Targeted left ventricular lead positioning to the site of latest activation in cardiac resynchronization therapy: a systematic review and meta-analysis.

AIMS: Several studies have evaluated the use of electrically- or imaging-guided left ventricular (LV) lead placement in cardiac resynchronization therapy (CRT) recipients. We aimed to assess evidence for a guided strategy that targets LV lead position to the site of latest LV activation. METHODS AND RESULTS: A systematic review and meta-analysis was performed for randomized controlled trials (RCTs) until March 2023 that evaluated electrically- or imaging-guided LV lead positioning on clinical and echocardiographic outcomes. The primary endpoint was a composite of all-cause mortality and heart failure hospitalization, and secondary endpoints were quality of life, 6-min walk test (6MWT), QRS duration, LV end-systolic volume, and LV ejection fraction. We included eight RCTs that comprised 1323 patients. Six RCTs compared guided strategy (n = 638) to routine (n = 468), and two RCTs compared different guiding strategies head-to-head: electrically- (n = 111) vs. imaging-guided (n = 106). Compared to routine, a guided strategy did not significantly reduce the risk of the primary endpoint after 12-24 (RR 0.83, 95% CI 0.52-1.33) months. A guided strategy was associated with slight improvement in 6MWT distance after 6 months of follow-up of absolute 18 (95% CI 6-30) m between groups, but not in remaining secondary endpoints. None of the secondary endpoints differed between the guided strategies. CONCLUSION: In this study, a CRT implantation strategy that targets the latest LV activation did not improve survival or reduce heart failure hospitalizations.

Magnetic resonance imaging in patients with temporary external pacemakers.

AIMS: To describe safety and feasibility of magnetic resonance imaging (MRI) in patients with transvenous temporary external pacemakers and whether artefacts affect the diagnostic image quality during cardiac MRI. METHODS AND RESULTS: We reviewed records of all patients treated with temporary external pacing between 2016 and 2020 at a tertiary centre. Temporary pacing was established using a transvenous standard active fixation pacing lead inserted percutaneously and connected to a MRI-conditional pacemaker taped to the skin. All patients undergoing cardiac or non-cardiac MRI during temporary transvenous pacing were identified. Before MRI, devices were programmed according to guidelines for permanent pacemakers, and patients were monitored with continuous electrocardiogram during MRI. Of 827 consecutive patients receiving a temporary external pacemaker, a total of 44 (5%) patients underwent MRI (mean age 71 years, 13 [30%] females). Cardiac MRI was performed in 22 (50%) patients, while MRI of cerebrum, spine, and other regions was performed in the remaining patients. Median time from implantation of the temporary device to MRI was 6 (3-11) days. During MRI, we observed no device-related malfunction or arrhythmia. Nor did we detect any change in lead sensing, impedance, or pacing threshold. We observed no artefacts from the lead or pacemaker compromising the diagnostic image quality of cardiac MRI. MRI provided information to guide the clinical management in all cases. CONCLUSION: MRI is feasible and safe in patients with temporary external pacing established with a regular MRI-conditional pacemaker and a standard active fixation lead. No artefacts compromised the diagnostic image quality.

Cardiac computed tomography-verified right ventricular lead position and outcomes in cardiac resynchronization therapy.

PURPOSE: To evaluate the association between different right ventricular (RV) lead positions as assessed by cardiac computed tomography (CT) and echocardiographic and clinical outcomes in patients receiving cardiac resynchronization therapy (CRT). METHODS: We reviewed patient records of all 278 patients included in two randomized controlled trials (ImagingCRT and ElectroCRT) for occurrence of heart failure (HF) hospitalization or all-cause death (primary endpoint) during long-term follow-up. Outcomes were compared between RV lead positions using adjusted Cox regression analysis. Six months after CRT implantation, we estimated left ventricular (LV) reverse remodeling by measuring LV end-systolic and end-diastolic volumes by echocardiography. Changes from baseline to 6 months follow-up were compared between RV lead positions. Device-related complications were recorded at 6-month follow-up. RESULTS: During median (interquartile range) follow-up of 4.7 (2.9-7.1) years, the risk of meeting the primary endpoint was similar for patients with non-apical vs. apical RV lead position (adjusted hazard ratio (HR) 0.78, 95% confidence interval (CI) 0.54-1.12, p = 0.17) and free wall vs. septal RV lead position (adjusted HR 1.03, 95% CI 0.72-1.47, p = 0.86). Changes in LV ejection fraction and dimensions were similar with the different RV lead positions. We observed no differences in device-related complications relative to the RV lead position. CONCLUSIONS: In patients receiving CRT, the risk of HF hospitalization or all-cause death during long-term follow-up, and LV remodeling and incidence of device-related complications after 6 months are not associated with different anatomical RV lead position as assessed by cardiac CT.

Long-term outcomes in a randomized controlled trial of multimodality imaging-guided left ventricular lead placement in cardiac resynchronization therapy.

AIMS: This study aims to investigate the long-term occurrence of the composite endpoint of heart failure (HF) hospitalization or all-cause death (primary endpoint) in patients randomized to cardiac resynchronization therapy (CRT) using individualized multimodality imaging-guided left ventricular (LV) lead placement compared with a routine fluoroscopic approach. Furthermore, this study aims to evaluate whether inter-lead electrical delay (IED) is associated with improved response rate of this endpoint. METHODS AND RESULTS: We reviewed follow-up data until November 2020 for all 182 patients included in the ImagingCRT trial for the occurrence of HF hospitalization and all-cause death. During median (inter-quartile range) time to primary endpoint/censuring of 6.7 (3.3-7.9) years, the rate of the primary endpoint was 60% (n = 53) in the imaging group compared with 52% (n = 48) in the control group [hazard ratio (HR) 1.22, 95% confidence interval (CI) 0.83-1.81, P = 0.31]. Neither the risk of HF hospitalization (HR 1.11, 95% CI 0.62-1.99, P = 0.72) nor of all-cause death differed between treatment groups (HR 1.23, 95% CI 0.82-1.85, P = 0.32). The risk of the primary endpoint was significantly reduced among those with IED ≥100 ms when compared with those with IED <100 ms (HR 0.62, 95% CI 0.39-0.98, P = 0.04). CONCLUSIONS: In this study, an individualized multimodality imaging-guided strategy targeting LV lead placement towards the latest mechanically activated non-scarred myocardial segment during CRT implantation did not reduce HF hospitalization or all-cause death when compared with routine LV lead placement during long-term follow-up. Targeting the latest electrical activation should be studied as an alternative individualized strategy for optimizing LV lead placement in CRT recipients.

Bipolar versus quadripolar left ventricular leads for cardiac resynchronization therapy: evidence to date.

INTRODUCTION: In cardiac resynchronization therapy (CRT) devices, transvenous left ventricular (LV) leads are more prone to instability, high pacing thresholds, and phrenic nerve stimulation (PNS) that may necessitate lead revision, replacement in a suboptimal position, or deactivation of the lead. To overcome some of these challenges, quadripolar (QP) LV leads have been developed and accounted for over 90% of implanted LV leads 5 years after they were introduced. AREAS COVERED: This review provides an overview of the current evidence of implanting QP leads in CRT as compared with traditional bipolar (BP) leads including details about feasibility, safety and lead performance, clinical outcomes and cost-effectiveness. EXPERT OPINION: Based on the current literature, implantation with a QP lead decreases revision rates but does not affect any clinical outcomes including mortality, hospitalization, symptoms, or echocardiographic parameters. Feasibility and stability do not differ between QP and BP leads. A QP lead should be preferred as first choice over a BP lead due to lower rates of PNS and lower pacing thresholds leading to less frequent lead revisions and battery replacements. In addition, this strategy may be cost saving despite a higher price of QP leads.

New-onset asthma in a bilateral lung transplant patient.

We present a case of new-onset asthma in a 35-year-old man who had undergone bilateral lung transplantation 11 years before due to idiopathic bronchiectasis and pulmonary hypertension. He presented with recurrent episodes of breathlessness, wheezing and coughing. Spirometry demonstrated severe airway obstruction. After treatment with systemic and inhaled corticosteroids and long-acting bronchodilators as well as short-acting beta-agonists as needed, his symptoms resolved and his spirometry normalised. A bronchial mannitol challenge test showed significant airway hyperresponsiveness and is thus consistent for a diagnosis of asthma. To our best knowledge, this is the first case of late new-onset asthma in a lung transplant recipient.

Electrically vs. imaging-guided left ventricular lead placement in cardiac resynchronization therapy: a randomized controlled trial.

AIMS: To test in a double-blinded, randomized trial whether the combination of electrically guided left ventricular (LV) lead placement and post-implant interventricular pacing delay (VVd) optimization results in superior increase in LV ejection fraction (LVEF) in cardiac resynchronization therapy (CRT) recipients. METHODS AND RESULTS: Stratified according to presence of ischaemic heart disease, 122 patients were randomized 1:1 to LV lead placement targeted towards the latest electrically activated segment identified by systematic mapping of the coronary sinus tributaries during CRT implantation combined with post-implant VVd optimization (intervention group) or imaging-guided LV lead implantation by cardiac computed tomography venography, 82Rubidium myocardial perfusion imaging and speckle tracking echocardiography targeting the LV lead towards the latest mechanically activated non-scarred myocardial segment (control group). Follow-up was 6 months. Primary endpoint was absolute increase in LVEF. Additional outcome measures were changes in New York Heart Association class, 6-minute walk test, and quality of life, LV reverse remodelling, and device related complications. Analysis was intention-to-treat. A larger increase in LVEF was observed in the intervention group (11 ± 10 vs. 7 ± 11%; 95% confidence interval 0.4-7.9%, P = 0.03); when adjusting for pre-specified baseline covariates this difference did not maintain statistical significance (P = 0.09). Clinical response, LV reverse remodelling, and complication rates did not differ between treatment groups. CONCLUSION: Electrically guided CRT implantation appeared non-inferior to an imaging-guided strategy considering the outcomes of change in LVEF, LV reverse remodelling and clinical response. Larger long-term studies are warranted to investigate the effect of an electrically guided CRT strategy.

Transmural Myocardial Scar Assessed by Cardiac Computed Tomography: Predictor of Echocardiographic Versus Clinical Response to Cardiac Resynchronization Therapy?

OBJECTIVES: Before cardiac resynchronization therapy (CRT) implantation, cardiac computed tomography (CT) can provide assessment of cardiac venous anatomy and visualize left ventricular (LV) myocardial scar. We hypothesized that localization and burden of transmural myocardial scar verified by cardiac CT are associated with echocardiographic and clinical response to CRT. METHODS: We prospectively included 140 CRT recipients undergoing preimplant cardiac CT. We assessed transmural scar, defined as hypoperfusion involving more than one-half of the myocardial wall in each LV segment using a 17-segment model. Echocardiographic nonresponse was defined as less than 5% absolute improvement in LV ejection fraction at 6 months' follow-up. Clinical nonresponse was defined as 1 or more of the following at 6 months' follow-up: death, heart failure hospitalization, or no improvement in New York Heart Association class and less than 10% increase in 6-minute walk-test distance. RESULTS: Higher burden of myocardial scar was associated with echocardiographic nonresponse (adjusted odds ratio, 3.02; 95% confidence interval, 1.03-8.91; P = 0.045). Scar concordant or adjacent to LV pacing site was associated with echocardiographic nonresponse (adjusted odds ratio, 8.2; 95% confidence interval, 1.51-44.27; P = 0.015). No association between scar and clinical nonresponse was demonstrated. CONCLUSIONS: Higher scar burden and scar in proximity to the LV pacing site assessed by cardiac CT are associated with echocardiographic nonresponse to CRT. Burden and location of scar were not associated with clinical nonresponse. Further large-scale studies are needed to assess the potential association between myocardial scar detected by cardiac CT and clinical CRT outcome.