Justin Gould

Comprehensive use of cardiac computed tomography to guide left ventricular lead placement in cardiac resynchronization therapy

Background Optimal lead positioning is an important determinant of cardiac resynchronization therapy (CRT) response. Objective The purpose of this study was to evaluate cardiac computed tomography (CT) selection of the optimal epicardial vein for left ventricular (LV) lead placement by targeting regions of late mechanical activation and avoiding myocardial scar. Methods Eighteen patients undergoing CRT upgrade with existing pacing systems underwent preimplant electrocardiogram-gated cardiac CT to assess wall thickness, hypoperfusion, late mechanical activation, and regions of myocardial scar by the derivation of the stretch quantifier for endocardial engraved zones (SQUEEZ) algorithm. Cardiac venous anatomy was mapped to individualized American Heart Association (AHA) bull’s-eye plots to identify the optimal venous target and compared with acute hemodynamic response (AHR) in each coronary venous target using an LV pressure wire. Results Fifteen data sets were evaluable. CT-SQUEEZ–derived targets produced a similar mean AHR compared with the best achievable AHR (20.4% ± 13.7% vs 24.9% ± 11.1%; P = .36). SQUEEZ-derived guidance produced a positive AHR in 92% of target segments, and pacing in a CT-SQUEEZ target vein produced a greater clinical response rate vs nontarget segments (90% vs 60%). Conclusion Preprocedural CT-SQUEEZ–derived target selection may be a valuable tool to predict the optimal venous site for LV lead placement in patients undergoing CRT upgrade.

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.

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.

Chronic Right Ventricular Pacing in the Heart Failure Population

Purpose of ReviewWe review the trials that have demonstrated potentially harmful effects from right ventricular (RV) apical pacing as well as reviewing the evidence of alternative RV pacing sites and cardiac resynchronization therapy (CRT) for patients who have heart failure and atrioventricular (AV) block.Recent FindingsThe role of CRT in patients with AV block and impaired left ventricular function remains an important consideration. The BLOCK HF trial demonstrated better outcomes with CRT pacing over RV pacing in patients with left ventricular systolic dysfunction (LVSD) and AV block who were expected to have a high RV pacing burden, but failed to demonstrate a mortality benefit.SummaryCRT seems to have a beneficial effect on left ventricular reverse remodeling, systolic function, and clinical outcomes in patients with New York Heart Association (NYHA) functional class I–III heart failure, moderate to severe LVSD, and AV block compared to RV pacing. However, it is less clear whether there is a similar benefit from CRT in patients with a high percentage of RV pacing who have normal or mild LVSD in the treatment of AV block.

Transseptal Delivery of a Leadless Left Ventricular Endocardial Pacing Electrode

A 79-year-old man with ischemic cardiomyopathy, left ventricular ejection fraction of 25%, an existing dual-chamber pacemaker (for complete heart blockage with >85% ventricular pacing), a broad QRS complex, and symptomatic heart failure was referred to our institution for cardiac resynchronization

The role of transvenous lead extraction in the management of redundant or malfunctioning pacemaker and defibrillator leads post ELECTRa

Cardiac implantable electronic devices implantation rates have increased over the past decade due to broader indications and an ageing population. Similarly, device and lead complications have also risen. The management of pacemaker/defibrillator leads that are no longer required (redundant) or malfunctioning, can be contentious. There is a need to balance the risk of transvenous lead extraction (TLE) against those of lead abandonment. The recently published European Lead Extraction ConTRolled Registry (ELECTRa) study provides contemporary outcomes for TLE across Europe with important implications for the management of redundant and/or malfunctioning leads. This review article discusses the potential complications for each interventional approach when managing redundant or malfunctioning pacemaker leads.

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.

Non-invasive electrophysiological assessment of the optimal configuration of quadripolar lead vectors on ventricular activation times

BACKGROUND Cardiac resynchronization therapy (CRT) is now generally delivered via quadripolar leads. Assessment of the effect of different vector programs from quadripolar leads on ventricular activation can be now done using non-invasive electrocardiographic mapping (ECM). MATERIAL AND METHODS In nineteen patients with quadripolar LV leads, activation maps were constructed. The total ventricular activation time (TVaT) and the time for the bulk of ventricular activation (VaT10-90) were calculated. RESULTS CRT delivered via a quadripolar lead significantly reduced TVaT and VaT10-90 by a mean of 16 ms and 31 ms, respectively, compared to baseline. There was a marked reduction in ventricular activation between the most and least synchronous vectors: 28% difference in baseline TVaT and 37% difference in VaT10-90. CONCLUSION Changes in the configuration of an LV quadripolar lead significantly affected ventricular activation timings in both ischaemic and non-ischaemic subjects. This suggests that programming of the optimal pacing vector may need to be individually tailored.

Variation in activation time during bipolar vs extended bipolar left ventricular pacing: SIENIEWICZ et al.

Cardiac resynchronization therapy (CRT) is typically delivered via quadripolar leads that allow stimulation using either true bipolar pacing, where stimulation occurs between two electrodes (BP) on the quadripolar lead, or extended bipole (EBP) left ventricular (LV) pacing, with the quadripolar electrodes and right ventricular coil acting as the cathode and anode, respectively. True bipolar pacing is associated with reductions in mortality and it has been postulated that these differences are the result of enhanced electrical activation.

Is heart failure with mid range ejection fraction (HFmrEF) a distinct clinical entity or an overlap group

Background The new category of heart failure (HF), Heart Failure with mid range Ejection Fraction (HFmrEF) has recently been proposed with recent publications reporting that HFmrEF represents a transitional phase. The aim of this study was to determine the prevalence and clinical characteristics of patients with HFmrEF and to establish what proportion of patients transitioned to other types of HF, and how this affected clinical outcomes. Methods and results Patients were diagnosed with HF according to the 2016 ESC guidelines. Clinical outcomes and variables were recorded for all consecutive in-patients referred to the heart failure service. In total, 677 patients with new HF were identified; 25.6% with HFpEF, 21% with HFmrEF and 53.5% with HFrEF. While clinical characteristics and prognostic factors of HFmrEF were intermediate between HFrEF and HFpEF, HFmrEF patients had the best outcome, with higher mortality in the HFrEF population (p 0.02) and higher HF rehospitalisation rates in the HFpEF population (p < 0.01). 38.7% of the HFmrEF patients transitioned (56.4% to HFpEF and 43.6% to HFrEF) with fewest deaths in the patients that transitioned to HFpEF (p 0.04), and fewest HF readmissions in the patients that remained as HFmrEF (<0.01) Conclusion HFmrEF patients had the best outcomes, compared to high rates of mortality seen in patients with HFrEF and high rates of HF readmissions seen in patients with HFpEF. Only 1/3 of HFmrEF patients transitioned during follow up, with the lowest mortality seen in patients transitioning to HFpEF.