Correlation of ventricular pacing burden and left ventricular function in patients with heart failure with reduced ejection fraction.

BACKGROUND: Pacemaker-induced cardiomyopathy is a well described phenomenon in patients with preserved ejection fraction at the time of permanent pacemaker implant. One of the identified risk factors for pacemaker-induced cardiomyopathy is the degree of ventricular pacing burden. However, it is unclear how a high right ventricular pacing burden affects patients with depressed left ventricular function at the time of pacemaker implantation. We sought to assess the relationship between right ventricular pacing and change in left ventricular function over time. METHODS: We conducted an analysis of all patients who had received either a single or dual lead cardiac implantable electronic devices, excluding biventricular devices, and had a prior transthoracic echocardiogram demonstrating an ejection fraction of less than 50%. The primary end-point was the correlation between the percentage of ventricular pacing and the change in LV ejection fraction. RESULTS: Fifty eight patients with preceding heart failure had pacemakers implanted and had follow up echocardiograms. There was no correlation between the degree of ventricular pacing and the absolute change in LV function (r = .04, p = .979). None of the previously identified risk factors for pacemaker induced cardiomyopathy were predictive of a significant fall in ejection fraction. CONCLUSION: The degree of RV pacing and other established risk factors for pacemaker-induced cardiomyopathy in patients with normal left ventricular function at the time of implantation do not appear to carry the same risk in patients with pre-existing heart failure who receive either single or dual lead pacemakers.

Efficacy of intravenous magnesium for the management of non-post operative atrial fibrillation with rapid ventricular response: A systematic review and meta-analysis.

BACKGROUND: Intravenous magnesium (IV Mg), a commonly utilized therapeutic agent in the management of atrial fibrillation (AF) with rapid ventricular response, is thought to exert its influence via its effect on cellular automaticity and prolongation of atrial and atrioventricular nodal refractoriness thus reducing ventricular rate. We sought to undertake a systematic review and meta-analysis of the effectiveness of IV Mg versus placebo in addition to standard pharmacotherapy in the rate and rhythm control of AF in the nonpostoperative patient cohort given that randomized control trials (RCTs) have shown conflicting results. METHODS: Randomized controlled trials comparing IV Mg versus placebo in addition to standard of care were identified via electronic database searches. Nine RCTs were returned with a total of 1048 patients. Primary efficacy endpoints were study-defined rate control and rhythm control/reversion to sinus rhythm. The secondary endpoint was patient experienced side effects. RESULTS: Our analysis found IV Mg in addition to standard care was successful in achieving rate control (odd ratio [OR] 1.87, 95% confidence interval [CI] 1.13-3.11, p = .02) and rhythm control (OR 1.45, 95% CI 1.04-2.03, p = .03). Although not well reported among studies, there was no significant difference between groups regarding the likelihood of experiencing side effects. CONCLUSIONS: IV Mg, in addition to standard-of-care pharmacotherapy, increases the rates of successful rate and rhythm control in nonpostoperative patients with AF with rapid ventricular response and is well tolerated.

Diabetes mellitus is an independent predictor of obstructive coronary artery disease in patients presenting with atrial fibrillation and elevated troponin.

Atrial fibrillation can present with symptoms of myocardial infarction and elevated troponin, even in the absence of obstructive coronary artery disease (CAD). We sought to determine the characteristics that predict underlying obstructive CAD. Obstructive CAD was far more likely in those with troponin elevation. In those with elevated troponin, diabetes mellitus was an independent predictor of obstructive CAD.

Comparison of 2 Smart Watch Algorithms for Detection of Atrial Fibrillation and the Benefit of Clinician Interpretation: SMART WARS Study.

BACKGROUND: Smart watches and wearable technology capable of heart rhythm assessment have increased in use in the general population. The Apple Watch Series 4 (AW4) and KardiaBand (KB) are devices capable of obtaining single-lead electrocardiographic recordings, presenting a novel opportunity for the detection of paroxysmal arrhythmias. OBJECTIVES: The aim of this study was to assess the diagnostic utility of the AW4 and KB in an elderly outpatient population. METHODS: Consecutive recordings were taken from patients attending cardiology outpatient clinic from the AW4 and KB concurrently with 12-lead electrocardiography. Automated diagnoses and blinded single-lead electrocardiographic tracing interpretations by 2 cardiologists were analyzed. Analysis was also conducted to assess the effect of combined device and clinician interpretation. RESULTS: One hundred twenty-five patients were prospectively recruited (mean age 76 ± 7 years, 62% men). The accuracy of the automated rhythm assessment was higher with the KB than the AW4 (74% vs 65%). For the detection of atrial fibrillation, the sensitivity and negative predictive value of the KB were 89% and 97%, respectively, and of the AW4 were 19% and 82%, respectively. Using hybrid automated and clinician interpretation, the overall accuracy of the KB and AW4 was 91% and 87%, respectively. CONCLUSIONS: The KB automated algorithm outperformed the AW4 in its accuracy and sensitivity for detecting atrial fibrillation in the outpatient setting. Clinician assessment of the single-lead electrocardiogram improved accuracy. These findings suggest that although these devices' tracings are of sufficient quality, automated diagnosis alone is not sufficient for making clinical decisions about atrial fibrillation diagnosis and management.

Role of renin-angiotensin system antagonists on long-term mortality post-percutaneous coronary intervention in reduced and preserved ejection fraction.

AIMS: The use of angiotensin-converting enzyme inhibitors (ACEi) or angiotensin II-receptor blockers (ARBs) post-myocardial infarction (MI) is supported by evidence based on trials performed in the thrombolysis era. This was prior to primary percutaneous coronary intervention (PCI) being routine practice, and with little direct evidence for the use of these medications in patients with preserved left ventricular (LV) function. This study sought to determine whether there is an association between ACEi/ARB use after PCI for acute coronary syndrome (ACS) and long-term all-cause mortality, with a particular focus on patients with preserved LV function. METHODS: This multicentre, observational study evaluated prospectively collected data of 21,388 patients (> 18 years old) that underwent PCI for NSTEMI and STEMI between 2005 and 2018, and were alive at 30 day follow-up. RESULTS: In total, 83.8% of patients were using ACEi/ARBs. Kaplan-Meier analysis demonstrated ACEi/ARB use was associated with a significantly lower mortality in the entire cohort (15.0 vs. 22.7%; p < 0.001) with a mean follow-up of 5.58 years; and independently associated with 24% lower mortality by Cox proportional hazards modelling (HR 0.76, CI 0.67-0.85, p < 0.001). ACEi/ARB therapy was also associated with significantly lower mortality in patients with reduced or preserved LV function, with greater survival benefit with worse LV dysfunction. CONCLUSION: ACEi/ARB therapy post-PCI is associated with significantly lower long-term mortality in patients with reduced and preserved LV function. These findings provide contemporary evidence for using these agents in the current era of routine primary PCI, including those with preserved EF.

Angiotensin-Converting Enzyme 2 Activity Is Associated With Embolic Stroke of Undetermined Source.

[Figure: see text].

The Atrium and Embolic Stroke: Myopathy Not Atrial Fibrillation as the Requisite Determinant?

Atrial fibrillation (AF) is well-recognized in the pathophysiology of left atrial thrombogenesis and resultant cardioembolic stroke. Subclinical AF is believed to account for a significant proportion of embolic stroke. However, recent randomized control trials failed to demonstrate a significant benefit for oral anticoagulation, in an unselected population with embolic stroke of undetermined source. This has reinvigorated the focus on finding robust markers to identify patients at risk of cardioembolic stroke. Several nonfibrillatory atrial electrical markers, along with structural and biochemical abnormalities, have been associated with ischemic stroke, independently of AF. An increasingly complex relationship exists among vascular risk factors, atrial remodeling, and thrombogenesis. Identifying robust markers of an underlying atrial myopathy may allow for early identification of patients at risk for cardioembolic stroke. This review outlines the inconsistencies in the evidence for AF as the prerequisite for left atrial thrombogenesis and embolic stroke. It will highlight the current evidence and controversies for adverse atrial remodeling, independent from rhythm, as a plausible mechanism for left atrial thrombogenesis and ischemic stroke.

Accuracy of a smartwatch based single-lead electrocardiogram device in detection of atrial fibrillation.

OBJECTIVE: The AliveCor KardiaBand (KB) is an Food and Drug Administration-approved smartwatch-based cardiac rhythm monitor that records a lead-Intelligent ECG (iECG). Despite the appeal of wearable integrated ECG devices, there is a paucity of data evaluating their accuracy in diagnosing atrial fibrillation (AF). We evaluated whether a smartwatch-based device for AF detection is an accurate tool for diagnosing AF when compared with 12-lead ECG. METHODS: A prospective, multi-centre, validation study was conducted in an inpatient hospital setting. The KB paired with a smartwatch, generated an automated diagnosis of AF or sinus rhythm (SR). This was compared with a 12-lead ECG performed immediately after iECG tracing. Where an unclassified or no-analysis tracing was generated, repeat iECG was performed. RESULTS: 439 ECGs (iECGs (n=239) and 12-lead ECG (n=200)) were recorded in 200 patients (AF: n=38; SR: n=162) from three tertiary centres. Sensitivity and specificity using KB was 94.4% and 81.9% respectively, with a positive predictive value of 54.8% and negative predictive value of 98.4%. Agreement between 12-lead ECG and KB diagnosis was moderate when unclassified tracings were included (κ=0.60, 95% CI 0.47 to 0.72). Combining the automated device diagnosis with blinded electrophysiologists (EP) interpretation of unclassified tracings improved overall agreement (EP1: κ=0.76, 95% CI 0.65 to 0.87; EP2: κ=0.74, 95% CI 0.63 to 0.86). CONCLUSION: The KB demonstrated moderate diagnostic accuracy when compared with a 12-lead ECG. Combining the automated device diagnosis with EP interpretation of unclassified tracings yielded improved accuracy. However, even with future improvements in automated algorithms, physician involvement will likely remain an essential component when exploring the utility of these devices for arrhythmia screening. CLINICAL TRIAL REGISTRATION: URL: https://www.anzctr.org.au/ Unique identifier: ACTRN12616001374459.

Accuracy of wrist-worn heart rate monitors for rate control assessment in atrial fibrillation.

BACKGROUND: Wrist-worn heart rate (HR) monitors are increasingly popular. A paucity of data exists on their accuracy in atrial fibrillation (AF) in ambulatory patients. We sought to assess the HR accuracy of two commercially available smart watches [SW] (Fitbit Charge HR [FB] and Apple Watch Series 3 [AW]) compared with Holter monitoring in an ambulant patient cohort. METHODS: Thirty-two participants ≥18 years referred for 24-hour Holter monitoring were prospectively recruited. Each participant was randomly allocated to wear either a FB or AW along with their Holter monitor. RESULTS: Across all devices, 53,288 heart rate values were analysed from 32 participants. Twenty wore the AW (17 had persistent AF and 3 had sinus rhythm [SR]) while 12 participants wore the FB (9 in persistent AF and 3 in SR). Participants in SR demonstrated strong agreement compared to Holter monitoring (bias <1 beat, limits of agreement [LoA] -11 to 11 beats). In AF, both devices underestimated HR measurements (bias -9 beats, LoA -41 to 23). The degree of underestimation was more pronounced when HR > 100 bpm (bias of -28 beats for HR range 100-120 bpm, -48 for 120-140 bpm, and -69 for >140 bpm) compared to a slower HR (bias of -6 for HR range 80-100 bpm, <1 for 60-80 bpm, and -1 for <60 bpm). CONCLUSION: In ambulatory patients, smartwatches underestimated HR in AF particularly at HR ranges >100 bpm. Further improvements in device technology are needed before integrating them into the clinical management of rate control in AF.

Impaired Cardiac Reserve on Dobutamine Stress Echocardiography Predicts the Development of Hepatorenal Syndrome.

OBJECTIVES: Cardiac dysfunction has been implicated in the genesis of hepatorenal syndrome (HRS). It is unclear whether a low cardiac output (CO) or attenuated contractile response to hemodynamic stress can predict its occurrence. We studied cardiovascular hemodynamics in cirrhosis and assessed whether a diminished cardiac reserve with stress testing predicted the development of HRS on follow-up. METHODS: Consecutive patients undergoing liver transplant workup with dobutamine stress echocardiography (DSE) were included. CO was measured at baseline and during low-dose dobutamine infusion at 10 µg/kg/min. HRS was diagnosed using guideline-based criteria. RESULTS: A total of 560 patients underwent DSE, of whom 488 were included after preliminary assessment. There were 64 (13.1%) patients with established HRS. The HRS cohort had a higher baseline CO (8.0 ± 2 vs 6.9 ± 2 L/min; P < 0.001) and demonstrated a blunted response to low-dose dobutamine (ΔCO 29 ± 22% vs 44 ± 32%, P < 0.001) driven primarily by inotropic incompetence. Optimal cutpoint for ΔCO in patients with HRS was determined to be <25% and was used to define a low cardiac reserve. Among the 424 patients without HRS initially, 94 (22.1%) developed HRS over a mean follow-up of 1.5 years. Higher proportion with a low cardiac reserve developed HRS (52 [55.0%] vs 56 [16.9%]; hazard ratio 4.5; 95% confidence interval 3.0-6.7; P < 0.001). In a Cox multivariable model, low cardiac reserve remained the strongest predictor for the development of HRS (hazard ratio 3.9; 95% confidence interval 2.2-7.0; P < 0.001). DISCUSSION: Patients with HRS demonstrated a higher resting CO and an attenuated cardiac reserve on stress testing. On longitudinal follow-up, low cardiac reserve was an independent predictor for the development of HRS. Assessment of cardiac reserve with DSE may provide a novel noninvasive risk marker for developing HRS in patients with advanced liver disease.HRS is a life-threatening complication of liver disease. We studied whether an inability to increase cardiac contraction in response to stress can assist in the prediction of HRS. We demonstrate that patients with liver disease who exhibit cardiac dysfunction during stress testing had a 4-fold increased risk of developing HRS. This may improve our ability for early diagnosis and treatment of patients at a higher risk of developing HRS.

Association between excessive premature atrial complexes and cryptogenic stroke: results of a case-control study.

OBJECTIVE: Recent anticoagulation trials in all-comer cryptogenic stroke patients have yielded equivocal results, reinvigorating the focus on identifying reproducible markers of an atrial myopathy. We investigated the role of excessive premature atrial complexes (PACs) in ischaemic stroke, including cryptogenic stroke and its association with vascular risk factors. METHODS AND RESULTS: A case-control study was conducted utilising a multicentre institutional stroke database to compare 461 patients with an ischaemic stroke or transient ischaemic attack (TIA) with a control group consisting of age matched patients without prior history of ischaemic stroke/TIA. All patients underwent 24-hour Holter monitoring during the study period and atrial fibrillation was excluded. An excessive PAC burden, defined as ≥200 PACs/24 hours, was present in 25.6% and 14.7% (p<0.01), of stroke/TIA and control patients, respectively. On multivariate regression, excessive PACs (OR 1.97; 95% CI 1.29 to 3.02; p<0.01), smoking (OR 1.58; 95% CI 1.06 to 2.36; p<0.05) and hypertension (OR 1.53; 95% CI 1.07 to 2.17; p<0.05) were independently associated with ischaemic stroke/TIA. Excessive PACs remained the strongest independent risk factor for the cryptogenic stroke subtype (OR 1.95; 95% CI 1.16 to 3.28; p<0.05). Vascular risk factors that promote atrial remodelling, increasing age (≥75 years, OR 3.64; 95% CI 2.08 to 6.36; p<0.01) and hypertension (OR 1.54; 95% CI 1.01 to 2.34; p<0.05) were independently associated with excessive PACs. CONCLUSIONS: Excessive PACs are independently associated with cryptogenic stroke and may be a reproducible marker of atrial myopathy. Prospective studies assessing their utility in guiding stroke prevention strategies may be warranted.

Wearable devices for cardiac arrhythmia detection: a new contender?

There has been increased consumer uptake of smart devices and wearable technology. They facilitate non-invasive, ambulatory assessment of numerous cardiac indices, including the heart rate and rhythm. Several studies have reported on the utility and deficiencies of these devices in identifying and monitoring cardiac arrhythmias. The rapid uptake of these consumer devices has the potential to generate vast amounts of biometric data. This coupled with gaps in knowledge pertaining to the optimal management of conditions such as sub clinical atrial fibrillation, may result in unnecessary and expensive downstream testing. An improved understanding of this nascent field by the clinician is vital.

Poor reliability of P-wave terminal force V1 in ischemic stroke.

INTRODUCTION: Several ECG markers are postulated to represent underlying atrial remodelling and have been associated with ischemic stroke. P-wave terminal force in lead V1 (PTFV1) is one such marker. We examined the factors that contribute to the reliability of PTFV1 and its association with ischemic stroke. MATERIAL AND METHODS: Four hundred and thirty-five patients that presented with an ischemic stroke or transient ischemic attack (TIA) were identified through a prospectively maintained multi-site institutional stroke database. Control group consisted of age matched patients without prior history of an ischemic stroke or TIA. All patients underwent a 12-lead ECG and 24-hour Holter monitoring during the study period to exclude atrial fibrillation. RESULTS: Morphology consistent with PTFV1 occurred commonly in both the stroke/TIA and control groups. There was no significant difference in the median PTFV1 value between the stroke 3.96 mV ms [Interquartile range (IQR) 2.78-5.58] and control 4.23 mV ms [IQR 2.91-5.57] groups. Measurements of PTFV1 demonstrated excellent intra-observer reliability on assessment of the same P-wave (Intra class correlation (ICC) 0.91, p < 0.001) with narrow limits of agreement 2.21 to -2.95 mV ms. A change in the P wave assessed led to a significant reduction in reliability (ICC 0.79, p < 0.001). Inter-observer, inter P-wave assessment demonstrated further reduction in reliability (ICC 0.68, p < 0.002) with wide limits of agreement 6.17 to -5.78 mV ms, indicating significant under and overestimation of PTFV1. CONCLUSION: The utility of PTFV1 as a clinical marker for ischemic stroke is limited by the reduction in reliability associated with inter-observer and inter P-wave measurements.

Accuracy of blinded clinician interpretation of single-lead smartphone electrocardiograms and a proposed clinical workflow.

Despite the appeal of smartphone-based electrocardiograms (ECGs) for arrhythmia screening, a paucity of data exists on the accuracy of primary care physicians' and cardiologists' interpretation of tracings compared with the device's automated diagnosis. Using 408 ECGs in 51 patients, we demonstrate a variable accuracy in clinician interpretation of smartphone-based ECGs, with only cardiologists demonstrating satisfactory agreement when referenced against a 12-lead ECG. Combining the device automated diagnostic algorithm with cardiologist interpretation of only uninterpretable traces yielded excellent results and provides an efficient, cost-effective workflow for the utilization of a smartphone-based ECG in clinical practice.

Modified positioning of a smartphone based single-lead electrocardiogram device improves detection of atrial flutter.

INTRODUCTION: The AliveCor Kardia Mobile (AKM) is a handheld, smartphone based cardiac rhythm monitor that records a lead-I electrocardiogram (ECG). Despite being efficacious for detection of atrial fibrillation (AF), it is unclear whether atrial flutter (AFL) may be misdiagnosed as sinus rhythm due to regular R-R intervals. We hypothesised that generating lead-II tracings through repositioning of the AKM may improve visualisation of flutter waves and clinician diagnosis of AFL compared to traditional lead-I tracings. MATERIALS AND METHODS: A prospective, multi-centre, validation study was conducted comparing standard lead-I AKM positioning with lead-II in AFL. A mixed cohort of lead I tracings from patients in AF and sinus rhythm were also included. Two independent electrophysiologists (EP) analysed all ECGs blinded to the automated device diagnosis. RESULTS: Fifty patients were recruited, 11 in atrial flutter, 14 in atrial fibrillation, and 25 in sinus rhythm. Lead-I AFL sensitivity was 27.3% for both EP's which individually improved to 72.7% and 54.6% in lead-II. AKM appropriately diagnosed lead-I AFL as unclassified in 18.2% of cases, compared to 54.5% in lead-II. Overall clinician agreement (AF, SR and AFL) was modest utilising AFL lead-I (EP1: κ = 0.71, EP2: κ = 0.73, p < 0.001), which improved with lead-II tracings (EP1: κ = 0.87, EP2: κ = 0.83, both p < 0.001). CONCLUSION: Repositioning of the AKM device improves clinician diagnosis of atrial flutter. A lead-II tracing may be considered in high-risk patients to improve detection of atrial flutter.

Smart watches for heart rate assessment in atrial arrhythmias.

BACKGROUND: Despite studies demonstrating the accuracy of smart watches (SW) and wearable heart rate (HR) monitors in sinus rhythm, no data exists regarding their utility in arrhythmias. METHODS: 102 hospitalized patients were evaluated at rest using continuous electrocardiogram (ECG) monitoring with concomitant SW-HR (FitBit, FB, Apple Watch, AW) for 30 min. RESULTS: Across all devices, 38,616 HR values were recorded. Sinus rhythm cohort demonstrated strong agreement for both devices with a low bias (FB & AW Bias = 1 beat). In atrial arrhythmias, AW demonstrated a stronger correlation than FB (AW rs = 0.83, FB rs = 0.56, both p < 0.01) with a lower bias (Bias AW = -5 beats, FB = -18 beats). Atrial flutter demonstrated strongest agreement in both devices with a mean bias <1 beat. However, in AF, there was significant HR underestimation (Bias FB = -28 beats, AW-8 beats) with wide limits of agreement. Despite HR underestimation in AF, when SW recorded HR ≥ 100 in arrhythmias, 98% of values were within ±10-beats of ECG-HR. CONCLUSIONS: SW demonstrate strong agreement for HR estimation in sinus rhythm and atrial flutter but underestimates HR in AF. Tachycardic episodes recorded at rest on a SW may be suggestive of an underlying atrial tachyarrhythmia and warrant further clinical evaluation. CLINICAL TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry (www.anzctr.org.au) ACTRN: 12616001374459.

Utility of photoplethysmography for heart rate estimation among inpatients.

The accuracy of photoplethysmography (PPG) for heart rate (HR) estimation in cardiac arrhythmia is unknown. PPG-HR was evaluated in 112 hospitalised inpatients (cardiac arrhythmias (n = 60), sinus rhythm (n = 52)) using a continuous electrocardiogram monitoring as a reference standard. Strong agreement was observed in sinus rhythm HR < 100 and atrial flutter (bias 1 beat), modest agreement in sinus tachycardia (bias 24 beats) and complete heart block (bias -6 beats) and weak agreement with significant HR underestimation was seen in atrial fibrillation (bias 23 beats). Routine utilisation of PPG for HR estimation may delay early recognition of clinical deterioration in certain arrhythmias and sinus tachycardia.