Atrial arrhythmias and heart failure: a "modern view" of an old paradox

BACKGROUND

Heart failure (HF) and atrial arrhythmias (AAs) are two clinical conditions that characterize the daily clinical practice of cardiologists. In this perspective review, we analyze the shared etiopathogenetic pathways of atrial arrhythmias, which are the most common cause of atrial arrhythmias-induced cardiomyopathy (AACM) and HF.

HYPOTHESIS

The aim is to explore the pathophysiology of these two conditions considering them as a "unicum", allowing the definition of a cardiovascular continuum where it is possible to predict the factors and to identify the patient phenotype most at risk to develop HF due to atrial arrhythmias.

METHODS

Potentially eligible articles, identified from the Electronic database (PubMed), and related references were used for a literature search that was conducted between January 2022 and January 2023. Search strategies were designed to identify articles that reported atrial arrhythmias in association with heart failure and vice versa. For the search we used the following keywords: atrial arrhythmias, atrial fibrillation, heart failure, arrhythmia-induced cardiomyopathy, tachycardiomyopathy. We identified 620 articles through the electronic database search. Out of the 620 total articles we removed 320 duplicates, thus selecting 300 eligible articles. About 150 titles/abstracts were excluded for the following reasons: no original available data, no mention of atrial arrhythmias and heart failure crosstalk, very low quality analysis or evidence. We excluded also non-English articles. When multiple articles were published on the same topic, the articles with the most complete set of data were considered. We preferentially included all papers that could provide the best evidence in the field. As a result, the present review article is based on a final number of 104 references.

RESULTS

While the pathophysiology of AACM and Heart Failure with reduced ejection fraction (HFrEF) has been studied in detail over the years, the causal link between atrial arrhythmias and heart failure with Preserved Ejection Fraction (HFpEF) has been often subject of interest. HFpEF is strictly related to AAs, which has always been considered significant risk factor. In this review we described the pathophysiological links between atrial fibrillation and heart failure (Fig. 1). Furthermore, we illustrated and discussed the preclinical and clinical predicting factors of AF and HFpEF, and the corresponding targets of the available therapeutic agents. Finally, we outlined the patient phenotype at risk of developing AF and HFpEF.

CONCLUSIONS

In this review, we underline how these two clinical conditions (AF and HFpEF) represent a "unicum" and, therefore, should be considered as a single disease that can manifest itself in the same phenotype of patients but at different times. Furthermore, considering that today we have few therapeutic strategies to treat these patients, it would be good to make an early diagnosis in the initial stages of the disease or intervene even before the development of signs and symptoms of HF. This is possible only by paying greater attention to patients with predisposing factors and carrying out a targeted screening with the correct diagnostic methods. A systemic approach aimed at improving the immuno-metabolic profile of these patients by lowering the body mass index, threatening the predisposing factors, lowering the mean heart rate and reducing the sympathetic nervous system activation is the key strategy to reduce the clinical impact of this disease. This article is protected by copyright. All rights reserved.

365 ANALYSIS OF PIVOT POINTS AND SLOW CONDUCTION AREAS IN PATIENTS UNDERGOING ATRIAL FIBRILLATION ABLATION

Introduction

Little is known about progression of atrial fibrillation (AF) from paroxysmal to persistent form. Electrical remodeling may play a pivotal role in the arrhythmia transition. The aim of the study was the characterization of the atrial electrical substrate in patients suffering from AF.

Methods

Twenty-seven patients were included in the study (14 with paroxysmal AF and 13 with persistent AF). Two simultaneous electroanatomical maps of the left atrium were collected using PentaRay catheter using the parallel mapping feature [first map during sinus rhythm and a second one with an extrastimulus from coronary sinus (CS)]. We analyzed the propagation of the wavefront and we identified zones of abnormal conduction: slow conduction (SC) corridors and pivot points (PP). SC corridors were defined by the slowing of conduction velocity; pivot points were zones in which propagation pattern changed the direction of 90° or more. Maximum delay between the recording dipoles located at the extremities of the PentaRay splines was calculated. At each of these sites, EGMs were collected and analyzed in terms of amplitude and duration. We checked if areas of abnormal conduction during sinus rhythm were present or they disappeared by delivering an extrastimulus from the coronary sinus.

Results

The average number of collected EGMs per map was 4790 ± 1333 (PAF 4829 ± 1407; PsAF 4745 ± 1402).

Total abnormal conduction areas in the 27 patients were 62, 65% of which were slow conduction. Pivot points and slow conduction manifested a trend to cluster in some areas: both of them were mostly present at the ostia of pulmonary veins, in a specific segment between LAA ostium and mitral annulus and in the posterior wall. During sinus rhythm, pivot points were 29, while pacing from distal CS catheter the same zones showed normal conduction in 14 cases: they were still present in 60% in PAF group and 50% in PsAF. Slow conduction corridors, instead, show a trend to remain while pacing from CS: 76% in the first group and 78% in the second one.

Conclusions

SC corridors are fixed alterations of atrial substrate, while pivot sites may be more dynamic entities: both of them may have a key role in remodeling atrial structures and atrial fibrillation progression and maintenance. These may represent future targets for AF therapy and prevention.

27 PROGNOSTIC FACTORS IN POST-OPERATIVE ATRIAL FIBRILLATION: A COHORT STUDY IN 53.387 PATIENTS

Introduction

Post-operative atrial fibrillation (POAF) represents the most common arrhythmia in the post-operative setting, with a peak incidence from day 0 to 5 after surgery and it represents a main cause of morbidity, mortality, length of stay, thromboembolic events and stroke. Cardiothoracic surgery has the highest rates of POAF, while data about other surgeries are contrasting amongst various studies. Aim of this study was to detect POAF onset in the 28 days after surgery and to better assess its predictors, especially the role of inflammation.

Methods

This is a retrospective single center cohort study of 53.387 patients undergoing surgery from January 2016 to January 2020. Patients were classified in four groups according to types of surgery performed: (I) orthopedic surgery, (II) not thoracic nor abdominal surgery, (III) abdominal and esophageal surgery and (IV) lung and cardiovascular surgery. Kaplan–Meier estimates were used to draw the cumulative incidence curves by surgery groups; finally, they were compared with a log-rank test. Furthermore, multivariable Cox proportional hazards (PH) models of prognostic factors were used. Confounders were selected according to a review of the literature, statistical relevance, and consensus opinion by an expert group of physicians and methodologists. After fitting the model, the PH assumption was examined on the basis of Schoenfeld residual.

Results

The primary endpoint of AF onset occurred in 570 patients (1.1%) with a mean incidence after surgery of 3.4±2.6 days. 90 patients died (0.17%) after an average of 13.7±8.4 days.

The Kaplan-Meier analysis showed the lowest 28-day event-free survival in group IV and the highest in group I (log-ranks test p=0.0001). In patients who developed AF, levels of C-Reactive Protein (CRP) were higher than the others (mean 0,70+0.03 log10 mg/dL versus mean 0,40+0.01 log10 mg/dl; p <0.0001) with higher levels in group III and group IV. In the univariable Cox regression, CRP was a strong predictor of AF (HR per 1 unit increase in log-scale, 2.64; 95% C.I,1.74–4.0; p<0.0001). This was confirmed at the multivariable analysis, adjusting for confounding factors like age, gender, length of stay in hospital and group of surgery (adjusted HR per 1 mg/dL increase in log-scale, 1.81; 95% CI,1.18–2.79; p = 0.007). Other strong predictors of POAF were age (HR per 1 year increase, 1.06; 95% CI, 1.04–1.08; p< 0.0001) and surgery of group III and IV (HR, 23.62; 95% CI, 5.65–98.73; p< 0.0001 and HR,6.26; 95% CI, 1.48–26.49; p 0.013, respectively).The PH assumption was not violated (p=0.12).

Conclusions

POAF represents a frequent complication of surgery and major burden for healthcare. Inflammation may represent a major driver in its pathophysiology, especially in non-cardiac surgery, in which manipulation of cardiac tissue is avoided. This may explain the poor response to antiarrhythmic drugs and its self-limiting nature, which expires when post-operative inflammation turns off.

113 RIGHT VENTRICULAR FREE WALL LONGITUDINAL STRAIN AS THE SOLE MARKER OF RIGHT VENTRICLE SYSTOLIC DYSFUNCION IN HYPERTROPHIC CARDIOMYOPATHY: A CLINICAL CASE

Background

The introduction of Cardiac-MRI (cMRI) in clinical practice has considerably improved risk stratification of patients with hypertrophic cardiomyopathy (HCM). However, the prediction of adverse outcome based on imaging markers remains suboptimal. Right ventricular (RV) involvement is an emerging finding in this disease of unknown clinical value. The identification of accurate and sensible imaging markers to detect morpho-functional alterations of the RV is therefore essential to establish, in the future, any prognostic impact of RV involvement in HCM in order to improve risk stratification. RV free wall longitudinal strain (RV-FWLS) is a promising marker to unveil subclinical RV dysfunction despite normal conventional indices of RV systolic function; however, RV-FWLS has been scarcely explored in HCM patients.

Case Summary

A 29-year-old man with sarcomeric HCM due to MYBPC3 mutation was referred to our Institution. Trans-Thoracic Echocardiography (TTE) showed left ventricular (LV) apical hypertrophy (27 mm) with an ace of spades morphology and mid-ventricular obstruction (peak gradient 38 mmHg). LV-EF was normal (62%) while LV global longitudinal strain was significantly impaired (-9.3% with a reverse apical sparing pattern). 2nd-degree diastolic dysfunction and left atrial enlargement (maximum volume: 42 ml/m2) were observed. No LV apical aneurysm nor paradoxical diastolic flow at the apex were noted. RV hypertrophy was present (maximum thickness 8 mm) with normal conventional indices of RV systolic function: TAPSE 26 mm, S’ TDI 12 cm/s, FAC 50%. In contrast, RV-FWLS was significantly reduced (–16%). cMRI confirmed normal bi-ventricular function in presence of left and right hypertrophy (maximum wall thickness 28 and 12 mm, respectively) and LV apical thinning. At tissue characterization, elevated native T1 and T2 values were evident in the apex (1071 +/- 45 ms and 54 +/- 6 ms, respectively) and a significant amount of patchy LGE was present in the mid-apical segments of the LV (28% of LV mass) and of the RV. After consideration of clinical and imaging data, an s-ICD for primary prevention was implanted.

Discussion

The present case highlights known issues and poses new challenges in managing HCM patients. First, it confirms the central role of cMRI, demonstrating its unique capability to spot myocardial fibrosis, guiding our decision to implant an s-ICD in our patient. Second, it draws attention to RV involvement in HCM, an emerging finding in this condition. MYBPC3 mutation has been associated with RV hypertrophy. Both of these conditions, together with patchy RV-LGE, were found in our patient. Notably, RV-FWLS was the only RV systolic index to be impaired and might represent an early and more accurate marker of RV systolic dysfunction compared to other conventional indices, including RV-EF by cMRI. Future studies assessing the prognostic value of RV involvement, including RV-LGE and RV-FWLS, are needed in HCM patients to potentially refine risk stratification in this challenging population.

The economic impact of battery longevity in implantable cardioverter-defibrillators for cardiac resynchronization therapy: the hospital and healthcare system perspectives

Aims

Patients receiving cardiac resynchronization therapy defibrillators (CRT-Ds) are likely to undergo one or more device replacements, mainly for battery depletion. We assessed the economic impact of battery depletion on the overall cost of CRT-D treatment from the perspectives of the healthcare system and the hospital. We also compared devices of different generations and from different manufacturers in terms of therapy cost.

Methods and results

We analysed data on 1792 CRT-Ds implanted in 1399 patients in 9 Italian centres. We calculated the replacement probability and the total therapy cost over 6 years, stratified by device generation and manufacturer. Public tariffs from diagnosis-related groups were used together with device prices and hospitalization costs. Generators were from 3 manufacturers: Boston Scientific (667, 37%), Medtronic (973, 54%), and St Jude Medical (152, 9%). The replacement probability at 6 years was 83 and 68% for earlier- and recent-generation devices, respectively. The need for replacement increased total therapy costs by more than 50% over the initial implantation cost for hospitals and by more than 30% for healthcare system. The improved longevity of recent-generation CRT-Ds reduced the therapy cost by ∼6% in both perspectives. Among recent-generation CRT-Ds, the replacement probability of devices from different manufacturers ranged from 12 to 70%. Consequently, the maximum difference in therapy cost between manufacturers was 40% for hospitals and 19% for the healthcare system.

Conclusions

Differences in CRT-D longevity strongly affect the overall therapy cost. While the use of recent-generation devices has reduced the cost, significant differences exist among currently available systems.

Applications of shape memory alloys for neurology and neuromuscular rehabilitation

Shape memory alloys (SMAs) are a very promising class of metallic materials that display interesting nonlinear properties, such as pseudoelasticity (PE), shape memory effect (SME) and damping capacity, due to high mechanical hysteresis and internal friction. Our group has applied SMA in the field of neuromuscular rehabilitation, designing some new devices based on the mentioned SMA properties: in particular, a new type of orthosis for spastic limb repositioning, which allows residual voluntary movement of the impaired limb and has no predetermined final target position, but follows and supports muscular elongation in a dynamic and compliant way. Considering patients in the sub-acute phase after a neurological lesion, and possibly bedridden, the paper presents a mobiliser for the ankle joint, which is designed exploiting the SME to provide passive exercise to the paretic lower limb. Two different SMA-based applications in the field of neuroscience are then presented, a guide and a limb mobiliser specially designed to be compatible with diagnostic instrumentations that impose rigid constraints in terms of electromagnetic compatibility and noise distortion. Finally, the paper discusses possible uses of these materials in the treatment of movement disorders, such as dystonia or hyperkinesia, where their dynamic characteristics can be advantageous.

Longevity of implantable cardioverter-defibrillators for cardiac resynchronization therapy in current clinical practice: an analysis according to influencing factors, device generation, and manufacturer

Aims

Device replacement at the time of battery depletion of implantable cardioverter-defibrillators (ICDs) may carry a considerable risk of complications and engenders costs for healthcare systems. Therefore, ICD device longevity is extremely important both from a clinical and economic standpoint. Cardiac resynchronization therapy defibrillators (CRT-D) battery longevity is shorter than ICDs. We determined the rate of replacements for battery depletion and we identified possible determinants of early depletion in a series of patients who had undergone implantation of CRT-D devices.

Methods and results

We retrieved data on 1726 consecutive CRT-D systems implanted from January 2008 to March 2010 in nine centres. Five years after a successful CRT-D implantation procedure, 46% of devices were replaced due to battery depletion. The time to device replacement for battery depletion differed considerably among currently available CRT-D systems from different manufacturers, with rates of batteries still in service at 5 years ranging from 52 to 88% (log-rank test, P < 0.001). Left ventricular lead output and unipolar pacing configuration were independent determinants of early depletion [hazard ratio (HR): 1.96; 95% 95% confidence interval (CI): 1.57–2.46; P < 0.001 and HR: 1.58, 95% CI: 1.25–2.01; P < 0.001, respectively]. The implantation of a recent-generation device (HR: 0.57; 95% CI: 0.45–0.72; P < 0.001), the battery chemistry and the CRT-D manufacturer (HR: 0.64; 95% CI: 0.47–0.89; P = 0.008) were additional factors associated with replacement for battery depletion.

Conclusion

The device longevity at 5 years was 54%. High left ventricular lead output and unipolar pacing configuration were associated with early battery depletion, while recent-generation CRT-Ds displayed better longevity. Significant differences emerged among currently available CRT-D systems from different manufacturers.

Cardiac resynchronization therapy in heart failure patients with atrial fibrillation

Cardiac resynchronization therapy (CRT) is an important device-based, non-pharmacological approach that has shown, in large randomized trials, to improve left ventricular (LV) function and reduce both morbidity and mortality rates in selected patients affected by advanced heart failure (HF): New York Heart Association (NYHA) functional class III–IV, reduced LV systolic function with an ejection fraction (EF) ≤35%, QRS duration ≥120 ms, on optimal medical therapy, and who were in sinus rhythm. For the first time, the latest ESC and AHA/ACC/HRS Guidelines have considered atrial fibrillation (AF) patients, who constitute an important subgroup of HF patients, as eligible to receive CRT. Nevertheless, these Guidelines did not include a strategy for defining differentiated approaches according to AF duration or burden. In this review, the authors explain in which way AF may interfere with adequate CRT delivery, how to manage different AF burden, and finally present a brief overview on the effects of CRT in AF patients.

Cardiac Resynchronisation Therapy in Heart Failure Patients with Atrial Fibrillation

Cardiac resynchronisation therapy (CRT) is an important device-based, non-pharmacological approach that has been shown to improve left ventricular (LV) function and reduce both morbidity and mortality rates in selected patients affected by advanced heart failure (HF), with New York Heart Association (NYHA) functional class III–IV, ejection fraction (EF) ≤35%, QRS duration ≥120ms and on optimal medical therapy. Patients with atrial fibrillation (AF), who constitute an important subgroup of HF patients, are nowadays considered eligible for receiving CRT as described in the latest European Society of Cardiology (ESC) and American Heart Association/American College of Cardiology/Heart Rhythm Society (AHA/ACC/HRS) guidelines, with some relevant differences in terms of how to manage the interference of natural rhythm and biventricular pacing. In this article, the authors explain how AF may interfere with adequate CRT delivery and how to manage different AF burdens, trying to obtain the best effects of CRT in AF patients.

Insulin-treated type 2 diabetes is associated with a decreased survival in heart failure patients after cardiac resynchronization therapy

BACKGROUND

Cardiac resynchronization therapy (CRT) improves cardiac performance and survival in patients with congestive heart failure. Recent observations suggest that diabetes is associated with a worse outcome in these patients. The aim of the study was to investigate the effect of diabetes and insulin treatment on outcome after CRT.

METHODS

Diabetic status and insulin treatment were assessed in 447 patients who underwent CRT (males 80.8%, mean age 65.7 +/- 9.7 years, ejection fraction 29.9 +/- 6.11%). Patients were stratified in three groups according to the presence or absence of diabetes and insulin treatment.

RESULTS

Nondiabetic patients were 366 (79.6%), noninsulin-treated diabetic patients 62 (13.9%), insulin-treated diabetic patients 29 (6.5%). The estimated death rate was 5.15 per 100 patients-year in the nondiabetic group, 8.63 in noninsulin-treated diabetics (HR 1.59, P = 0.240), and 15.84 in insulin-treated diabetics (HR 3.05, P = 0.004). Cardiac mortality accounted for 81% of deaths in nondiabetic patients and for 56% of deaths in diabetic patients. Diabetic patients tended to have a worse recovery of left ventricular ejection fraction over time (P = 0.057) and of the distance at 6-minute walking test (6MWT) (P = 0.018).

CONCLUSIONS

Insulin-treated diabetes is associated with a worse functional recovery and a higher mortality in patients with advanced heart failure after CRT. While cardiac death accounts for the majority of deaths in nondiabetic patients, a relevant proportion of the mortality in diabetic patients seem to result from noncardiac causes.

Remission of left ventricular systolic dysfunction and of heart failure symptoms after cardiac resynchronization therapy: temporal pattern and clinical predictors

BACKGROUND

The aim of the study was to determine whether cardiac resynchronization therapy (CRT) may induce a heart failure (HF) remission phase (recovery to New York Heart Association functional class I-II and regression of left ventricular [LV] dysfunction: LV ejection fraction [EF] > or = 50%) and to define the incidence and predictors of such a process.

METHODS

Cardiac resynchronization therapy devices were successfully implanted in 520 consecutive HF patients from 1999 to 2006 (mean age 66 years, 82% male sex, New York Heart Association class > or = II, LVEF 28%, QRS 164 milliseconds, 6-minute hall walk distance 302 m) at our institution. Follow-up data were prospectively collected every 3 to 6 months. Continuous variables were stratified in tertiles.

RESULTS

Over a median follow-up of 28 months, 26% of patients achieved LV remission (rate: 16 per 100 person-years). At univariate analysis, female sex (P = .032), non-coronary artery disease (CAD) etiology (P < .001), mitral regurgitation < 2/4 (P = .022), higher EF tertile (P < .001), lower diameter and volume tertiles (both P < .001), previous conventional right ventricle pacing (P = .029), and post-CRT-paced QRS (P = .008) predicted remission. At multivariate analysis, non-CAD etiology, LVEF 30% to 35%, and LV end-diastolic volume < 180 mL were strongly associated with HF remission phase (all P < .001). Concomitance of these 3 factors yielded a significantly higher remission rate compared with either no or only 1 factor (respectively, 60 vs 7 and 11 per 100 person-years, P < .001).

CONCLUSIONS

Cardiac resynchronization therapy induces HF remission phase in 26% of patients, even after 3 years. Non-CAD etiology and moderately compromised LV function at baseline may easily predict this process.

Three Years of Cardiac Resynchronization Therapy: Could Superior Benefits be Obtained in Patients with Heart Failure and Narrow QRS?

AIM OF THE STUDY

To examine the long-term effects of cardiac resynchronization therapy (CRT) in patients presenting with heart failure (HF) and QRS </= 120 ms.

METHODS

This was a prospective, longitudinal study of 376 patients [mean age = 65 years, mean left ventricular (LV) ejection fraction (EF) = 29%, mean QRS duration = 165 ms, mean distance covered during a 6-minute hall walk (6-MHW) = 325 m], who underwent successful implantation of CRT systems. The QRS duration at baseline was </= 120 ms in 45 patients (12%) who were not pre-selected by echocardiographic criteria of dyssynchrony, and > 120 ms in the remaining 331 patients. The baseline characteristics of the 2 groups were similar. We evaluated indices of cardiac function, percentage of responders, and survival rates over a mean 28-month follow-up.

RESULTS

Both groups experienced similar long-term increases in 6-MHW, and decreases in New York Heart Association functional class and LV end-systolic volume (all comparisons P < 0.0001 in both groups). Time interaction of changes in LVEF and percentage of responders were significantly different (P = 0.03 and P = 0.004, respectively), in favor of the narrow QRS group, where the changes were sustained and persisted at 2 and 3 years. The long-term death rate from HF was lower in the group with narrow than in the group with wide QRS complex (P = 0.04; log-rank test).

CONCLUSIONS

CRT confers considerable long-term clinical, functional, and survival benefits in patients presenting with HF and narrow QRS, not preselected by echocardiographic criteria of dyssynchrony. Caution is advised before denying CRT to these patients on the basis of QRS width only.

Four-Year Efficacy of Cardiac Resynchronization Therapy on Exercise Tolerance and Disease Progression

OBJECTIVES

The goal of this study was to investigate the effects of cardiac resynchronization therapy (CRT) in heart failure patients with permanent atrial fibrillation (AF) and the role of atrioventricular junction (AVJ) ablation.

BACKGROUND

Cardiac resynchronization therapy has been proven effective in heart failure patients with sinus rhythm (SR). However, little is known about the effects of CRT in heart failure patients with permanent AF.

METHODS

Efficacy of CRT on ventricular function, exercise performance, and reversal of maladaptive remodeling process was prospectively compared in 48 patients with permanent AF in whom ventricular rate was controlled by drugs, thus resulting in apparently adequate delivery of biventricular pacing (>85% of pacing time), and in 114 permanent AF patients, who had undergone AVJ ablation (100% of resynchronization therapy delivery). The clinical and echocardiographic long-term outcomes of both groups were compared with those of 511 SR patients treated with CRT.

RESULTS

Both SR and AF groups showed significant and sustained improvements of all assessed parameters (model p < 0.001 for all parameters). However, within the AF group, only patients who underwent ablation showed a significant increase of ejection fraction (p < 0.001), reverse remodeling effect (p < 0.001), and improved exercise tolerance (p < 0.001); no improvements were observed in AF patients who did not undergo ablation.

CONCLUSIONS

Heart failure patients with ventricular conduction disturbance and permanent AF treated with CRT showed large and sustained long-term (up to 4 year) improvements of left ventricular function and functional capacity, similar to patients in SR, only if AVJ ablation was performed.

Delayed Defibrillation Testing in Patients Implanted with Biventricular ICD (CRT-D): A Reliable and Safe Approach

BACKGROUND

Defibrillation testing (DT) at the end of the implantation of cardiac resynchronization pacemaker with a defibrillator (CRT-D) exposes heart failure (HF) patients to increased procedural risks. However, until now, delayed DT has not been assessed as a possible option in HF patients implanted with CRT-D.

OBJECTIVE

Aim of the present study is to assess safety and feasibility of delayed DT in HF patients treated with CRT-D.

MATERIAL AND METHODS

Two hundred and eleven consecutive patients (mean age: 65 years, mean NYHA class 3.0, mean EF: 29.3%) underwent CRT-D implantation from October 1999 to December 2004. In the first 17 patients, DT was performed at the end of CRT-D implantation. In the other 194 consecutive patients, DT was performed at 2 months after CRT-D implantation. Outcome of DT, as well as "acute" LV lead dislodgment rate were evaluated in the latter group of 194 patients undergoing a delayed DT. Also, ICD function was assessed through device telemetry analysis at 2 months.

RESULTS

At delayed DT, first shock was effective in 187 of 194 patients (96%), ineffective VF interruption at maximum energy occurred only in one patient (0.5%), and acute LV lead dislodgment was 1%. No ICD therapy failure occurred in the 2-month untested period.

CONCLUSION

DT performed 2 months after CRT-D implantation is safe and feasible; this is possibly related to the improvement of clinical conditions and hemodynamic status as well as greater lead stability 2 months after CRT-D.

Flecainide test in Brugada syndrome: a reproducible but risky tool

The flecainide test is widely used in Brugada syndrome. However, its reproducibility and safety remain ill-defined. This study included 22 patients (18 men, mean age 34 years). Mutations in the SCN5A gene were found in eight patients. Two patients had aborted sudden cardiac death, 8 had syncope/presyncope, and 12 were asymptomatic. The ECG was diagnostic in 19 patients and suggestive in 3. At baseline, 21 of 22 patients underwent a flecainide test (2 mg/kg IV bolus over 10 minutes). In 21 of 21 patients the test was diagnostic or amplified the typical ECG pattern. At the end of drug infusion, sustained VT lasting 7-10 minutes developed in two patients. A second flecainide test was performed within 2 months in 20 patients. The test was not repeated in the two patients with prior development of VT. The flecainide test was diagnostic in 20 of 20 patients. Sustained VT occurred in one patient and recurrent VF in another. The reproducibility of the flecainide test was 100%. In 4 (18%) of 22 patients major VAs were documented after the end of flecainide infusion. VA occurred in 3 (43%) of 7 patients with, versus 1 (7%) 15 without SCN5A gene mutation (P < 0.05). No diagnostic ECG changes or arrhythmias developed in 25 control patients without structural heart disease who underwent the same study protocol. This study shows a high flecainide reproducibility, supporting its diagnostic value in Brugada syndrome. However, the occurrence of major VA, significantly higher in patients with documented SCN5A gene mutation, including in asymptomatic patients, mandates the performance under appropriate medical supervision. Whether a slower rate of drug infusion can lower the risk of VA induction, while maintaining the sensitivity of the test should be explored.

Biventricular pacing via a persistent left superior vena cava: report of four cases

Persistence of left superior vena cava (LSVC) is an uncommon finding during pacemaker implantation, which may be particularly relevant in performing LV transvenous pacing. Rarely, it is further complicated by the presence of atresia of the coronary sinus ostium (CSO). This article reports the authors experience with biventricular pacing (Biv-P) in this unusual clinical setting. From October 1999 to April 2002, 158 patients underwent biventricular pacing. In four of them (mean age 62.2 years), the presence of a persistent LSVC draining into the coronary sinus (CS) was detected at implantation, associated with atresia of the CSO in two patients. A common characteristic was the angiographic finding of a large CS with few tributaries. The LV leads were successfully positioned in the middle cardiac vein in three patients and in a posterolateral vein in one patient. All vessels were large and their cannulation via downstream CS catheterization required the lead to be manipulated through sharp angles. Mean fluoroscopic exposure and procedural times were not significantly different from the overall Biv-P population. In all patients, at a mean follow-up of 11 months, sensing and capture threshold remained stable and a significant decrease in NYHA functional class and increase in LVEF were noted. The direct lead placement in large CS tributaries in the presence of persistent LSVC was feasible and safe. The leads remained stable up to a mean follow-up of nearly 1 year.

Relief of drug refractory angina by biventricular pacing in heart failure

Since cardiac resynchronization therapy (CRT) improves LV function at the cost of low energetic expenditure, the authors hypothesized that it may increase the threshold of drug refractory angina in selected patients with CHF and CAD who are not amenable to myocardial revascularization. From October 1999 to April 2002, 75 patients with CHF and CAD were treated with CRT. Drug refractory angina occurred nearly daily in 8 of the 75 patients. The mean age of these eight men was 71 years, mean NYHA functional Class 3.4 +/- 0.5, mean QRS duration (QRSd) 168 +/- 20 ms, and mean left ventricular ejection fraction (LVEF) 0.29 +/- 0.4. Diffuse CAD not amenable to myocardial revascularization was confirmed on angiography. At baseline, no patient was able to complete a 6-minute walk test because of angina. In the 6 months before CRT, the mean number of hospitalizations per patient for management of CHF or angina was 3.1 +/- 0.3. All patients underwent successful CRT. Mean QRSd decreased to 141 +/- 16 ms (P = 0.01 vs baseline). After 9 +/- 6.1 months, LVEF increased to 0.317 +/- 0.028 (P = 0.03 vs baseline), while the NYHA class decreased to 2.6 +/- 0.5 (P = 0.02 vs baseline). All patients also experienced a marked decrease in angina episodes, from a mean of 8.3 +/- 11.6 to 0.6 +/- 1.3 episodes/week (P < 0.05), and completed a 6-minute walk test, covering a mean distance of 337 +/- 68 m (vs 237 +/- 136 m at baseline, P = 0.007). No further hospitalization was necessary. The beneficial effects of CRT on overall cardiac function may include a better control of angina in severely symptomatic patients.

Programmed electrical stimulation in Brugada syndrome: how reproducible are the results?

INTRODUCTION

Inducibility of ventricular arrhythmias at programmed electrical stimulation (PES) ranges between 50% and 80% of patients with Brugada syndrome. However, the variety of PES protocols and the lack of data relative to a control group or to ventricular arrhythmia reproducibility contribute to a still undefined interpretation of PES outcome in Brugada syndrome.

METHODS AND RESULTS

Twenty-one patients with Brugada syndrome (18 men and 3 women; mean age 34 years; 9/21 symptomatic; 8/21 with SCN5A gene mutation) underwent a PES protocol from two right ventricular sites. The endpoint was PES protocol completion or induction of sustained or reproducible (>6 consecutive inductions) nonsustained (>6 beats) fast ventricular arrhythmia. In 17 of 21 patients with Brugada syndrome, PES was repeated 2 months later to test ventricular arrhythmia reproducibility. Twenty-five healthy patients (17 men; mean age 36 years) formed the control group. In patients with Brugada syndrome, ventricular arrhythmia inducibility rate at PES was high (18/21 patients [85%]) and increased with protocol aggressiveness, independent of clinical presentation. In control subjects, no ventricular arrhythmias were induced. Among patients with Brugada syndrome, 14 (82%) of 17 patients remained inducible at a second PES.

CONCLUSION

In our experience, ventricular arrhythmia inducibility in patients with Brugada syndrome, at variance with healthy controls, is high and does not correlate with clinical presentation. PES inducibility is deeply influenced by the protocol used. PES outcome is reproducible at a mid-term follow-up mainly if a categorical endpoint (inducible vs noninducible) is used. The need to assess the predictive value of specific PES protocols in targeted studies is widely emerging and is confirmed by our results.

The Barnes-Jewish Hospital/Washington University Renal Transplant Program: comparison of two eras 1991-1994 and 1995-2000

The first cadaveric transplant at Barnes-Jewish Hospital/Washington University was performed in 1963, the first living related transplant in 1965, and the first living unrelated transplant in 1983. Changes in the renal transplant program initiated in 1993 and 1994 resulted in many improvements over the past decade. Our comparison of 2 modern eras of transplant, 1991-1994 and 1995-2000, showed the following: 1. No significant differences in patient and donor characteristics. 2. Trends toward greater use of living donors (p = 0.07), older cadaveric donors (p = 0.084) and particularly cadaveric donors > 55 years of age (p = 0.09). 3. Decreasing mean CIT: 19.2 hours vs. 14.2 hours (p < 0.001). 4. Decreasing use of donors with CIT > 24 hours: 22% to 3%, (p < 0.001). 5. Decreased rate of DGF: 13% vs. 8% (p = 0.044). 6. Decreased rate of symptomatic CMV: 35% vs. 14% (p < 0.001). 7. Decreased rate of PTLD: 3.5% vs. 0.5% (p = 0.004). 8. Decreased one-year rate of acute rejection: 41% vs. 15% (p < 0.001). 9. Current one-year rate of acute rejection < 8%. 10. Decreased length of initial hospital stay: 12.7 days to 8.0 days (p < 0.001). 11. Decreased length of hospital in the first year after transplant: 10.6 days vs. 6.4 days (p < 0.001). 12. There were no improvements in patient and graft survival at one and 3 years. a. one-year patient survival rates: 95% vs. 96%. b. 3-year patient survival rates: 90% vs. 90%. c. one-year death-censored graft survival rates: 91% vs. 94%. d. 3-year death-censored graft survival rates: 87% vs. 88%.

Inferior vena cava loop of the implantable cardioverter defibrillator endocardial lead: a possible solution of the growth problem in pediatric implantation

The ICD is an important treatment option in adults and children with life-threatening tachyarrhythmias. The possibility of lead displacement caused by growth and the lack of dedicated leads and devices poses special problems in pediatric ICD implantation. We describe our experience in three children in whom we left a redundant lead loop within the inferior vena cava (IVC) is allow for further growth. Since February 1998, three children underwent ICD implantation at our institution. A lead (screw-in) was advanced into the right ventricular apex, and a loop was created in the IVC by progressively withdrawing the stylet and pushing in the lead. Satisfactory sensing and pacing threshold values were obtained and a successful single 16-J defibrillation test was performed. No complications were encountered. After a mean follow-up of 16 months, with a mean increase in body weight and height of 4.1 +/- 0.5 Kg and 6.3 +/- 0.4 cm, respectively, chest X ray showed some release of additional lead length, in the absence of dislodgments, while significant changes in pacing/sensing parameters were not found. In conclusion, the creation of a loop within the IVC allows the lead to adjust for growth in children receiving an ICD. This approach is feasible and safe.

Noncontact system-guided simplified right atrial linear lesions using radiofrequency transcatheter ablation for treatment of refractory atrial fibrillation

This article describes our experience with a staged "hybrid" approach to the treatment of drug resistant AF, in which the completeness of a single linear lesion in the RA was verified with a noncontact mapping system. Inferior vena cava-tricuspid annulus ablation was performed and followed by the creation of a single intercaval lesion. The study population consisted of 24 patients with a 3.4 +/- 1.6-year history of drug resistant, severely symptomatic, lone paroxysmal (n = 19), or persistent (n = 5) AF. During a follow-up of 8 +/- 2.6 months, 12 (50%) patients remained asymptomatic and 6 (25%) had a significant decrease in AF episodes, while the arrhythmia was unchanged in 5 (21%) patients and aggravated in 1 (4%) patient. Overall, a favorable clinical result was achieved in 18 (75%) patients.

Mapping of ventricular repolarization potentials in patients with arrhythmogenic right ventricular dysplasia: principal component analysis of the ST-T waves

BACKGROUND

Nonuniform recovery of ventricular excitability has been demonstrated to facilitate the reentry circuits leading to the development of ventricular tachyarrhythmias. This can also occur in arrhythmogenic right ventricular dysplasia (ARVD). In fact, in patients with ARVD, abnormalities of ventricular repolarization are often observed on 12-lead ECGs, but their predictive value for the occurrence of malignant arrhythmias is yet to be established. Because body-surface potential mapping has been proved to be useful for the detection of heterogeneities in ventricular recovery even though they are not revealed by conventional 12-lead ECGs, we attempted to analyze repolarization potentials on the entire chest surface to find abnormalities that can be predictive of ventricular arrhythmias.

METHODS AND RESULTS

Body-surface potential maps were recorded from 62 anterior and posterior thoracic leads in 22 patients affected by ARVD, 9 with episodes of sustained ventricular tachycardias (VT) and 13 without. Thirty-five healthy subjects were also studied as control subjects. The 62 chest ECGs were simultaneously recorded, digitally converted at a rate of 2000 Hz, and stored on a hard disk of a body-surface mapping computer system. In each subject, the QRST integral map was obtained by calculating at each lead point the algebraic sum of all instantaneous potentials, from the QRS onset to the T-wave end, multiplied by the sampling interval. In most ARVD patients, we observed a larger-than-normal area of negative values on the right anterior thorax. This abnormal pattern could be explained by a delayed repolarization of the right ventricle. Nevertheless, it was not related to the occurrence of VT in our patient population. To detect minor heterogeneities of ventricular repolarization, the principal component analysis was applied to the 62 ST-T waves recorded in each subject. We assumed that a low value of the first or of the first three components (components 1, 2, and 3) indicates a greater-than-normal variety of the ST-T waves, a likely expression of a more complex recovery process. The mean values of the first three components were not significantly different in ARVD patients and control subjects. Nevertheless, considering the two subsets of patients with and without VT, the values of component 1, components 1 + 2, and component 1 + 2 + 3 were significantly lower in the group of ARVD patients with VT. Values of component 1 < 69% (equal to 1 SD below the mean value for control subjects) were found in 6 of 9 VT patients and in 1 patient without VT (sensitivity, 67%; specificity, 92%). A low value of component 1 was the only variable significantly associated with the occurrence of VT.

CONCLUSIONS

Principal component analysis provides a better quantitative assessment of the complexity of repolarization than other ECG measurements. When applied to ARVD patients, principal component analysis of the ST-T waves recorded from the entire chest surface revealed abnormalities not detected by conventional ECG that can be considered indexes of arrhythmia vulnerability.

Living-unrelated renal transplantation provides comparable results to living-related renal transplantation: a 12-year single-center experience

BACKGROUND

The increasing success of renal transplantation is paralleled by the increased size of the waiting list. Efforts to increase the donor pool have included the use of living-unrelated kidney donors (LURDs).

METHODS

During a 12-year period our center performed 309 transplantation from living donors; 279 patients received living-related donor (LRD) transplants, and 30 patients received LURD transplants. During the same period 543 patients received cadaveric renal donor transplants. A total of 86.7% of LURD transplants were spousal transplants. A total of 29% of the patients who received LRDs were human leukocyte antigen-identical with their donors and 53% were haploidentical, versus 0 human leukocyte antigen-identical or haploidentical in the LURD group.

RESULTS

Twenty-seven (90%) Of 30 LURD recipients are alive, as are 240 (86%) of 279 LRD recipients. Mean current creatinine is 1.6 mg/dl for the LURD group and 1.7 mg/dl for the LRD group Kaplan-Meier 1- and 5-year graft survival was 94.9% and 82.9% for the LRD group, 93.1% and 85.9% for the LURD group (p = not significant), and 84.6% and 70.7% for the cadaveric renal donor group (p < 0.05).

CONCLUSIONS

LURD patient and graft survival is comparable to LRD transplants despite inferior human leukocyte antigen matching. LURD transplant survival is superior to that of cadaveric renal donor transplants. LURDs are an excellent but underused source of organs for renal transplant recipients.