Effect of sotalol on heart rate, QT interval, and atrial fibrillation cycle length in horses with atrial fibrillation

Background: Based on its pharmacokinetic profile and electrophysiological effects in healthy horses, sotalol potentially could be used as a long-term PO antiarrhythmic drug in horses. Objectives: To evaluate the effect of sotalol on heart rate (HR), QT interval, atrial fibrillatory rate, and success of cardioversion in horses with naturally occurring chronic atrial fibrillation (AF). Animals: Twenty-eight horses referred for transvenous electrical cardioversion of AF were treated with 2 mg/kg sotalol PO q12h for 3 days before cardioversion, and 13 horses underwent the same protocol without sotalol administration. Methods: Retrospective study. Before and after sotalol or no treatment, the HR was measured at rest and during an exercise test. The QT interval and atrial fibrillation cycle length (AFCL) were measured at rest using tissue Doppler velocity imaging. Results: In the control group, no significant differences were found between the 2 examinations. In the sotalol group, the HR at rest and during exercise was significantly lower after sotalol treatment, whereas the QT interval and AFCL measured by tissue Doppler increased significantly. Cardioversion to sinus rhythm was achieved in 25/28 horses in the sotalol group and all horses in the control group, but the median number of shocks and energy at cardioversion were significantly lower in the sotalol group. Conclusions and Clinical Importance: In horses with AF, sotalol administration results in class III antiarrhythmic effects and -blocking activity, with moderate HR reduction during exercise

Accuracy of advanced versus strictly conventional 12-lead ECG for detection and screening of coronary artery disease, left ventricular hypertrophy and left ventricular systolic dysfunction

<p>Abstract</p> <p>Background</p> <p>Resting conventional 12-lead ECG has low sensitivity for detection of coronary artery disease (CAD) and left ventricular hypertrophy (LVH) and low positive predictive value (PPV) for prediction of left ventricular systolic dysfunction (LVSD). We hypothesized that a ~5-min resting 12-lead <it>advanced </it>ECG test ("A-ECG") that combined results from both the advanced and conventional ECG could more accurately screen for these conditions than strictly conventional ECG.</p> <p>Methods</p> <p>Results from nearly every conventional and advanced resting ECG parameter known from the literature to have diagnostic or predictive value were first retrospectively evaluated in 418 healthy controls and 290 patients with imaging-proven CAD, LVH and/or LVSD. Each ECG parameter was examined for potential inclusion within multi-parameter A-ECG scores derived from multivariate regression models that were designed to optimally screen for disease in general or LVSD in particular. The performance of the best retrospectively-validated A-ECG scores was then compared against that of optimized pooled criteria from the strictly conventional ECG in a test set of 315 additional individuals.</p> <p>Results</p> <p>Compared to optimized pooled criteria from the strictly conventional ECG, a 7-parameter A-ECG score validated in the training set increased the sensitivity of resting ECG for identifying disease in the test set from 78% (72-84%) to 92% (88-96%) (P < 0.0001) while also increasing specificity from 85% (77-91%) to 94% (88-98%) (P < 0.05). In diseased patients, another 5-parameter A-ECG score increased the PPV of ECG for LVSD from 53% (41-65%) to 92% (78-98%) (P < 0.0001) without compromising related negative predictive value.</p> <p>Conclusion</p> <p>Resting 12-lead A-ECG scoring is more accurate than strictly conventional ECG in screening for CAD, LVH and LVSD.</p

Evaluation and prognostic significance of premature ventricular contractions in patients without structural heart disease

Introduction: Premature ventricular contractions (PVCs) are a common form of arrhythmia associated with poor prognosis in patients with structural heart disease. However, their prognostic impact on healthy individuals is unclear. There is also a lack of evidence about risk stratification of this group through cardiac imaging and electrocardiographic features. With this project we wanted to study whether patients with PVCs in which structural heart disease had thoroughly been excluded, have a worse prognosis than a control population. Moreover, we wanted to investigate whether PVC morphology and/or PVC duration are associated with the clinical outcome. Finally, we explored whether cardiac magnetic resonance imaging (CMR) and advanced echocardiographic parameters could unmask signs of structural heart disease in patients with high PVC-burden and normal echocardiogram. Methods: To study the prognostic impact of PVCs, we identified 807 patients with no history of structural heart disease, normal echocardiography and exercise test and verified PVCs. During a follow-up period of 5.2 years, we compared the clinical outcome–in terms of total mortality and cardiovascular morbidity–with a population matched by sex and age. To explore whether electrocardiographic features have a prognostic significance among healthy PVC-patients, we identified 541 patients to which we had access to PVC recording on 12-lead ECG and analysed PVC morphology and QRS width. For the studies focusing on diagnostic evaluation through advanced cardiac imaging, we included patients with a PVC burden of at least 10,000 beats/day and with normal results at exercise test and echocardiography. They underwent additional investigation with CMR (study 2) or advanced echocardiographic parameters that are normally not included in clinical praxis (study 3). Results: Healthy PVC-patients had a generally favourable prognosis, showing no worse clinical outcome than the sex- and age-matched control group that had not undergone investigation to rule out heart disease. However, patients with high PVC-burden showed signs of myocardial dysfunction when advanced imaging techniques were used, despite normal results at standard investigation that included echocardiogram. Sub-group analysis based on PVC-morphology showed that PVC originating from the outflow tract and the right ventricle was associated with a more favourable prognosis than intra cavity- and left ventricular PVCs respectively. Analysis of PVC-duration– measured as QRS-width during PVC–showed no impact on clinical outcome. Conclusions: PVC patients who had undergone a thorough medical examination with normal results did not have a worse outcome than matched controls during a median follow-up time of 5.2 years. PVC duration did not seem to be associated with the clinical outcome in our study including 541 patients with different sites of origin. However, PVCs with a morphology originating from the outflow tract and the right ventricle were associated with a better outcome. CMR and comprehensive advanced echocardiography could identify signs of myocardial dysfunction in patients with high PVC burden and normal findings at standard echocardiography. The clinical significance of these imaging findings needs to be assessed by larger longitudinal studies

Innovations and mechanisms in pacing therapy for heart failure

Despite pharmacological advances, heart failure remains a major cause of mortality and morbidity. Pacing therapy for heart failure was achieved in the 1990s with the advent of biventricular pacing (BVP). BVP shortens ventricular activation time and has thus been referred to as ‘cardiac resynchronization therapy’ (CRT). However BVP has other effects including shortening of atrioventricular delay: the contributions of its effects to its overall benefit have yet to be elucidated. Ventricular activation is not normalised by BVP, indicating scope for more effective resynchronization. This thesis explores mechanisms and innovations in pacing therapy for heart failure through measurement of haemodynamic and electrical parameters with high precision and resolution during BVP, right ventricular pacing (RVP) and His bundle pacing (HBP), where the His-Purkinje conduction system is directly stimulated. HBP offers both an innovation in pacing and a model to study conventional pacing. HBP can deliver physiological CRT by overcoming left bundle branch block (LBBB) to normalise QRS appearances but its performance relative to BVP is not known. When performed proximally, or using lower energy, HBP can preserve intrinsic LBBB. In Chapter 3, the electro-mechanical effects of conventional BVP are compared with LBBB correction by HBP. Chapter 4 uses non-invasive electrical mapping to identify mechanisms and predictors of LBBB correction by HBP, comparing it with narrow QRS. Capture of the His bundle can be alone (selective HBP) or alongside myocardial capture (non-selective): the effect of this on HBP is studied in Chapter 5. In Chapter 6, the haemodynamic effects of proximal/low-energy HBP, where LBBB is preserved but atrioventricular timing can be optimised, is compared to BVP and RVP to measure the contribution of atrioventricular delay shortening to the overall benefit of BVP. By evaluating innovative therapies and improving our understanding of existing therapies, hopefully this thesis will advance pacing therapy for heart failure.Open Acces

Implantable cardioverter defibrillators for the treatment of arrhythmias and cardiac resynchronisation therapy for the treatment of heart failure: systematic review and economic evaluation

Background This assessment updates and expands on two previous technology assessments that evaluated implantable cardioverter defibrillators (ICDs) for arrhythmias and cardiac resynchronisation therapy (CRT) for heart failure (HF). Objectives To assess the clinical effectiveness and cost-effectiveness of ICDs in addition to optimal pharmacological therapy (OPT) for people at increased risk of sudden cardiac death (SCD) as a result of ventricular arrhythmias despite receiving OPT; to assess CRT with or without a defibrillator (CRT-D or CRT-P) in addition to OPT for people with HF as a result of left ventricular systolic dysfunction (LVSD) and cardiac dyssynchrony despite receiving OPT; and to assess CRT-D in addition to OPT for people with both conditions. Data sources Electronic resources including MEDLINE, EMBASE and The Cochrane Library were searched from inception to November 2012. Additional studies were sought from reference lists, clinical experts and manufacturers’ submissions to the National Institute for Health and Care Excellence. Review methods Inclusion criteria were applied by two reviewers independently. Data extraction and quality assessment were undertaken by one reviewer and checked by a second. Data were synthesised through narrative review and meta-analyses. For the three populations above, randomised controlled trials (RCTs) comparing (1) ICD with standard therapy, (2) CRT-P or CRT-D with each other or with OPT and (3) CRT-D with OPT, CRT-P or ICD were eligible. Outcomes included mortality, adverse events and quality of life. A previously developed Markov model was adapted to estimate the cost-effectiveness of OPT, ICDs, CRT-P and CRT-D in the three populations by simulating disease progression calculated at 4-weekly cycles over a lifetime horizon. Results A total of 4556 references were identified, of which 26 RCTs were included in the review: 13 compared ICD with medical therapy, four compared CRT-P/CRT-D with OPT and nine compared CRT-D with ICD. ICDs reduced all-cause mortality in people at increased risk of SCD, defined in trials as those with previous ventricular arrhythmias/cardiac arrest, myocardial infarction (MI) > 3 weeks previously, non-ischaemic cardiomyopathy (depending on data included) or ischaemic/non-ischaemic HF and left ventricular ejection fraction ≤ 35%. There was no benefit in people scheduled for coronary artery bypass graft. A reduction in SCD but not all-cause mortality was found in people with recent MI. Incremental cost-effectiveness ratios (ICERs) ranged from £14,231 per quality-adjusted life-year (QALY) to £29,756 per QALY for the scenarios modelled. CRT-P and CRT-D reduced mortality and HF hospitalisations, and improved other outcomes, in people with HF as a result of LVSD and cardiac dyssynchrony when compared with OPT. The rate of SCD was lower with CRT-D than with CRT-P but other outcomes were similar. CRT-P and CRT-D compared with OPT produced ICERs of £27,584 per QALY and £27,899 per QALY respectively. The ICER for CRT-D compared with CRT-P was £28,420 per QALY. In people with both conditions, CRT-D reduced the risk of all-cause mortality and HF hospitalisation, and improved other outcomes, compared with ICDs. Complications were more common with CRT-D. Initial management with OPT alone was most cost-effective (ICER £2824 per QALY compared with ICD) when health-related quality of life was kept constant over time. Costs and QALYs for CRT-D and CRT-P were similar. The ICER for CRT-D compared with ICD was £27,195 per QALY and that for CRT-D compared with OPT was £35,193 per QALY. Limitations Limitations of the model include the structural assumptions made about disease progression and treatment provision, the extrapolation of trial survival estimates over time and the assumptions made around parameter values when evidence was not available for specific patient groups. Conclusions In people at risk of SCD as a result of ventricular arrhythmias and in those with HF as a result of LVSD and cardiac dyssynchrony, the interventions modelled produced ICERs of < £30,000 per QALY gained. In people with both conditions, the ICER for CRT-D compared with ICD, but not CRT-D compared with OPT, was < £30,000 per QALY, and the costs and QALYs for CRT-D and CRT-P were similar. A RCT comparing CRT-D and CRT-P in people with HF as a result of LVSD and cardiac dyssynchrony is required, for both those with and those without an ICD indication. A RCT is also needed into the benefits of ICD in non-ischaemic cardiomyopathy in the absence of dyssynchrony. Study registration This study is registered as PROSPERO number CRD42012002062. Funding The National Institute for Health Research Health Technology Assessment programme

Assessment of Hypertension Using Clinical Electrocardiogram Features: A First-Ever Review

Hypertension affects an estimated 1.4 billion people and is a major cause of morbidity and mortality worldwide. Early diagnosis and intervention can potentially decrease cardiovascular events later in life. However, blood pressure (BP) measurements take time and require training for health care professionals. The measurements are also inconvenient for patients to access, numerous daily variables affect BP values, and only a few BP readings can be collected per session. This leads to an unmet need for an accurate, 24-h continuous, and portable BP measurement system. Electrocardiograms (ECGs) have been considered as an alternative way to measure BP and may meet this need. This review summarizes the literature published from January 1, 2010, to January 1, 2020, on the use of only ECG wave morphology to monitor BP or identify hypertension. From 35 articles analyzed (9 of those with no listed comorbidities and confounders), the P wave, QTc intervals and TpTe intervals may be promising for this purpose. Unfortunately, with the limited number of articles and the variety of participant populations, we are unable to make conclusions about the effectiveness of ECG-only BP monitoring. We provide 13 recommendations for future ECG-only BP monitoring studies and highlight the limited findings in pregnant and pediatric populations. With the advent of convenient and portable ECG signal recording in smart devices and wearables such as watches, understanding how to apply ECG-only findings to identify hypertension early is crucial to improving health outcomes worldwide

ECG measurement parameters of athletes are reliable when made with a smartphone based ECG device

Pre-participation cardiac screening including electrocardiogram (ECG) is a subject of controversy among sports medicine practitioners. Opponents of pre-participation ECG screen site concerns regarding the cost and accuracy of the testing. Recently, a single lead ECG accessory has become available for use with smartphones. The purpose of this study was to evaluate the between and within rater validity and reliability of the Kardia device in recording the ECG parameters rate, rhythm, and PR, QRS, and QT intervals. The ECG parameter made with the smartphone were also compared to same measures made using a 12 lead electrocardiograph. This investigation used a repeated measures cross-sectional design. The investigation was conducted in 2 separate phases using separate participant samples. Phase 1 (N=10) was used to determine the within rater reliability with the Kardia device. Phase 2 (N=12) was used to determine the reliability between the Kardia device and the 12 lead electrocardiograph. The between rater and between device reliability for the rate, QT interval and QRS duration parameters ranged good to very good (ICC = 0.667 – 0.981). The current investigation showed that the reliability of the ECG parameters measured using the smartphone technology ranged from good to very good. This paper serves as support for a technological advancement that will help advance the debate on the utility of ECG testing as part of the athletic pre-participation physical

Evaluation of depolarization changes during acute myocardial ischemia by analysis of QRS slopes.

OBJECTIVE: This study evaluates depolarization changes in acute myocardial ischemia by analysis of QRS slopes. METHODS: In 38 patients undergoing elective percutaneous coronary intervention, changes in upward slope between Q and R waves and downward slope between R and S waves (DS) were analyzed. In leads V1 to V3, upward slope of the S wave was additionally analyzed. Ischemia was quantified by myocardial scintigraphy. Also, conventional QRS and ST measures were determined. RESULTS: QRS slope changes correlated significantly with ischemia (for DS: r = 0.71, P < .0001 for extent, and r = 0.73, P < .0001 for severity). Best corresponding correlation for conventional electrocardiogram parameters was the sum of R-wave amplitude change (r = 0.63, P < .0001; r = 0.60, P < .0001) and the sum of ST-segment elevation (r = 0.67, P < .0001; r = 0.73, P < .0001). Prediction of extent and severity of ischemia increased by 12.2% and 7.1% by adding DS to ST. CONCLUSIONS: The downward slope between R and S waves correlates with ischemia and could have potential value in risk stratification in acute ischemia in addition to ST-T analysis