Jessica Webb

Comparative efficacy testing — Fractional flow reserve by coronary computed tomography for the evaluation of patients with stable chest pain

BACKGROUND To evaluate diagnostic strategies in a rapid access chest pain clinic (RACPC) in the United Kingdom and to predict the economical and clinical impacts of incorporating fractional flow reserve by coronary computed tomographic angiography (FFRCT) into future pathways. METHODS A retrospective analysis of consecutive patients referred to a RACPC in the United Kingdom. All patients had an evaluation of cardiovascular risk factors and symptoms from which the pre-test likelihood (PTL) of coronary artery disease (CAD) was evaluated using the Diamond Forrester (DF) criteria. All investigative strategies and their results were recorded. For the FFRCT economic evaluation of 1000 patients, standard National Health Service Tariffs were then applied and compared with a strategy that utilised FFRCT for varying PTL categories. RESULTS There were 410 patients with a median age of 57 (31-85) years. The DF criteria classified 39 (9.5%) patients as having a PTL of <10%, 76 (18.5%) 10-29% PTL, 117 (28.5%) 30-60% PTL, 114 (27.8%) 60-90% PTL and 64 (15.6%) >90% PTL. The concordance with the NICE recommended guidelines was <50% with the prevalence of obstructive CAD being <5% in patients with a PTL <90%. A model utilising FFRCT for patients with a PTL 10-90% predicted a 48% and 49% reduction in invasive angiography and percutaneous coronary intervention, a saving of £200 per patient and a reduction in relative adverse event rates of 4%. CONCLUSIONS The DF algorithm overestimates the PTL of CAD supporting an extended role for coronary CTA. Strategies incorporating FFRCT may confer benefits in evaluating patients with stable chest pain.

Peer mentoring for core medical trainees: uptake and impact

Objective To assess the uptake and impact of a peer mentoring scheme for core medical trainees on both mentors and mentees. Method All second year core medical trainees in the Southwest London Training programme in September 2012 were invited to mentor a first year core medical trainee. In parallel, all first year core medical trainees were invited to be mentored. Both potential mentors and mentees were asked to submit personal statements, to attend a three-session mentoring training programme and to be matched into mentoring pairs. The impact of the mentoring scheme on trainees’ behaviour and outlook was assessed through questionnaires distributed at the start and at the end of the year. Results 31 of 72 (43%) core medical trainees submitted personal statements and 40 of 72 (56%) attended training sessions. 42 trainees (58%) participated in the scheme (21 mentor/mentee pairs were established). Of the trainees who participated, 23 of 42 (55%) completed the end of year questionnaire. Participating trainees viewed the scheme positively. Reported benefits included changes in their behaviour and acquiring transferable skills that might help them in later career roles, such as an educational supervisor. The end of year questionnaire was sent to all trainees and 10 responded who had not participated. They were asked why they had not participated and their reasons included lack of time, lack of inclination and a desire for more senior mentors. Their suggestions for improvement included more structured sessions to allow the mentor/mentee pairs to meet. Conclusions This simple peer mentoring scheme was popular despite busy workloads and benefited all concerned. It is a simple effective way of supporting doctors. More work is needed to improve training for mentors and to improve access to mentoring.

Autonomic Modulation in Patients with Heart Failure Increases Beat-to-Beat Variability of Ventricular Action Potential Duration

Background: Exaggerated beat-to-beat variability of ventricular action potential duration (APD) is linked to arrhythmogenesis. Sympathetic stimulation has been shown to increase QT interval variability, but its effect on ventricular APD in humans has not been determined. Methods and Results: Eleven heart failure patients with implanted bi-ventricular pacing devices had activation–recovery intervals (ARI, surrogate for APD) recorded from LV epicardial electrodes under constant RV pacing. Sympathetic activity was increased using a standard autonomic challenge (Valsalva) and baroreceptor indices were applied to determine changes in sympathetic stimulation. Two Valsalvas were performed for each study and were repeated, both off and on bisoprolol. In addition sympathetic nerve activity (SNA) was measured from skin electrodes on the thorax using a novel validated method. Autonomic modulation significantly increased mean short-term variability in ARI; off bisoprolol mean STV increased from 3.73 ± 1.3 to 5.27 ± 1.04 ms (p = 0.01), on bisoprolol mean STV of ARI increased from 4.15 ± 1.14 to 4.62 ± 1 ms (p = 0.14). Adrenergic indices of the Valsalva demonstrated significantly reduced beta-adrenergic function when on bisoprolol (Δ pressure recovery time, p = 0.04; Δ systolic overshoot in Phase IV, p = 0.05). Corresponding increases in SNA from rest both off (1.4 uV, p < 0.01) and on (0.7 uV, p < 0.01) bisoprolol were also seen. Conclusions: Beat-to-beat variability of ventricular APD increases during brief periods of increased sympathetic activity in patients with heart failure. Bisoprolol reduces, but does not eliminate, these effects. This may be important in the genesis of ventricular arrhythmias in heart failure patients.

The role of multi modality imaging in selecting patients and guiding lead placement for the delivery of cardiac resynchronization therapy

ABSTRACT Introduction: Cardiac resynchronization therapy (CRT) is an effective pacemaker delivered treatment for selected patients with heart failure with the target of restoring electro-mechanical synchrony. Imaging techniques using echocardiography have as yet failed to find a metric of dyssynchrony to predict CRT response. Current guidelines are thus unchanged in recommending prolonged QRS duration, severe systolic function and refractory heart failure symptoms as criteria for CRT implantation. Evolving strain imaging techniques in 3D echocardiography, cardiac MRI and CT may however, overcome limitations of older methods and yield more powerful CRT response predictors. Areas covered: In this review, we firstly discuss the use of multi modality cardiac imaging in the selection of patients for CRT implantation and predicting the response to CRT. Secondly we examine the clinical evidence on avoiding areas of myocardial scar, targeting areas of dyssynchrony and in doing so, achieving the optimal positioning of the left ventricular lead to deliver CRT. Finally, we present the latest clinical studies which are integrating both clinical and imaging data with X-rays during the implantation in order to improve the accuracy of LV lead placement. Expert commentary: Image integration and fusion of datasets with live X-Ray angiography to guide procedures in real time is now a reality for some implanting centers. Such hybrid facilities will enable users to interact with images, allowing measurement, annotation and manipulation with instantaneous visualization on the catheter laboratory monitor. Such advances will serve as an invaluable adjunct for implanting physicians to accurately deliver pacemaker leads into the optimal position to deliver CRT.

Effects of Epicardial and Endocardial Cardiac Resynchronization Therapy on Coronary Flow: Insights From Wave Intensity Analysis.

Background The increase in global coronary flow seen with conventional biventricular pacing is mediated by an increase in the dominant backward expansion wave (BEW). Little is known about the determinants of flow in the left‐sided epicardial coronary arteries beyond this or the effect of endocardial pacing stimulation on coronary physiology. Methods and Results Eleven patients with a chronically implanted biventricular pacemaker underwent an acute hemodynamic and electrophysiological study. Five of 11 patients also took part in a left ventricular endocardial pacing protocol at the same time. Conventional biventricular pacing, delivered epicardially from the coronary sinus, resulted in a 9% increase in flow (average peak velocity) in the left anterior descending artery (LAD), mediated by a 13% increase in the area under the BEW (P=0.004). Endocardial pacing resulted in a 27% increase in LAD flow, mediated by a 112% increase in the area under the forward compression wave (FCW) and a 43% increase in the area under the BEW (P=0.048 and P=0.036, respectively). There were no significant changes in circumflex parameters. Conventional biventricular pacing resulted in homogenization of timing of coronary flow compared with baseline (mean difference in time to peak in the LAD versus circumflex artery: FCW 39 ms [baseline] versus 3 ms [conventional biventricular pacing], P=0.008; BEW 47 ms [baseline] versus 8 ms [conventional biventricular pacing], P=0.004). Conclusions Epicardial and endocardial pacing result in increased coronary flow in the left anterior descending artery and homogenization of the timing of waves that determine flow in the LAD and the circumflex artery. The increase in both the FCW and the BEW with endocardial pacing may be the result of a more physiological activation pattern than that of epicardial pacing, which resulted in an increase of only the BEW.

Cost-effectiveness of a risk-stratified approach to cardiac resynchronisation therapy defibrillators (high versus low) at the time of generator change

Objective Responders to cardiac resynchronisation therapy whose device has a defibrillator component and who do not receive a therapy in the lifetime of the first generator have a very low incidence of appropriate therapy after box change. We investigated the cost implications of using a risk stratification tool at the time of generator change resulting in these patients being reimplanted with a resynchronisation pacemaker. Methods A decision tree was created using previously published data which had demonstrated an annualised appropriate defibrillator therapy risk of 2.33%. Costs were calculated at National Health Service (NHS) national tariff rates (2016–2017). EQ-5D utility values were applied to device reimplantations, admissions and mortality data, which were then used to estimate quality-adjusted life-years (QALYs) over 5 years. Results At 5 years, the incremental cost of replacing a resynchronisation defibrillator device with a second resynchronisation defibrillator versus resynchronisation pacemaker was £5045 per patient. Incremental QALY gained was 0.0165 (defibrillator vs pacemaker), resulting in an incremental cost-effectiveness ratio (ICER) of £305 712 per QALYs gained. Probabilistic sensitivity analysis resulted in an ICER of £313 612 (defibrillator vs pacemaker). For reimplantation of all patients with a defibrillator rather than a pacemaker to yield an ICER of less than £30 000 per QALY gained (current NHS cut-off for approval of treatment), the annual arrhythmic event rate would need to be 9.3%. The budget impact of selective replacement was a saving of £2 133 985 per year. Conclusions Implanting low-risk patients with a resynchronisation defibrillator with the same device at the time of generator change is not cost-effective by current NHS criteria. Further research is required to understand the impact of these findings on individual patients at the time of generator change.

Updates in Cardiac Resynchronization Therapy for Chronic Heart Failure: Review of Multisite Pacing

Purpose of ReviewCardiac resynchronization therapy (CRT) reduces the morbidity and mortality of patients with left ventricular (LV) systolic dysfunction and intra-ventricular conduction delay. However, its clinical outcomes are heterogeneous and not all patients show a beneficial response. Multisite pacing (MSP), by stimulating the myocardium from more than one locations, is a potential therapeutic option in patients requiring CRT. This article provides a current update in the methods and outcomes of MSP, as well as in challenges in this field and opportunities for further research and development.Recent FindingsMSP can be delivered either with multiple leads or with quadripolar LV leads which can stimulate the LV from two separate sites. Initial results are promising but not always consistent across studies. Larger patient subgroups and longer follow-up duration are required for more conclusive evaluation of MSP.SummaryRoutine use of MSP in clinical practice cannot be advocated at present. In selected patient subgroups, however, MSP could be considered. Newer devices and expanding knowledge are expected to facilitate the more widespread implementation of MSP and the assessment of its effects in the clinical outcomes of CRT.

Narrow QRS systolic heart failure: is there a target for cardiac resynchronization?

Cardiac resynchronization therapy has revolutionized the management of systolic heart failure in patients with prolonged QRS during the past 20 years. Initially, the use of this treatment in patients with shorter QRS durations showed promising results, which have since been opposed by larger randomized controlled trials. Despite this, some questions remain, such as, whether correction of mechanical dyssynchrony is the therapeutic target by which biventricular pacing may confer benefit in this group, or are there other mechanisms that need consideration? In addition, novel techniques of cardiac resynchronization therapy delivery such as endocardial and multisite pacing may reduce potential detrimental effects of biventricular pacing, thereby improving the benefit/harm balance of this therapy in some patients.

Phoning the patient’s general practitioner

Jessica Webb and David Ward investigated how long it takes for hospital doctors to speak to patients’ general practitioners by telephone

Predictors and outcomes of patients requiring repeat transvenous lead extraction of pacemaker and defibrillator leads

A proportion of patients who undergo an initial lead extraction procedure will require a second, repeat extraction. Data regarding this clinical entity are scarce and neither the predisposing risk factors for, nor outcomes from, these procedures have been described previously. We sought to determine the incidence, risk factors, and outcomes of repeat lead extraction.