Continuous cardiac rhythm monitoring post-stroke: A feasibility study in REGARDS

OBJECTIVES

Cardiac rhythm monitoring is increasingly used after stroke. We studied feasibility of telephone guided, mail-in ambulatory long-term cardiac rhythm monitoring in Black and White stroke survivors. MATERIALS AND METHODS;: We contacted 28 participants of the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study who had an ischemic stroke during follow-up. After obtaining informed consent by telephone, a noninvasive 14-day cardiac rhythm monitoring device (ZIO® XT patch; iRhythm Technologies, San Francisco, CA) was mailed to each participant. We evaluated the results of telephone consent, follow-up calls, compliance and wear time as the primary objective. Secondarily, we reported prevalence of atrial and ventricular arrhythmias.

RESULTS

The majority of those contacted (20/28 = 71%) agreed to enroll in the monitoring study. Non-participation was nominally more common in Black than White participants; 6/16 (37.5%) vs. 2/12 (17%). Of those who agreed, 15 participants (75%, 6 Black, 9 White) completed ambulatory monitoring with mean wear time 12.9 ± 2.5 days. Arrhythmias were observed in two-thirds of the 15 participants: AF in 2, brief atrial tachycardia in 12, NSVT in 2, premature ventricular contractions in 3, and pause or atrioventricular block in 2.

CONCLUSIONS

Non-invasive rhythm monitoring was feasible in this pilot from a large, national cohort study of stroke survivors that employed a telephone guided, mail-in monitoring system, and these preliminary results suggest a high prevalence of arrhythmias. Increased emphasis on recruitment strategies for Black stroke survivors may be required. We demonstrated a high yield of significant cardiac arrhythmias among post-stroke participants who completed monitoring.

Genome-wide analyses identify SCN5A as a susceptibility locus for premature atrial contraction frequency

Premature atrial contractions (PACs) are frequently observed on electrocardiograms and are associated with increased risks of atrial fibrillation (AF), stroke, and mortality. In this study, we aimed to identify genetic susceptibility loci for PAC frequency. We performed a genome-wide association study meta-analysis with PAC frequency obtained from ambulatory cardiac monitoring in 4,831 individuals of European ancestry. We identified a genome-wide significant locus at the SCN5A gene. The lead variant, rs7373862, located in an intron of SCN5A, was associated with an increase of 0.12 [95% CI 0.08–0.16] standard deviations of the normalized PAC frequency per risk allele. Among genetic variants previously associated with AF, there was a significant enrichment in concordance of effect for PAC frequency (n = 73/106, p = 5.1 × 10⁻⁵). However, several AF risk loci, including PITX2, were not associated with PAC frequency. These findings suggest the existence of both shared and distinct genetic mechanisms for PAC frequency and AF.

•

Variants in SCN5A are associated with premature atrial contractions (PAC) frequency

•

Other atrial fibrillation (AF) risk variants are also associated with PAC frequency

•

Both shared and distinct genetic mechanisms exist for PAC frequency and AF

Genetic analyses of the electrocardiographic QT interval and its components identify additional loci and pathways

The QT interval is an electrocardiographic measure representing the sum of ventricular depolarization and repolarization, estimated by QRS duration and JT interval, respectively. QT interval abnormalities are associated with potentially fatal ventricular arrhythmia. Using genome-wide multi-ancestry analyses (>250,000 individuals) we identify 177, 156 and 121 independent loci for QT, JT and QRS, respectively, including a male-specific X-chromosome locus. Using gene-based rare-variant methods, we identify associations with Mendelian disease genes. Enrichments are observed in established pathways for QT and JT, and previously unreported genes indicated in insulin-receptor signalling and cardiac energy metabolism. In contrast for QRS, connective tissue components and processes for cell growth and extracellular matrix interactions are significantly enriched. We demonstrate polygenic risk score associations with atrial fibrillation, conduction disease and sudden cardiac death. Prioritization of druggable genes highlight potential therapeutic targets for arrhythmia. Together, these results substantially advance our understanding of the genetic architecture of ventricular depolarization and repolarization.

Endophenotype effect sizes support variant pathogenicity in monogenic disease susceptibility genes

Accurate and efficient classification of variant pathogenicity is critical for research and clinical care. Using data from three large studies, we demonstrate that population-based associations between rare variants and quantitative endophenotypes for three monogenic diseases (low-density-lipoprotein cholesterol for familial hypercholesterolemia, electrocardiographic QTc interval for long QT syndrome, and glycosylated hemoglobin for maturity-onset diabetes of the young) provide evidence for variant pathogenicity. Effect sizes are associated with pathogenic ClinVar assertions (P < 0.001 for each trait) and discriminate pathogenic from non-pathogenic variants (area under the curve 0.82-0.84 across endophenotypes). An effect size threshold of ≥ 0.5 times the endophenotype standard deviation nominates up to 35% of rare variants of uncertain significance or not in ClinVar in disease susceptibility genes with pathogenic potential. We propose that variant associations with quantitative endophenotypes for monogenic diseases can provide evidence supporting pathogenicity.

Relationship Between High Blood Pressure, Atrial Cardiopathy, and Mortality in the General Population

BACKGROUND

Atrial cardiopathy is associated with an increased risk of mortality. However, it is unclear whether this association is modified by hypertension, a risk factor for both atrial cardiopathy and mortality.

METHODS

This analysis included 8,023 participants from the Third National Health and Nutrition Examination Survey. Electrocardiographic deep terminal negativity of P-wave in V1 ≥100 µV defined atrial cardiopathy. National Death Index was used to identify the date and cause of death. Cox proportional hazard analysis was used to examine the association of atrial cardiopathy with mortality among participants stratified by hypertension status.

RESULTS

In total 2.7% of the participants had atrial cardiopathy. Over a median follow-up of 14 years, 2,922 all-cause deaths occurred, of which 1,058 were CVD. All-cause death rates were almost double among participants with concomitant atrial cardiopathy and elevated blood pressure (BP) (120-129/<80), stage 1 (130-139/80-89), or stage 2 hypertension (≥140/≥90) compared to their counterparts in the same hypertension stages without atrial cardiopathy (47.8, 61.3, and 80.2 vs. 23, 24.7, and 44.8 per 1,000 person-years (PY), respectively). In multivariable-adjusted models, a stronger association between atrial cardiopathy and all-cause mortality was observed in the presence compared to the absence of hypertension (HR (95% CI): 1.59 (1.25-2.01) vs. 0.67 (0.41-1.10), respectively, interaction P-value = 0.009). Similarly, an association between atrial cardiopathy and cardiovascular disease (CVD) mortality was observed in the presence compared to the absence of hypertension (HR (95% CI): 1.64 (1.08-2.47) vs. 0.63 (0.20-2.00), respectively, interaction P-value = 0.20).

CONCLUSIONS

Concomitant presence of high BP and atrial cardiopathy carries a higher risk of mortality, and the risk increases with higher BP levels.

Monogenic and Polygenic Contributions to QTc Prolongation in the Population

BACKGROUND

Rare sequence variation in genes underlying cardiac repolarization and common polygenic variation influence QT interval duration. However, current clinical genetic testing of individuals with unexplained QT prolongation is restricted to examination of monogenic rare variants. The recent emergence of large-scale biorepositories with sequence data enables examination of the joint contribution of rare and common variations to the QT interval in the population.

METHODS

We performed a genome-wide association study of the QTc in 84 630 UK Biobank participants and created a polygenic risk score (PRS). Among 26 976 participants with whole-genome sequencing and ECG data in the TOPMed (Trans-Omics for Precision Medicine) program, we identified 160 carriers of putative pathogenic rare variants in 10 genes known to be associated with the QT interval. We examined QTc associations with the PRS and with rare variants in TOPMed.

RESULTS

Fifty-four independent loci were identified by genome-wide association study in the UK Biobank. Twenty-one loci were novel, of which 12 were replicated in TOPMed. The PRS composed of 1 110 494 common variants was significantly associated with the QTc in TOPMed (ΔQTc/decile of PRS=1.4 ms [95% CI, 1.3 to 1.5]; P=1.1×10-196). Carriers of putative pathogenic rare variants had longer QTc than noncarriers (ΔQTc=10.9 ms [95% CI, 7.4 to 14.4]). Of individuals with QTc>480 ms, 23.7% carried either a monogenic rare variant or had a PRS in the top decile (3.4% monogenic, 21% top decile of PRS).

CONCLUSIONS

QTc duration in the population is influenced by both rare variants in genes underlying cardiac repolarization and polygenic risk, with a sizeable contribution from polygenic risk. Comprehensive assessment of the genetic determinants of QTc prolongation includes incorporation of both polygenic and monogenic risk.

Left Atrial Remodeling and Stroke in Patients With Sinus Rhythm and Normal Ejection Fraction: ARIC-NCS

Background Age-related left atrial (LA) structural and functional abnormalities may be related to subclinical cerebral infarcts (SCIs) and stroke. We evaluated the association of 3-dimensional echocardiographic LA contractility parameters with SCIs and stroke across the spectrum of tertiles of age increment in elderly patients with sinus rhythm, normal ejection fraction, and no history of atrial fibrillation. Methods and Results We enrolled 407 participants (mean age, 76±8 years; 40% men) from ARIC-NCS (Atherosclerosis Risk in Communities Neurocognitive Study) undergoing a brain magnetic resonance imaging and 3-dimensional echocardiographic examinations in 2011 to 2013. The sample was analyzed among age tertiles and subgroups: no cerebral magnetic resonance imaging-detectable infarcts (n=315), magnetic resonance imaging-diagnosed SCIs (n=58), and clinically diagnosed stroke (n=34). The frequency of SCIs significantly increased over age tertiles (P trend 0.023). LA global longitudinal strain-a 3-dimensional echocardiographic index of LA reservoir function-and E/e' divided by LA global longitudinal strain-an index of LA stiffness-worsened across age tertiles (P trend 0.014 and 0.001, respectively), and only in the categories of SCIs (P trend <0.001 and 0.045, respectively) and stroke (P trend 0.001 and 0.011, respectively). LA global longitudinal strain was negatively associated with increased odds of SCIs (P=0.036, P=0.008, and P=0.001, respectively) and strokes (P=0.043, P=0.015, and P=0.001, respectively) over age tertiles, with a significant interaction between age tertiles (interaction P=0.043 and P=0.010, respectively). E/e' divided by LA global longitudinal strain was positively associated with the presence of SCIs (P=0.037, P=0.007, and P=0.001, respectively) and strokes (P=0.045, P=0.007, and P=0.003, respectively) over age tertiles, with a significant interaction only for SCIs (interaction P=0.040) and not for clinical stroke. Conclusions In a large cohort study of elderly patients, among participants with sinus rhythm, normal ejection fraction, and no history of atrial fibrillation, measures of worse age-related LA reservoir function and stiffness are associated with higher odds of SCIs and stroke.

Association of physical activity with the incidence of atrial fibrillation in persons > 65 years old: the Atherosclerosis Risk in Communities (ARIC) study

AIMS

To evaluate the association of physical activity (PA) with atrial fibrillation (AF) incidence in an elderly population.

METHODS

We studied 5166 participants of the Atherosclerosis Risk in Communities cohort examined in 2011-2013 free of AF. Self-reported PA was evaluated with a validated questionnaire. Weekly minutes of leisure-time moderate to vigorous physical activity (MVPA) were calculated and categorized using the 2018 Physical Activity Guidelines for Americans (no activity [0 min/week], low [> 0- < 150 min/week], adequate [150- < 300 min/week], high [≥ 300 min/week]). Incident AF through 2019 was ascertained from hospital discharges and death certificates. Cox models were used to calculate hazard ratios (HR) and 95% confidence intervals (CI) for AF by levels of physical activity adjusting for potential confounders.

RESULTS

The mean (SD) age for the sample was 75 (5) years (59% female, 22% Black). During a mean (SD) follow-up time of 6.3 (2.0) years, 703 AF events were identified. The association of MVPA with AF incidence showed a U-shaped relationship. Compared to those not engaging in MVPA, individuals with low MVPA had a 23% lower hazard of AF (HR = 0.77; 95% CI 0.61, 0.96), while those with adequate MVPA had a 14% lower hazard (HR 0.86; 95% CI 0.69, 1.06). High levels of MVPA were not associated with AF risk (HR 0.97; 95% CI 0.78, 1.20).

CONCLUSION

This study suggests that being involved in low to moderate levels of MVPA is associated with lower AF risk, with no evidence of increased risk of AF in those with higher levels of MVPA.

Thirty-Year Trends in the Incidence of Atrial Fibrillation: The ARIC Study

Background Long-term data to study recent trends in the incidence of atrial fibrillation (AF), overall and among sex and race groups, are scarce. We evaluated the 30-year trends in the incidence of AF in the ARIC (Atherosclerosis Risk in Communities) study cohort and explored race and sex differences in these trends. Methods and Results We included 15 343 men and women aged 45 to 64 years in 1987 to 1989 without AF from 4 US communities in the ARIC cohort. Incident AF was identified based on study ECGs, hospital discharge codes, and death certificates through 2017. We calculated age and period-specific incidence rates (IRs) of AF. We used Poisson regression to calculate IR ratios of AF over time adjusting for age, sex, and race. A total of 3241 AF cases were identified during a mean (SD) follow-up of 22 years (8.4 years) (599 in Black participants, 2642 in White participants, 1582 in women, and 1659 in men). Overall, the IR of AF in the ARIC cohort was 9.6 per 1000 person-years (6.9 in Black participants, 10.5 in White participants, 8.1 in women, and 11.6 in men). Age-specific IR by time period did not show significant changes over time. In a model adjusted for sex, race, and age group, the rate of AF did not change significantly from 1987 to 1991 compared with 2012 to 2017 (IR ratio, 1.10 [95% CI, 0.88-1.36] comparing 2012-2017 with 1987-1991). Similarly, no evidence of changes over time in AF rates were identified in men and women or White and Black participants separately. Conclusions Even though IRs of AF increase as age increases, our analysis provided evidence suggesting that the overall IRs of AF have not changed over time in a multicenter cohort of Black and White individuals in the United States from 1987 to 2017.

P Wave Parameters and Indices: A Critical Appraisal of Clinical Utility, Challenges, and Future Research-A Consensus Document Endorsed by the International Society of Electrocardiology and the International Society for Holter and Noninvasive Electrocardiology

Atrial cardiomyopathy, characterized by abnormalities in atrial structure and function, is associated with increased risk of adverse cardiovascular and neurocognitive outcomes, independent of atrial fibrillation. There exists a critical unmet need for a clinical tool that is cost-effective, easy to use, and that can diagnose atrial cardiomyopathy. P wave parameters (PWPs) reflect underlying atrial structure, size, and electrical activation; alterations in these factors manifest as abnormalities in PWPs that can be readily ascertained from a standard 12-lead ECG and potentially be used to aid clinical decision-making. PWPs include P wave duration, interatrial block, P wave terminal force in V₁, P wave axis, P wave voltage, P wave area, and P wave dispersion. PWPs can be combined to yield an index (P wave index), such as the morphology-voltage-P-wave duration ECG risk score. Abnormal PWPs have been shown in population-based cohort studies to be independently associated with higher risks of atrial fibrillation, ischemic stroke, sudden cardiac death, and dementia. Additionally, PWPs, either individually or in combination (as a P wave index), have been reported to enhance prediction of atrial fibrillation or ischemic stroke. To facilitate translation of PWPs to routine clinical practice, additional work is needed to standardize measurement of PWPs (eg, via semiautomated or automated measurement), confirm their reliability and predictive value, leverage novel approaches (eg, wavelet analysis of P waves and machine learning algorithms), and finally, define the risk-benefit ratio of specific interventions in high-risk individuals. Our ultimate goal is to repurpose the ubiquitous 12-lead ECG to advance the study, diagnosis, and treatment of atrial cardiomyopathy, thus overcoming critical challenges in prevention of cardiovascular disease and dementia.

Prediction of Incident Heart Failure in CKD: The CRIC Study

Introduction

Heart failure (HF) is common in chronic kidney disease (CKD); identifying patients with CKD at high risk for HF may guide clinical care. We assessed the prognostic value of cardiac biomarkers and echocardiographic variables for 10-year HF prediction compared with a published clinical HF prediction equation in a cohort of participants with CKD.

Methods

We studied 2147 Chronic Renal Insufficiency Cohort (CRIC) participants without prior HF with complete clinical, cardiac biomarker (N-terminal brain natriuretic peptide [NT-proBNP] and high sensitivity troponin-T [hsTnT]), and echocardiographic data (left ventricular mass [LVM] and left ventricular ejection fraction [LVEF] data). We compared the discrimination of the 11-variable Atherosclerosis Risk in Communities (ARIC) HF prediction equation with LVM, LVEF, hsTnT, and NT-proBNP to predict 10-year risk of hospitalization for HF using a Fine and Gray modeling approach. We separately evaluated prediction of HF with preserved and reduced LVEF (LVEF ≥50% and <50%, respectively). We assessed discrimination with internally valid C-indices using 10-fold cross-validation.

Results

Participants' mean (SD) age was 59 (11) years, 53% were men, 43% were Black, and mean (SD) estimated glomerular filtration rate (eGFR) was 44 (16) ml/min per 1.73 m2. A total of 324 incident HF hospitalizations occurred during median (interquartile range) 10.0 (5.7-10.0) years of follow-up. The ARIC HF model with clinical variables had a C-index of 0.68. Echocardiographic variables predicted HF (C-index 0.70) comparably to the published ARIC HF model, while NT-proBNP and hsTnT together (C-index 0.73) had significantly better discrimination (P = 0.004). A model including cardiac biomarkers, echocardiographic variables, and clinical variables had a C-index of 0.77. Discrimination of HF with preserved LVEF was lower than for HF with reduced LVEF for most models.

Conclusion

The ARIC HF prediction model for 10-year HF risk had modest discrimination among adults with CKD. NT-proBNP and hsTnT discriminated better than the ARIC HF model and at least as well as a model with echocardiographic variables. HF clinical prediction models tailored to adults with CKD are needed. Until then, measurement of NT-proBNP and hsTnT may be a low-burden approach to predicting HF in this population, as they offer moderate discrimination.

Association of Echocardiographic Measures of Left Atrial Function and Size With Incident Dementia

IMPORTANCE

Atrial myopathy-characterized by alterations in left atrial (LA) function and size-is associated with ischemic stroke, independent of atrial fibrillation (AF). Electrocardiographic markers of atrial myopathy are associated with dementia, but it is unclear whether 2-dimensional echocardiographic (2DE)-defined LA function and size are associated with dementia.

OBJECTIVE

To examine the association of LA function and size with incident dementia.

DESIGN, SETTING, AND PARTICIPANTS

The Atherosclerosis Risk in Communities (ARIC) study is a community-based prospective cohort. An exploratory, retrospective analysis was conducted. ARIC centers are located in Forsyth County, North Carolina; Jackson, Mississippi; Washington County, Maryland; and suburban Minneapolis, Minnesota. For this analysis, visit 5 (2011-2013) served as the baseline. Participants without prevalent AF and stroke and who had 2DEs in 2011-2013 were included and surveilled through December 31, 2019.

EXPOSURES

LA function (reservoir strain, conduit strain, contractile strain, emptying fraction, passive emptying fraction, and active emptying fraction), and LA size (maximal and minimal volume index) as evaluated by 2DE.

MAIN OUTCOMES AND MEASURES

Dementia cases were identified using in-person and phone cognitive assessments, hospitalization codes, and death certificates. Cox proportional hazards models were used.

RESULTS

Among 4096 participants (mean [SD] age, 75 [5] years; 60% women; 22% Black individuals), 531 dementia cases were ascertained over a median follow-up of 6 years. Dementia incidence for the lowest LA quintile was 4.80 for reservoir strain, 3.94 for conduit strain, 3.29 for contractile strain, 4.20 for emptying fraction, 3.67 for passive emptying fraction, and 3.27 for active emptying fraction per 100 person-years. After full-model adjustments, there were statistically significant associations between measures of LA function and dementia; the hazard ratios (HRs) from the lowest vs highest quintile for reservoir strain were 1.98 (95% CI, 1.42-2.75); for conduit strain, 1.50 (95% CI, 1.09-2.06); for contractile strain, 1.57 (95% CI, 1.16-2.14); for emptying fraction, 1.87 (95% CI, 1.31-2.65); and for active emptying fraction, 1.43 (95% CI, 1.04-1.96). LA passive emptying fraction was not significantly associated with dementia (HR, 1.26 [95% CI, 0.93-1.71]). Dementia incidence for the highest LA maximal volume index quintile was 3.18 per 100 person-years (HR for highest vs lowest quintile, 0.77 [95% CI, 0.58-1.02]) and for the highest minimal volume index quintile was 3.50 per 100 person-years (HR for the highest vs lowest quintile, 0.95 [95% CI, 0.71-1.28]). Both measures were not significantly associated with dementia. These findings were robust to sensitivity analyses that excluded participants with incident AF or stroke.

CONCLUSIONS AND RELEVANCE

In this exploratory analysis of a US community-based cohort, several echocardiographic measures of lower LA function were significantly associated with an increased risk of subsequent dementia. Measures of LA size were not significantly associated with dementia risk. These findings suggest that impaired LA function may be a risk factor associated with dementia.

Continuous Glucose Monitoring in Adults With Type 1 Diabetes With 35 Years Duration From the DCCT/EDIC Study

OBJECTIVE

We evaluated blinded continuous glucose monitoring (CGM) profiles in a subset of adults with type 1 diabetes from the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications (DCCT/EDIC) study to characterize the frequency of glycemic excursions and contributing factors.

RESEARCH DESIGN AND METHODS

CGM-derived metrics were compared for daytime and nighttime periods using blinded CGM for a minimum of 6.5 days (average 11.9 days) and correlated with HbA1c levels, routine use of diabetes devices, and other characteristics in 765 participants.

RESULTS

Participants were 58.9 ± 6.5 years of age with diabetes duration 36.8 ± 4.9 years and HbA1c 7.8 ± 1.2%; 58% used insulin pumps, and 27% used personal, unblinded CGM. Compared with daytime, nighttime mean sensor glucose was lower, percent time in range 70-180 mg/dL (TIR) was similar, and hypoglycemia was more common. Over the entire recording period, only 9% of the 765 participants achieved >70% TIR and only 28% achieved <1% of observations of <54 mg/dL. Indeed, participants with the highest percentage of hypoglycemia had the lowest HbA1c levels. However, use of insulin pumps and CGM decreased the percent time at <54 mg/dL.

CONCLUSIONS

In adults with long-standing type 1 diabetes, short-term blinded CGM profiles revealed frequent clinically significant hypoglycemia (<54 mg/dL) during the night and more time in hyperglycemia during the day. The small subset of participants using routine CGM and insulin pumps had fewer hypoglycemic and hyperglycemic excursions and lower HbA1c levels. Thus, strategies to lower meal-stimulated hyperglycemia during the day and prevent hypoglycemia at night are relevant clinical goals in older patients with type 1 diabetes.

Relation of Cannabis Use to Elevated Atherosclerotic Cardiovascular Disease Risk Score

We hypothesized that cannabis use is associated with cardiovascular disease (CVD) risk factors. This could explain the reported link between cannabis and cardiovascular events including stroke and myocardial infarction. This analysis included 7,159 participants (age 37.8 ± 12.4 years, 48.6% men, and 61.5% Caucasian) from the National Health and Nutrition Examination Survey years 2011 to 2018. Cannabis use was defined by self-report. Participants with a history of stroke or myocardial infarction were excluded. Composite CVD risk was assessed using the American College of Cardiology/American Heart Association 10-year atherosclerotic cardiovascular risk (ASCVD) score. Participants were classified based on their ASCVD risk levels as low (<5.0%), borderline (5.0% to 7.4%), intermediate (7.5% to 19.9%), and high (≥20.0%). Multinomial logistic regression was used to examine the association between cannabis use and ASCVD risk category using low-risk ASCVD category as the reference level. About 63.9% (n = 4,573) of participants had ever used cannabis. Ever cannabis use was associated with 60% increased odds of high-risk ASCVD score (odds ratio [OR] 95% confidence interval [CI] 1.60 [1.04 to 2.45], p = 0.03). We also observed a dose-response relation between increased use of cannabis and a higher risk of ASCVD. Those reporting ≥2 uses per month had 79% increased odds of high-risk ASCVD score (OR [95% CI] 1.79 [1.10 to 2.92], p = 0.02) and those reporting ≥1 use per day had 87% increased odds of high-risk ASCVD score (OR [95% CI] 1.87 [1.16 to 3.01], p <0.001]. In conclusion, cannabis use is associated with elevated CVD risk. Individuals using cannabis should be screened for CVD risk, and appropriate risk reduction strategies should be implemented.