Conduction system pacing in difficult cardiac anatomies: Systematic approach with the 3D electroanatomic mapping guide.

INTRODUCTION: Restoring physiological cardiac electrical activity in patients with conduction disease can be crucial for the survival and quality of life. Conduction system pacing (CSP) is a valuable option, although it is limited by technical challenges in difficult anatomies. 3D electroanatomical mapping (3D-EAM) can support CSP ensuring high electro-anatomical precision and low fluoroscopy. OBJECTIVES: We evaluated the feasibility and effectiveness of a systematic 3D-EAM use to guide CSP in difficult anatomical scenarios (highly dilated atria, congenital cardiomyopathies, failed biventricular implants (BiV) and pacing-induced cardiomyopathy (PICM)). METHODS: Forty-three consecutive patients (27 males, 75 ± 10 years old) with standard pacing indications and difficult anatomical scenarios were included. The right atrium, His cloud, and atrio-ventricular septum were reconstructed by 3D-EAM. The His bundle (HB) was the initial target, while left bundle branch area pacing (LBBAP) was aimed at in case of unsatisfactory parameters, sub-optimally paced QRS, or impossibility of reaching the HB. RESULTS: CSP was successful in 37 (86%) patients (15 HBP; 22 LBBAP). Mean mapping, fluoroscopy, and procedural times were 18 ± 7 min, 7 ± 5 min, 98 ± 47 min, respectively. The mean pacing threshold, R wave sensing, and pacing impedance of CSP lead were 1.2 ± 0.5V@0.5ms, 11.4 ± 6.2 mV, 736 ± 306 Ω, respectively. Baseline and paced QRS were 139 ± 38 ms and 114 ± 23 ms, respectively. No procedural complications were observed. CONCLUSIONS: 3D-EAM allowed the accurate definition of the His cloud and high ventricular septum and effectively guided CSP. It facilitated CSP in complex anatomies, with a procedural success rate of 86%. The results were satisfactory and reproducible, with acceptable fluoroscopy and procedural times.

Occurrence of persistent atrial fibrillation during pacing for sinus node disease: The influence of His bundle pacing versus managed ventricular pacing.

INTRODUCTION: In patients with sinus node disease (SND), the dual-chamber pacemaker (PM) is programmed in DDDR mode with an algorithm to avoid unnecessary right ventricular (RV) pacing. This pacing mode may prolong PR interval with consequently atrioventricular (AV) asynchrony which is associated with a higher risk of atrial fibrillation (AF). We evaluate whether preserving AV synchrony by setting a fixed AV delay during physiological RV pacing, that is, His bundle pacing (HBP), could reduce the risk of AF occurrence in comparison with a standard pacing mode with an algorithm to avoid unnecessary RV pacing (DDD-VPA). METHODS AND RESULTS: We collected retrospective data from 313 consecutive patients who had undergone PM for SND. The first occurrence of persistent AF (>7 consecutive days) as a function of the pacing mode was evaluated. HBP and DDD-VPA were implemented in 82 and 231 patients, respectively. Persistent AF occurred in 128 (40.9%) patients over a median follow-up of 70 months (67-105). The DDD-VPA pacing mode was significantly correlated with the occurrence of persistent AF only when the basal PR was long (>180 ms). The risk of persistent AF was significantly lower in patients on HBP than in those on DDD-VPA, adjusted HR = .57 (95% CI, .36- .89, p=.014). Other independent predictors of persistent AF occurrence were: A history of AF (HR = 3.91; 95% CI, 2.48-6.19, p = .001), age, and long PR interval (HR = 2.98; 95% CI, 2.00-4.43, p=.001). CONCLUSION: In SND patients and long basal PR interval, the HBP may reduce the risk of persistent AF in comparison with the DDD-VPA.

Electrogram-only guided approach to His bundle pacing with minimal fluoroscopy: A single-center experience.

INTRODUCTION: His bundle pacing (HBP) is the most physiological pacing. The standard technique based on fluoroscopic approach might be challenging and fluoro consuming. Targeting the His guided exclusively by the electrical signals could enable a precise lead implant, thus reducing fluoroscopy time (FT) and X-ray dose, desirable both for patients and operators. The aim of the study is to evaluate the feasibility, efficacy, and safety both acutely and at 30 days of the electrogram (EGM)-guided HBP with minimal or no fluoroscopy. METHODS AND RESULTS: Between October and December 2018, 41 consecutive patients underwent EGM-guided HBP. Successful HBP was obtained in 39 (95%) patients, (30 males, 78 ± 10 years). Selective HBP (S-HBP) was achieved in 23 (59%), nonselective HBP (NS-HBP) in 16 (41%) patients. The final HBP lead position was reached in 31 (79.4%) patients without fluoroscopy, only guided by electrical signals. In eight patients a minimal fluoroscopy (mean, 8 seconds) has been required. The sheath's cutting and the slack of the lead were routinely performed under fluoroscopy. No difference was observed in FT for HBP lead placement in S-HBP and NS-HBP (mean, 8.1 ± 25 vs 7.5 ± 20 seconds, P = .8; median value 0 vs 0 seconds). No differences were observed in FT for the entire procedure, total dose area product and total procedural time in S-HBP and NS-HBP. Lead dislodgement occurred in one (2.6%) patient 1 day after the procedure. CONCLUSIONS: HBP could be performed safely and efficiently using the EGMs, with minimal or no fluoroscopy. Fluoroscopy was required during sheath removal and atrial lead placement.

Long term performance and safety of His bundle pacing: A multicenter experience.

INTRODUCTION: Several single-center short-term studies have demonstrated the feasibility, safety, and positive clinical outcomes of permanent His bundle pacing (HBP). We performed a retrospective study to evaluate long-term technical and safety performances of HBP in a large population of pacemaker patients from two different centers. METHODS AND RESULTS: The analysis includes 844 patients (345 female, mean age = 75 ± 9 years) who underwent successful permanent HBP for pacemaker indications from 2004 to 2016. The main endpoints were long term electrical performances including pacing threshold, sensing, impedance, and freedom from pacing related complications. The pacing indication was AV Block in 348 (41.2%) patients, sinus node disease in 147 (17.4%), any bradycardia indication in patients with atrial fibrillation in 335 (39.7%) patients and need for cardiac resynchronization therapy in 14 (1.7%) patients. Mean pacing capture thresholds and sensed R waves were 1.6 V and 5.8 mV, respectively at implant and 2.0 V and 6.1 mV at chronic follow-up. During the median follow up of 3 years (interquartile range = 1-6 years), HBP was free of any complication in 91.6% of patients. In the first 368 patients, HBP was achieved using a deflectable curve delivery system, while in 476 using the fixed curve sheath. A significant difference was found in the thresholds (2.4 ± 1.0 V and 1.7 ± 1.1 V, P < .001, respectively) and complications (11.9% and 4.2%, P < .001, respectively) between the two groups. CONCLUSIONS: Permanent HBP was safe and effective during long-term follow-up. The fixed curved delivery sheath offered significantly better electrical parameters and reliability over time. The results of this multicenter study are consistent with recent studies.

Patients with right bundle branch block and concomitant delayed left ventricular activation respond to cardiac resynchronization therapy.

Aims: Right bundle branch block (RBBB) typically presents with only delayed right ventricular activation. However, some patients with RBBB develop concomitant delayed left ventricular (LV) activation. Such patients may show a specific electrocardiographic (ECG) pattern resembling RBBB in the precordial leads in association with an insignificant S-wave in lateral limb leads (atypical RBBB). We therefore postulated that the ECG pattern of atypical RBBB might be able to identify a subgroup of patients likely to respond to cardiac resynchronization therapy (CRT). The purpose of this study was to assess the impact of RBBB ECG morphology on CRT response in patients with heart failure (HF). Methods and results: We evaluated the echocardiographic clinical response of 66 patients with RBBB treated with CRT and followed up for almost 2 years. The patients were divided electrocardiographically into 2 groups: 31 with typical RBBB and 35 with atypical RBBB. Responders were classified in terms of reduction in LV end-systolic volume index (ESVi) ≥ 15% or reduction in the New York Heart Association (NYHA) Class ≥ 1 or Packer score variation (NYHA response with no HF-related hospitalization events or death). The atypical RBBB group presented a longer LV activation time compared with the typical RBBB group (111.9 ± 17.6 vs. 73.2 ± 15.4 ms; P < 0.001). In the atypical and typical RBBB groups, respectively, 71.4% and 19.4% of patients were ESVi responders (P = 0.001) 74.3% and 32.3% were NYHA responders (P = 0.002); similarly, 71.4% and 29.0% of patients exhibited a 2-year Packer score of 0 (P = 0.002). Conclusion: Patients with atypical RBBB, which is a pattern highly suggestive of concomitant delayed LV conduction, may show a satisfactory response to CRT.

The risk of atrial fibrillation during right ventricular pacing.

AIMS: Right ventricular pacing adversely affects left atrial (LA) structure and function that may trigger atrial fibrillation (AF). This study compares the occurrence of persistent/permanent AF during long-term Hisian area (HA), right ventricular septal (RVS), and right ventricular apex (RVA) pacing in patients with complete/advanced atrioventricular block (AVB). METHODS AND RESULTS: We collected retrospective data from 477 consecutive patients who underwent pacemaker implantation for complete/advanced AVB. Ventricular pacing leads were located in the HA, RVS, and RVA in 148, 140, and 189 patients, respectively. The occurrence of persistent/permanent AF was observed in 114 (23.9%) patients (follow-up 58.5 ± 26.5 months). Hisian area groups presented a lower rate of AF occurrence (16.9%) compared with RVS and RVA groups (25.7 and 28.0%, respectively), P = 0.049. Cox's proportional hazard model was used to estimate HR. The risk of persistent/permanent AF was significantly lower in the patients paced from HA compared with those paced from RVA, HR = 0.28 (95% CI 0.16-0.48, P = 0.0001). The RVS and RVA pacing groups showed a similar AF risk: HR 1.04 (95% CI 0.66-1.64, P = 0.856). Other independent predictors of persistent/permanent AF occurrence included previous (before device implantation) paroxysmal AF (HR = 4.08; 95% CI 3.15-7.31, P = 0.0001), LA diameter, and age, whereas baseline bundle-branch block was associated with a lower risk of AF occurrence (HR = 0.56; 95% CI 0.35-0.81, P = 0.003). CONCLUSIONS: HA pacing compared with RVA or RVS pacing seems to be associated with a lower risk of persistent/permanent AF occurrence. The risk of persistent/permanent AF was similar in the RVA vs. RVS groups.

Hisian area and right ventricular apical pacing differently affect left atrial function: an intra-patients evaluation.

AIMS: Right ventricular apex (RVA) pacing has adverse effects on left atrial (LA) function and may contribute to atrial arrhythmias. The effects of Hisian area (HA) pacing on LA function are still lacking. The objective of this study is to assess the left ventricular (LV) electromechanical activation/relaxation, systolic (S), diastolic (D) phases, and their effects on LA function during pacing from HA and RVA. METHODS AND RESULTS: Thirty-seven patients with normal cardiac function underwent permanent HA pacing. In all patients, a RVA backup lead was added. The patients first underwent 3 months of HA pacing, followed by 3 months of RVA pacing. After each 3-month period, we compared by echocardiography: S-D LV electromechanical delay (S-D EMD), S-D intra-LV dyssynchrony, LV S-D phases, and their function evaluated by myocardial performance index (MPI) and mitral annular tissue Doppler early diastolic velocity (E'), pulmonary arterial systolic pressure (PASP), and LA function (LA phasic volumes and their emptying fraction). Right ventricular apex compared with HA pacing increased S-D EMD (P < 0.001) and intra-LV dyssynchrony (P < 0.001). As a consequence, a significant longer LV isovolumetric contraction time (P < 0.001) and LV isovolumetric relaxation time (P = 0.05) were measured during RVA compared with HA pacing, whereas LV ejection time was shorter (P = 0.033). Moreover, HA pacing resulted in significantly better MPI (P = 0.039), higher value of E' (P = 0.049), and lower PASP (P < 0.001). Finally, RVA compared with HA pacing was associated to higher LA volumes pre-atrial contraction (P = 0.001) and minimal volume (P = 0.003) with reduction in passive emptying fraction (P < 0.001) and total emptying fraction (P = 0.005). CONCLUSION: Hisian area compared with RVA pacing resulted in a more physiological LV electromechanical activation/relaxation and consequently better LA function.

A new integrated approach to improve left ventricular electromechanical activation during right ventricular septal pacing.

AIMS: The deleterious effects of apical right ventricular pacing has fostered the utilization of alternative pacing sites. Although right ventricular septal (RVS) sites are commonly used, the results have been controversial because of poor standardization of lead position by fluoroscopy. This study investigated the utility of a new RVS pacing technique based on the combination of fluoroscopy (F), and electrophysiological mapping (F + EP). Left ventricular (LV) electromechanical activation was determined in patients undergoing RVS pacing and the results of the F + EP approach were compared with those derived from standard F alone. METHODS AND RESULTS: Between December 2008 and November 2010 we enrolled 156 consecutive patients undergoing permanent RVS pacing. The standard F approach was used in 93 patients and the F + EP technique was applied to 63 patients. Electromechanical activation was assessed by: (i) electromechanical latency (EML) interval measured from the QRS onset to the mechanical activation of the basal LV and (ii) intra-LV dyssynchrony measured as the interval from the earliest to the latest LV basal motion. Intra-LV dyssynchrony was found in 46.2% patients in the F group compared with 15.9% in the group F + EP (P < 0.001). The F group demonstrated a significantly higher degree of intra-LV dyssynchrony than F + EP group (43.9 ± 24.3 vs. 26.5 ± 15.4 ms; P < 0.001). The F group exhibited a significantly higher EML duration compared with the F + EP group (215.8 ± 25.3 vs. 195.1 ± 17.4 ms; P < 0.001). CONCLUSION: During RVS pacing, the F + EP approach provides a more physiological LV activation than the standard F technique. The prognostic significance of these short-term findings needs to be correlated with long-term data.

Failure of transvenous ICD to terminate ventricular fibrillation in a patient with left ventricular noncompaction and polycystic kidneys.

Implantable cardioverter defibrillator (ICD) testing in patients with left ventricular noncompaction (LVNC) at the time of implantation and potential difficulties with ventricular fibrillation (VF) induction/termination in LVNC patients are often not stated in the literature. This report describes the failure of transvenous implantation of an ICD in a 40-year-old patient with LVNC and polycystic kidneys. A high defibrillation threshold (DFT) prevented termination of ICD-induced VF. This case suggests that DFT testing should be considered in any LVNC patient during ICD implantation. The association of LVNC and polycystic kidneys is also discussed.

His Bundle Pacing: My Experience, Tricks, and Tips.

His Bundle Pacing (HBP) is a form of physiologic pacing achieved through implantation of a pacing electrode into the His bundle. HBP began 20 years ago without any dedicated tools. As specific tools became available HBP quickly spread and proved to be a viable alternative to traditional right ventricle pacing. HBP is reliable and effective in preserving the physiologic ventricular synchrony with clinical benefits particularly evident when a high percentage of pacing is required. Unipolar signals from the lead tip guide the implant. 3D electroanatomical mapping could further assist the procedure.

Prognostic Impact of New-Onset Atrial Fibrillation After Single or Double Stent Left Main Bifurcation PCI.

OBJECTIVE: Incidence and prognostic value of new-onset atrial fibrillation after single versus double stent strategy in bifurcation left main disease has not been yet investigated. METHODS: We retrospectively analyzed the procedural and medical data of patients referred to our center for complex left main bifurcation disease, treated using crossover provisional stenting, T or T-and-Protrusion, Culotte, and Nano-inverted-T techniques between January 1, 2008, and May 1, 2018. Multivariate Cox-regression analysis was used to assess the role of different stent strategies, adjusted for confounders, on the risk of new-onset atrial fibrillation during the follow-up period. RESULTS: Five hundred two patients (316 males, mean age 70.3 ± 12.8 years, mean Syntax score 31.6 ± 6.3) were evaluated. At a mean follow-up of 37.1 ± 10.8 months (range: 22.1- 39.3 months); Target lesion failure rate was 10.1%. Stent thrombosis and cardiovascular mor- tality were observed in 1.2% and 3.6% in of cases, respectively. New-onset atrial fibrillation occurred in 23 out of 502 patients (4.6%). Patients with new-onset atrial fibrillation resulted more frequently female, older, obese, and diabetic and more frequently experienced target lesion failure and cardiovascular death. New-onset atrial fibrillation-free survival favored single versus double stent technique and among double stent techniques nano-inverted-T tech- niques compared to the others. Single stent strategy had a lower risk of new-onset atrial fibril- lation compared to double stent technique on multivariate analysis (Hazard Ratio (HR): 1.14, 95% CI: 1.10-1.19, P < .001 vs. HR: 1.28, 95% CI: 1.23-1.32, P < .0001). CONCLUSION: New-onset atrial fibrillation in distal left main bifurcation disease treated with per- cutaneous coronary intervention had a low incidence but resulted more frequently after double than after single stenting technique and was associated with worse outcomes.

Variability of left ventricular electromechanical activation during right ventricular pacing: implications for the selection of the optimal pacing site.

BACKGROUND: The right ventricular septum (RVS) and Hisian area (HA) are considered more "physiological" pacing sites than right ventricular apex (RVA). Studies comparing RVS to RVA sites have produced controversial results. There are no data about variability of electromechanical activation obtained by an approach using fluoroscopy and electrophysiological markers. This study compared the variability of left ventricular (LV) electromechanical activation in patients undergoing short-term RVA and RVS with that measured during HA pacing based on fluoroscopy and electrophysiological markers. METHODS: Tissue Doppler echocardiography was performed in 142 patients before and after RVA (54), RVS (44), and HA (44) pacing. Electromechanical activation was assessed by: (1) electromechanical latency (EML)-interval between QRS onset and mechanical activation of basal LV; (2) intra-LV dyssynchrony (intra-LV)-interval between earliest to the latest LV basal motion. The intra- and interpatients variability among pacing groups were assessed. RESULTS: Pacing from RVA showed longer EML and higher degree of intra-LV than RVS and HA pacing. RVA and RVS showed a higher variability than HA pacing with regard to intrapatient changes of EML (RVA vs RVS, P = 0.4; RVS vs HA, P = 0.01, RVA vs HA, P = 0.0002) and intra-LV (RVA vs RVS, P = 0.2; RVS vs HA, P = 0.04; RVA vs HA, P = 0.005). Similar results were found in interpatients variability from paced-values. CONCLUSIONS: RVA and RVS pacing produce a variable effect on LV electromechanical activation that is significantly more pronounced than HA pacing. A pacing site such as HA selected by fluoroscopic and electrophysiological markers maintains baseline and homogeneous LV activation pattern.

Implantation technique of His bundle pacing.

His bundle pacing (HBP) preserves physiological ventricular synchrony, with clinical benefits particularly evident when a high percentage of ventricular pacing is required. First experiences with standard leads and manually shaped stylets produced the impression that HBP is highly complex and time-consuming. However, with dedicated leads and sheaths, reliable HBP can be achieved in routine clinical practice. Implantation success in more than 90% of patients can be reached with current technology and has been shown to be reliable and effective, both at implantation and during long-term follow-up. At the same time, fluoroscopy and total procedural time can be reduced. New customized technologies will continue to improve the implant success rate and system performance. Large randomized trials will prove the long-term clinical benefits of HBP definitively and may render HBP the first choice in patients requiring ventricular pacing.

The QR-max index, a novel electrocardiographic index for the determination of left ventricular conduction delay and selection of cardiac resynchronization in patients with non-left bundle branch block.

Non-left bundle branch block (non-LBBB) remains an uncertain indication for cardiac resynchronization therapy (CRT). Non-LBBB includes right bundle branch block (RBBB) and non-specific LV conduction delay (NSCD), two different electrocardiogram (ECG) patterns which are not generally considered to be associated with LV conduction delay as judged by the invasive assessment of the Q-LV interval. We evaluated whether a novel ECG interval (QR-max index) correlated with the degree of LV conduction delay regardless of the type of non-LBBB ECG pattern, and could, therefore, predict CRT response. In 173 non-LBBB patients on CRT (92 NSCD, 81 RBBB), the QR-max index was measured as the maximum interval from QRS onset to R-wave offset in the limb leads. The correlation between QR-max index and Q-LV interval and the impact of the QR-max index on time to first heart failure hospitalization during 3-year follow-up were assessed. Q-LV correlated better with the QR-max index than with QRSd, particularly in the RBBB group (r = 0.91; p < 0.001 vs. r = 0.19; p < 0.089), while the correlations were r = 0.79 (p < 0.01) and r = 0.68 (p < 0.01), respectively, in the NSCD group. In both groups, the QR-max index was significantly more able than QRSd to identify CRT responders (AUC 0.825 vs. 0.576; p = 0.0008 in RBBB; AUC 0.738 vs. 0.701; p = 0.459 in NSCD). A QR-max index exceeding a cutoff value of 120 ms was associated with CRT response, with predictive values of 86.8 and 81.4% in RBBB and NSCD, respectively. The QR-max index reflects the degree of LV electrical delay regardless of QRS duration in RBBB and NSCD patients and is a useful indicator of suitability for CRT in non-LBBB patients.

Ventricular-arterial coupling in patients with heart failure treated with cardiac resynchronization therapy: may we predict the long-term clinical response?

OBJECTIVE: To evaluate the effects of cardiac resynchronization therapy (CRT) on ventricular-arterial coupling (VAC) in patients with refractory congestive heart failure (HF), left bundle brunch block, and sinus rhythm. BACKGROUND: The ratio between arterial elastance (Ea) and left ventricular end-systolic elastance (Ees), the so-called VAC, defines the efficiency of the myocardium in pumping blood. METHODS: Seventy-eight patients were studied with echocardiography before CRT, and 1 year later. End-systolic elastance was calculated according to the method of Chen. Arterial elastance (ratio of the systolic pressure to the stroke volume), end-systolic volume (ESV), and quality of life (QoL) (Minnesota Living with Heart Failure Questionnaire) were assessed at the baseline and after 1 year. Patients with a reduction>15% of ESV or a decrease>33% in QoL score were considered responders to CRT. RESULTS: QRS duration and interventricular delay were significantly reduced with CRT compared with baseline (156+/-2 vs. 195+/-3 ms, P<0.001; and 25+/-2 vs. 55+/-3 ms, P<0.001, respectively). Arterial elastance/Ees decreased significantly on CRT (2.47+/-1.48 vs. 1.41+/-0.87, P<0.0001). The lowering of Ea/Ees was congruent to a decrease in intraventricular delay (83.1+/-55.7 vs. 28.4+/-49.5 ms, P<0.0001) and an increase in ejection fraction (26+/-6.3 vs. 36.9+/-8.0%, P<0.0001). Responders to CRT were 74 and 71% of the overall patient population, considering as endpoint QoL or ESV, respectively. The analysis of VAC showed a baseline cut-off value of 2, above which 88% and 69% of patients responded to CRT, considering as endpoint QoL or ESV, respectively. CONCLUSIONS: The non-invasive assessment of VAC may be proposed as an immediate, easy, and optimal tool for quantifying the effect of CRT in patients with HF.

Long-Term Clinical Outcomes of Isolated Ostial Left Anterior Descending Disease Treatment: Ostial Stenting Versus Left Main Cross-Over Stenting.

BACKGROUND: The optimal strategy for treating ostial left anterior descending coronary artery (LAD) disease remains matter of speculation. We evaluated the impact on long-term outcomes of ostial LAD disease treated by means of ostial stenting (the floating-stent) or left main (LM)-to-LAD cross-over stenting. METHODS: Clinical and instrumental records of 74 consecutive patients with isolated ostial LAD disease, enrolled between the 1st January 2012 and the 1st January 2017 were reviewed. Patients have been stratified according the stenting techniques adopted: ostial stenting (OS) or LM cross-over (CO). RESULTS: Seventy-four consecutive patients (54 males, mean age 73.39 ±â€¯9.54 years old) have been analyzed. In CO patients the SYNTAX score (16.2 ±â€¯3.3 vs 24.1 ±â€¯2.5, p < 0.0001) and the percentages of rotablation resulted higher than in OS group. IVUS has been predominantly used in CO groups revealing a significant extension of plaque burden of at least 10 mm of LM proximal to the LAD ostium in all the 18 out of 21 patients (85.7%) undergone IVUS-guided procedure. Fluoroscopy time and contrast medium volume were higher in OS versus CO group of patients. On a mean follow-up of 49.7 ±â€¯7.9 months, MACE and target vessel revascularization (TVR) were 21.0% and 21.0% in OS groups versus 10.1 and 5.6% in the CO group (p = 0.20 and p = 0.04, respectively). Restenosis was higher in the OS than in CO group of patients and was located angiographically at the ostium. CONCLUSIONS: On long-term follow-up CO seems to be superior to OS technique for isolated ostial LAD disease especially in the presence of heavy calcification.

Direct His bundle pacing preserves coronary perfusion compared with right ventricular apical pacing: a prospective, cross-over mid-term study.

AIMS: The His bundle is regarded as the most physiological site for ventricular pacing, in that it avoids the adverse effects of right ventricular apical pacing (RVAP). However, very few studies have compared the effects of direct His bundle pacing (DHBP) and RVAP. The aim of our study was the intra-patient comparison of myocardial perfusion corresponding to these two different pacing techniques, as perfusion expresses local workload and is related to long-term outcome. METHODS AND RESULTS: Twelve consecutive patients with standard pacemaker indication (9 male, 74 +/- 9 years) entered the study. Pacing leads were implanted in the right ventricular apex and directly in the His bundle, and were connected to different ports of the pacemaker. All patients first underwent 3 months of DHBP, followed by 3 months of RVAP. At the end of each 3-month period, myocardial perfusion was measured at rest using scintigraphy with Tc99m-SestaMIBI. The average values of perfusion were evaluated on a 20-segment basis. All patients also underwent clinical evaluation, echocardiography, and tissue Doppler imaging (TDI), to measure dyssynchrony, and a blood sample was taken for brain natriuretic peptide (BNP) assay. The perfusion score during DHBP pacing was significantly better than during RVAP (0.44 +/- 0.5 vs. 0.71 +/- 0.53, respectively; P = 0.011). None of the patients showed lower perfusion during DHBP than during RVAP. We found no significant difference in NYHA class, ventricular volumes, ejection fraction, or plasmatic BNP between DHBP and RVAP. However, mitral regurgitation (0.26 +/- 0.21 vs. 0.37 +/- 0.25; P < 0.001) and dyssynchrony (13.75 +/- 4.28 vs. 22.02 +/- 8.44; P = 0.008) were significantly less during DHBP than during RVAP. CONCLUSION: Direct His bundle pacing is superior to RVAP in preserving the physiologic distribution of myocardial blood flow and reducing mitral regurgitation and left ventricular dyssynchrony.

Left ventricular dyssynchrony resulting from right ventricular apical pacing: relevance of baseline assessment.

OBJECTIVES: Evaluation of left ventricular (LV) dyssynchrony in patients undergoing short-term right ventricular apical (RVA) pacing and correlation with baseline echocardiographic and clinical characteristics. BACKGROUND: RVA pacing causes abnormal ventricular depolarization that may lead to mechanical LV dyssynchrony. The relationships between pacing-induced LV dyssynchrony and baseline echocardiographic and clinical variables have not been fully clarified. METHODS: Tissue Doppler echocardiography was performed in 153 patients before and after RVA pacing. LV dyssynchrony was measured by the time between the shortest and longest electromechanical delays in the five basal LV segments (intra-LV). The prevalence and degree of LV dyssynchrony after RVA pacing was evaluated in three groups: baseline LV ejection fraction (LVEF) <35%, 35-55%, and >or=55%. The intrapatient effect of RVA pacing was determined as the percent increase in intra-LV value (Deltaintra-LV%). The pacing-induced intra-LV was correlated with baseline variables. RESULTS: The prevalence and degree of LV dyssynchrony after RVA pacing was significantly higher in patients with lower LVEF (P < 0.001). DeltaIntra-LV% was inversely correlated with baseline intra-LV and LVEF (B =-2.6, B =-4.2, P < 0.001). Baseline intra-LV and LV end-systolic volume correlated positively with intra-LV after RVA pacing (B = 0.49, B = 0.6, P < 0.001), whereas LVEF showed an inverse correlation. CONCLUSIONS: The degree of LV dyssynchrony induced by RVA is variable. Patients with higher baseline LV dyssynchrony, more dilated LV, and more depressed LVEF showed a higher degree of LV dyssynchrony during pacing. These findings may assume importance in predicting the risk of heart failure in pacemaker patients.

Hemodynamic comparison of different multisites and multipoint pacing strategies in cardiac resynchronization therapies.

PURPOSE: In order to increase the responder rate to CRT, stimulation of the left ventricular (LV) from multiple sites has been suggested as a promising alternative to standard biventricular pacing (BIV). The aim of the study was to compare, in a group of candidates for CRT, the effects of different pacing configurations-BIV, triple ventricular (TRIV) by means of two LV leads, multipoint (MPP), and multipoint plus a second LV lead (MPP + TRIV) pacing-on both hemodynamics and QRS duration. METHODS: Fifteen patients (13 male) with permanent AF (mean age 76 ± 7 years; left ventricular ejection fraction 33 ± 7%; 7 with ischemic cardiomyopathy; mean QRS duration 178 ± 25 ms) were selected as candidates for CRT. Two LV leads were positioned in two different branches of the coronary sinus. Acute hemodynamic response was evaluated by means of a RADI pressure wire as the variation in LVdp/dtmax. RESULTS: Per patient, 2.7 ± 0.7 veins and 5.2 ± 1.9 pacing sites were evaluated. From baseline values of 998 ± 186 mmHg/s, BIV, TRIV, MPP, and MPP-TRIV pacing increased LVdp/dtmax to 1200 ± 281 mmHg/s, 1226 ± 284 mmHg/s, 1274 ± 303 mmHg, and 1289 ± 298 mmHg, respectively (p < 0.001). Bonferroni post-hoc analysis showed significantly higher values during all pacing configurations in comparison with the baseline; moreover, higher values were recorded during MPP and MPP + TRIV than at the baseline or during BIV and also during MPP + TRIV than during TRIV. Mean QRS width decreased from 178 ± 25 ms at the baseline to 171 ± 21, 167 ± 20, 168 ± 20, and 164 ± 15 ms, during BIV, TRIV, MPP, and MPP-TRIV, respectively (p < 0.001). CONCLUSIONS: In patients with AF, the acute response to CRT improves as the size of the early activated LV region increases.