Use of ambulatory electrocardiography for the detection of paroxysmal atrial fibrillation in patients with stroke. Canadian Task Force on Preventive Health Care

Burden of Premature Atrial Complexes and Risk of Recurrent Stroke and Death in Patients with Mild to Moderate Ischemic Stroke

BACKGROUND

Premature atrial complexes (PACs) meet increased attention as a potential intermediary between sinus rhythm and atrial fibrillation (AF). Patients with even high numbers of PACs do not fulfill current guidelines for oral anticoagulation treatment though an associated stroke risk is suspected.

OBJECTIVE

We aimed to determine whether a high number of PACs or runs of AF less than 30 seconds in 2-day continuous electrocardiogram (ECG) recording was associated with risk of recurrent ischemic stroke/transient ischemic attack (TIA) or death in a large cohort of patients with acute ischemic stroke or TIA and no prior AF.

METHODS

We performed 48 hours continuous ECG recording within 1 week after ischemic stroke/TIA. PACs were reported as mean number of PACs per hour. Patients were followed in Danish Stroke Registry, Danish Civil Registration System, and Danish National Patient Registry. Cox Regression analysis was used to calculate hazard ratios.

RESULTS

We included 1507 patients with TIA (40%) or ischemic stroke (60%), of which 98.7% had mild to moderate strokes. Mean age was 72.9 (7.8) years, 43.4% were females. Follow-up was 2.3 (1.3) years. Hazard ratio for recurrent stroke/TIA or death did not differ between quartiles of PAC burden, nor did any of the 2 components of this composite endpoint. Nonsustained AF less than 30 seconds was not associated with higher risk of recurrent stroke/TIA or death.

CONCLUSIONS

In a large cohort of patients with recent ischemic stroke or TIA, burden of PACs or nonsustained AF less than 30 seconds were not associated to higher risk of recurrent stroke/TIA or death.

The quest for indicators of paroxysmal atrial fibrillation in sinus rhythm - the DETECT AF trial

Background: Atrial fibrillation (AF) is related to an increased stroke risk. At present, differentiation between patients with paroxysmal AF (pAF) and without is only possible during AF episodes and not during sinus rhythm. If AF could be diagnosed more quickly and reliably, anticoagulation therapy may be administered and prevent from cardioembolic strokes. The DETECT AF trial evaluated the hypothesis that propagation of electric activities in patients with pAF differs from propagation in healthy atria and that this can be detected with a three-dimensional electrocardiogram in patients during sinus rhythm. Methods: We conducted a case-control study including patients with a history of pAF and a control group with no history of AF. Vectorcardiographic beat-to-beat variability of atrial activation in sinus rhythm was tested and compared between the two groups. Results: One hundred and eight patients with a history of pAF in sinus rhythm and 121 controls in sinus rhythm were included. With a combination of specific vectorcardiographic beat-to-beat variability parameters discrimination between the two groups was possible with a specificity of 82% and a sensitivity of 71% (p≤.01). Using heart rate independent parameters, both specificity and sensitivity were reduced to 70%. Conclusions: Analysis of atrial vectorcardiographic beat-to-beat variability indicates that atrial conduction variability in patients with pAF differs from patients without AF and may be used as an indicator to estimate the risk for pAF in patients during sinus rhythm. Further studies to investigate the potential of this parameter are needed. Clinical trial registration number: NCT02270112.

External continuous ECG versus loop recording for atrial fibrillation detection in patients who had a stroke

BACKGROUND

Detection of atrial fibrillation (AF) in patients who had ischaemic stroke and transient ischaemic attack (IS/TIA) is recommended. We aimed to compare external loop recording (ELR) against simultaneous continuous ECG recording for AF detection in patients who had acute IS/TIA and determine sensitivity, specificity and positive predictive value of AF detection using ELR. We hypothesised ELR to detect 15% fewer patients with AF than continuous ECG recording.

METHODS

In this prospective cohort study, we included 1412 patients who had acute IS/TIA without prior AF. Monitoring was 48 hours. Primary outcome was AF >30 s. Cardiologist verified AF in continuous ECG was gold standard.

RESULTS

In continuous ECG, 38 (2.7%) patients had AF. ELR automatically categorised 219/1412 patients (15.5%) with AF, including 32/38 (85%) patients with AF in continuous ECG. After cardiologist adjudication of ELR recordings, AF was diagnosed in 57/219 patients, of which 32 (56%) had AF in continuous ECG. For adjudicated AF detection by ELR, sensitivity was 84%, 95% CI (69% to 94%), specificity was 98%, 95% CI (97% to 99%) and positive predictive value was 56%, 95% CI (42% to 69%).

CONCLUSION

Automatic AF detection with ELR results in an AF diagnosis in more than five patients without AF for each patient with AF as verified in continuous ECG. For adjudicated AF detection by ELR, sensitivity was confirmed to 84% and specificity 98%. Automatic ELR as investigated in this study may be considered to rule out AF, but it is not suitable as a single monitoring device for AF screening in patients early after stroke.

TRIAL REGISTRATION NUMBER

NCT02155907.

Cryptogenic Acute Ischemic Stroke: Assessment of the Performance of a New Continuous Long-Term Monitoring System in the Detection of Atrial Fibrillation

Background

Long-term monitoring has been advocated to enhance the detection of atrial fibrillation (AF) in patients with stroke.

Objective

To evaluate the performance of a new ambulatory monitoring system with mobile data transmission (PoIP) compared with 24-hour Holter. We also aimed to evaluate the incidence of arrhythmias in patients with and without stroke or transient ischemic attack.

Methods

Consecutive patients with and without stroke or TIA, without AF, were matched by propensity score. Participants underwent 24-hour Holter and 7-day PoIP monitoring.

Results

We selected 52 of 84 patients (26 with stroke or TIA and 26 controls). Connection and recording times were 156.5 ± 22.5 and 148.8 ± 20.8 hours, with a signal loss of 6,8% and 11,4%, respectively. Connection time was longer in ambulatory (164.3 ± 15.8 h) than in hospitalized patients (148.8 ± 25.6 h) (p = 0.02), while recording time did not differ between them (153.7 ± 16.9 and 143.0 ± 23.3 h). AF episodes were detected in 1 patient with stroke by Holter, and in 7 individuals (1 control and 6 strokes) by PoIP. There was no difference in the incidence of arrhythmias between the groups.

Conclusions

Holter and PoIP performed equally well in the first 24 hours. Data transmission loss (4.5%) occurred by a mismatch between signal transmission (2.5G) and signal reception (3G) protocols in cell phone towers (3G). The incidence of arrhythmias was not different between stroke/TIA and control groups.

Atrial fibrillation detected by external loop recording for seven days or two-day simultaneous Holter recording: A comparison in patients with ischemic stroke or transient ischemic attack

Atrial fibrillation (AF) is the most common cardiac cause of ischemic stroke and transient ischemic attack (IS/TIA).

AIM

To compare the diagnostic value of seven-day external loop recording (ELR) and two-day Holter recording for detecting AF after IS/TIA.

METHODS

191 IS/TIA patients without AF history. Endpoint was AF >30s. We started two-day Holter recording and seven-day ELR simultaneously.

RESULTS

Seven-day ELR and two-day Holter recording detected the same three AF patients. ELR detected another six patients with AF adjudicated by cardiologists, four detections after Holter (3 vs. 7, p=0.125) and two false-positive detections during Holter. Seven-day ELR automatically classified 50/191 patients (26%) with AF, but only 7/50 (14%) were confirmed as AF by cardiologists.

CONCLUSION

Seven-day ELR did not detect significantly more patients with AF than two-day Holter recording. 86% of patients with ELR-classified AF were false positives, indicating a poor performance of the automatic AF detection algorithm used.

Clinical Logistics in 24-Hour Ambulatory Electrocardiographic Monitoring

In total, 493 ambulatory ECG recordings were studied. Women were preponderant (62.3% vs 37.7%). The average age of women and men patients was 66.9 and 64.7 years, respectively. Of the ECGs studied, 71.4% showed abnormalities and 28.6% appeared completely normal. Urgent abnormalities were noted in 1.4% of the recordings and significant abnormalities were present in 14.6%. Subjective complaints were noted in their logbooks by 18.8% of patients, but correlation of complaints with the electrocardiographic abnormalities was noted in only 1.2% of cases. The attending cardiologist concluded that 23.9% of the tests supported reasons of valid necessity for performance. Two hundred seventy-three recordings were clas sified as electrocardiographically abnormal (55.4%) but were clinically insignificant. General practitioners requested 59.8% of the tests versus 40.2% by specialists. Preponderant abnor malities included premature atrial and ventricular contractions, supraventricular tachycardia, and atrial fibrillation. Less frequent abnormalities included ventricular tachycardia (4.6%), atrial flutter, atrioventricular block, artificial pacemaker rhythm, nodal rhythm, and intermit tent bundle branch block.

Detection of occult atrial fibrillation in patients with embolic stroke of uncertain source: a work in progress

Atrial fibrillation accounts for a substantial proportion of ischemic strokes of known etiology and may be responsible for an additional subset of the 25–40% of strokes of unknown cause (so-called cryptogenic). Oral anticoagulation is significantly more effective than antiplatelet therapy in the secondary prevention of atrial fibrillation-related strokes, providing justification for developing more sensitive approaches to detecting occult paroxysms of atrial fibrillation. In this article, we summarize the current state of knowledge regarding the value of in-hospital and out-patient monitoring for detecting atrial fibrillation in the context of cryptogenic stroke. We review the evidence for and against screening with standard Holter monitors, external loop recorders, the newer real-time continuous attended cardiac monitoring systems, cardiac implantable electronic devices, and insertable loop recorders. We review key questions regarding prolonged cardiac arrhythmia monitoring, including the relationship between duration of the atrial fibrillation episode and risk of thromboembolism, frequency of monitoring and its impact on the diagnostic yield in detecting occult or subclinical atrial fibrillation, and the temporal proximity of device-detected atrial fibrillation to stroke events. We conclude by proposing avenues for further research.

Cryptogenic Stroke And Role Of Loop Recorder

Ischemic stroke is an important cause of morbidity and mortality when untreated. Identifying atrial fibrillation is important because atrial fibrillation ischemic related strokes are associated with an increased risk of disability and death compared with strokes of other etiologies and tend to recur without anticoagulation. However, atrial fibrillation detection can be difficult when it is asymptomatic and paroxistic and may be the underlying cause of some cryptogenic strokes or strokes of unknown origin. In this review, the different methods of cardiac monitoring to detect atrial fibrillation in patients with cryptogenic stroke are summarized, with a focus on loop recorder monitoring.

Detection of atrial fibrillation after ischemic stroke or transient ischemic attack: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

Atrial fibrillation (AF) confers a high risk of recurrent stroke, although detection methods and definitions of paroxysmal AF during screening vary. We therefore undertook a systematic review and meta-analysis to determine the frequency of newly detected AF using noninvasive or invasive cardiac monitoring after ischemic stroke or transient ischemic attack.

METHODS

Prospective observational studies or randomized controlled trials of patients with ischemic stroke, transient ischemic attack, or both, who underwent any cardiac monitoring for a minimum of 12 hours, were included after electronic searches of multiple databases. The primary outcome was detection of any new AF during the monitoring period. We prespecified subgroup analysis of selected (prescreened or cryptogenic) versus unselected patients and according to duration of monitoring.

RESULTS

A total of 32 studies were analyzed. The overall detection rate of any AF was 11.5% (95% confidence interval, 8.9%-14.3%), although the timing, duration, method of monitoring, and reporting of diagnostic criteria used for paroxysmal AF varied. Detection rates were higher in selected (13.4%; 95% confidence interval, 9.0%-18.4%) than in unselected patients (6.2%; 95% confidence interval, 4.4%-8.3%). There was substantial heterogeneity even within specified subgroups.

CONCLUSIONS

Detection of AF was highly variable, and the review was limited by small sample sizes and marked heterogeneity. Further studies are required to inform patient selection, optimal timing, methods, and duration of monitoring for detection of AF/paroxysmal AF.

Atrial fibrillation and paroxysmal atrial fibrillation detection in patients with acute ischemic stroke

BACKGROUND

Studies about continuous electrocardiographic (ECG) monitoring in detection of paroxysmal atrial fibrillation (PAF) in Asian patients with acute ischemic stroke are very limited. We looked for the prevalence and associated factors of atrial fibrillation (AF) and PAF in Thai patients with acute ischemic stroke.

METHODS

In all, 204 patients with acute ischemic stroke were prospectively included. Snapshot 12-lead ECG and continuous ECG monitoring for at least the first 24 hours were performed. Multivariate analyses were performed to find out the associated factors of AF and PAF.

RESULTS

AF was diagnosed in 31 patients (15%) and PAF in 15 patients (7%). Twelve and 3 patients with PAF were diagnosed by continuous ECG monitoring and snapshot 12-lead ECG, respectively. Mean duration of continuous ECG monitoring and mean time to detect PAF were 55 and 23 hours, respectively. Multivariate analysis revealed that age of 70 years or older (odds ratio [OR] 3.52, 95% confidence interval [CI] 1.68-7.35, P = .001) and heart diseases (OR 4.26, 95% CI 1.14-15.95, P = .031) were associated with AF and PAF.

CONCLUSIONS

AF/PAF was one of the common causes of ischemic stroke in Thai patients. Most PAF was detected by continuous ECG monitoring. Snapshot 12-lead ECG and continuous ECG monitoring should be recommended in all patients with acute ischemic stroke.

Unexpected low prevalence of atrial fibrillation in cryptogenic ischemic stroke: a prospective study

Purpose

Ischemic stroke is a frequent pathology with high rate of recurrence and significant morbidity and mortality. There are several causes of stroke, affecting prognosis, outcomes, and management, but in many cases, the etiology remains undetermined. We hypothesized that atrial fibrillation was involved in this pathology but underdiagnosed by standard methods. The aim of the study was to determine the incidence of atrial fibrillation in cryptogenic ischemic stroke by using continuous monitoring of the heart rate over several months. The secondary objective was to test the value of atrial vulnerability assessment in predicting spontaneous atrial fibrillation.

Methods and results

We prospectively enrolled 24 patients under 75 years of age, 15 men and 9 women of mean age 49 years, who within the last 4 months had experienced cryptogenic stroke diagnosed by clinical presentation and brain imaging and presumed to be of cardioembolic mechanism. All causes of stroke were excluded by normal 12-lead ECG, 24-h Holter monitoring, echocardiography, cervical Doppler, hematological, and inflammatory tests. All patients underwent electrophysiological study. Of the patients, 37.5% had latent atrial vulnerability, and 33.3% had inducible sustained arrhythmia. Patients were secondarily implanted with an implantable loop recorder to look for spontaneous atrial fibrillation over a mean follow-up interval of 14.5 months. No sustained arrhythmia was found. Only one patient had non-significant episodes of atrial fibrillation.

Conclusion

In this study, symptomatic atrial fibrillation or AF with fast ventricular rate has not been demonstrated by the implantable loop recorder in patients under 75 years with unexplained cerebral ischemia. The use of this device should not be generalized in the systematic evaluation of these patients. In addition, this study attests that the assessment of atrial vulnerability is poor at predicting spontaneous arrhythmia in such patients.

Excessive Supraventricular Ectopic Activity and Increased Risk of Atrial Fibrillation and Stroke

Background— Prediction of stroke and atrial fibrillation in healthy individuals is challenging. We examined whether excessive supraventricular ectopic activity (ESVEA) correlates with risk of stroke, death, and atrial fibrillation in subjects without previous stroke or heart disease.

Methods and Results— The population-based cohort of the Copenhagen Holter Study, consisting of 678 healthy men and women aged between 55 and 75 years with no history of cardiovascular disease, atrial fibrillation, or stroke, was evaluated. All had fasting laboratory tests and 48-hour ambulatory ECG monitoring. ESVEA was defined as ≥30 supraventricular ectopic complexes (SVEC) per hour or as any episodes with runs of ≥20 SVEC. The primary end point was stroke or death, and the secondary end points were total mortality, stroke, and admissions for atrial fibrillation. Median follow-up was 6.3 years. Seventy subjects had SVEC ≥30/h, and 42 had runs of SVEC with a length of ≥20 SVEC. Together, 99 subjects (14.6%) had ESVEA. The risk of primary end point (death or stroke) was significantly higher in subjects with ESVEA compared with those without ESVEA after adjustment for conventional risk factors (hazard ratio=1.64; 95% confidence interval, 1.03 to 2.60; P =0.036). ESVEA was also associated with admissions for atrial fibrillation (hazard ratio=2.78; 95% confidence interval, 1.08 to 6.99; P =0.033) and stroke (hazard ratio=2.79; 95% confidence interval, 1.23 to 6.30; P =0.014). SVEC, as a continuous variable, was also associated with both the primary end point of stroke or death and admissions for atrial fibrillation.

Conclusions— ESVEA in apparently healthy subjects is associated with development of atrial fibrillation and is associated with a poor prognosis in term of death or stroke.

Cardiac workup of ischemic stroke: can we improve our diagnostic yield?

BACKGROUND AND PURPOSE

Discovering potential cardiac sources of stroke is an important part of the urgent evaluation of the ischemic stroke patient as it often impacts treatment decisions that are essential for determining secondary stroke prevention strategies, yet the optimal approach to the cardiac workup of an ischemic stroke patient is not known.

METHODS

A review of the literature concerning the utility of cardiac rhythm monitoring (ECG, telemetry, Holter monitors, and event recorders) and structural imaging (transthoracic and transesophageal echocardiography) was performed.

RESULTS

Data supporting a definitive, optimal, and cost-effective approach are lacking, though some data suggest that appropriate patient selection can improve the diagnostic and therapeutic yield of rhythm monitoring and echocardiography in the evaluation of stroke etiology.

CONCLUSIONS

Based on available data, an algorithmic approach for the evaluation of patients with acute ischemic cerebrovascular events that takes into account therapeutic and diagnostic yield as well as cost-efficiency is proposed.

Noninvasive Cardiac Monitoring for Detecting Paroxysmal Atrial Fibrillation or Flutter After Acute Ischemic Stroke

Background and Purpose— Identifying paroxysmal atrial fibrillation/flutter is an essential part of the etiological workup of patients with ischemic stroke. However, there is controversy in the literature regarding the use of noninvasive cardiac rhythm monitoring with previous reviews reporting a low detection rate with routine monitoring. We performed a systematic review to determine the frequency of occult atrial fibrillation/flutter detected by noninvasive methods of continuous cardiac monitoring after acute ischemic stroke or transient ischemic attack.

Methods— Studies were identified from comprehensive searches of PubMed, EMBASE, Science Citation Index, and bibliographies of relevant articles. Only English language articles were included. Randomized controlled trials and prospective cohort studies of consecutive patients with acute ischemic stroke that fulfilled predefined criteria were eligible. Two authors conducted searches and abstracted data from eligible studies independently.

Results— Sixty studies were deemed potentially eligible. After application of eligibility criteria, 5 studies (736 participants) were included in the analysis. All studies evaluated Holter monitoring; 2 also evaluated event loop recording. In studies that evaluated Holter monitoring (588 participants), new atrial fibrillation/flutter was detected in 4.6% (95% CI: 0% to 12.7%) of consecutive patients with ischemic stroke. Duration of monitoring ranged from 24 to 72 hours. Two studies (140 participants) evaluated event loop recorders after Holter monitoring. New atrial fibrillation/flutter was detected in 5.7% and 7.7% of consecutive patients in these 2 studies.

Conclusions— Screening consecutive patients with ischemic stroke with routine Holter monitoring will identify new atrial fibrillation/flutter in approximately one in 20 patients. Although based on limited data, extended duration of monitoring may improve the detection rate. Further research is required before definitive recommendations can be made.

Frequent Atrial Premature Beats Predict Paroxysmal Atrial Fibrillation in Stroke Patients

Background and Purpose— For patients having suffered ischemic stroke, the current diagnostic strategies often fail to detect atrial fibrillation as a potential cause of embolic events. The aim of the study was to identify paroxysmal atrial fibrillation in stroke patients. We hypothesized that patients with frequent atrial premature beats (APBs) recorded in 24-hour ECG will show more often atrial fibrillation when followed by repeated long-term ECG recordings than patients without or infrequent APBs.

Methods— 127 patients with acute ischemic stroke and without known AF were enrolled in a prospective study to detect paroxysmal AF. Patients were stratified according to the number of APBs recorded in a 24-hour ECG (≥70 APBs versus <70 APBs). Subsequently, they all underwent serial 7-day event-recorder monitoring at 0, 3, and 6 months.

Results— Serial extended ECG monitoring identified AF in 26% of patients with frequent APBs but only in 6.5% when APBs were infrequent ( P =0.0021). A multivariate analysis showed that the presence of frequent APBs in the initial 24-hour ECG was the only independent predictor of paroxysmal AF during follow-up (odds ratio 6.6, 95% confidence intervals 1.6 to 28.2, P =0.01).

Conclusions— In patients with acute ischemic stroke, frequent APBs (≥70/24 hours) are a marker for individuals who are at greater risk to develop or have paroxysmal AF. For such patients, we propose a diagnostic workup with repeated prolonged ECG monitoring to diagnose paroxysmal AF.

Holter monitoring for 24 hours in patients with thromboembolic stroke and sinus rhythm diagnosed in the emergency department

It is well known that patients with ischemic stroke show ST-T abnormalities and various rhythm abnormalities on an electrocardiogram (ECG). The most commonly encountered rhythm abnormality is atrial fibrillation. It was recently shown that paroxysmal atrial fibrillation (PAF) is an important causative factor in patients with stroke. Detection of PAF is important in identifying the cause, prognosis, and treatment in patients with thromboembolic stroke. Investigators in the present study followed patients with thromboembolic stroke who had been admitted to the emergency department in sinus rhythm; 24-h Holter monitoring was used, and patients were assessed at referral and every 6 h for 24 h with ECG, which was used to detect rhythm disturbances, especially PAF. In 26 patients with stroke who came to the emergency department, acute thromboembolic stroke was diagnosed on the basis of magnetic resonance imaging; no rhythm abnormalities were noted on Holter monitoring. Eighteen patients were male and 8 were female (mean age: 66+/-13 y). Arrhythmia was identified on ECG in 3 patients (11%) and on 24-h Holter monitoring in 24 patients (92%). PAF was diagnosed in 3 patients (11%) on ECG and in 11 patients (42%) on Holter monitoring. In 2 patients, nonsustained ventricular tachycardia was detected only on Holter monitoring, which was found to be significantly superior to ECG for the detection of arrhythmias (P<.001). Investigators found no significant relationship between PAF and variables such as hypertension, diabetes, coronary artery disease, history of myocardial infarction, ST-T changes, and elevations in cardiac markers. However, a significant relationship (P<.01) was seen between nonsustained ventricular tachycardia and a history of myocardial infarction. No relationship was discerned between arrhythmia and stroke localization. Study results suggested that (1) PAF is a commonly diagnosed rhythm abnormality, and (2) Holter monitoring is superior to routine ECG for the detection of arrhythmias such as PAF in patients anticipated to have thromboembolic stroke with sinus rhythm.

Comparison of autotriggered memory loop recorders versus standard loop recorders versus 24-hour Holter monitors for arrhythmia detection

To determine the relative yields of Holter monitoring (HM), memory loop recording (MLR), and autotriggered MLR (AT-MLR), we retrospectively interrogated the very large database of Lifewatch (a Card Guard company and a commercial monitoring company) and compared the results obtained by each method. From among a total database of approximately 100,000 patients, records of 1,800 patients from 2003 were randomly selected and examined, 600 from each of the 3 different monitoring groups. Each session of MLR and AT-MLR was applied for 30 days. For each patient we determined the symptomatic and asymptomatic events that were documented, including those that met predefined immediate physician notification criteria and the time to first notification event. The groups were identical in age and symptoms that necessitated monitoring; fewer women had HM. Information on the type of underlying structural heart disease, if present, and medications taken, if any, was not available to us in this database. The AT-MLR approach provided a higher yield of diagnostic events (e.g., 37, 108, and 216 total patients who had events; 37, 212, and 524 total events; and 6.2%, 17%, and 36% with a diagnostic yield for HM, MLR, and AT-MLR, respectively) and an earlier diagnosis. AT-MLR was also the most effective technique for capturing asymptomatic significant events, such as atrial fibrillation (52 with AT-MLR vs 1 for standard MLR). AT-MLR detected more than half as many asymptomatic episodes of atrial fibrillation (n = 52) as the total number of symptomatic episodes detected by patient activated recording (n = 94), thus confirming the common presence of asymptomatic atrial fibrillation. AT-MLR provided electrocardiographic documentation of tachyarrhythmias (n = 392) more often than MLR (n = 47) or HM (n = 44) and bradyarrhythmias/pauses/atrioventricular block (n = 38) more often than MLR (n = 13) or HM (n = 18). Thus, MLR and AT-MLR provide a diagnosis more often than does HM, thus confirming the benefit of prolonged monitoring. Further, the higher yield of AT-MLR versus MLR demonstrates the significantly enhanced benefit of autotriggered programmable recording.

The use of a modified sphygmomanometer to detect atrial fibrillation in outpatients

This study was designed to assess the accuracy of a modified sphygmomanometer, that measures pulse irregularity, to detect atrial fibrillation (AF). An irregularity index, defined as the standard deviation of the time intervals between beats divided by the mean of the time intervals, was used to analyze standard 12-lead ECGs from hospitalized patients. A threshold irregularity index was selected such that all ECGs with AF exceeded this irregularity index value. A modified automatic blood pressure monitor was designed to detect AF by calculating the irregularity index of the pulse. The device was used to calculate the irregularity index in an unselected group of outpatients during scheduled office visits in which a standard 12-lead ECG was performed. A total of 125 ECGs, 53 with AF, were analyzed. Using a threshold irregularity index of 0.066, the sensitivity for detecting AF was 100%, the specificity was 92% and diagnostic accuracy 95%. A modified sphygmomanometer was used to analyze the pulse of 450 outpatients, 54 of whom were documented by ECG to be in AF. When paired readings were analyzed, the rhythm was considered to be irregular if both readings were greater than the threshold index. Using a threshold index of 0.06, all the AF patients were correctly identified while 37 non-AF patients also exceeded the threshold irregularity index. In this analysis, the sensitivity was 100%, the specificity 91%, and the diagnostic accuracy 92% for detecting AF. The irregularity index determined using a modified sphygmomanometer can accurately identify AF.

Holter monitoring in the diagnosis of stroke mechanism

BACKGROUND

Atrial fibrillation (AF), an important and treatable cause of ischaemic stroke, can occur as a sustained or a paroxysmal arrhythmia. Continuous cardiac rhythm monitoring (Holter monitoring) is often performed in stroke patients to identify paroxysmal AF, which is an indication for warfarin anti-coagulation in this patient population.

AIM

The aim of this study was to assess the clinical utility of Holter monitoring in detecting occult AF in patients with possible cardioembolic stroke.

METHODS

The medical records of ischaemic stroke patients consecutively hospitalized at a single academic centre during a one-year period were reviewed. Data regarding patient demographics, stroke characteristics, electrocardiography and echocardiography results and duration and findings of Holter monitoring were abstracted. The primary outcome was yield of newly diagnosed AF on Holter monitoring.

RESULTS

Of 465 consecutive patients admitted with a diagnosis of new ischaemic stroke, 210 underwent Holter monitoring. The mean duration of monitoring was 22.8 +/- 4.0 h. Previously undiscovered AF was -identified in five cases (2.4%), all of which represented non-rheumatic AF. In three cases, the Holter test was negative despite AF documented on an admission electro-cardiogram.

CONCLUSIONS

Holter monitoring can identify occult paroxysmal AF, assisting targeted secondary prevention in patients with new ischaemic stroke. However, the standard 24-h duration of monitoring probably under-estimates the prevalence of paroxysmal AF in this population. Prospective studies are indicated to evaluate the value of longer monitoring periods in stroke populations.

Thrombolytic Therapy for Acute Ischemic Stroke: The CAEP Position Statement: another perspective

The cautiously-worded Position Statement recently issued by the Canadian Association of Emergency Physicians (see Appendix 1) regarding the use of intravenous recombinant tissue-plasminogen activator (tPA, alteplase) for acute ischemic stroke underscores the reality that many physicians in Canada have been reluctant to embrace this therapy. Much of the caution expressed in the CAEP document is related to 2 major areas of concern: evidence of efficacy (i.e., did tPA really “prove” itself in randomized trials?) and effectiveness (i.e., are the trial results generalizable to everyday practice?). While we support the development of documents that help to clarify controversial treatments, and agree with much of what is presented in the CAEP Position Statement, we offer the following comments.