P5432Invasive assessment by atrial volume-pressure loops of the acute changes in left atrial function induced by pulmonary vein antral isolation

Background

Atrial volume-pressure loops are considered the best method to assess left atrium (LA) function. Changes in atrial function induced by pulmonary vein (PV) antral isolation of atrial fibrillation (AF) have not been documented thus far using this approach.

Purpose

We aimed to evaluate changes in LA function in patients with paroxysmal atrial fibrillation (PAF) undergoing catheter ablation by atrial volume-pressure loops.

Methods

Patients undergoing for the first time catheter ablation of PAF by PV antral isolation and PV-LA junction ablation, as clinically indicated, were enrolled from 2 centers. Each center enrolled consecutive patients undergoing PV antral isolation using the same method i.e. radiofrequency or cryoballoon ablation. Patients with severe mitral stenosis or regurgitation, any prosthetic valve, left atrial thrombus or severe systolic or diastolic dysfunction of the left ventricle were excluded. Before and after the procedure, all patients underwent real-time three-dimensional transthoracic echocardiogram to evaluate volume changes of the LA during an entire cardiac cycle, while simultaneously recording LA pressure by a 6F angiographic catheter following transseptal puncture. After the procedure, LA volume and pressure recordings were gated offline by ECG, and were used to plot the LA pressure as a function of LA volume, thus creating a volume-pressure loop. The A loop area is a measure of the booster pump function of the LA. The V loop area expresses the reservoir function of the LA. Pressure and volume data at the clockwise ascending limb of the volume-pressure loop were fitted to the exponential function P = bxea·V, where P = instantaneous LA pressure; V = LA volume; a is the passive elastic chamber stiffness constant (cm–3) that determines the slope of the exponential curve, and b is the elastic constant (mm Hg).

Results

34 patients with PAF were analysed, 12 treated with radiofrequency ablation and 22 with cryoablation. The procedure was uneventful in all cases. Mean LA pressure, A-wave amplitude, and V-wave amplitude were all significantly increased post-procedurally (p<0.001 for all). The area of the A-loop decreased (Post: 40.69 ml·mm Hg [IQR 13.7–71.3] vs. Pre: 64.2 ml·mm Hg [IQR 30.9–86.9]; p=0.001), whereas the area of the V-loop increased (Post: 96.5 ml·mm Hg [IQR 45.1–230.5] vs. Pre: 79.2 ml·mm Hg [IQR 46.9–149.7]; p=0.016). Although the elastic constant increased (p<0.001), there was no significant difference in the passive chamber elastic constant (p=0.30).

Conclusion

Volume-pressure loops can assess procedural changes in LA function. Catheter ablation of AF is associated with a decrease the LA booster pump function of the LA, and in increase in the left atrial reservoir function. Moreover, there is an increase in LA pressures that is observed in the absence of change in LA stiffness.

P1910Impact of pulmonary vein antral isolation by radiofrequency catheter or cryoballoon on left atrial function assessed by volume-pressure loops

Background

Atrial volume-pressure loops are used to assess left atrium (LA) function. Catheter ablation of paroxysmal atrial fibrillation (PAF) by pulmonary vein (PV) antral isolation can be performed either with radiofrequency (RF) catheter or with cryoballoon and might affect LA function.

Purpose

We explored a potential difference in changes in LA function by volume-pressure loops between patients with PAF undergoing either RF catheter or cryoballoon ablation.

Methods

Patients undergoing for the first time catheter ablation of PAF by PV antral isolation and PV-LA junction ablation, as clinically indicated, were enrolled from 2 centers. Each center enrolled consecutive patients undergoing PV antral isolation using the same method ie RF or cryoballoon ablation. Patients with severe mitral stenosis or regurgitation, any prosthetic valve, left atrial thrombus or severe systolic or diastolic dysfunction of the left ventricle were excluded. Pre and post procedure, all patients underwent real-time 3D transthoracic echocardiogram to evaluate volume changes of the LA during an entire cardiac cycle, while recording LA pressure by a 6F angiographic catheter following transseptal puncture. After the procedure, LA volume and pressure recordings were gated offline by ECG, and were used to plot the LA pressure as a function of LA volume, thus creating a volume-pressure loop. The A loop area is a measure of the LA booster pump function. The V loop area expresses the LA reservoir function. Pressure and volume data at the clockwise ascending limb of the volume-pressure loop were fitted to the exponential function P = bxea·V, where P = instantaneous LA pressure; V = LA volume; a is the passive elastic chamber stiffness constant (cm–3) that determines the slope of the exponential curve, and b is the elastic constant (mm Hg).

Results

34 patients with PAF were analysed, 12 treated with RF ablation and 22 with cryoablation. The procedure was uneventful in all cases. In the overall cohort, mean LA pressure, A-wave and V-wave amplitude were all increased post-procedurally (p<0.001); A-loop area decreased (p=0.001), whereas V-loop area increased (p=0.016). Although the elastic constant increased (p<0.001), there was no significant difference in the passive chamber elastic constant (p=0.30).

Changes in both A-loop and V-loop areas were similar between RF and cryoablation (p=0.18 and p=0.36, respectively). However, compared to cryoablation, RF ablation had a lower increase in the elastic constant (b=-2.24; 95% CI: −10.56 to −1.78), and a higher increase in the passive elastic chamber stiffness constant (b=0.078; 95% CI: 0.016 to 0.140).

Conclusion

Both in RF- and cryo-ablation and in a similar extent, the LA booster pump function is decreased, and LA reservoir function is increased. LA pressure is increased in RF ablation mainly due to an acute increase in LA stiffness, whereas in cryoablation this increase is observed in the absence of change in LA stiffness.

P4529Atrioventricular optimization in cardiac resynchronization therapy with quadripolarleads, improves energy handling and quality of life in heart failure patients: HUMVEE Trial

Background

Cardiac resynchronization therapy (CRT) is a well-established technique for symptomatic heart failure (HF) patients, producing significant clinical benefits. Recent studies have revealed the potential role of multipoint pacing (MPP) in improving response and clinical outcomes. The aim of Heart failUre study of Multisite pacing effects on VEntriculoartErial coupling (HUMVEE) trial was to evaluate the association between MPP of the left ventricle vs those of standard biventricular pacing (BVP) on: a) ventriculoarterial coupling (VAC) and energy efficiency of the failing heart, b) diastolic function, c) quality of life, and d) NT-proBNP levels.

Methods

HUMVEE is a single-center, prospective (13 months) trial (clinicaltrials.gov identifier NCT03189368), of 54 NYHA III patients (69±9 years; 79% men; 50% dilated cardiomyopathy), under optimal tolerated medical therapy, with standard BVP indication, having being implanted with a CRT system able to deliver both modes of pacing. Creatinine and NT-proBNP levels and echocardiographic measurements (VAC calculation, strain rate, diastolic function assessment), as well as 6-min-walking-test and quality of life (MLHF questionnaire) were measured at baseline, 6 months post BVP optimization (right before MPP activation) and at the end of follow-up (6 months post MPP optimization). Cardiac power (CP) was calculated according the equation: CP=Cardiac Output x Mean Aortic Pressure/451.

Results

Both CRT and MPP improved 6-min-walk (differences at baseline/6 mo/end of FU: 277±27 vs. 345±27 vs 363±27 m, p=0.07); left ventricular ejection fraction (24,2% vs 30,6%vs, 32%, p=0.05); end -diastolic diameters of left ventricle (65±1,4 vs. 63±1.7 vs. 61±1.1, p=0.03); end-systolic volume (150±15 vs. 140±10 vs. 131±13, p=0.08); stroke volume (41.6±9 vs. 53.6±14 vs. 62±9, p=0.0001 for MPP); left atrial volume (76±5 vs. 74±10 vs 61±6, p=0.001 for MPP), E/Emv (14±5 vs. 12±4 vs. 11±3, p=0.05 for MPP); NtproBNP (2782±1000 vs. 2080±2500 vs. 2000±1000, p=0.05 for MPP). VAC was reduced from 1.14±0.27 to 1.1±0.17 (p=0.1) while CP increased from 564.2±142 to 768±103 (p=0.009). Quality of life score (the lower the better) improved from 23.75±17 at baseline to 17.25±10 at end of FU (p=0.05).

Conclusions

MPP is a new, promising pacing modality with the potential to improve HF patients' outcome, offering additive effects on myocardial energy balance, cardiac power, systolic and diastolic ventricular function and aortoventricular coupling, especially in ischemic patients. HUMVEE trial illustrates those clinical, imaging and biochemical divergences of MPP from standard BVP that reflect significant improvement in quality of life in patients with advanced HF and cardiac dysychronization.

Biomarkers Associated with Atrial Fibrosis and Remodeling

Atrial fibrillation is the most common rhythm disturbance encountered in clinical practice. Although often considered as solely arrhythmic in nature, current evidence has established that atrial myopathy constitutes both the substrate and the outcome of atrial fibrillation, thus initiating a vicious, self-perpetuating cycle. This myopathy is triggered by stress-induced (including pressure/volume overload, inflammation, oxidative stress) responses of atrial tissue, which in the long term become maladaptive, and combine elements of both structural, especially fibrosis, and electrical remodeling, with contemporary approaches yielding potentially useful biomarkers of these processes. Biomarker value becomes greater given the fact that they can both predict atrial fibrillation occurrence and treatment outcome. This mini-review will focus on the biomarkers of atrial remodeling (both electrical and structural) and fibrosis that have been validated in human studies, including biochemical, histological and imaging approaches.

Biomarkers Associated with Bleeding Risk in the Setting of Atrial Fibrillation

BACKGROUND

Prevention of thromboembolic disease, mainly stroke, with oral anticoagulants remains a major therapeutic goal in patients with atrial fibrillation. Unfortunately, despite the high efficacy, anticoagulant therapy is associated with a significant risk of, frequently catastrophic, and hemorrhagic complications. Among different clinical and laboratory parameters related to an increased risk of bleeding, several biological markers have been recognized and various risk scores for bleeding have been developed.

OBJECTIVES/METHODS

The aim of the present study is to review current evidence regarding the different biomarkers associated with raised bleeding risk in atrial fibrillation.

RESULTS

Data originating from large cohorts or the recent large-scale trials of atrial fibrillation have linked numerous individual biomarkers to an increased bleeding risk. Such a relation was revealed for markers of cardiac physiology, such as troponin, BNP and NT-proBNP, markers of renal function, such as GFR and Cystatin or hepatic function, markers involving the system of coagulation, such as D-dimer and Von Willebrand factor, hematologic markers, such as low haemoglobin or low platelets, inflammatory markers, such as interleukin-6, other factors such as GDF-15 and vitamin-E and finally genetic polymorphisms. Many such biomarkers are incorporated in the bleeding risk schemata developed for the prediction of the hemorrhagic risk.

CONCLUSIONS

Biomarkers were introduced in clinical practice in order to better estimate the potential risk of haemorrhage in these patients and increase the prognostic impact of clinical risk scores. In the last years this concept is gaining significant importance.

Sudden unexplained death in the young: epidemiology, aetiology and value of the clinically guided genetic screening

Aims

To determine the incidence and the causes of sudden death (SD) in persons aged 1-35 years old and the diagnostic yield of clinically guided genetic screening in the sudden arrhythmic death syndrome (SADS) victims' families.

Methods and results

Incidence and causes of SD in the Attica region of Greece in 2002-10 were determined using death certificates and autopsy reports. We evaluated clinically consecutive families of SADS victims and if a clinical diagnosis was established, we proceeded to targeted genetic analysis. Out of 6030 deaths, 56% were due to traumatic or violent causes, 40.5% were natural deaths, and 3.3% were of undetermined cause. There were 349 SD cases. Cardiovascular causes accounted for 65%, non-cardiovascular causes for 17%, and SADS for 18%. Clinical evaluation identified an inherited heart disease in 5/20 SADS families (25%). Targeted genetic analysis identified a causative mutation in all of the five screened families and reconfirmed the diagnosis in three of five proband victims. Clinical and genetic evaluation of 28 family members identified eight affected carriers and eight non-affected carriers. Molecular autopsy failed to identify any of these families.

Conclusion

Sudden death in the young is of cardiovascular origin in the majority of cases. A considerable rate of SD cases remains of unknown cause on post-mortem. Apart from channelopathies, subclinical forms of inherited structural heart diseases would appear to be implicated in SADS. Clinically guided genetic screening has a significant diagnostic yield and identifies affected families that would have been missed by the current suggested molecular autopsy panel.

Heart failure study of multipoint pacing effects on ventriculoarterial coupling: Rationale and design of the HUMVEE trial

Cardiac resynchronization therapy (CRT) is an established therapy for symptomatic heart failure (HF). Unfortunately, many recipients remain nonresponders. Studies have revealed the potential role of multipoint pacing (MPP) in improving response and outcomes. The aim of this study is to compare the effects of MPP against those of standard biventricular pacing (BVP) on (i) ventriculoarterial coupling (VAC) and energy efficiency of the failing heart, (ii) diastolic function, (iii) quality of life, and (iv) NT-proBNP levels and glomerular filtration rate (GFR) during a follow-up of 13 months. HUMVEE is a single-center, prospective, observational, crossover cohort study. Seventy-six patients with BVP indication will be implanted with a system able to deliver both pacing modes. BVP will be activated at implantation and optimized 1 month after. At 6 months postoptimization MPP will be activated and optimized. Optimization will be performed based on stroke volume maximization, as assessed by ultrasound. Laboratory measurements (GFR and NT-proBNP) and echocardiographic studies (VAC calculation, strain rate, diastolic function) will be performed at implantation, 6 months post-BVP optimization and at the end of 13 months of follow-up (6 months post-MPP optimization). Potential reduction in arrhythmogenesis by MPP will also be assessed. MPP is a pacing modality with the potential to improve HF patients' outcomes. The HUMVEE trial will attempt to associate any potential added beneficial effects of MPP over standard BVP with alterations in VAC and energy efficiency of the heart, thus uncovering a novel mechanistic link between MPP and improved outcomes in HF.

T wave axis deviation and QRS-T angle - Controversial indicators of incident coronary heart events

Abnormal orientation of the T-wave axis and increased angle between the QRS complex (depolarization) and the T-wave (repolarization) have long been assumed to provide a global measure of repolarization abnormality, and have been used to assess ventricular repolarization. The ability of the T wave axis deviation and the QRS-T angle to predict incident coronary heart events was examined in several studies. However, conflicting results have led to significant controversy in the literature concerning their purported ability. Potential explanations involve true variation between study populations, non-standardized cut-off values, different baseline cardiovascular risk levels or different patterns of confounding by other concomitant cardiovascular risk factors. In the present article we will attempt to briefly present the rationale and pathophysiology behind these indices, summarize existing knowledge regarding their prognostic significance and their correlation with established cardiovascular disease risk factors. Further prospective studies are necessary to confirm or refute whether T-wave axis deviation, QRS-T angle and ventricular gradient may in the future serve as indicators of incident coronary heart events and mortality, both in populations with higher prevalence of subclinical advanced atherosclerotic heart disease and in apparently healthy subjects.

QT Prolongation and Malignant Arrhythmia: How Serious a Problem?

QT prolongation constitutes one of the most frequently encountered electrical disorders of the myocardium. This is due not only to the presence of several associated congenital syndrome but also, and mainly, due to the QT-prolonging effects of several acquired conditions, such as ischaemia and heart failure, as well as multiple medications from widely different categories. Propensity of repolarization disturbances to arrhythmia appears to be inherent in the function of and electrophysiology of the myocardium. In the present review the issue of QT prolongation will be addressed in terms of pathophysiology, arrhythmogenesis, treatment and risk stratification approaches. Although already discussed in literature, it is hoped that the mechanistic approach of the present review will assist in improved understanding of the underlying changes in electrophysiology, as well as the rationale for current diagnostic and therapeutic approaches.

Sustained ventricular tachycardia as a first manifestation of hypertrophic cardiomyopathy with mid-ventricular obstruction and apical aneurysm in an elderly female patient

Sustained ventricular tachycardia complicating left ventricular apical aneurysms has been reported previously solely in middle-aged patients with hypertrophic cardiomyopathy and mid-cavity obstruction. We report a case of an elderly female patient who presented with incessant ventricular tachycardia as the first clinical manifestation of hypertrophic cardiomyopathy with mid-ventricular obstruction and apical aneurysm.

Left Ventricular Pacing through Coronary Sinus Is Feasible and Safe for Patients with Prior Tricuspid Valve Intervention

BACKGROUND

In the presence of tricuspid valve intervention, right ventricular lead implantation is associated with the potential risk of tricuspid valve malfunction leading to a tricuspid regurgitation. Few cases have been reported with successful left ventricular pacing via the coronary sinus (CS) after tricuspid valve replacement or repair. In this retrospective study, we present the long-term clinical outcomes of 17 patients who underwent CS lead implantation and left ventricular pacing.

METHODS

Seventeen consecutive patients referred to our institution with an indication of postprocedural pacemaker (PM) implantation after tricuspid valve intervention were retrospectively included in the study. The indication for device implantation in all patients was atrial fibrillation with a symptomatic pause ≥ 3.0 seconds. Thus, all devices implanted were ventricular rate responsive (VVIR).

RESULTS

All device implantations were successful and uncomplicated. Mean operation time was 60 ± 8 minutes. Mean fluoroscopy time was 8.3 ± 2.1 minutes. Mean R-wave sensing was 7.5 ± 2.0 mV with a mean slew rate of 2.2 V/s. A mean pacing threshold of 1.9 ± 0.3 V/0.4 ms was accepted as patients were not PM-dependent. The pacing impedance was 743.5 ± 109.71 Ohm. At 2-year follow-up, pacing sensing, threshold, and impedance values were unchanged and no lead dislodgement has been noted.

CONCLUSIONS

In patients with tricuspid valve intervention, left ventricular pacing might be the treatment of choice for permanent ventricular pacing, with all the advantages of the endovenous route as a minimally invasive approach.