An update on insertable cardiac monitors: examining the latest clinical evidence and technology for arrhythmia management

Usefulness of echocardiography for predicting ventricular tachycardia detected by implantable loop recorder in syncope patients

Ventricular tachycardia (VT) may lead to syncope and sudden cardiac death. Implantable loop recorders (ILR) are recommended in the clinical work-up of patients with unexplained syncope. Our aim was to evaluate if echocardiographic parameters assessed prior to ILR implantation in patients with unexplained syncope may aid in identifying individuals with an increased risk of VT. The present study included 288 ambulatory patients (mean age 58 ± 19 years, 51% women) with syncope (90%) and presyncope (10%) who had an ILR implanted in the diagnostic workup. All patients underwent an echocardiographic examination prior to device implantation (median 3 months [IQR 1 to 6 months]). We examined incident VT, defined as a first-time episode of VT (> 30 s) or non-sustained VT (< 30 s) detected by the ILR. During median follow-up of 2.9 years [IQR 1.3 to 3.5 years] of continuous rhythm monitoring, 36 patients (13%) were diagnosed with incident VT (n = 25 non-sustained VT, n = 11 sustained VT). In unadjusted Cox proportional hazards models, left ventricular (LV) mass index (HR: 1.04 per 1 g/m² increase [1.00 to 1.08], P = 0.047), mean LV wall thickness (HR: 1.36 per 1 mm increase [1.08 to 1.71], P = 0.009), and global longitudinal strain (HR: 1.15 per 1% decrease [1.05 to 1.25], P = 0.002) were significantly associated with VT. After adjusting for age, sex, implantable loop recorder indication and known heart failure, the above-mentioned parameters remained significantly associated with incident VT. LV mass index, LV wall thickness, and GLS may aid in identifying patients with increased risk of incident VT among patients with syncope. Echocardiography may potentially help select patients who can benefit from ILR.

Relationship between left atrial strain, diastolic dysfunction and subclinical atrial fibrillation in patients with cryptogenic stroke: the SURPRISE echo substudy

Paroxysmal atrial fibrillation (PAF) may be the cause of a substantial part of cryptogenic strokes (CS). Echocardiography could assist risk stratification for PAF to select patients in need of prolonged rhythm monitoring. We aimed to assess the value of left atrial (LA) strain and a revised diastolic dysfunction (DDF) model with LA strain for predicting PAF. This was a prospective study of 56 CS patients who had a cardiac monitor implanted for 3 year monitoring for PAF, and an echocardiogram performed prior to monitoring. Conventional echocardiography, global longitudinal strain (GLS) and LA strain were performed. LA speckle tracking provided the LA reservoir strain (LAs). Patients were stratified into high versus low LAs by ROC curves (28.2%), and this cut-off was used to refine DDF grading. During follow-up of median 20 months, 13 (23%) patients were diagnosed with PAF. No conventional echocardiographic parameters differed between patients who developed PAF and those without PAF. However, LAs was significantly impaired in PAF patients (LAs: 30 vs. 27% for non-PAF and PAF, p = 0.046). Low LAs significantly predicted PAF independent of LA volume and GLS [OR 5.88 (1.30; 26.55), p = 0.021]. Revised DDF grading significantly predicted PAF, even when adjusted for the CHADS₂ risk-score (OR 1.88 [1.01;3.50], per increase in DDF grade, p for trend = 0.047), which was not the case for conventional DDF grading. In conclusion, LAs associates with PAF independent of GLS and LA size, and may be used to improve the performance of DDF grading for identifying PAF in CS patients.

Evaluating the benefits of home-based management of atrial fibrillation: current perspectives

Atrial fibrillation (AF) is the most common arrhythmia worldwide, leading to an extensive public health and economic burden. The increasing incidence and prevalence of AF is due to the advancing age of the population, structural heart disease, hypertension, diabetes, and thyroid disease. The majority of costs associated with AF have been attributed to the cost of hospitalization. In order to minimize costs and decrease hospitalizations, counseling on modifiable risk factors contributing to AF has been strongly emphasized. With the release of novel oral anticoagulants bypassing the need for anticoagulant bridging or laboratory monitoring, post-discharge nurse-led home intervention, and novel methods of heart rate monitoring, home-based AF management has reached a new level of ease and sophistication. In this review, we aimed to review modifiable risk factors for AF and various methods of home-based management of AF, along with their benefits.

Insertable cardiac monitors in the diagnosis of syncope and the detection of atrial fibrillation: A systematic review and meta-analysis

BACKGROUND

Insertable or implantable cardiac monitors (ICMs) continuously monitor the heart rhythm and record irregularities over 3 years, enabling the diagnosis of infrequent rhythm abnormalities associated with syncope and stroke. The enhanced recognition capabilities of recent ICM models are able to accurately detect atrial fibrillation (AF) and have led to new applications of ICMs for the detection and monitoring of AF.

METHODS AND RESULTS

Based on a systematic literature search, two indications were identified for ICMs for which considerable evidence, including randomized studies, exists: diagnosing the underlying cardiac cause of unexplained recurrent syncope and detecting AF in patients after cryptogenic stroke (CS). Three randomized controlled trials (RCTs) were identified that compared the effectiveness of ICMs in diagnosing patients with unexplained syncope (n = 556) to standard of care. A meta-analysis was conducted in order to generate an overall effect size and confidence interval of the diagnostic yield of ICMs versus conventional monitoring. In the indication CS, one RCT and five observational studies were included in order to assess the performance of ICMs in diagnosing patients with AF (n = 1129). Based on these studies, there is strong evidence that ICMs provide a higher diagnostic yield for detecting arrhythmias in patients with unexplained syncope and for detection of AF in patients after CS compared to conventional monitoring.

CONCLUSIONS

Prolonged monitoring with ICMs is an effective tool for diagnosing the underlying cardiac cause of unexplained syncope and for detecting AF in patients with CS. In all RCTs, ICMs have a superior diagnostic yield compared to conventional monitoring.

Predicting Paroxysmal Atrial Fibrillation in Cerebrovascular Ischemia Using Tissue Doppler Imaging and Speckle Tracking Echocardiography

BACKGROUND

Often the underlying cause of cerebral ischemia (CI) cannot be found during a routine diagnostic investigation, but paroxysmal atrial fibrillation (PAF) could be the culprit.

AIM

The objective of the study is to investigate whether advanced echocardiography improves the diagnostic approach for PAF in CI.

METHODS

The study included 286 CI patients with an echocardiogram in sinus rhythm. Patients were divided by PAF occurrence (PAF: n = 86, non-PAF: n = 200). PAF was defined as 1 or more reported episodes of atrial fibrillation. Echocardiograms consisted of conventional measures, tissue Doppler imaging (TDI), and speckle tracking. TDI was performed to acquire myocardial peak velocities during systole/ventricular contraction (global s'), early diastole/ventricular filling (global e'), and late diastole/atrial contraction (global a'). Speckle tracking was performed for myocardial strain analysis, thereby retrieving global longitudinal strain and global strain rate (s, e, a) values.

RESULTS

Patients with PAF exhibited significantly impaired atrial contractile measures: global a' (-7.0 cm/second versus -5.7 cm/second, P < .001) and global strain rate a (.97 second(-1) versus .81 second(-1), P < .001). Both were univariable markers of PAF, and along with age remained the only independent significant determinants of PAF after multivariable logistic regression. Area under the curve (AUC) for age, global a', and global strain rate a significantly exceeded AUC for age alone (.79 versus .76, P = .032). Cutoff values with the highest sensitivity and specificity for these 3 parameters improved the diagnostic accuracy (sensitivity = 97%, specificity = 32%, negative predictive value = 95%, and positive predictive value = 38%).

CONCLUSIONS

Atrial contractile measures by advanced echocardiography are significant determinants of PAF in CI. However, there is no discriminatory power to make them clinically useful at the current moment.