Identification of paroxysmal atrial fibrillation subtypes in over 13,000 individuals.

BACKGROUND: Paroxysmal atrial fibrillation (PAF) is broadly defined despite high variability in the occurrence and duration of PAF episodes. OBJECTIVE: The purpose of this study was to identify rhythm patterns in a large cohort of individuals with PAF who wore an ambulatory single-lead electrocardiogram (ECG) patch sensor as part of standard clinical care. METHODS: We performed a retrospective analysis of longitudinal rhythm data obtained from 13,293 individuals with PAF. RESULTS: In this study, 7934 men and 5359 women with PAF wore an ambulatory single-lead ECG patch sensor for 11.4 days on average, experiencing 1,041,504 PAF episodes. The median daily rate of PAF was 1.21 episodes per day (interquartile range [IQR] 0.31-4.99), and the median maximum duration per individual was 7.5 hours (IQR 2.4-18.6 hours). There was an inverse relationship between the duration of PAF episodes and the frequency in which they occurred, which became pronounced at moderate and high overall burdens of AF. This produced a spectrum of PAF flanked by 2 distinct subtypes of the disease: the staccato subtype, characterized by many, short AF episodes; and the legato subtype, characterized by fewer, longer episodes. Longer but less frequent episodes became more common with increasing age. Only 49.4% of individuals experienced an episode in the first 24 hours of monitoring, increasing to 89.7% after 1 week of monitoring. CONCLUSION: We identified subtypes of the disease that we labeled staccato and legato. Although further study is required, these subtypes may result from differing elements of pathophysiology and disease progression, and may confer differing stroke risks.

Validation of a genetic risk score for atrial fibrillation: A prospective multicenter cohort study.

BACKGROUND: Atrial fibrillation (AF) is the most commonly encountered arrhythmia and is associated with an elevated risk of stroke. Improving the identification of patients with the highest risk for AF to enable appropriate surveillance and treatment, if necessary, is critical to reducing AF-associated morbidity and mortality. Multiple common single nucleotide polymorphisms (SNPs) are unequivocally associated with the lifetime risk of AF. In the current study we aimed to prospectively validate an AF genetic risk score (GRS) in previously undiagnosed patients at risk for AF. METHODS AND FINDINGS: Individuals 40 years of age or older with 1 clinical risk factor for AF, presenting with symptoms of AF, or with a first diagnosis of AF, were enrolled for genetic testing and ambulatory cardiac rhythm monitoring with an adhesive patch monitor or a long-term Holter monitor (mean wear time 10 days 21 hours and 13 days 18 hours, respectively). An AF event was the first diagnosis of AF by ECG, patch monitor, or long-term Holter monitor. The AF GRS was determined for each participant based on the weighted contribution of 12 genetic risk loci. Of 904 participants, 85 manifested AF. Their mean age was 66.2 (SD 11.8) years; 38% of participants were male. Participants in the highest quintile of AF GRS were more likely (odds ratio 3.11; 95% CI 1.27-7.58; p = 0.01) to have had an AF event than participants in the lowest quintile after adjusting for age, sex, smoking status, BMI, hypertension, diabetes mellitus, heart failure, and prior myocardial infarction. Study limitations included an ethnically homogenous population, a restricted rhythm monitoring period, and the evolving discovery of SNPs associated with AF. CONCLUSIONS: Prospective assessment of a GRS for AF identified participants with elevated risk of AF beyond established clinical criteria. Accordingly, a GRS for AF could be incorporated into overall risk assessment to better identify patients at the highest risk of developing AF, although further testing in larger populations is needed to confirm these findings. TRIAL REGISTRATION: ClinicalTrials.gov NCT01970969.

Point-of-Care Technologies for Precision Cardiovascular Care and Clinical Research: National Heart, Lung, and Blood Institute Working Group.

Point-of-care technologies (POC or POCT) are enabling innovative cardiovascular diagnostics that promise to improve patient care across diverse clinical settings. The National Heart, Lung, and Blood Institute convened a working group to discuss POCT in cardiovascular medicine. The multidisciplinary working group, which included clinicians, scientists, engineers, device manufacturers, regulatory officials, and program staff, reviewed the state of the POCT field; discussed opportunities for POCT to improve cardiovascular care, realize the promise of precision medicine, and advance the clinical research enterprise; and identified barriers facing translation and integration of POCT with existing clinical systems. A POCT development roadmap emerged to guide multidisciplinary teams of biomarker scientists, technologists, health care providers, and clinical trialists as they: 1) formulate needs assessments; 2) define device design specifications; 3) develop component technologies and integrated systems; 4) perform iterative pilot testing; and 5) conduct rigorous prospective clinical testing to ensure that POCT solutions have substantial effects on cardiovascular care.

Comparison of 24-hour Holter monitoring with 14-day novel adhesive patch electrocardiographic monitoring.

BACKGROUND: Cardiac arrhythmias are remarkably common and routinely go undiagnosed because they are often transient and asymptomatic. Effective diagnosis and treatment can substantially reduce the morbidity and mortality associated with cardiac arrhythmias. The Zio Patch (iRhythm Technologies, Inc, San Francisco, Calif) is a novel, single-lead electrocardiographic (ECG), lightweight, Food and Drug Administration-cleared, continuously recording ambulatory adhesive patch monitor suitable for detecting cardiac arrhythmias in patients referred for ambulatory ECG monitoring. METHODS: A total of 146 patients referred for evaluation of cardiac arrhythmia underwent simultaneous ambulatory ECG recording with a conventional 24-hour Holter monitor and a 14-day adhesive patch monitor. The primary outcome of the study was to compare the detection arrhythmia events over total wear time for both devices. Arrhythmia events were defined as detection of any 1 of 6 arrhythmias, including supraventricular tachycardia, atrial fibrillation/flutter, pause greater than 3 seconds, atrioventricular block, ventricular tachycardia, or polymorphic ventricular tachycardia/ventricular fibrillation. McNemar's tests were used to compare the matched pairs of data from the Holter and the adhesive patch monitor. RESULTS: Over the total wear time of both devices, the adhesive patch monitor detected 96 arrhythmia events compared with 61 arrhythmia events by the Holter monitor (P < .001). CONCLUSIONS: Over the total wear time of both devices, the adhesive patch monitor detected more events than the Holter monitor. Prolonged duration monitoring for detection of arrhythmia events using single-lead, less-obtrusive, adhesive-patch monitoring platforms could replace conventional Holter monitoring in patients referred for ambulatory ECG monitoring.

The fibrillin-1 gene: unlocking new therapeutic pathways in cardiovascular disease.

The dramatic reductions in DNA sequencing costs allow us to delve deeper into the genomic alterations that increase susceptibility to many polygenic cardiovascular diseases. One such condition is an abnormal proximal aorta. Until recently, many believed that dilated, distorted or dissected proximal aortas might represent a forme fruste of Marfan syndrome or a continuum of aortopathy. Although an FBN-1 mutation does not guarantee the diagnosis of Marfan syndrome it is clear however that FBN-1 mutations independently confer additional risk for many of the cardiovascular complications classically associated with the disease. Furthermore, treatment with an angiotensin receptor blocker has proven effective in reducing rates of thoracic aortic root dilatation in preliminary studies of Marfan syndrome patients. Awareness of an FBN-1 mutation then highlights the need for increased vigilance for the associated cardiovascular phenotypes. Knowledge of an FBN-1 gene mutation may allow actionable interventions earlier in the natural history of the condition.

Pharmacogenomics in Interventional Pharmacology: Present Status and Future Directions.

Pharmacogenomics offers the possibility of tailoring a drug to a patient's unique genetic signature, improving the likelihood of clinical efficacy while minimizing risks. Clopidogrel, a platelet P2Y12 receptor inhibitor that forms the cornerstone of dual antiplatelet therapy in patients with unstable coronary artery disease and those undergoing percutaneous coronary intervention, is the first broadly used drug in cardiovascular medicine in which genotyping may help optimize outcomes. This article describes techniques to identify the genetic determinants of drug response, their application (ie, clopidogrel), and the challenges to integration of pharmacogenomics into the practice of interventional cardiology.