Prolonged QTc Interval Predicts Poststroke Paroxysmal Atrial Fibrillation

ECG predictors of AF: A systematic review (predicting AF in ischaemic stroke-PrAFIS)

In 25% of patients presenting with embolic stroke, a cause is not determined. Atrial fibrillation (AF) is a commonly identified mechanism of stroke in this population, particularly in older patients. Conventional investigations are used to detect AF, but can we predict AF in this population and generally? We performed a systematic review to identify potential predictors of AF on 12-lead electrocardiogram (ECG).

METHOD

We conducted a search of EMBASE and Medline databases for prospective and retrospective cohorts, meta-analyses or case-control studies of ECG abnormalities in sinus rhythm predicting subsequent atrial fibrillation. We assessed quality of studies based on the Newcastle-Ottawa scale and data were extracted according to PRISMA guidelines.

RESULTS

We identified 44 studies based on our criteria. ECG patterns that predicted the risk of developing AF included interatrial block, P-wave terminal force lead V1, P-wave dispersion, abnormal P-wave-axis, abnormal P-wave amplitude, prolonged PR interval, left ventricular hypertrophy, QT prolongation, ST-T segment abnormalities and atrial premature beats. Furthermore, we identified that factors such as increased age, high CHADS-VASC, chronic renal disease further increase the positive-predictive value of some of these parameters. Several of these have been successfully incorporated into clinical scoring systems to predict AF.

CONCLUSION

There are several ECG abnormalities that can predict AF both independently, and with improved predictive value when combined with clinical risk factors, and if incorporated into clinical risk scores. Improved and validated predictive models could streamline selection of patients for cardiac monitoring and initiation of oral anticoagulants.

Detecting atrial fibrillation in the polysomnography-derived electrocardiogram: a software validation study

PURPOSE

The present study validated a software-based electrocardiogram (ECG) analysis tool for detection of atrial fibrillation (AF) and risk for AF using polysomnography (PSG)-derived ECG recordings.

METHODS

The Stroke Risk Analysis® (SRA®) software was applied to 3-channel ECG tracings from diagnostic PSG performed in enrolled subjects including a subgroup of subjects with previously documented AF. No subjects used positive airway pressure therapy. All ECG recordings were visually analyzed by a blinded cardiologist.

RESULTS

Of subjects enrolled in the study, 93 had previously documented AF and 178 of 186 had an ECG that could be analyzed by either method. In subjects with known history of AF, automated analysis using SRA® classified 47 out of 87 ECG as either manifest AF or showing increased risk for paroxysmal AF (PAF) by SRA® (sensitivity 0.54, specificity 0.86). On visual analysis, 36/87 ECG showed manifest AF and 51/87 showed sinus rhythm. Among the latter subgroup, an increased risk for PAF was ascribed by SRA® in 11 cases (sensitivity 0.22, specificity 0.78) and by expert visual analysis in 5 cases (sensitivity 0.1, specificity 0.90). Among 36/178 ECG with manifest AF on visual analysis, 33 were correctly identified by the SRA® software (sensitivity and specificity 0.92).

CONCLUSION

Sleep studies provide a valuable source of ECG recordings that can be easily subjected to software-based analysis in order to identify manifest AF and automatically assess the risk of PAF. For optimal evaluability of data, multiple channel ECG tracings are desirable. For assessment of PAF risk, the SRA® analysis probably excels visual analysis, but sensitivity of both methods is low, reflecting that repeated ECG recording remains essential.

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.

Dapagliflozin reduces pulmonary vascular damage and susceptibility to atrial fibrillation in right heart disease

AIMS

Sodium-glucose cotransporter 2 inhibitors (SGLT2is) have made considerable progress in the field of heart failure, but their application in arrhythmia remains to be in-depth. Right heart disease (RHD) often leads to right heart dysfunction and is associated with atrial fibrillation (AF). Here, we explored the possible electrophysiologic effect of dapagliflozin (a type of SGLT2is) in the development of AF in rats with RHD.

METHODS AND RESULTS

Rats in the experimental group were intraperitoneally injected with a single dose of 60 mg/kg monocrotaline (MCT group, n = 32) on the first day of the experiment, whereas rats in the control group were injected with vehicle (CTL group, n = 32). Rats in the treatment subgroup were treated with dapagliflozin solution orally (MCT + DAPA and CTL + DAPA groups) for a total of 4 weeks, whereas rats in the rest of subgroups were given sterile drinking water. After 4 weeks, echocardiography demonstrated that MCT group rats developed obvious pulmonary arterial hypertension and right heart dysfunction. In addition, there were also obvious inflammatory infiltration, fibrosis, and muscularization in right atrial and pulmonary arteries. The P-wave duration (17.00 ± 0.53 ms, vs. 14.43 ± 0.57 ms in CTL; 14.00 ± 0.65 ms in CTL + DAPA; 14.57 ± 0.65 ms in MCT + DAPA; P < 0.05), RR interval (171.60 ± 1.48 ms, vs. 163.10 ± 1.10 ms in CTL; 163.30 ± 1.19 ms in CTL + DAPA; 163.10 ± 1.50 ms in MCT + DAPA; P < 0.05), Tpeak-Tend interval (65.93 ± 2.55 ms, vs. 49.55 ± 1.71 ms in CTL; 48.27 ± 3.08 ms in CTL + DAPA; P < 0.05), and corrected QT interval (200.90 ± 2.40 ms, vs. 160.00 ± 0.82 ms in CTL; 160.40 ± 1.36 ms in CTL + DAPA; 176.6 ± 1.57 ms in MCT + DAPA; P < 0.01) were significantly prolonged in the MCT group after 4 weeks, whereas P-wave amplitude (0.07 ± 0.0011 mV, vs. 0.14 ± 0.0009 mV in CTL; 0.14 ± 0.0011 mV in CTL + DAPA; 0.08 ± 0.0047 mV in MCT + DAPA; P < 0.05) and T-wave amplitude (0.04 ± 0.002 mV, vs. 0.13 ± 0.003 mV in CTL; 0.13 ± 0.003 mV in CTL + DAPA; P < 0.01) were decreased, and atrial 90% action potential duration (47.50 ± 0.93 ms, vs. 59.13 ± 2.1 ms in CTL; 59.75 ± 1.13 ms in CTL + DAPA; 60.63 ± 1.07 ms in MCT + DAPA; P < 0.01) and effective refractory periods (41.14 ± 0.88 ms, vs. 62.86 ± 0.99 ms in CTL; 63.14 ± 0.67 ms in CTL + DAPA; 54.86 ± 0.70 ms in MCT + DAPA; P < 0.01) were shortened. Importantly, the inducibility rate (80%, vs. 0% in CTL; 10% in CTL + DAPA; 40% in MCT + DAPA; P < 0.05) and duration of AF (30.85 ± 22.90 s, vs. 0 ± 0 s in CTL; 0.24 ± 0.76 s in CTL + DAPA; 5.08 ± 7.92 s in MCT + DAPA; P < 0.05) were significantly increased, whereas the expression levels of cardiac ion channels and calcium-handling proteins such as potassium/calcium channels and calmodulin were decreased. Mechanistically, 'NACHT, LRR, and PYD domain-containing protein 3' inflammasome-related pathway was significantly activated in the MCT group. Nevertheless, in the MCT + DAPA group, the above abnormalities were significantly improved.

CONCLUSIONS

Dapagliflozin reduces pulmonary vascular damage and right heart dysfunction, as well as the susceptibility to AF in RHD rats.

Biomarkers for Atrial Fibrillation Detection After Stroke: Systematic Review and Meta-analysis

BACKGROUND AND OBJECTIVE

To identify clinical, ECG, and blood-based biomarkers associated with atrial fibrillation (AF) detection after ischaemic stroke or TIA that could help inform patient selection for cardiac monitoring.

METHODS

We performed a systematic review and meta-analysis and searched electronic databases for cohort studies from January 15, 2000, to January 15, 2020. The outcome was AF ≥30 seconds within 1 year after ischemic stroke/TIA. We used random effects models to create summary estimates of risk. Risk of bias was assessed using the Quality in Prognostic Studies tool.

RESULTS

We identified 8,503 studies, selected 34 studies, and assessed 69 variables (42 clinical, 20 ECG, and 7 blood-based biomarkers). The studies included 11,569 participants and AF was detected in 1,478 (12.8%). Overall, risk of bias was moderate. Variables associated with increased likelihood of AF detection are older age (odds ratio [OR] 3.26, 95% confidence interval [CI] 2.35-4.54), female sex (OR 1.47, 95% CI 1.23-1.77), a history of heart failure (OR 2.56, 95% CI 1.87-3.49), hypertension (OR 1.42, 95% CI 1.15-1.75) or ischemic heart disease (OR 1.80, 95% CI 1.34-2.42), higher modified Rankin Scale (OR 6.13, 95% CI 2.93-12.84) or National Institutes of Health Stroke Scale score (OR 2.50, 95% CI 1.64-3.81), no significant carotid/intracranial artery stenosis (OR 3.23, 95% CI 1.14-9.11), no tobacco use (OR 1.93, 95% CI 1.48-2.51), statin therapy (OR 2.07, 95% CI 1.14-3.73), stroke as index diagnosis (OR 1.59, 95% CI 1.17-2.18), systolic blood pressure (OR 1.61, 95% CI 1.16-2.22), IV thrombolysis treatment (OR 2.40, 95% CI 1.83-3.16), atrioventricular block (OR 2.12, 95% CI 1.08-4.17), left ventricular hypertrophy (OR 2.21, 95% CI 1.03-4.74), premature atrial contraction (OR 3.90, 95% CI 1.74-8.74), maximum P-wave duration (OR 3.19, 95% CI 1.40-7.25), PR interval (OR 2.32, 95% CI 1.11-4.83), P-wave dispersion (OR 7.79, 95% CI 4.16-14.61), P-wave index (OR 3.44, 95% CI 1.87-6.32), QTc interval (OR 3.68, 95% CI 1.63-8.28), brain natriuretic peptide (OR 13.73, 95% CI 3.31-57.07), and high-density lipoprotein cholesterol (OR 1.49, 95% CI 1.17-1.88) concentrations. Variables associated with reduced likelihood are minimum P-wave duration (OR 0.53, 95% CI 0.29-0.98), low-density lipoprotein cholesterol (OR 0.73, 95% CI 0.57-0.93), and triglyceride (OR 0.51, 95% CI 0.41-0.64) concentrations.

DISCUSSION

We identified multimodal biomarkers that could help guide patient selection for cardiac monitoring after ischaemic stroke/TIA. Their prognostic utility should be prospectively assessed with AF detection and recurrent stroke as outcomes.

QT as a predictor of recurrence after atrial fibrillation ablation and the impact of amiodarone: results from the placebo-controlled AMIO-CAT trial

Aims

Prolonged corrected QT interval (QTc) might be associated with arrhythmia recurrence after atrial fibrillation (AF) ablation. The effect of short-term amiodarone in this setting remains unknown. This study seeks to quantify short-term amiodarone’s impact on QTc, and to investigate QTc and amiodarone treatment as predictors of recurrence of arrhythmia after ablation.

Methods and results

The Short-term AMIOdarone treatment after CATheter ablation for atrial fibrillation (AMIO-CAT) trial randomized patients to 8 weeks of oral amiodarone or placebo following AF ablation. Scheduled and symptom-driven 12-lead electrocardiography and 3-day Holter-monitorings were performed. The endpoint was atrial fibrillation, atrial flutter or atrial tachycardia (AF/AT) lasting >30 s. The cut-off for prolonged QTc was 450 ms for men and 460 ms for women. A total of 212 patients were included, of which 108 were randomized to amiodarone and 104 to placebo. From baseline to 1 month QTc in the amiodarone group increased by 27 (±30) ms, while at 6 months QTc had normalized. After 3-months of blanking, new AF/AT recurrence was detected in 63% of patients with prolonged QTc vs. 41% of patients with normal QTc at baseline, and in multivariate Cox regression, prolonged QTc was associated with AF/AT recurrence [hazard ratio (HR) 2.19, P = 0.023]. Among patients with baseline QTc below median, amiodarone treatment decreased the rate of AF/AT recurrences (HR 0.43, P = 0.008).

Conclusions

Amiodarone increased QTc with 27 ms compared to placebo, and this effect decreased rapidly after drug discontinuation. Prolonged QTc at baseline independently predicted AF/AT recurrence, and baseline QTc identified patients who would possibly benefit from short-term amiodarone following ablation.

Action potential shortening rescues atrial calcium alternans

KEY POINTS

Cardiac alternans refers to a beat-to-beat alternation in contraction, action potential (AP) morphology and Ca²⁺ transient (CaT) amplitude, and represents a risk factor for cardiac arrhythmia, including atrial fibrillation. We developed strategies to pharmacologically manipulate the AP waveform with the goal to reduce or eliminate the occurrence of CaT and contraction alternans in atrial tissue. With combined patch-clamp and intracellular Ca²⁺ measurements we investigated the effect of specific ion channel inhibitors and activators on alternans. In single rabbit atrial myocytes, suppression of Ca²⁺ -activated Cl^- channels eliminated AP duration alternans, but prolonged the AP and failed to eliminate CaT alternans. In contrast, activation of K⁺ currents (I_Ks and I_Kr ) shortened the AP and eliminated both AP duration and CaT alternans. As demonstrated also at the whole heart level, activation of K⁺ conductances represents a promising strategy to suppress alternans, and thus reducing a risk factor for atrial fibrillation.

ABSTRACT

At the cellular level alternans is observed as beat-to-beat alternations in contraction, action potential (AP) morphology and magnitude of the Ca²⁺ transient (CaT). Alternans is a well-established risk factor for cardiac arrhythmia, including atrial fibrillation. This study investigates whether pharmacological manipulation of AP morphology is a viable strategy to reduce the risk of arrhythmogenic CaT alternans. Pacing-induced AP and CaT alternans were studied in rabbit atrial myocytes using combined Ca²⁺ imaging and electrophysiological measurements. Increased AP duration (APD) and beat-to-beat alternations in AP morphology lowered the pacing frequency threshold and increased the degree of CaT alternans. Inhibition of Ca²⁺ -activated Cl^- channels reduced beat-to-beat AP alternations, but prolonged APD and failed to suppress CaT alternans. In contrast, AP shortening induced by activators of two K⁺ channels (ML277 for Kv7.1 and NS1643 for Kv11.1) abolished both APD and CaT alternans in field-stimulated and current-clamped myocytes. K⁺ channel activators had no effect on the degree of Ca²⁺ alternans in AP voltage-clamped cells, confirming that suppression of Ca²⁺ alternans was caused by the changes in AP morphology. Finally, activation of Kv11.1 channel significantly attenuated or even abolished atrial T-wave alternans in isolated Langendorff perfused hearts. In summary, AP shortening suppressed or completely eliminated both CaT and APD alternans in single atrial myocytes and atrial T-wave alternans at the whole heart level. Therefore, we suggest that AP shortening is a potential intervention to avert development of alternans with important ramifications for arrhythmia prevention and therapy.

Prolonged corrected QT interval in predicting atrial fibrillation: A systematic review and meta-analysis

BACKGROUND

Corrected QT interval (QTc) on the electrocardiogram is a marker of ventricular repolarization. Recent studies have examined its value in predicting the occurrence of atrial fibrillation (AF).

METHODS AND RESULTS

We conducted a meta-analysis to determine whether alterations in QTc interval are associated with an increased risk of incident AF. The PUBMED and EMBASE databases were searched for all studies that evaluated the incident AF associated with prolonged QTc interval published before December 2016. Sensitivity and subgroup analysis were subsequently performed. A total of six studies including eight data sets for prolonged QTc interval were eligible. Subjects with prolonged QTc interval as a categorical variable had a significantly higher risk of AF during follow-up (hazard ratio [HR]: 1.16; 95% confidence interval [CI], 1.09-1.24, I2  = 90%) based on Bazett formula. In continuous variable analysis, we found a statistically significant risk for AF (HR, 1.17; 95% CI, 1.09-1.25; I2  = 0) every 10-ms prolongation in QTc. AF type, QTc cut-off value, geographical location, follow-up duration, and study population may be the possible reasons for the significant heterogeneity among the studies.

CONCLUSIONS

Prolonged QTc interval is associated with an increased risk of AF. And the potential mechanisms underlying this cause-and-effect relationship need further investigation.

P-Wave Terminal Force in Lead V1 Predicts Paroxysmal Atrial Fibrillation in Acute Ischemic Stroke

BACKGROUND

Detection of paroxysmal atrial fibrillation (PAF) in cryptogenic stroke is critical to selecting an antithrombotic therapy for preventing recurrent stroke. However, the predictor of PAF in patients with acute ischemic stroke is not well elucidated. P-wave terminal force in lead V₁ (PTFV₁) is a standard electrocardiogram marker of left atrial abnormality. In this study, we aimed to investigate the utility of PTFV₁ for the prediction of PAF in patients with acute ischemic stroke.

METHODS

The study included 295 consecutive patients who had acute ischemic stroke and were admitted to the hospital between September 2014 and August 2016. Patients with a known history of PAF, persistent atrial fibrillation, or cardiac pacemaker were excluded from the study. The clinical characteristics of patients with or without PAF were compared, and multiple logistic regression analysis was performed to assess the independent contribution of each variable.

RESULTS

Among 226 patients eligible for our analysis, 16 (7.1%) were diagnosed with PAF after admission. PTFV₁ was significantly higher in patients with PAF than those without PAF (.051 versus .027 mm⋅s; P < .001). Multivariate analysis showed that PTFV₁ per .01 mm⋅s increase was strongly associated with PAF (odds ratio, 1.61; 95% confidence interval, 1.24-2.09; P < .001). The optimal cutoff value of PTFV₁ for the prediction of PAF was .04 mm⋅s.

CONCLUSIONS

PTFV₁ is a strong predictor of PAF detection in acute ischemic stroke.

Screening strategies for atrial fibrillation: a systematic review and cost-effectiveness analysis

Background

Atrial fibrillation (AF) is a common cardiac arrhythmia that increases the risk of thromboembolic events. Anticoagulation therapy to prevent AF-related stroke has been shown to be cost-effective. A national screening programme for AF may prevent AF-related events, but would involve a substantial investment of NHS resources.

Objectives

To conduct a systematic review of the diagnostic test accuracy (DTA) of screening tests for AF, update a systematic review of comparative studies evaluating screening strategies for AF, develop an economic model to compare the cost-effectiveness of different screening strategies and review observational studies of AF screening to provide inputs to the model.

Design

Systematic review, meta-analysis and cost-effectiveness analysis.

Setting

Primary care.

Participants

Adults.

Intervention

Screening strategies, defined by screening test, age at initial and final screens, screening interval and format of screening {systematic opportunistic screening [individuals offered screening if they consult with their general practitioner (GP)] or systematic population screening (when all eligible individuals are invited to screening)}.

Main outcome measures

Sensitivity, specificity and diagnostic odds ratios; the odds ratio of detecting new AF cases compared with no screening; and the mean incremental net benefit compared with no screening.

Review methods

Two reviewers screened the search results, extracted data and assessed the risk of bias. A DTA meta-analysis was perfomed, and a decision tree and Markov model was used to evaluate the cost-effectiveness of the screening strategies.

Results

Diagnostic test accuracy depended on the screening test and how it was interpreted. In general, the screening tests identified in our review had high sensitivity (> 0.9). Systematic population and systematic opportunistic screening strategies were found to be similarly effective, with an estimated 170 individuals needed to be screened to detect one additional AF case compared with no screening. Systematic opportunistic screening was more likely to be cost-effective than systematic population screening, as long as the uptake of opportunistic screening observed in randomised controlled trials translates to practice. Modified blood pressure monitors, photoplethysmography or nurse pulse palpation were more likely to be cost-effective than other screening tests. A screening strategy with an initial screening age of 65 years and repeated screens every 5 years until age 80 years was likely to be cost-effective, provided that compliance with treatment does not decline with increasing age.

Conclusions

A national screening programme for AF is likely to represent a cost-effective use of resources. Systematic opportunistic screening is more likely to be cost-effective than systematic population screening. Nurse pulse palpation or modified blood pressure monitors would be appropriate screening tests, with confirmation by diagnostic 12-lead electrocardiography interpreted by a trained GP, with referral to a specialist in the case of an unclear diagnosis. Implementation strategies to operationalise uptake of systematic opportunistic screening in primary care should accompany any screening recommendations.

Limitations

Many inputs for the economic model relied on a single trial [the Screening for Atrial Fibrillation in the Elderly (SAFE) study] and DTA results were based on a few studies at high risk of bias/of low applicability.

Future work

Comparative studies measuring long-term outcomes of screening strategies and DTA studies for new, emerging technologies and to replicate the results for photoplethysmography and GP interpretation of 12-lead electrocardiography in a screening population.

Study registration

This study is registered as PROSPERO CRD42014013739.

Funding

The National Institute for Health Research Health Technology Assessment programme.

Prolonged Corrected QT Interval as a Predictor of Clinical Outcome in Acute Ischemic Stroke

BACKGROUND

This study aimed to investigate changes of corrected QT (QTc) interval during acute ischemic stroke and its correlation with high-sensitivity troponin I (hsTnI), brain natriuretic peptide (BNP), neurological outcome, and 1-year mortality.

METHODS

We registered electrocardiogram in 69 patients immediately after admission to the intensive care unit and then after 24 and 48 hours. Computed tomography was performed on admission to determine brain infarct size and localization. Neurological outcome was assessed by modified Rankin scale (mRS) at discharge.

RESULTS

Forty-five (65.2%) patients had prolonged QTc at baseline; only 18 (26.1%) patients had prolonged QTc after 48 hours. Baseline QTc was not associated with neurological outcome (P = .27). However, prolonged QTc after 48 hours was associated with worse mRS at discharge (4.5 [4.0-6.0] versus 2.0 [1.0-3.0]; P < .0001). Patients who deceased during hospitalization (n = 7 [10.1%]) as compared with survivors had more frequently prolonged QTc after 48 hours (38.9 versus 0%; P < .0001), higher level of hsTnI (48.4 [36.1-75.0] versus 8.6 [3.4-26.5]; P = .003), and BNP (334 [224-866] versus 109 [30-190]; P = .014). In univariate analysis, 1-year mortality was associated with prolonged QTc after 48 hours, hsTnI, and BNP. In multivariate analysis, only BNP remained to be associated with 1-year mortality (odds ratio 3.41, 95% confidence interval 1.06-11.03).

CONCLUSIONS

QTc interval in patients with acute ischemic stroke is a dynamic parameter. Prolonged QTc after 48 hours, but not baseline QTc, correlated with neurological outcome and 1-year mortality. Patients with prolonged QTc had higher level of hsTnI.

Differences in the Slope of the QT-RR Relation Based on 24-Hour Holter ECG Recordings between Cardioembolic and Atherosclerotic Stroke

Objective Detecting paroxysmal atrial fibrillation in patients with ischemic stroke presenting in sinus rhythm is difficult because such episodes are often short, and they are also frequently asymptomatic. It is possible that the ventricular repolarization dynamics may reflect atrial vulnerability and cardioembolic stroke. Hence, we compared the QT-RR relation between cardioembolic stroke and atherosclerotic stroke during sinus rhythm. Methods The subjects comprised 62 consecutive ischemic stroke patients including 31 with cardioembolic strokes (71.8±12.7 years, 17 men) and 31 with atherosclerotic strokes (74.8±10.8 years, 23 men). The QT and RR intervals were measured from ECG waves based on a 15-sec averaged ECG during 24-hour Holter recording using an automatic QT analyzing system. The QT interval dependence on the RR interval was analyzed using a linear regression line for each subject ([QT]=A[RR]+B; where A is the slope and B is the y-intercept). Results The mean slope of the QT-RR relation was significantly greater in cardioembolic stroke than in atherosclerotic stroke (0.187±0.044 vs. 0.142±0.045, p<0.001). The mean QT, RR, or QTc during 24-hour Holter recordings did not differ between them. An increased slope (≥0.14) of the QT-RR regression line could predict cardioembolic stroke with 97% sensitivity, 55% specificity and a positive predictive value of 64%. Conclusion The increased slope of the QT-RR linear regression line based on 24-hour Holter ECG in patients with ischemic stroke presenting in sinus rhythm may therefore be a simple and useful marker for cardioembolic stroke.

Diagnosing Paroxysmal Atrial Fibrillation: Are Biomarkers the Solution to This Elusive Arrhythmia?

Atrial fibrillation (AF) is the commonest sustained arrhythmia globally and results in significantly increased morbidity and mortality including a fivefold risk of stroke. Paroxysmal atrial fibrillation (PAF) constitutes approximately half of all AF cases and is thought to represent an early stage of the disease. This intermittent form of atrial arrhythmia can be a challenge to identify and as a result many affected individuals are not prescribed appropriate antithrombotic therapy and hence are at risk of stroke and thromboembolism. Despite these adverse outcomes there have been relatively few diagnostic advances in the field since the introduction of the Holter monitor in 1949. This review aims to establish the available evidence for electrophysiological, molecular, and morphological biomarkers to improve the detection of PAF with reference to the underlying mechanisms for the condition.

Insular Cortex Lesions, Cardiac Troponin, and Detection of Previously Unknown Atrial Fibrillation in Acute Ischemic Stroke

Background and Purpose—

Detection rates of paroxysmal atrial fibrillation (AF) after acute ischemic stroke increase with duration of ECG monitoring. To date, it is unknown which patient group may benefit most from intensive monitoring strategies. Therefore, we aimed to identify predictors of previously unknown AF during in-hospital ECG monitoring.

Methods—

All consecutive patients with imaging-confirmed ischemic stroke admitted to our tertiary care hospital from February 2011 to December 2013 were registered prospectively. Patients received continuous bedside ECG monitoring for at least 24 hours. Detection of previously unknown AF during in-hospital ECG monitoring was obtained from medical records. Patients with AF on admission ECG or known history of AF were excluded from analysis.

Results—

Among 1228 patients (median age, 73 years; median National Institutes of Health Stroke Scale, 4; 43.4% women), previously unknown AF was detected in 114 (9.3%) during a median time of continuous ECG monitoring of 3 days (interquartile range, 2–4 days). Duration of monitoring ( P <0.01), older age ( P <0.01), history of hypertension ( P =0.03), insular cortex involvement ( P <0.01), and higher high-sensitivity cardiac troponin T ( P =0.04) on admission were independently associated with subsequent detection of AF in a multiple regression analysis. Addition of high-sensitivity cardiac troponin T, insular cortex stroke, or both to the CHADS2 score (congestive heart failure, hypertension, age ≥75 years, diabetes mellitus, stroke [2P]) significantly improved c -statistics from 0.63 to 0.68 ( P =0.01), 0.70 ( P <0.01), and 0.72 ( P <0.001), respectively.

Conclusions—

Insular cortex involvement, higher admission high-sensitivity cardiac troponin T, older age, hypertension, and longer monitoring are associated with new detection of AF during in-hospital ECG monitoring. Patients with higher high-sensitivity cardiac troponin T or insular cortex involvement may be candidates for prolonged ECG monitoring.