Paroxysmal atrial fibrillation in cryptogenic stroke

Useful indices of thrombogenesis in the exclusion of intra-cardiac thrombus

Background

Cardioversion in patients with atrial fibrillation (AF) can cause cardioembolic stroke, and effective clinical management is necessary to reduce morbidity and mortality. Currently, transesophageal echocardiography (TEE) is the accepted standard to diagnose cardiogenic thromboemboli; however, a negative TEE does not eliminate the possibility of left atrial thrombus. The objective of this study was to evaluate the diagnostic value of supplementing the TEE with additional noninvasive markers to ensure thrombus absence.

Methods

A prospective study was conducted on 59 patients who underwent TEE for suspected intra‐cardiac thrombi. The TEE indications included acute ischemic stroke (45.7%) and AF or flutter (59.3%). D‐dimer level and white blood cell counts were assessed.

Results

A negative D‐dimer level (<200 ng/mL) excluded the presence of intra‐cardiac thrombi. Groups with either negative (n = 14) or positive (n = 45) D‐dimer levels had comparable clinical characteristics. Comparing positive D‐dimer–level patients with thrombus (n = 7) and without thrombus (n = 33), patients with thrombus had reduced left atrial appendage (LAA) velocity (P = .0024), reduced left ventricular ejection fraction (LVEF) (P = .0263), increased neutrophil percent (P = .0261), decreased lymphocyte percent (P = .0216), and increased monocyte counts (P = .0220). The area under the receiver operating characteristic (ROC) curve for thrombus diagnostics was larger for combinations of clinical and biochemical data than for each parameter individually.

Conclusions

Supplementing the gold standard TEE with the analysis of LAA velocity, noninvasive LVEF, D‐dimer, and hemostatic markers provided additional useful diagnostic information. Larger studies are needed to further validate the efficacy of supplementing the TEE to better assess patients for intra‐cardiac thrombi.

Atrial fibrillation detection using single lead portable electrocardiographic monitoring: a systematic review and meta-analysis

OBJECTIVES

Recent technology advances have allowed for heart rhythm monitoring using single-lead ECG monitoring devices, which can be used for early diagnosis of atrial fibrillation (AF). We sought to investigate the AF detection rate using portable ECG devices compared with Holter monitoring.

SETTING, PARTICIPANTS AND OUTCOME MEASURES

We searched the Medline, Embase and Scopus databases (conducted on 8 May 2017) using search terms related to AF screening and included studies with adults aged >18 years using portable ECG devices or Holter monitoring for AF detection. We excluded studies using implantable loop recorders and pacemakers. Using a random-effects model we calculated the overall AF detection rate. Meta-regression analysis was performed to explore potential sources for heterogeneity. Quality of reporting was assessed using the tool developed by Downs and Black.

RESULTS

Portable ECG monitoring was used in 18 studies (n=117 436) and Holter monitoring was used in 36 studies (n=8498). The AF detection rate using portable ECG monitoring was 1.7% (95% CI 1.4 to 2.1), with significant heterogeneity between studies (p<0.001). There was a moderate linear relationship between total monitoring time and AF detection rate (r=0.65, p=0.003), and meta-regression identified total monitoring time (p=0.005) and body mass index (p=0.01) as potential contributors to heterogeneity. The detection rate (4.8%, 95% CI 3.6% to 6.0%) in eight studies (n=10 199), which performed multiple ECG recordings was comparable to that with 24 hours Holter (4.6%, 95% CI 3.5% to 5.7%). Intermittent recordings for 19 min total produced similar AF detection to 24 hours Holter monitoring.

CONCLUSION

Portable ECG devices may offer an efficient screening option for AF compared with 24 hours Holter monitoring.

PROSPERO REGISTRATION NUMBER

CRD42017061021.

Embolic Stroke Diagnosed by Elevated D-Dimer in a Patient With Negative TEE for Cardioembolic Source

We report a case of cerebrovascular accident with thromboembolic stroke etiology in a patient who had atrial flutter and negative transesophageal echocardiography (TEE) results. The increased D-dimer levels (1877 ng/mL) initiated referral for magnetic resonance imaging and magnetic resonance angiography of the brain that showed classic recanalization of an embolic thrombus in the angular branch of the left middle cerebral distribution. The D-dimer level of this patient was normalized after 3 months of anticoagulation therapy. Although TEE is considered the gold standard for evaluation of cardiac source of embolism, exclusion of intracardiac thrombus with TEE alone does not eliminate the risk of thromboembolic events. This case highlights the utility of D-dimer as a potential adjunct in the decision-making process to guide investigation of thromboembolism, determine subsequent therapy, and hence reduce the risk of embolic stroke recurrence.

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.

Serum albumin levels are associated with cardioembolic and cryptogenic ischemic strokes: Northern Manhattan Study

BACKGROUND AND PURPOSE

Low serum albumin concentrations have been associated with increased stroke risk, but the underlying mechanisms are less well studied. We aimed to investigate the association between serum albumin levels and ischemic stroke etiologies in a large, population-based, multiethnic, prospective, cohort study.

METHODS

Participants from the Northern Manhattan Study (NOMAS; n=2986; mean age, 69±10 years) free of stroke at baseline were followed for incident stroke (a median follow-up of 12 years). Cox proportional hazard models were used to estimate the hazard ratios (HRs) and 95% confidence intervals (CIs) for baseline serum albumin levels and risk of ischemic stroke and ischemic stroke subtypes after adjusting for vascular risk factors.

RESULTS

The mean baseline serum albumin level was 4.42±0.33 g/dL. There were 271 ischemic strokes during follow-up. Participants with serum albumin levels of 2.7 to 4.2 g/dL (the lowest tertile) had increased risk of all stroke (HR, 1.76; 95% CI, 1.32-2.35), ischemic stroke (HR, 1.67; 95% CI, 1.21-2.29), cardioembolic stroke (HR, 1.92; 95% CI, 1.10-3.34), and cryptogenic stroke (HR, 2.59; 95% CI, 1.21-5.53), compared with those with levels of 4.6 to 5.5 g/dL (the top tertile; reference). Low albumin levels (2.7-4.2 g/dL) were not associated with large vessel or lacunar stroke.

CONCLUSIONS

Our study shows an association between low serum albumin levels and ischemic stroke, particularly cardioembolic and cryptogenic subtypes. These results suggest the potential shared pathophysiological relationship between low serum albumin levels, cardiac embolism, and cryptogenic infarction, which warrants further investigation.