or paroxysmal AF (RR = 1.45, 95% CI, 1.20–1.76) than were patients without LVH. After catheter ablation of AF, patients with LVH were more likely to recur (RR = 1.58, 95% CI, 1.27–1.95).

Conclusion: LVH is strongly associated with AF and has a negative impact on outcome in patients with AF.

Update on the efficacy of statins in primary and secondary prevention of atrial fibrillation

Atrial fibrillation is the most common arrhythmia in adults and its prevalence is growing rapidly. It has been shown that AF is associated with increased risk of heart failure, ischemic and hemorrhagic stroke, and mortality. Hence, there is growing interest among researchers in seeking preventive and therapeutic interventions regarding AF. In recent decades, it has been suggested that statins may decrease the incidence of AF and may also decrease its recurrence after cardioversion and catheter ablation. These effects are thought to be mediated by different mechanisms such as modulating inflammation, altering the properties of transmembrane ion channels, interfering with activation of matrix metalloproteinases, and acting on endothelial function. In this article, we review and update current knowledge about the role of statins in primary and secondary prevention of AF in general and specific populations.

Update on the efficacy of statins in primary and secondary prevention of atrial fibrillation

Atrial fibrillation is the most common arrhythmia in adults and its prevalence is growing rapidly. It has been shown that AF is associated with increased risk of heart failure, ischemic and hemorrhagic stroke, and mortality. Hence, there is growing interest among researchers in seeking preventive and therapeutic interventions regarding AF. In recent decades, it has been suggested that statins may decrease the incidence of AF and may also decrease its recurrence after cardioversion and catheter ablation. These effects are thought to be mediated by different mechanisms such as modulating inflammation, altering the properties of transmembrane ion channels, interfering with activation of matrix metalloproteinases, and acting on endothelial function. In this article, we review and update current knowledge about the role of statins in primary and secondary prevention of AF in general and specific populations.

The Pleiotropic Effects of Statins - From Coronary Artery Disease and Stroke to Atrial Fibrillation and Ventricular Tachyarrhythmia

Statins, 3-hydroxy-methylglutaryl coenzyme A reductase inhibitors, have been used for decades for the prevention of coronary artery disease and stroke. They act primarily by lowering serum cholesterol through the inhibition of cholesterol synthesis in the liver, which results in the upregulation of low-density lipoprotein receptors in the liver. This results in the removal of low-density lipoproteincholesterol. Studies have suggested that statins may demonstrate additional effects that are independent of their effects on low-density lipoprotein-cholesterol. These have been termed "pleiotropic" effects. Pleiotropic effects may be due to the inhibition of isoprenoid intermediates by statins. Isoprenoid inhibition has effects on the small guanosine triphosphate binding proteins Rac and Rho which in turn effects nicotinamide adenine dinucleotide phosphate oxidases. Therefore, there are changes in endothelial nitric oxide synthase expression, atherosclerotic plaque stability, pro-inflammatory cytokines and reactive oxygen species production, platelet reactivity, and cardiac fibrosis and hypetrophy development. Recently, statins have been compared to the ezetimibe and the recently published outcomes data on the proprotein convertase subtilisin kexin type 9 inhibitors has allowed for a reexamination of statin pleiotropy. As a result of these diverse effects, it has been suggested that statins also have anti-arrhythmic effects. This review focuses on the mechanisms of statin pleiotropy and discusses evidence from the statin clinical trials as well as examining the possible anti-arrhythmic effects atrial fibrillation and ventricular tachyarrhythmias.

Factors Modifying the Risk of Atrial Fibrillation Associated With Atrial Premature Complexes in Patients With Hypertension

Patients with hypertension who develop atrial premature complexes (APCs) are at a particularly high risk for atrial fibrillation (AF). We sought to identify medications and modifiable risk factors that could reduce the risk of AF imposed by presence of APCs in such a high risk group. This analysis included 4,331 participants with treated hypertension from the Reasons for Geographic and Racial Differences in Stroke study who were free of AF and cardiovascular disease at the time of enrollment (2003-2007). APCs were detected in 8.2% (n = 356) of the participants at baseline. During a median follow-up of 9.4 years, 9.9% (n = 429) of the participants developed AF. Participants with APCs, compared with those without, were more than twice as likely to develop AF (Odds ratio [95% confidence interval]: 2.36[1.75, 3.19]). This association was significantly weaker in statin users than nonusers (Odds ratio [95% confidence interval]:1.42[0.81,2.48] vs 3.01[2.11,4.32], respectively; interaction p-value = 0.02), and in angiotensin-II receptor blocker users than nonusers (Odds ratio [95% confidence interval]:1.31[0.66,2.61] vs 2.78[1.99,3.89], respectively; interaction p-value = 0.05). Borderline weaker associations between APCs and AF were also observed in alpha-blocker users than nonusers, nondiabetics than diabetics, and in those with systolic blood pressure level 130 to 139 mm Hg compared with those with other systolic blood pressure levels. No significant effect modifications were observed by use of other medications or by presence of other cardiovascular risk factors. In conclusion, the significant AF risk associated with APCs in patients with hypertension could potentially be reduced by treatment with angiotensin-II receptor blockers and statins along with lowering blood pressure and management of diabetes.

Spatial QRS-T Angle and Cognitive Decline in Older Subjects

BACKGROUND

An abnormally wide spatial QRS-T angle on an ECG is a marker of heterogeneity in electrical activity of cardiac ventricles and is linked with cardiovascular events. Growing evidence suggests that cardiac dysfunction might signal future cognitive decline.

OBJECTIVE

In this study, we investigated whether spatial QRS-T angle associates with future cognitive decline in older subjects at high cardiovascular risk.

METHODS

We included 4,172 men and women (mean age 75.2±3.3 years) free of cardiac arrhythmias from the PROSPER cohort. Spatial QRS-T angle was calculated from baseline 12-lead ECGs using a matrix transformation method. Cognitive function was assessed using 4 neuropsychological tests including Stroop test, letter-digit coding test, immediate and delayed picture word learning tests. Cognitive function was assessed at baseline and repeatedly during a mean follow-up time of 3.2 years. Using linear mixed models, we calculated the annual changes of cognitive scores in sex-specific thirds of spatial QRS-T angle.

RESULTS

Participants with wider spatial QRS-T angle had a steeper decline in letter-digit coding test (β= -0.0106, p = 0.004), immediate picture-word learning test (β= -0.0049, p = 0.001), and delayed picture-word learning test (β= -0.0055, p = 0.013). All associations were independent of arrhythmias, cardiovascular risk factors, comorbidities, medication use, cardiovascular events, and other ECG abnormalities including QRS duration, QTc interval, T wave abnormalities, and left ventricular hypertrophy.

CONCLUSION

Abnormal cardiac electrical activity characterized by wide spatial QRS-T angle associates with accelerated cognitive decline independent of conventional cardiovascular factors. These findings suggest a link between a non-traditional ECG measure of pre-clinical cardiac pathology and future cognitive decline.

Nonspecific intraventricular conduction delay is associated with future occurrence of atrial fibrillation in patients with structurally normal heart

BACKGROUND

We aimed to elucidate the long-term prognosis of nonspecific intraventricular conduction delay (NIVCD) in patients with structurally normal heart.

METHODS

We included 107,838 patients (age, 52.1 ± 15.5 years; men, 46.8%) who underwent electrocardiography in outpatient clinics or medical checkup (unmatched cohort). NIVCD was defined as QRS duration ≥110 ms without meeting the criteria for bundle branch block. Patients with structurally normal heart and sinus rhythm were assigned to the NIVCD and normal QRS groups according to propensity score with matching variables of age, sex, hypertension, and diabetes (matched cohort 1), and additional PR interval (matched cohort 2). Baseline characteristics, electrocardiographic parameters, and clinical outcomes were compared in the unmatched cohort and the matched cohort.

RESULTS

In the unmatched cohort, the frequencies of male sex and preexisting atrial fibrillation were significantly higher in the NIVCD group than in the normal QRS group. In matched cohort 1 (n = 690), the NIVCD group exhibited significant slower sinus rate and longer PR interval than the normal QRS group. In matched cohort 2 (n = 598), the cumulative incidence of atrial fibrillation was significantly higher in the NIVCD group than in the normal QRS group during a follow-up period of 8.8 ± 2.9 years. NIVCD significantly increased the risk for AF (hazard ratio, 2.571; 95% confidence interval, 1.074-6.156; p = 0.034).

CONCLUSIONS

It is suggested that NIVCD may be associated with future occurrence of atrial fibrillation in patients with structurally normal heart and sinus rhythm.

Electrocardiographic predictors of atrial fibrillation in nonhypertensive and hypertensive individuals

OBJECTIVE

The aim of this study was to compare the predictive value of ECG abnormalities for atrial fibrillation in nonhypertensive versus hypertensive individuals.

METHODS

We recorded ECG and measured conventional cardiovascular risk factors in a nationwide population-based sample of 5813 Finns. We divided the participants into nonhypertensive (n = 3148) and hypertensive (n = 2665) individuals and followed the participants for incident atrial fibrillation events. We evaluated the predictive ability of 12 ECG abnormalities for atrial fibrillation using multivariable-adjusted Fine-Gray models.

RESULTS

During a follow-up of 11.9 ± 2.9 years, 111 nonhypertensive and 301 hypertensive participants developed atrial fibrillation. Negative T wave in lateral leads predicted atrial fibrillation in both nonhypertensive [hazard ratio (HR), 4.59; 95% confidence interval (95% CI) 1.84-11.44] and hypertensive participants (HR, 1.81; 95% CI 1.16-2.84). In nonhypertensive participants, 1-SD increments in corrected QT interval (HR, 1.42; 95% CI, 1.18-1.71) and T-wave amplitude in lead augmented vector R (aVR) (HR, 1.40; 95% CI, 1.10-1.80) were related to atrial fibrillation. In hypertensive participants, prolonged PR interval (HR, 1.59; 95% CI 1.05-2.41), prolonged P-wave duration (HR, 1.43; 95% CI 1.07-1.91), left ventricular hypertrophy by Sokolow-Lyon criteria (HR, 1.55; 95% CI, 1.12-2.14) and poor R-wave progression (HR, 1.59; 95% CI, 1.02-2.48) predicted atrial fibrillation. Corrected QT interval and T-wave amplitude in lead aVR were stronger predictors of atrial fibrillation in nonhypertensive than in hypertensive participants. ECG abnormalities improved risk prediction only marginally (delta area under receiver-operating-characteristic curve = 0.000-0.005).

CONCLUSION

Several ECG abnormalities associate with incident atrial fibrillation in hypertensive and nonhypertensive individuals but provide only marginal incremental predictive value. Corrected QT interval and T-wave amplitude in lead aVR may relate stronger to incident atrial fibrillation in nonhypertensive than in hypertensive individuals.

Occurrence of significant long PR intervals in patients implanted for sinus node dysfunction and monitored with SafeR™: The PRECISE study

BACKGROUND

Long PR intervals may increase cardiovascular complications, including atrial fibrillation. In pacemakers, the SafeR™ mode monitors PR intervals, switching from AAI to DDD when criteria for atrioventricular block are met.

AIMS

The PRECISE study evaluated the incidence and predictors of long PR intervals and their association with incident atrial fibrillation after 1 year in patients implanted for sinus node dysfunction and free from significant conduction disorders at baseline.

METHODS

This French, prospective, multicentre, observational trial enrolled patients implanted with a REPLY™ dual-chamber pacemaker. Pacemaker memory recorded long PR intervals (defined as first-degree atrioventricular block mode switches occurring after six consecutive PR/AR intervals≥350/450ms) and atrial fibrillation incidence (fallback mode switch>1minute/day). Predictors were identified from baseline variables (age, sex, AR and PR intervals, atrial rhythm disorder and medication) using logistic regression.

RESULTS

Of 291 patients with sinus node dysfunction enrolled, 214 were free from significant conduction disorders at baseline (mean age 79±8 years; 44% men; PR/AR intervals<350/450ms). After 1 year, long PR intervals had occurred in 116 patients (54%) and atrial fibrillation in 63 patients (30%). Amiodarone was the only independent predictor of long PR interval occurrence (odds ratio 2.50, 95% confidence interval 1.20-5.21; P=0.014). There was a strong trend towards an association between long PR interval and atrial fibrillation incidence (odds ratio 1.86, 95% confidence interval 0.97-3.61; P=0.051).

CONCLUSIONS

Half of the patients with pure sinus node dysfunction developed long PR intervals in the year following pacemaker implantation. Amiodarone was the only independent predictor of long PR intervals. There was a strong trend towards an association between long PR intervals and incident atrial fibrillation.

Novel Insights in the Activation Patterns at the Pulmonary Vein Area

BACKGROUND

Extensiveness of conduction delay and block at the pulmonary vein area (PVA) was quantified in a previous study. We hypothesized that the combination of lines of conduction block with multiple concomitantly entering sinus rhythm wavefronts at the PVA may result in increased arrhythmogenicity and susceptibility to atrial fibrillation (AF).

METHODS

Intraoperative high-density epicardial mapping of PVA (N≈450 sites, interelectrode distances: 2 mm) was performed during sinus rhythm in 327 patients (241 male [74%], 67±10 [21-84] years) with and without preoperative AF. For each patient, activation patterns at the PVA were quantified, including the location of entry sites of wavefronts, direction of propagation, and their relative activation times. The association between activation patterns and the presence of AF was examined.

RESULTS

Excitation of the PVA occurred via multiple consecutive wavefronts in the vast majority of patient (N=216, 81%). In total, 561 wavefronts were observed, which mostly propagated through the septal or paraseptal regions towards the PVA (N=461, 82%). A substantial dissociation of consecutive wavefronts was observed with Δactivation times of 10.6±8.8 (0-46) ms. No difference was observed in Δactivation times of consecutive wavefronts during sinus rhythm between patients without and with AF. An excitation-based risk factor model, including conduction delay ≥6 mm, conduction block ≥6 mm, and conduction delay and block ≥16 mm, wavefronts via the posteroinferior to posterosuperior regions and multiple opposing wavefronts, demonstrated a 5-fold risk of AF when multiple risk factors were present.

CONCLUSIONS

In contrast to previous findings, quantification of activation patterns at the PVA on high-resolution scale demonstrated complex patterns with often multiple entry sites and high interindividual variability. Altered patterns of activation, consisting of multiple opposing wavefronts combined with long lines of conduction slowing, were associated with the presence of AF.

Non-Invasive Pulmonary Capillary Wedge Pressure Assessment on Speckle Tracking Echocardiography as a Predictor of New-Onset Non-Valvular Atrial Fibrillation - Four-Year Prospective Study (NIPAF Study)

BACKGROUND

Although new-onset atrial fibrillation (AF) increases with ageing, the prediction of new-onset AF is complicated. We previously reported that pulmonary capillary wedge pressure (ePCWP) estimated by the combination of left atrial volume index (LAVI) and active left atrial emptying function (aLAEF) had a strong relationship with PCWP on catheterization (r=0.92): ePCWP=10.8-12.4×log (aLAEF/minimum LAVI). We sought to determine the usefulness of ePCWP to predict new-onset AF. Methods and Results: We measured LAVI, aLAEF and ePCWP on speckle tracking echocardiography (STE) in 566 consecutive elderly patients (72±6 years) without a history of AF. A total of 63 patients (73±6 years) developed electrocardiographically confirmed AF during a mean follow-up period of 50 months. Baseline aLAEF was significantly lower in patients with than without new-onset AF (17.9±6.5 vs. 28.2±7.5%), whereas ePCWP was significantly higher (14.8±3.7 vs. 10.3±3.1 mmHg). In multivariate logistic regression analysis, ePCWP and aLAEF were strong independent predictors of AF. Using ePCWP >13 mmHg or aLAEF ≤22% on univariate Cox regression analysis, the HR for new-onset AF were 3.53 (95% CI: 1.68-7.44, P<0.001) and 4.06 (95% CI: 1.90-8.65, P<0.001), respectively. By combining these 2 criteria (>13 mmHg and ≤22%), the HR increased to 11.84 (95% CI: 6.85-20.5, P<0.001).

CONCLUSIONS

ePCWP and aLAEF measured on STE are useful predictors of new-onset AF. ePCWP provides added value for risk stratification of new-onset AF.

Preoperative QTc Interval is Not Associated With Intraoperative Cardiac Events or Mortality in Liver Transplantation Patients

OBJECTIVES

The primary objective of this study was to determine whether liver transplantation recipients with preoperative prolonged corrected (QTc) intervals have a higher incidence of intraoperative cardiac events and/or postoperative mortality compared with their peers with normal QTc intervals.

DESIGN

This was a retrospective cohort study.

SETTING

Single academic hospital in New York, NY.

PARTICIPANTS

Patients undergoing liver transplantation between 2007 and 2016.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Data relating to all liver transplantation recipients with preoperative electrocardiograms were queried from an institutional anesthesia data warehouse and electronic medical records. Primary outcomes were a composite outcome of intraoperative cardiac events and postoperative mortality. Patients with a prolonged QTc interval (>450 ms for men, >470 ms for women) did not demonstrate an association with intraoperative cardiac events, 30- or 90-day mortality, in-hospital mortality, or overall mortality compared with recipients in the normal QTc interval group. A prolonged QTc was found to be associated with increased anesthesia time, surgical time, length of hospital stay, and incidence of fresh frozen plasma and platelets transfusion.

CONCLUSIONS

Prolonged QTc interval is not associated with an increased incidence of intraoperative cardiac events or mortality in liver transplantation recipients. The demonstrated correlation among QTc length and Model for End-stage Liver Disease score, blood component requirements, surgical and anesthetic times, and hospital length of stay likely represents the association between QTc length and severity of liver disease.

Association between sleep disordered breathing and electrocardiographic markers of atrial abnormalities: the MESA study

Aims

Electrocardiographic (ECG) markers of left atrial (LA) abnormalities have been linked to increased risk of atrial fibrillation (AF). Sleep disordered breathing (SDB) has been associated with increased risk of AF. We aimed to examine the association of ECG markers of LA abnormalities with SDB.

Methods and results

1546 participants (mean age 67.2 years, 53.4% women, and 63.3% non-whites) from the Multi-Ethnic Study of Atherosclerosis Exam 5 Sleep ancillary study were included in this analysis. ECG markers of LA abnormalities (P wave terminal force in V1 (PTFV1), maximum P wave duration, PR interval and heart rate corrected PR interval) were measured from resting standard digital ECG tracings using standardized processing. Linear and logistic regression analyses were utilized to examine the cross-sectional associations of measures of SDB (apnea hypopnea index [AHI] and % time spent with oxygen saturation <90% [%SpO290]) with each ECG marker. In a multivariable analysis adjusting for demographics, cardiovascular risk factors, and comorbidities, AHI was associated with greater PTFV1 but not with other ECG markers of LA abnormalities. A 1-SD increase of AHI (16.6/hr) was associated with higher levels of PTFV1 (175.1 µV.ms, 95% confidence interval [95%CI] 75.4, 274.7) and higher odds of abnormally elevated PTFV1 (≥4000 µV.ms) (Odds Ratio: 1.21 [95%CI 1.05, 1.39]). No association was found between %SpO290 and ECG markers of LA abnormalities.

Conclusion

Severity of SDB, as measured by AHI, is associated with subclinical LA disease, as indicated by PTFV1. PTFV1 may be an important ECG marker linking SDB and AF.

Electrocardiogram (ECG) for the Prediction of Incident Atrial Fibrillation: An Overview

Electrocardiograms (ECGs) have been employed to medically evaluate participants in population-based studies, and ECG-derived predictors have been reported for incident atrial fibrillation (AF). Here, we reviewed the status of ECG in predicting new-onset AF. We surveyed population-based studies and revealed ECG variables to be risk factors for incident AF. When available, the predictive values of each ECG risk marker were calculated. Both the atrium-related and ventricle-related ECG variables were risk factors for incident AF, with significant hazard risks (HRs) even after multivariate adjustments. The risk factors included P-wave indices (maximum P-wave duration, its dispersion or variation and P-wave morphology) and premature atrial contractions (PACs) or runs. In addition, left ventricular hypertrophy (LVH), ST-T abnormalities, intraventricular conduction delay, QTc interval and premature ventricular contractions (PVCs) or runs were a risk of incident AF. An HR of greater than 2.0 was observed in the upper 5th percentile of the P-wave durations, P-wave durations greater than 130 ms, P-wave morpholyg, PACs (PVCs) or runs, LVH, QTc and left anterior fascicular blocks. The sensitivity , specificity and the positive and negative predictive values were 3.6-53.8%, 61.7-97.9%, 2.9-61.7% and 77.4-97.7%, respectively. ECG variables are risk factors for incident AF. The correlation between the ECG-derived AF predictors, especially P-wave indices, and underlying diseases and the effects of the reversal of the ECG-derived predictors on incident AF by treatment of comorbidities require further study.

Impact of Alcohol Consumption on Atrial Fibrillation Outcomes Following Pulmonary Vein Isolation

Background

Moderate to heavy alcohol use has been shown to be associated with increased atrial fibrillation (AF) incidence. However, the relationship between alcohol use and AF recurrence after pulmonary vein isolation (PVI) is not well known.

Objective

We sought to study the impact of different alcohol consumption levels on outcomes after AF ablation.

Methods

A retrospective analysis was performed of 226 consecutive patients undergoing first time PVI for AF. Clinical data were collected including alcohol intake classified into 3 groups: none-rare (< 1 drink/ week), moderate (1-7 drinks/ week), and heavy (> 7 drinks/ week). Patients were followed for recurrences within the first 3 months (blanking period; early recurrence) and after 3 months up to 1 year (late recurrence) after the ablation.

Results

Paroxysmal and persistent AF had early recurrence rates of 29.1% and 32.2%, and late recurrence rates of 30.2% and 44.1%, respectively. The none-rare alcohol group had a higher frequency of diabetes mellitus (p=0.007). Neither moderate or heavy alcohol consumption, in reference to the none-rare group, was significantly predictive of early or late AF recurrence on adjusted multivariate logistic regression analysis (p>0.05).

Conclusion

Despite known associations between alcohol and incidence of AF, alcohol consumption is not associated with early or late AF recurrence after PVI in this cohort.

Pharmacologic Prevention of Incident Atrial Fibrillation: Long-Term Results From the ALLHAT (Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial)

BACKGROUND

Although atrial fibrillation (AF) guidelines indicate that pharmacological blockade of the renin-angiotensin system may be considered for primary AF prevention in hypertensive patients, previous studies have yielded conflicting results. We sought to determine whether randomization to lisinopril reduces incident AF or atrial flutter (AFL) compared with chlorthalidone in a large clinical trial cohort with extended post-trial surveillance.

METHODS AND RESULTS

We performed a secondary analysis of the ALLHAT (Antihypertensive and Lipid-Lowering Treatment to Prevent Heart Attack Trial), a randomized, double-blind, active-controlled clinical trial that enrolled hypertensive individuals ≥55 years of age with at least one other cardiovascular risk factor. Participants were randomly assigned to receive amlodipine, lisinopril, or chlorthalidone. Individuals with elevated fasting low-density lipoprotein cholesterol levels were also randomized to pravastatin versus usual care. The primary outcome was the development of either AF or AFL as diagnosed by serial study ECGs or by Medicare claims data. Among 14 837 participants without prevalent AF or AFL, 2514 developed AF/AFL during a mean 7.5±3.2 years of follow-up. Compared with chlorthalidone, randomization to either lisinopril (hazard ratio, 1.04; 95% confidence interval, 0.94-1.15; P=0.46) or amlodipine (hazard ratio, 0.93; 95% confidence interval, 0.84-1.03; P=0.16) was not associated with a significant reduction in incident AF/AFL.

CONCLUSIONS

Compared with chlorthalidone, treatment with lisinopril is not associated with a meaningful reduction in incident AF or AFL among older adults with a history of hypertension.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00000542.

Comparison and Validation of Recommended QT Interval Correction Formulas for Predicting Cardiac Arrhythmias in Patients With Advanced Heart Failure and Cardiac Resynchronization Devices

QT interval prolongation is an important marker for the development of cardiac arrhythmias (CAs). Optimal methods to estimate QT/QTc intervals in patients with ventricular pacing (VP) and its correlation with CA have not been widely investigated. We aimed to validate the currently available formulas for QT determination during VP and to compare their abilities in predicting the occurrence of CA (atrial fibrillation [AF] and malignant ventricular arrhythmias [VAs] in patients with advanced heart failure and cardiac resynchronization therapy). Consecutive patients with advanced heart failure who underwent cardiac resynchronization therapy implantation between August 2001 and April 2015 were included in a retrospective study. Four proposed formulas for QT correction in VP rhythms were evaluated. One hundred eighty patients were enrolled. During 44 months of follow-up, 43 patients (37.7%) developed AF and 16 patients (8.9%) developed VA. There was no correlation between corrected QT increments and AF risk with any of the formulas for paced rhythms. Regarding VA, higher corrected QT values measured with Massachusetts' formula (QTcM) were found to have a higher risk of event (p = 0.036) (Beta = 1.012 [1.001 to 1.023]). Each 1 ms increase in QTc increased the probability of experiencing VA by 12‰. QTcM >444 was found to be a strong predictor of VA. In conclusion, there are significant differences in mean QTc interval measured by the currently advised formulas. QTc interval was not associated with AF in any of the formulas. Only the QTcM formula showed a significant stepwise increase in the risk of experiencing malignant VA.

The Use of Statins in the Treatment and Prevention of Atrial Fibrillation

The hydroxy-methyl-glutaryl-CoA reductase inhibitors (statins) are used extensively in the treatment of hyperlipidemia and in the primary and secondary prevention of cardiovascular and cerebrovascular diseases. Statins have also been demonstrated to confer secondary pleiotropic benefits in a variety of other disease processes, including a potential advantage in treating and preventing atrial fibrillation. These effects are primarily due to the up-regulation of endothelial nitric oxide synthase activity and a decrease in nicotinamide adenine dinucleotide phosphate oxidase production, which leads to downstream effects that improve the electromechanical function of atrial and myocardial tissue. The following serves as a focused and updated review of the published clinical data regarding the pleiotropic effects of statins in atrial fibrillation.

Angiotensin-Receptor Blocker, Angiotensin-Converting Enzyme Inhibitor, and Risks of Atrial Fibrillation: A Nationwide Cohort Study

Both angiotensin-receptor blockers (ARB) and angiotensin-converting enzyme inhibitors (ACEI) have protective effects against atrial fibrillation (AF). The differences between ARB and ACEI in their effects on the primary prevention of AF remain unclear. This study compared ARB and ACEI in combined antihypertensive medications for reducing the risk of AF in patients with hypertension, and determined which was better for AF prevention in a nationwide cohort study.Patients aged ≥55 years and with a history of hypertension were identified from Taiwan National Health Insurance Research Database. Medical records of 25,075 patients were obtained, and included 6205 who used ARB, 8034 who used ACEI, and 10,836 nonusers (no ARB or ACEI) in their antihypertensive regimen. Cox regression models were applied to estimate the hazard ratio (HR) for new-onset AF.During an average of 7.7 years' follow-up, 1619 patients developed new-onset AF. Both ARB (adjusted HR: 0.51, 95% CI 0.44-0.58, P < 0.001) and ACEI (adjusted HR: 0.53, 95% CI 0.47-0.59, P < 0.001) reduced the risk of AF compared to nonusers. Subgroup analysis showed that ARB and ACEI were equally effective in preventing new-onset AF regardless of age, gender, the presence of heart failure, diabetes, and vascular disease, except for those with prior stroke or transient ischemic attack (TIA). ARB prevents new-onset AF better than ACEI in patients with a history of stroke or TIA (log-rank P = 0.012).Both ARB and ACEI reduce new-onset AF in patients with hypertension. ARB prevents AF better than ACEI in patients with a history of prior stroke or TIA.

Atrial Fibrillation Predictors: Importance of the Electrocardiogram

Atrial fibrillation (AF) is the most common arrhythmia in adults and is associated with significant morbidity and mortality. Substantial interest has developed in the primary prevention of AF, and thus the identification of individuals at risk for developing AF. The electrocardiogram (ECG) provides a wealth of information, which is of value in predicting incident AF. The PR interval and P wave indices (including P wave duration, P wave terminal force, P wave axis, and other measures of P wave morphology) are discussed with regard to their ability to predict and characterize AF risk in the general population. The predictive value of the QT interval, ECG criteria for left ventricular hypertrophy, and findings of atrial and ventricular ectopy are also discussed. Efforts are underway to develop models that predict AF incidence in the general population; however, at present, little information from the ECG is included in these models. The ECG provides a great deal of information on AF risk and has the potential to contribute substantially to AF risk estimation, but more research is needed.

Age and CHADS2 Score Predict the Effectiveness of Renin-Angiotensin System Blockers on Primary Prevention of Atrial Fibrillation

Renin-angiotensin system (RAS) blockers have potential protective effects against atrial fibrillation (AF). The purpose of this study was to determine if patient characteristics and underlying co-morbidities could predict the efficacy of RAS blockers in AF prevention. Patients aged ≥ 45 years with hypertension were identified from the Taiwan National Health Insurance Research Database. After propensity-score matching, a total of 22,324 patients were included in this study. Risk of new-onset AF in RAS blockers users and non-users was estimated. During up to 10 years of follow-up, 1,475 patients experienced new-onset AF. Overall, RAS blockers reduced the risk of AF by 36% (adjusted HR 0.64; 95% CI 0.58 to 0.71; p < 0.001). Subgroup analysis showed that RAS blockers use was beneficial for AF prevention in patients aged ≥ 55 years or with a CHADS2 score of 1, 2, or 3. The therapy provided no obvious beneficial effect for AF prevention in those aged less than 55 years or with a CHADS2 score ≥ 4. In conclusion, RAS blockers reduced the risk of new-onset AF in patients aged ≥ 55 years or with a CHADS2 score of 1, 2, or 3, but not in patients aged less than 55 years or with a CHADS2 score ≥ 4.

Statin Therapy for Primary Prevention of Atrial Fibrillation: Guided by CHADS2/CHA2DS2VASc Score

Atrial fibrillation (AF) is the most common arrhythmia and is associated with increased cardiovascular morbidity and mortality. The anti-arrhythmic effect of statins on AF prevention appears to be highly significant in most clinical studies. However, some discrepancies do exist among different clinical studies. Different clinical settings and types of stains used may explain these differences between trials. The CHADS₂ and CHA₂DS₂VASc scoring systems have been used for stroke risk stratification in AF patients. The recent study suggested that these scores can also be used to guide statin therapy for AF prevention. Patients with higher scores had a higher risk of developing AF and gained more benefits from statins therapy than those with lower scores. This review article focused on the ability of these scores to predict AF prevention by statins.

Clinical update on the management of atrial fibrillation

Atrial fibrillation (AF) is a cardiac arrhythmia associated with significant morbidity and mortality, affecting more than 3 million people in the United States and 1-2% of the population worldwide. Its estimated prevalence is expected to double within the next 50 years. During the past decade, there have been significant advances in the treatment of AF. Studies have demonstrated that a rate control strategy, with a target resting heart rate between 80 and 100 beats/minute, is recommended over rhythm control in the vast majority of patients. The CHA2 DS2 ≥ (congestive heart failure, hypertension, age ≥ 65 yrs, diabetes mellitus, stroke or transient ischemic attack, vascular disease, female gender) scoring system is a potentially useful stroke risk stratification tool that incorporates additional risk factors to the commonly used CHADS2 (congestive heart failure, hypertension, age ≥ 75 years, diabetes mellitus, stroke transient ischemic attack) scoring tool. Similarly, a convenient scheme, termed HAS-BLED (hypertension, abnormal renal/liver function, stroke, bleeding history or predisposition, labile international normalized ratio, elderly, drugs/alcohol concomitantly), to assess bleeding risk has emerged that may be useful in select patients. Furthermore, new antithrombotic strategies have been developed as potential alternatives to warfarin, including dual-antiplatelet therapy with clopidogrel plus aspirin and the development of new oral anticoagulants such as dabigatran, rivaroxaban, and apixaban. Vernakalant has emerged as another potential option for pharmacologic conversion of AF, whereas recent trials have better defined the role of dronedarone in the maintenance of sinus rhythm. Finally, catheter ablation represents another alternative to manage AF, whereas upstream therapy with inhibitors of the renin-angiotensin-aldosterone system, statins, and polyunsaturated fatty acids could potentially prevent the occurrence of AF. Despite substantial progress in the management of AF, significant uncertainty surrounds the optimal treatment of this condition.

Holiday heart syndrome revisited after 34 years

The cardiovascular effects of alcohol are well known. However, most research has focused on the beneficial effects (the "French paradox") of moderate consumption or the harmful consequences, such as dilated cardiomyopathy, associated with heavy consumption over an extended period. An association between the ingestion of acute alcohol and onset of cardiac arrhythmias was first reported in the early 70's. In 1978, Philip Ettinger described "Holiday heart syndrome" (HHS) for the first time, as the occurrence, in healthy people without heart disease known to cause arrhythmia, of an acute cardiac rhythm disturbance, most frequently atrial fibrillation, after binge drinking. The name is derived from the fact that episodes were initially observed more frequently after weekends or public holidays. Since the original description of HHS, 34 years have passed and new research in this field has increased the volume of knowledge related to this syndrome. Throughout this paper the authors will comprehensively review most of the available data concerning HHS and highlight the questions that remain unresolved.

SNP rs3825214 in TBX5 is associated with lone atrial fibrillation in Chinese Han population

BACKGROUND

A prolonged PR interval is a sign of increased risk of cardiac arrhythmia. Recent genome-wide association studies found that the single-nucleotide polymorphism (SNP) rs3825214 in T-box 5 (TBX5) was positively associated with PR interval, QRS duration, QT interval, and common arrhythmia disorders such as atrial fibrillation (AF) and advanced atrioventricular block. However, other independent replication studies are required to validate the result. This study assessed associations between rs3825214 and ECG parameters, AF, and ventricular tachycardia (VT) in a Chinese Han population.

METHODOLOGY/PRINCIPAL FINDINGS

To assess the association between rs3825214 and AF and VT, we carried out case-control association studies with 692 AF patients (including 275 lone AF patients), 235 VT patients, and 856 controls. Genotyping was performed using a Rotor-Gene TM 6000 High Resolution Melt system. Statistical analyses of associations were adjusted for potential confounding factors. A moderate association was detected between rs3825214 and AF (P(adj) = 0.036, OR = 0.79) and a highly significant association was detected between the G allele of rs3825214 and lone AF (P(adj) = 0.001, OR = 0.65; genotypic P = 3.75×10⁻⁴ with a dominant model). We also found that rs3825214 showed a significant association with atrial-ventricular block (AVB; P = 0.028; P(adj) = 0.035, OR = 0.494).

CONCLUSIONS

Our results indicate that rs3825214 conferred a significant risk of lone AF in this Chinese Han population.

Sinus node disease in subjects with type 1 ECG pattern of Brugada syndrome

BACKGROUND

The spectrum of phenotypes related to mutations of the SCN5A gene include Brugada syndrome (BS), long QT syndrome, progressive cardiac conduction defect, and sinus node disease (SND). The present study investigated the incidence of SND in subjects with type 1 electrocardiogram (ECG) pattern of BS.

METHODS AND RESULTS

The study population consisted of 68 individuals (55 males, mean age 44.8±12.8 years) with spontaneous (n=27) or drug-induced (n=41) type 1 ECG pattern of BS. Twenty-eight subjects were symptomatic with a history of syncope (41.2%). SND was observed in 6 symptomatic subjects (8.8%), and was mainly attributed to sino-atrial block with sinus pauses. Two patients were initially diagnosed with SND, and received a pacemaker. Patients with SND displayed an increased P-wave duration in leads II and V2, PR interval in leads II and V2, QRS duration in leads II and V2, and increased QTc interval in lead V2 (p<0.05). AH and HV intervals as well as corrected sinus node recovery time (cSNRT) were significantly prolonged in subjects with SND (p<0.05). During a mean follow-up period of 5.0±3.6 years, five subjects with a history of syncope suffered appropriate implantable cardioverter defibrillator (ICD) discharges due to ventricular arrhythmias (7.4%). None of those diagnosed with SND suffered syncope or ICD therapies.

CONCLUSION

SND is not an uncommon finding in subjects with type 1 ECG pattern of BS. The occurrence of SND in relatively young patients may deserve meticulous investigation including sodium channel blocking test.

CHADS(2) score, statin therapy, and risks of atrial fibrillation

OBJECTIVE

Little is known about the effectiveness of statins on primary prevention of atrial fibrillation in elderly patients. This study aimed to evaluate the efficacy of statin treatment for atrial fibrillation prevention in elderly patients with hypertension, and to determine if comorbidity or CHADS(2) (Congestive heart failure, Hypertension, Age ≥75 years, Diabetes mellitus, prior Stroke or transient ischemic attack) score can predict the effectiveness of statin treatment.

METHODS

Patients aged ≥65 years with hypertension were identified from a National Health Insurance research database (a systemic sampling from 2000 to 2009 with a total of 1,000,000 subjects). Medical records of 27,002 patients were used in this study, in which 2400 (8.9%) were receiving statin therapy. Risk of new-onset atrial fibrillation in statin users and nonusers was analyzed.

RESULTS

During the 9-year follow-up period, 2241 patients experienced new-onset atrial fibrillation. Statin users were younger than nonusers (72.4 vs 73.4 years) but had a higher prevalence of ischemic heart disease, diabetes mellitus, stroke, and chronic renal disease. Overall, statin therapy reduced the risk of atrial fibrillation by 19% (adjusted hazard ratio 0.81; 95% confidence interval, 0.69-0.95; P=.009). Subgroup analysis showed that statin use was beneficial in patients with or without a particular comorbidity. The effectiveness of statins was significant in patients with CHADS(2) score ≥2 (adjusted hazard ratio 0.69; 95% confidence interval, 0.57-0.85; P <.001). However, statin therapy was not as beneficial in hypertensive patients without other cardiovascular comorbidities (CHADS(2) score =1).

CONCLUSION

Statin therapy in elderly patients with hypertension reduces the risk of new-onset atrial fibrillation. Statins are more beneficial in patients with CHADS(2) score ≥2 than in those with score of 1.

The preventive effect of statin therapy on new-onset and recurrent atrial fibrillation in patients not undergoing invasive cardiac interventions: a systematic review and meta-analysis

BACKGROUND

Previous meta-analyses suggest that pre-procedural use of statin therapy may reduce atrial fibrillation (AF) following invasive cardiac interventions (coronary artery by-pass grafting and percutaneous coronary intervention). However, the current evidence on the benefit of statins unrelated to invasive cardiac interventions has not been clarified systematically.

METHODS

Through a systematic literature search, trials examining the effect of statin therapy on AF were selected. Trials using statins before any percutaneous or surgical cardiac interventions were excluded.

RESULTS

The search identified 11 randomized and 16 observational eligible studies, totaling 106,640 patients receiving statin therapy and 129,305 serving as controls. Fourteen studies investigated the effect of statins on new-onset AF, 13 studies investigated the effect of statins on recurrent AF and one in both new-onset and recurrent AF. In the statin versus control group the mean age was 60.7 ± 8.3 versus 68.6 ± 6.2 years and females comprised 8.4% versus 10.3%. Statin therapy was associated with significant reduction of AF (Risk ratio (RR): 0.81 [95% confidence interval (CI): 0.80-0.83], p<0.001) combining all studies. Assessing exclusively randomized trials, statin therapy showed no significant risk reduction (RR: 0.97 [95%CI: 0.90-1.05], p=0.509), heterogeneity p>0.05. Assessing exclusively observational studies the risk reduction of new-onset AF was 12% (RR: 0.88 [95%CI: 0.85-0.91], p<0.001) and recurrent AF 15% (RR: 0.85 [95%CI: 0.80-0.90], p<0.001), heterogeneity p<0.001.

CONCLUSION

The hitherto published randomized clinical trials do not support a beneficial effect of statins on AF in patients not undergoing invasive cardiac interventions. This is in contrast to the results of observational and interventional studies.

Effect of lipid lowering on new-onset atrial fibrillation in patients with asymptomatic aortic stenosis: the Simvastatin and Ezetimibe in Aortic Stenosis (SEAS) study

BACKGROUND

Lipid-lowering drugs, particularly statins, have anti-inflammatory and antioxidant properties that may prevent atrial fibrillation (AF). This effect has not been investigated on new-onset AF in asymptomatic patients with aortic stenosis (AS).

METHODS

Asymptomatic patients with mild-to-moderate AS (n = 1,421) were randomized (1:1) to double-blind simvastatin 40 mg and ezetimibe 10 mg combination or placebo and followed up for a mean of 4.3 years. The primary end point was the time to new-onset AF adjudicated by 12-lead electrocardiogram at a core laboratory reading center. Secondary outcomes were the correlates of new-onset AF with nonfatal nonhemorrhagic stroke and a combined end point of AS-related events.

RESULTS

During the course of the study, new-onset AF was detected in 85 (6%) patients (14.2/1,000 person-years of follow-up). At baseline, patients who developed AF were, compared with those remaining in sinus rhythm, older and had a higher left ventricular mass index a smaller aortic valve area index. Treatment with simvastatin and ezetimibe was not associated with less new-onset AF (odds ratio 0.89 [95% CI 0.57-1.97], P = .717). In contrast, age (hazard ratio [HR] 1.07 [95% CI 1.05-1.10], P < .001) and left ventricular mass index (HR 1.01 [95% CI 1.01-1.02], P < .001) were independent predictors of new-onset AF. The occurrence of new-onset AF was independently associated with 2-fold higher risk of AS-related outcomes (HR 1.65 [95% CI 1.02-2.66], P = .04) and 4-fold higher risk of nonfatal nonhemorrhagic stroke (HR 4.04 [95% CI 1.18-13.82], P = .03).

CONCLUSIONS

Simvastatin and ezetimibe were not associated with less new-onset AF. Older age and greater left ventricular mass index were independent predictors of AF development. New-onset AF was associated with a worsening of prognosis.

Subclinical thyroid dysfunction and the risk of heart failure in older persons at high cardiovascular risk

CONTEXT

Subclinical thyroid dysfunction is common in older people. However, its clinical importance is uncertain.

OBJECTIVE

Our objective was to determine the extent to which subclinical hyperthyroidism and hypothyroidism influence the risk of heart failure and cardiovascular diseases in older people.

SETTING AND DESIGN

The Prospective Study of Pravastatin in the Elderly at Risk (PROSPER) is an prospective cohort study.

PATIENTS

Patients included men and women aged 70-82 yr (n=5316) with known cardiovascular risk factors or previous cardiovascular disease.

MAIN OUTCOME MEASURES

Incidence rate of heart failure hospitalization, atrial fibrillation, and cardiovascular events and mortality according to baseline thyroid status were evaluated. Euthyroid participants (TSH=0.45-4.5 mIU/liter) were compared with those with subclinical hyperthyroidism (TSH<0.45 mIU/liter) and those with subclinical hypothyroidism (TSH≥4.5 mIU/liter, both with normal free T4).

RESULTS

Subclinical hyperthyroidism was present in 71 participants and subclinical hypothyroidism in 199 participants. Over 3.2 yr follow-up, the rate of heart failure was higher for subclinical hyperthyroidism compared with euthyroidism [age- and sex-adjusted hazard ratio (HR)=2.93, 95% confidence interval (CI)=1.37-6.24, P=0.005; multivariate-adjusted HR=3.27, 95% CI=1.52-7.02, P=0.002). Subclinical hypothyroidism (only at threshold>10 mIU/liter) was associated with heart failure (age- and sex-adjusted HR=3.01, 95% CI=1.12-8.11, P=0.029; multivariate HR=2.28, 95% CI=0.84-6.23). There were no strong evidence of an association between subclinical thyroid dysfunction and cardiovascular events or mortality, except in those with TSH below 0.1 or over 10 mIU/liter and not taking pravastatin.

CONCLUSION

Older people at high cardiovascular risk with low or very high TSH along with normal free T4 appear at increased risk of incident heart failure.