Search

Drylands are ecohydrologically-coupled ecosystems whose functioning depends on the interplay between hydrological connectivity between runoff source areas and the capacity of vegetation to retain water fluxes and associated resources. In this study we present a new easily applicable methodology for the ecohydrological characterization of dryland ecosystem functioning grounded in the balance between these two strongly interrelated processes using easily obtainable remote sensing data (e.g. UAV and SENTINEL-2 images), the BalanCR method (Balance between Connectivity and potential Water Retention Capacity). This methodology was first tested on synthetic hillslopes representing different configurations of the patchy and heterogenic distribution of vegetation in drylands. The analysis of these synthetic vegetation spatial patterns involving different vegetation patch densities, sizes, and fractional coverage values showed that BalanCR properly characterizes the expected ecohydrological interactions between potential conditions of runoff connectivity and water retention by plants operating in drylands. In a second step, we applied the BalanCR method on four semiarid hillslopes along an altitudinal aridity gradient covered by Mediterranean alpha steppes at very detailed spatial resolution (0.2 m) and at medium resolution (10 m). The obtained results were validated based on soil moisture data and vegetation greening and clearly recognized the four study sites as functional ecosystems, with very low water resource losses, and a pattern of increasing water redistribution processes as vegetation coverage declines. However, the sensitivity of methodology depends on the resolution of the input data (vegetation map and Digital Elevation Model; DEM), and the expected positive effect of small vegetation structures (vegetation patches smaller than the pixel size) on water redistribution is underestimated. Even in this case, the functionality and connectivity of the analyzed sites is correctly characterized as ecosystems showed similar values of both components for the methodology BalanC (hydrological connectivity component) and BalanR (potential water retention capacity component) than those obtained at very detailed scale, with a similar pattern of water allocation values in response to increased aridity. Thus, the proposed metric represents a promising tool for the proper evaluation of dryland conditions and to incorporate hillslope processes in climate change models, which is one of the main gaps to better understand the drylands response upon ongoing climate change.

Introduction and objectives There are few data on emergency visits after cryoballoon-based pulmonary vein isolation. The aim of this study was to quantify emergency department visits during the first 3 months after the procedure and to identify the reasons for consultation, final diagnoses, and the therapeutic approach. Methods Observational, retrospective study of 330 consecutive patients undergoing a first cryoballoon-based ablation procedure. Patients were followed up for 90 days after the procedure. We recorded emergency visits, symptoms, electrocardiographic data, and the therapeutic approach. Final diagnoses were classified as rhythm disorder, confirmed complication, possible complication, and unrelated to the procedure or to the arrhythmic disorder. Results A total of 112 (34%) patients attended the emergency department, 50 (44.6%) for palpitations. Sustained atrial arrhythmias were documented in 44 (39.3%) patients. Among the 29 (25.9%) visits for complications potentially related to the procedure, 5 were confirmed inguinal puncture complications and 10 were classified as unconfirmed possible complications. Forty-one visits were unrelated to the procedure or to the arrhythmic disorder. A total of 21.4% of the visits were due to palpitations requiring no therapeutic action. Conclusions A third of the patients attended the emergency department at least once, with the most frequent reason being arrhythmia-related symptoms. Late complications were rare and generally mild. Up to 20% of emergency visits could potentially be avoided by the availability of a teleconsulting system with remote electrocardiogram transmission.

Resumen Introduccion y objetivos Existe poca informacion sobre la frecuentacion a urgencias en las semanas siguientes a un procedimiento de aislamiento de venas pulmonares con criobalon. El objetivo del estudio es cuantificar las visitas a urgencias en los primeros 3 meses tras el procedimiento, evaluando los motivos, el diagnostico final y la actitud terapeutica. Metodos Estudio observacional retrospectivo sobre 330 pacientes sometidos a un primer procedimiento de crioablacion de fibrilacion auricular. Se realizo un seguimiento de 90 dias tras el procedimiento durante el que se registraron las visitas a urgencias con los sintomas que motivaron la consulta, electrocardiograma, actitud terapeutica y diagnostico final, clasificado como alteracion del ritmo, complicacion confirmada, complicacion posible y sin relacion con el procedimiento ni con el trastorno arritmico. Resultados Un total de 112 pacientes (34%) consultaron en urgencias, 50 de ellos (44,6%) por palpitaciones. En 44 pacientes (39,3%) se documento una arritmia auricular sostenida. De las 29 consultas (25,9%) por sintomas potencialmente relacionados con complicaciones del procedimiento, 5 fueron complicaciones confirmadas de la puncion inguinal, 10 quedaron con diagnostico no confirmado de posible complicacion y 41 visitas no guardaron relacion con el procedimiento. El 21,4% del total de consultas fueron por palpitaciones en las que no se tomo ninguna medida terapeutica. Conclusiones Un tercio de los pacientes consultaron en urgencias al menos 1 vez, y los sintomas arritmicos fueron el motivo mas frecuente. Las complicaciones diferidas del procedimiento son raras y, en general, benignas. La disponibilidad de un sistema de teleconsulta con transmision del ECG a distancia podria evitar hasta un 20% de los desplazamientos a urgencias.

Cryoablation is safe and effective for the treatment of atrial fibrillation (AF) in controlled clinical trials, but contemporary real-world usage and outcomes are limited. The Report of the Spanish Cryoballoon Ablation Registry (RECABA) was designed to evaluate acute and 12-month outcomes of cryoballoon ablation for the treatment of AF in Spain. Patients from 27 Spanish centers were prospectively enrolled. Patients were treated with cryoballoon ablation and managed according to standard of care protocols at each center. The primary endpoint was ≥ 30 s freedom from AF at 12-month after a 3-month blanking period. Secondary endpoints included a description of patient characteristics, cryoablation procedural strategy and safety, and predictors of efficacy. In total, 1742 patients (71.4% PAF, 68.8% male, mean age 58.02 ± 10.40 years, 76.1% overweight or obese, CHA2DS2-VASc index 1.40 ± 1.28) were enrolled. Patients received 7.2 ± 2.67 cryo-applications. PV potentials could be detected in 61% of the PVs during ablation, with a mean time to block of 52.9 ± 37.02 s. Acute PVI was observed in 97% of PVs with 75.8% isolated with the first cryo-application. Mean procedural time was 113 ± 41 min. Acute complications occurred in 4.4% of the cases. With follow-up in 1628 patients, AF-free survival was 78.5% (PAF: 80.6% vs PersAF 73.3%; p ClinicalTrials.gov number: NCT02785991.

Background Cryoablation is safe and effective for the treatment of atrial fibrillation (AF) in controlled clinical trials, but contemporary real-world usage and outcomes are limited. Objectives The Report of the Spanish Cryoballoon Ablation Registry (RECABA) was designed to evaluate acute and 12-month outcomes of cryoballoon ablation for the treatment of AF in Spain. Methods Patients from 27 Spanish centers were prospectively enrolled. Patients were treated with cryoballoon ablation and managed according to standard of care protocols at each center. Theprimary endpoint was ≥ 30 sec freedom from AF at 12-mo after a 3-mo blanking period. Secondary endpoints included a description of patient characteristics, cryoablation procedural strategy and safety, and predictors of efficacy. Results In total, 1742 patients (71.4% PAF, 68.8% male, mean age 58.02 ± 10.40 years, 76.1% overweight or obese, CHA2DS2-VASc index 1.40 ± 1.28) were enrolled. Patients received 7.2 ± 2.67 cryoapplications. PV potentials could be detected in 61% of the PVs during ablation, with a mean time to block of 52.9 ± 37.02 seconds. Acute PVI was observed in 97% of PVs with 75.8% isolated with the first cryoapplication. Mean procedural time was 113 ± 41 minutes. Acute complications occurred in 4.4% of the cases21. With follow-up in 1628 patients, AF-free survival was 78.5% (PAF: 80.6% vs PersAF 73.3%; p

Background There are limited data on ventricular arrhythmias (VAs) associated with left ventricular noncompaction (LVNC) cardiomyopathy. Objectives This study aims to analyze the clinical and electrocardiographic characteristics of VAs in a group of patients with LVNC. Methods Forty-two nonrelated patients with LVNC and VAs were included that were evaluated at the Inherited Cardiac Disease Unit of the University Hospital Virgen Arrixaca (Murcia-Spain) (ERN Guard-Heart Centre, European Reference Network for Rare and Low Prevalence Complex Diseases of the Heart). Results Thirteen patients (30.9%) had isolated LVNC, 27 (64.3%) had LVNC associated with dilated cardiomyopathy, and 2 (4.8%) had LVNC associated with hypertrophic cardiomyopathy. Among isolated LVNC individuals, 9 (69.2%) had premature ventricular complexes (PVCs)/nonsustained ventricular tachycardias (VTs), and 4 (30.8%) VTs (1 VT degenerating in ventricular fibrillation). In the dilated cardiomyopathy group, 11 (40.7%) patients had PVCs, 14 (51.9%) VTs, and 2 (7.4%) ventricular fibrillation. In the hypertrophic cardiomyopathy group, one patient had PVCs and the other VTs. Endocardial mapping and ablation were performed in 19 patients (45.2%): 7 ventricular outflow tracts (4 right ventricular outflow tract, 1 left coronary cusp, and 2 right coronary cusp), 2 in the left ventricular summit, 5 related to Purkinje potentials at the mid inferoseptal area, and 5 associated with endocardial scar localized in the basal anterolateral and inferolateral segments. Epicardial ablation was performed in 3 cases. Conclusion The substrate of VAs in LVNC cardiomyopathy is heterogeneous, with origin in ventricular outflow tracts, Purkinje system related, and resembling scar patterns in nonischemic cardiomyopathy.

Recent research has proven the existence of statistical relation among fragmented QRS and several highly prevalence diseases, such as cardiac sarcoidosis, acute coronary syndrome, arrythmogenic cardiomyopathies, Brugada syndrome, and hypertrophic cardiomyopathy. One out of five hundred people suffer from hypertrophic cardiomyopathies. The relation among the fragmentation and arrhythmias drives the objective of this work, which is to propose a valid method for QRS fragmentation detection. With that aim, we followed a two-stage approach. First, we identified the features that better characterize the fragmentation by analyzing the physiological interpretation of multivariate approaches, such as principal component analysis (PCA) and independent component analysis (ICA). Second, we created an invariant transformation method for the multilead electrocardiogram (ECG), by scrutinizing the statistical distributions of the PCA eigenvectors and of the ICA transformation arrays, in order to anchor the desired elements in the suitable leads in the feature space. A complete database was compounded incorporating real fragmented ECGs, surrogate registers by synthetically adding fragmented activity to real non-fragmented ECG registers, and standard clean ECGs. Results showed that the creation of beat templates together with the application of PCA over eight independent leads achieves 0.995 fragmentation enhancement ratio and 0.07 dispersion coefficient. In the case of ICA over twelve leads, the results were 0.995 fragmentation enhancement ratio and 0.70 dispersion coefficient. We conclude that the algorithm presented in this work constructs a new paradigm, by creating a systematic and powerful tool for clinical anamnesis and evaluation based on multilead ECG. This approach consistently consolidates the inconspicuous elements present in multiple leads onto designated variables in the output space, hence offering additional and valid visual and non-visual information to standard clinical review, and opening the door to a more accurate automatic detection and statistically valid systematic approach for a wide number of applications. In this direction and within the companion paper, further developments are presented applying this technique to fragmentation detection.

Hypertrophic cardiomyopathy, according to its prevalence, is a comparatively common disease related to the risk of suffering sudden cardiac death, heart failure and stroke. This illness is characterized by the excessive deposition of collagen among healthy myocardium cells. This situation, which is medically known as fibrosis, constitutes effective conduction obstacles in the myocardium electrical path, and when severe enough, it can be outlined as additional peaks or notches in the QRS, clinically entitled as fragmentation. Nowadays, the fragmentation detection is performed by visual inspection, but the fragmented QRS can be confused with the noise present in the electrocardiogram (ECG). On the other hand, fibrosis detection is performed by magnetic resonance imaging with late gadolinium enhancement, the main drawback of this technique being its cost in terms of time and money. In this work, we propose two automatic algorithms, one for fragmented QRS detection and another for fibrosis detection. For this purpose, we used four different databases, including the subrogated database described in the companion paper and incorporating three additional ones, one compounded by more accurate subrogated ECG signals and two compounded by real and affected subjects as labeled by expert clinicians. The first real-world database contains QRS fragmented records and the second one contains records with fibrosis and both were recorded in Hospital Cl&iacute, nico Universitario Virgen de la Arrixaca (Spain). To deeply analyze the scope of these datasets, we benchmarked several classifiers such as Neural Networks, Support Vector Machines (SVM), Decision Trees and Gaussian Na&iuml, ve Bayes (NB). For the fragmentation dataset, the best results were 0.94 sensitivity, 0.88 specificity, 0.89 positive predictive value, 0.93 negative predictive value and 0.91 accuracy when using SVM with Gaussian kernel. For the fibrosis databases, more limited accuracy was reached, with 0.47 sensitivity, 0.91 specificity, 0.82 predictive positive value, 0.66 negative predictive value and 0.70 accuracy when using Gaussian NB. Nevertheless, this is the first time that fibrosis detection is attempted automatically from ECG postprocessing, paving the way towards improved algorithms and methods for it. Therefore, we can conclude that the proposed techniques could offer a valuable tool to clinicians for both fragmentation and fibrosis diagnoses support.

Introduccion y objetivos. Los mecanismos de inicio de la fibrilacion ventricular (FV) son poco conocidos. El objetivo de este estudio es analizar el inicio de la FV en los electrogramas almacenados en los desfibriladores automaticos implantables (DAI). Metodos. Hemos analizado los electrogramas de pacientes con DAI y al menos un episodio de FV. Resultados. De una poblacion de 250 pacientes portadores de DAI, 13 tuvieron al menos un episodio de FV, 10 varones y 3 mujeres (edad, 49 ± 22 anos), diagnosticados de sindrome de Brugada (n = 4), cardiopatia isquemica (n = 3), miocardiopatia dilatada (n = 2), miocardiopatia hipertrofica (n = 1), torsades de pointes por extrasistole ventricular (EV) con acoplamiento corto (n = 1), fibroelastosis cardiaca (n = 1) y FV idiopatica (n = 1). En 7 pacientes la FV fue el motivo del implante. Se registraron 31 episodios de FV (3 tormentas arritmicas). En cada paciente, todos los episodios comenzaron con una EV de la misma morfologia y similar intervalo de acoplamiento en los 7 pacientes con mas de un episodio (minutos-3 anos). Se objetivo ciclo corto-largo-corto en 2 pacientes. En 21 episodios, se registraron EV en ritmo sinusal que no desencadenaron FV. La morfologia, el intervalo de acoplamiento (409 ± 121 frente a 411 ± 123 ms) y el ciclo del latido sinusal precedente (801 ± 233 frente a 793 ± 230 ms) no presentaron diferencias significativas al compararlas con las EV inductoras de FV. Conclusiones. La FV espontanea se desencadena por EV en las tormentas arritmicas y en episodios aislados. En ocasiones las EV preceden a la FV sin desencadenarla

Introduccion y objetivos Las miocardiopatias (MCP) y las canalopatias (CP) son causas importantes de muerte subita (MS). Existe poca informacion en la literatura sobre el contexto en el que se produce la MS, y proviene de unos pocos centros de referencia. El objetivo del presente trabajo es estudiar las circunstancias de la MS en familias con cardiopatias hereditarias. Metodos Se registraron 152 casos de MS en un total de 103 familias (media de edad, 43 ± 19 anos). Los motivos de inclusion fueron: MS resucitada, 7%; MS reciente, 8%; diagnostico de MCP o CP en un familiar vivo, 72%. El 13% eran deportistas. Se trazaron arboles familiares y se recogieron los detalles sobre las circunstancias del fallecimiento. Se revisaron historias clinicas e informes autopsicos. Resultados El 18% de las MS ocurrieron durante el ejercicio fisico, el 32% en actividades cotidianas y el 37% en reposo/sueno. Hubo una asociacion estadistica entre el sexo varon y la MS (111 [73%] frente a 41 [27%]; p = 0,03). La MS relacionada con el ejercicio se asocio con la edad joven (p = 0,01). En el grupo de MCP se registro de forma significativa un mayor porcentaje de MS en relacion con ejercicio/estres/actividad cotidiana respecto al grupo de CP (el 61 frente al 41%; p = 0,057). Todos los deportistas eran varones y la mayoria de ellos fallecieron realizando ejercicio (el 50 frente al 11% de los no deportistas; p = 0,0002). El grupo de sindrome de Brugada presento el porcentaje mas elevado de MS en reposo/sueno (47%). En el 33% del total no fue posible identificar claramente el desencadenante. Conclusiones La MS es frecuente en las cardiopatias hereditarias y supone un numero importante de casos. Entre los casos de MS (independientemente del tipo de afeccion) los varones predominan claramente sobre las mujeres (3:1). La mayoria de las MS ocurrieron realizando ejercicio o una actividad cotidiana en las miocardiopatias y durante el reposo o el sueno en las canalopatias. El porcentaje de MS relacionadas con el ejercicio (18%) es superior al esperado.

Introduction and objectives Cardiomyopathy and channelopathy are major causes of sudden death (SD). The little information available on the context in which SD occurs has come from only a few referral centers. The objective was to investigate the circumstances surrounding SD in families with inherited heart disease. Methods The study included 152 SD patients (mean age, 43[19] years) from 103 families. The reasons for inclusion were resuscitated SD in 7%, recent SD in 8%, and a diagnosis of cardiomyopathy or channelopathy in a living relative in 72%. Also, 13% were athletes. Family trees were constructed and each death's circumstances were recorded. Autopsy and medical records were reviewed. Results Overall, 18% of SDs occurred during physical exercise, 32% during normal daily activities, and 37% during rest or sleep. There was a significant association between male sex and SD: 111 males (73.0%) versus 41 females (27.0%; P =.03). Exercise-related SD was associated with young age (P=.01). The percentage of SDs associated with exercise, stress, or normal daily activities was significantly greater with cardiomyopathy than channelopathy (61% vs 41%, P =.057). All athletes were male and the majority died during exercise (50% vs 11% of non-athletes; P =.0002). Patients with Brugada syndrome had the highest percentage of SDs during rest or sleep (ie, 47%). No clear trigger could be identified in 33%. Conclusions SD was common in inherited heart disease, which accounted for a significant number of cases. Males clearly predominated over females (ratio, 3:1) among SD cases (irrespective of pathological type). Most SDs occurred during exercise or normal daily activities in cardiomyopathies and during rest or sleep in channelopathies. The percentage of exercise-related SDs (i.e. 18%) was higher than expected.

Introduction and objectives The mechanisms that trigger ventricular fibrillation (VF) are poorly understood. The aim of this study was to analyze the initiation of VF in electrograms stored in implantable cardioverter-defibrillators (ICDs). Methods We analyzed ICD electrograms from patients who had suffered at least one episode of VF. Results Of 250 patients with ICDs, 13 (10 male and 3 female, age 49±22 years) had at least one episode of VF. The diagnoses were Brugada syndrome (n=4), ischemic heart disease (n=3), dilated cardiomyopathy (n=2), hypertrophic cardiomyopathy (n=1), short-coupled variant of torsades de pointes (n=1), endocardial fibroelastosis (n=1) and idiopathic VF (n=1). In 7 patients, VF was the reason for ICD implantation. Overall, 31 episodes of VF were recorded, including three episodes of arrhythmic storm. In the 7 patients who had more than one episode of VF (within minutes or up to 3 years apart), all episodes started with premature ventricular complexes (PVCs) that had the same morphology and similar coupling intervals. A short-long-short cycle was observed in 2 patients. In 21 episodes, PVCs that did not trigger VF were observed during sinus rhythm. There was no significant difference between them and PVCs that did trigger VF in terms of morphology, coupling interval (409±121 ms vs. 411±123 ms) or the preceding sinus rhythm RR interval (801±233 ms vs. 793±230 ms). Conclusions Spontaneous VF in the form of an arrhythmic storm or an isolated episode were triggered by PVCs. On occasions, PVCs preceded VF without triggering it.

Los mecanismos de mantenimiento y finalizacion de la fibrilacion ventricular (FV) son poco conocidos. El objetivo del estudio es comparar las caracteristicas espectrales de la senal electrica de la FV sostenida y no sostenida en pacientes portadores de desfibrilador implantable. Se incluyo a 51 pacientes con al menos un episodio de FV sostenida (de mas de 5 s y que precisara choque) y no sostenida (de mas de 3 s y terminacion espontanea) registrados por el dispositivo en configuracion monopolar. Se realizo un analisis espectral de los primeros 3 s de cada episodio. La frecuencia dominante fue mayor en las FV sostenidas (4,6 ± 0,7 frente a 4,3 ± 0,6 Hz en las no sostenidas; p = 0,01), y los demas parametros fueron similares. Durante los primeros 3 s, si bien las caracteristicas espectrales son parecidas, hay diferencias utilizables en algoritmos de deteccion precoz de FV no sostenida.

AIMS Very limited data are available on the differences between spontaneous and induced episodes of ventricular fibrillation (VF) in humans. The aim of the study was to compare the spectral characteristics of the electrical signal recorded by an implantable cardioverter defibrillator (ICD) during both types of episodes. METHODS AND RESULTS Thirteen ICD patients with at least one spontaneous and one induced VF recorded by the device were included in the study. A spectral representation was obtained for the first 3 s of the intracardiac unipolar electrogram during VF. The dominant frequency (f(d)), the peak power at f(d), an organization index (OI), a bandwidth measurement, and an estimate of the correlation with a sinusoidal wave (leakage) were estimated for each episode. The f(d) was higher in induced episodes (4.75 +/- 0.57 vs. 3.95 +/- 0.59 Hz for the spontaneous episodes, P = 0.002), as well as the degree of organization assessed by the OI, bandwidth, and leakage parameters. CONCLUSION Clinical and induced VF episodes in humans have different spectral characteristics. Changes in the electrophysiological substrate or in the location of the arrhythmia wavefront at onset could play a role to explain the observed differences.

Introduccion y objetivos La historia natural de la insuficiencia cardiaca puede ser distinta en mujeres, debido a su diferente perfil clinico, terapeutico y pronostico. Nuestro objetivo fue definir las caracteristicas diferenciales de mujeres hospitalizadas por insuficiencia cardiaca. Metodos Estudiamos prospectivamente a los pacientes consecutivos dados de alta con el diagnostico de insuficiencia cardiaca (n = 412). Al alta, se registraron las variables clinicas, analiticas, ecocardiograficas y terapeuticas. Durante el seguimiento (16 ± 9 meses) se registraron mortalidad y reingreso hospitalario. Resultados Respecto a los varones, las mujeres (n = 157; 38%) presentaron: mayor edad (75 ± 12 y 71 ± 18 anos; p hazard ratio [HR] = 1,05 [1,01-1,09]) y anemia (p = 0,015; HR = 2,43 [1,16-5,12]). Conclusiones Las mujeres hospitalizadas por insuficiencia cardiaca presentan un perfil clinico diferente, con FEVI mas preservada y mayores comorbilidades, que conlleva un manejo terapeutico distinto. Su pronostico es similar al de los varones.

Introduction and objectives. To study the usefulness of incremental atrial pacing for evaluating the effect of radiofrequency catheter ablation on slow pathway conduction in patients with atrioventricular (AV) nodal reentrant tachycardia. Methods. A prospective study was carried out in patients either with (ie, AV nodal reentrant tachycardia group) or without (ie, control group) inducible AV nodal reentrant tachycardia who were referred for electrophysiologic study. Incremental atrial pacing involved gradually decreasing the pacing cycle length until the PR interval exceeded the R-R interval (ie, PR>RR) or AV nodal block occurred. The presence of dual anterograde AV nodal physiology was assessed during programmed atrial stimulation using standard criteria. In the AV nodal reentrant tachycardia group, electrophysiologic study was repeated 30 minutes after successful catheter ablation. Results. In the AV nodal reentrant tachycardia group (n=85), 52 patients (61%) exhibited dual AV nodal physiology during programmed atrial stimulation and 66 (78%) had a PR>RR during incremental atrial pacing. In the control group, the corresponding proportions were 10/56 (18%) and 7/56 (12%), respectively. After successful slow pathway catheter ablation (81/85), 37/81 exhibited dual AV nodal physiology during programmed atrial stimulation while 1/81 had a PR>RR during incremental atrial pacing. The positive predictive value of successful slow pathway ablation for the absence of a PR>RR was 98%. Conclusions. Incremental atrial pacing demonstrated that the PR interval exceeded the R-R interval in the majority of patients with inducible AV nodal reentrant tachycardia. This technique could provide a fast and simple way of evaluating the effect of radiofrequency catheter ablation on slow pathway conduction.

Introduccion y objetivos Estudiar la utilidad de la estimulacion auricular progresiva para evaluar el efecto de la ablacion con cateter sobre la conduccion por via lenta en pacientes con taquicardia por reentrada nodal comun. Metodos Estudio prospectivo en pacientes remitidos para estudio electrofisiologico en los que se indujo taquicardia por reentrada nodal comun, empleando como grupo control a los pacientes en los que no se indujo. La estimulacion auricular progresiva se practico mediante la disminucion paulatina del ciclo de estimulacion hasta obtener un intervalo PR > RR o bloqueo auriculoventricular. Durante la estimulacion auricular programada se evaluo la presencia de doble fisiologia nodal siguiendo el criterio estandarizado. En el grupo en que se indujo taquicardia se repitio el estudio electrofisiologico 30 min despues de la ablacion. Resultados En el grupo con taquicardia por reentrada nodal comun (n = 85), 52 pacientes (61%) mostraron criterios de doble via nodal durante la estimulacion auricular programada y 66 (78%) mantenian PR > RR durante la estimulacion auricular progresiva. En el grupo control, la incidencia de estos criterios fue de 10/56 (18%) y 7/56 (12%), respectivamente. Tras la ablacion eficaz de via lenta (81/85), 37 mostraban doble via nodal durante la estimulacion auricular programada y uno tenia PR > RR durante estimulacion auricular progresiva (valor predictivo positivo de la ausencia de PR > RR para ablacion eficaz de via lenta del 98%). Conclusiones La estimulacion auricular progresiva muestra un intervalo PR > RR en la mayoria de los pacientes en los que se induce taquicardia por reentrada nodal comun y puede emplearse como un metodo sencillo y rapido para evaluar el efecto de las aplicaciones de radiofrecuencia sobre la conduccion por via lenta.

Introduction and objectives Mathematical models of cardiac electrical activity may help to elucidate the electrophysiological mechanisms involved in the genesis of arrhythmias. The most realistic simulations are based on reaction-diffusion models and involve a considerable computational burden. The aim of this study was to develop a computer model of cardiac electrical activity able to simulate complex electrophysiological phenomena but free of the large computational demands required by other commonly used models. Material and method A cellular automata system was used to model the cardiac tissue. Each individual unit had several discrete states that changed according to simple rules as a function of the previous state and the state of the neighboring cells. Activation was considered as a probabilistic process and was adjusted using restitution curves. In contrast, repolarization was modeled as a deterministic phenomenon. Cell currents in the model were calculated with a prototypical action potential that allowed virtual monopolar and bipolar electrograms to be simulated at any point in space. Results Reproducible flat activation fronts, propagation from a focal stimulus, and reentry processes that were stable and unstable in two dimensions (with their corresponding electrograms) were obtained. The model was particularly suitable for the simulation of the effects observed in curvilinear activation fronts. Fibrillatory conduction and stable rotors in two- and three-dimensional substrates were also obtained. Conclusions The probabilistic cellular automata model was simple to implement and was not associated with a high computational burden. It provided a realistic simulation of complex phenomena of interest in electrophysiology.

Introduccion y objetivos Hay pocos datos sobre el pronostico del presincope en pacientes con cardiopatia. El objetivo del estudio es comparar las caracteristicas clinicas y el pronostico de los pacientes con cardiopatia estructural ingresados por sincope y por presincope en un servicio de cardiologia. Metodos Se ha revisado las historias clinicas de 449 pacientes (el 65%, varones; edad, 66,8 ± 13,1 anos) con cardiopatia estructural ingresados por sincope (n = 272) o presincope (n = 177) entre 1992 y 1998, y se ha clasificado el diagnostico final segun los criterios de la Sociedad Europea de Cardiologia. El seguimiento (completo en el 97,1%) se efectuo por conversacion con el paciente, revision de informes clinicos y entrevista con los familiares en caso de fallecimiento. Resultados No hubo diferencias significativas en las variables clinicas entre ambos grupos, excepto la fibrilacion auricular al ingreso y el antecedente de sincope previo, mas frecuentes en el grupo de presincope y sincope, respectivamente. El episodio se considero arritmico en el 25,7% de los pacientes con sincope y en el 22,0% con presincope (p = 0,37). Tras un seguimiento medio de 57,4 ± 30,5 meses, las curvas de supervivencia fueron similares en ambos grupos, sin que hubiera diferencias significativas en las causas de muerte ni en la tasa de muerte subita. Conclusiones Las caracteristicas clinicas de los pacientes con cardiopatia estructural ingresados por presincope son similares a las de los pacientes con sincope. El pronostico tampoco difiere significativamente, por lo que la aproximacion diagnostica y la estratificacion de riesgo deben ser similares en ambos grupos.

Introduccion y objetivos El desfibrilador implantable mejora la supervivencia en pacientes postinfarto de miocardio con a) fraccion de eyeccion ≤ 0,30 y b) fraccion de eyeccion ≤ 0,40, taquicardias ventriculares no sostenidas y arritmias ventriculares inducibles. Estos criterios no han sido evaluados en el contexto de la angioplastia primaria. El objetivo del estudio es evaluar el impacto de ambos criterios en las indicaciones de desfibrilador en pacientes con infarto revascularizados con angioplastia primaria. Pacientes y metodo Se estudio a 102 pacientes postinfarto (80 varones; edad, 63,6 ± 11,5 anos) incluidos en un programa regional de angioplastia primaria. Se realizo un registro Holter de 24 h entre las semanas 2 y 6 postinfarto, al mes, y se estimo la fraccion de eyeccion por ecocardiografia practicando estimulacion ventricular programada en el grupo con fraccion de eyeccion ≤ 0,40 y taquicardia ventricular no sostenida. Resultados Un total de 22 pacientes (21,6%; intervalo de confianza [IC] del 95%, 13,6-29,6) presentaron taquicardia ventricular no sostenida en el Holter. Seis de ellos tuvieron fraccion de eyeccion ≤ 0,40, siendo inducibles 2 de 5 en el estudio electrofisiologico. La fraccion de eyeccion fue ≤ 0,30 en 3 pacientes, ninguno de los cuales presento taquicardia ventricular no sostenida. En total, 5 pacientes (4,9%) tuvieron indicacion de desfibrilador aplicando alguno de los 2 criterios. Conclusiones La prevalencia de taquicardia ventricular no sostenida en pacientes con infarto tratados con angioplastia primaria es elevada. Sin embargo, la mayoria tiene una funcion ventricular conservada, por lo que la prevencion primaria con desfibrilador estaria indicada en un 5% aproximadamente utilizando los criterios evaluados en este estudio.

Arrhythmia Rounds. A 39-year-old woman with no structural heart disease and frequent episodes of sudden onset palpitations was referred for the electrophysiological study. During the study, a slightly irregular narrow QRS tachycardia with AV dissociation was repeatedly induced and spontaneously terminated. Apparently, irregular cycles and termination of the tachycardia were related to the dissociated sinus rhythm: atrial depolarizations timed when the AV junction was refractory were able to reset the tachycardia, while early atrial depolarizations caused its termination. This observation was enough to diagnose the tachycardia mechanism in our case. (J Cardiovasc Electrophysiol, Vol. 24, pp. 364-366, March 2013)

Introduction and objectives. Numerous variations of the head-up tilt-table test potentiated with nitrates have been reported. After the administration of nitroglycerin, between 10 and 25 min of continued tilting have been recommended. The aim of this study was to assess the optimal duration of the pharmacological phase of the headup tilt-table test potentiated with sublingual administration of nitroglycerin spray (NTG-TT). Method. The records of 498 consecutive NTG-TT were reviewed. Our protocol consisted of a 20-min drug-free phase at a 60 o angle. If syncope does not develop, 400 µg of sublingual nitroglycerin spray is administered and the patient continues to be tilted for a further 25 min. The test results and time to a positive response were analyzed. Results. The result of NTG-TT was positive in 288 procedures, most of them after nitroglycerin administration (255, 88.5%). The mean time to a positive response was 10.7 ± 6.7 and 5.0 ± 2.4 min during the control and pharmacological phases respectively. Most positive responses were concentrated in the 3 to 5 min after drug administration. The time to syncope after nitroglycerin administration was over 10 min in 9 patients and 15 min in only 2 patients. Conclusions. The duration of the pharmacological phase of NTG-TT using the described protocol can be reduced to 15 min without loss of sensitivity. A further reduction to 10 min would decrease the rate of positive responses by a small amount and might be considered clinically acceptable.

A 62-year-old woman who underwent heart transplantation 6 years later presented a regular atrial tachycardia. Electrophysiologic evaluation showed an atrial arrhythmia in the recipient atrium with 2:1 conduction to the donor atrium, with a confusing electroanatomical map. With the suspect of alternant conduction through two different breakthroughs, the map was split in two concordant maps, corresponding to two connections that were successfully ablated. Later on, a third connection was detected and therefore ablated. (PACE 2011; 1–3)

Introduction and objectives Long QT syndrome is an inherited ion channelopathy that leads to syncope and sudden death. Because of the heterogeneous phenotype of this disease, genetic testing is fundamental to detect individuals with concealed long QT syndrome. In this study, we determined the features of a family with 13 carriers of the KCNH2-H562R missense mutation, which affects the pore region of the HERG channel. Methods We identified the KCNH2-H562R mutation in a 65-year-old man with a prolonged QTc interval who had experienced an episode of torsade de pointes. Subsequently, a total of 13 mutation carriers were identified in the family. Carriers (age 48 [26] years; 46% males) underwent clinical evaluation, electrocardiography and echocardiography. Results The mean (standard deviation) QTc in carriers was 493 (42) ms (3 [23%] showed normal QTc); 6 (46%) had symptoms (4, syncope; 1, sudden death; 1, aborted sudden death [proband]). While under treatment with beta-blockers, 11 of 12 carriers (92%) remained asymptomatic at 5 years of follow-up (1 patient required left cardiac sympathectomy). The QTc shortening with beta-blockers was 50 (37) ms. There was 1 sudden death in a patient who refused treatment. Conclusions Family study is essential in the interpretation of a genetic testing result. This article describes the heterogeneous and variable phenotype of a large family with the KCNH2-H562R mutation and highlights the role of genetic study for the appropriate identification of at-risk individuals who would benefit from treatment.

Presentamos el caso de un paciente de 61 anos con antecedentes de un episodio de muerte subita reanimada y frecuentes episodios sincopales. En el ECG se observo el patron tipico del sindrome de Brugada y un intervalo QTc de 425 ms. La estimulacion ventricular programada indujo, de forma reproducible, taquicardia ventricular polimorfica sincopal autolimitada. Con el diagnostico de sindrome de Brugada se indico un desfibrilador automatico implantable. Dos dias despues del implante el paciente presento dos episodios de taquicardia ventricular polimorfica convertidos por el dispositivo. El ECG realizado en ese momento demostro un intervalo QTc prolongado (500 ms), ademas del patron tipico de Brugada. Se inicio tratamiento con atenolol y en los siguientes 36 meses el paciente ha permanecido asintomatico, sin nuevos episodios arritmicos. Se trata, pues, de un paciente con sindrome de Brugada que tambien cumple criterios clinicos y electrocardiograficos de sindrome de QT largo. Esto puede sugerir un vinculo genetico entre ambos sindromes.

Introduccion y objetivos La induccion de arritmias ventriculares por estimulacion ventricular antibradicardia apropiada en pacientes portadores de desfibrilador automatico implantable es un tipo de proarritmia raramente descrito. El objetivo del estudio es evaluar la incidencia, caracteristicas y manejo de este tipo de episodios. Metodos Revisamos de manera retrospectiva los registros de seguimiento de 180 pacientes portadores de desfibrilador automatico implantable con capacidad de almacenamiento de electrogramas. Se analizaron los episodios de arritmia ventricular inducidos por marcapasos, definidos como aquellos que empiezan inmediatamente despues de un estimulo apropiado de marcapasos, en un paciente con ritmo propio habitual. Se evaluaron el numero de episodios por paciente, el tipo de arritmia inducida, el modo de inicio, la terapia administrada y la efectividad de las medidas adoptadas para corregir el problema. Resultados Se detectaron episodios de arritmia ventricular inducidos por estimulacion en 9 pacientes (5%). Siete de ellos recibieron terapia, que fue efectiva en todos los casos. El numero de episodios por paciente oscilo entre uno y 95 (138 taquicardias ventriculares y 20 taquicardias ventriculares polimorficas/fibrilaciones ventriculares) y se iniciaron por estimulacion ventricular tras una pausa postextrasistolica o durante fibrilacion auricular. Los cambios en la frecuencia de estimulacion resolvieron el problema en 3 de 6 pacientes y la disminucion del voltaje de estimulacion en 3 de 3 casos. En 4 pacientes se anulo la funcion de marcapasos. Conclusiones La induccion de arritmias ventriculares por terapia antibradicardia apropiada es relativamente frecuente en pacientes portadores de desfibrilador automatico implantable. Se puede corregir cambiando la frecuencia y/o la energia de estimulacion, aunque en algun caso puede ser necesario anular la funcion de marcapasos.

An episode of device-related proarrhythmia is reported. Ventricular tachycardia was induced by ventricular pacing in a dual-chamber implantable cardioverter-defibrillator due to an inappropriate interaction of programmed device settings with the atrial preference pacing, an automatic algorithm designed to prevent atrial tachyarrhythmias.

Background: The purpose of this study was to test the feasibility of using the recording of discrete electrical potentials to guide radiofrequency catheter ablation of atriofascicular accessory pathways with Mahaim-like properties. Methods and Results: Four patients (3 females, 1 male) who fulfilled criteria for having atriofascicular accessory pathways with Mahaim-like properties and preexcited reciprocating tachycardia underwent radiofrequency catheter ablation. The mean age was 35 years (range 27–47). Symptoms were present for a mean of 10.5 years (range 6–18). Recording of discrete electrical potentials of the atriofascicular pathway was attempted by mapping the tricuspid annulus in sinus rhythm, during atrial pacing, and during reciprocating tachycardia. During atrial pacing, a mean of seven radiofrequency pulses (range 1–14), delivered to the tricuspid annulua at the area where electrical potentials were recorded, eliminated conduction through the atriofascicular accessory pathway in all patients. No complications occurred. Tachycardia did not reoccur during a mean follow-up of 5 months (range 3–9). Conclusions: Recording of discrete electrical potentials at the tricuspid annulus identifies an optimal ablation site where radiofrequency current can safely eliminate conduction through atriofascicular accessory pathways with Mahaim-like properties.

Episodes ventricular fibrillation (VF) initiated by ventricular premature complexes (VPCs) of a single morphology have been reported. However, the characteristics of the VPCs over long periods of time are unknown. To compare the morphologies and coupling intervals of VPCs that initiate episodes of VF that occur at different time periods. The database of the follow-up of the International Classification of Diseases (ICD) unit was reviewed and patients having at least two spontaneous VF episodes with available recorded EGMs in unipolar and bipolar configuration were included in the study. The coupling interval and morphology of the initiating beat were analyzed. Nine out of 300 patients with ICD had two or more spontaneous VF episodes. The time interval between episodes ranged from seconds (arrhythmic storm) to 3 years. The fibrillatory VPCs presented the same morphology in both recordings in all episodes of each patient. The coupling intervals of VPCs initiating VF were close for the episodes that occurred during a single arrhythmic storm and were more variable when the time intervals between episodes of VF were longer. VPCs triggering VF that occur at different times in the same patient have similar morphologies suggesting similar sites of origin for the initial VPC of VF in each patient.

An episode of device-related proarrhythmia is reported. Ventricular tachycardia was induced by ventricular pacing in a dual-chamber implantable cardioverter-defibrillator due to an inappropriate interaction of programmed device settings with the atrial preference pacing, an automatic algorithm designed to prevent atrial tachyarrhythmias.

The mechanisms responsible for the maintenance and termination of ventricular fibrillation (VF) are poorly understood. The aim of this study was to compare the spectral characteristics of the electrical signal during sustained and non-sustained VF in patients with an implantable cardioverter-defibrillator. The study included 51 patients who had had at least one episode of sustained VF (ie, duration >5 s and requiring shock administration) and non-sustained VF (ie, duration >3 s and spontaneously terminated) that were recorded by the device set in a unipolar configuration. Spectral analysis of the first 3 s of each episode was performed. The dominant frequency was higher in sustained VF (4.6 [0.7] Hz) than in non-sustained VF (4.3 [0.6] Hz; P=.01), while the other parameters were similar. Although the spectral characteristics of sustained and non-sustained VF were similar, differences were observed during the first 3 s that could be used in algorithms for the early detection of non-sustained VF.

Background and objectives. The natural history of heart failure (HF) may be different in women due to their clinical characteristics, treatment and prognosis being distinct. Our aim was to describe the differential characteristics of women hospitalized with HF. Methods. We prospectively studied consecutive patients who were discharged with a diagnosis of HF (n=412). Clinical, laboratory, echocardiographic, and therapeutic variables were recorded at discharge. During follow-up (16 [9] months), all-cause mortality and the need for rehospitalization were recorded. Results. Compared with men, women (n=157, 38%) were older (75 [12] years vs 71 [18] years, P

To study the usefulness of incremental atrial pacing for evaluating the effect of radiofrequency catheter ablation on slow pathway conduction in patients with atrioventricular (AV) nodal reentrant tachycardia.A prospective study was carried out in patients either with (i.e., AV nodal reentrant tachycardia group) or without (i.e., control group) inducible AV nodal reentrant tachycardia who were referred for electrophysiologic study. Incremental atrial pacing involved gradually decreasing the pacing cycle length until the PR interval exceeded the R-R interval (i.e., PRRR) or AV nodal block occurred. The presence of dual anterograde AV nodal physiology was assessed during programmed atrial stimulation using standard criteria. In the AV nodal reentrant tachycardia group, electrophysiologic study was repeated 30 minutes after successful catheter ablation.In the AV nodal reentrant tachycardia group (n=85), 52 patients (61%) exhibited dual AV nodal physiology during programmed atrial stimulation and 66 (78%) had a PRRR during incremental atrial pacing. In the control group, the corresponding proportions were 10/56 (18%) and 7/56 (12%), respectively. After successful slow pathway catheter ablation (81/85), 37/81 exhibited dual AV nodal physiology during programmed atrial stimulation while 1/81 had a PRRR during incremental atrial pacing. The positive predictive value of successful slow pathway ablation for the absence of a PRRR was 98%.Incremental atrial pacing demonstrated that the PR interval exceeded the R-R interval in the majority of patients with inducible AV nodal reentrant tachycardia. This technique could provide a fast and simple way of evaluating the effect of radiofrequency catheter ablation on slow pathway conduction.

A 63-year-old female with sinus node dysfunction underwent to implantation of dual-chamber pacemaker (Reply DR, Sorin Group CRM USA, Inc.) programmed in SafeR mode (AAI DDD). Two months later, she referred a presyncopal episode. Device interrogation showed atrial fibrillation (AF) …

Patent foramen ovale (PFO) of the interatrial septum is a cardiac foetal remnant, which frequent persistence in adulthood has important implications in a variety of clinical conditions. Echographic diagnosis of PFO is based on detection of interatrial shunt by means of contrast microbubbles identification after venous injection of a first-generation echographic contrast agent. Current recommendations propose venous femoral injection of contrast for enhanced echographic detection of PFO instead of venous brachial administration, as femoral injection has been shown to have higher sensitivity for PFO detection. Inferior vena cava inflow directed toward interatrial septum has been considered the explanation for increased sensitivity of femoral delivery of contrast. In the present paper, it is hypothesised that the main determinants of these differences between injection sites are technical factors related to right atrial contrast opacification and proper transient right atrial pressure rise, rather than intraatrial flow streaming. Effects of inferior vena cava inflow stream, although significant during foetal life, would be negligible after birth. Rationale and evidence, basis for further research, and practical implications leading to a simpler and safer routine technique for echographic detection of PFO are presented and discussed.

Introduction and objectives. The magnitude of the change in heart rate during the first few minutes of the head-up tilt test has been used to predict the test’s result. The aim of this study was to investigate whether the heart rate increase during the head-up tilt test potentiated with nitroglycerin is related to the development of syncope. Patients and method. The study included 158 consecutive patients with syncope, with stable sinus rhythm, and without structural cardiac disease who were undergoing a head-up tilt test with nitroglycerin. The heart rate increment induced by the tilt maneuver and by nitroglycerin administration was calculated, and its relationship to clinical variables and to the test’s results was analyzed. Results. The head-up tilt test gave positive results in 117 patients (74%). The heart rate was 68.7 (11.3) bpm in the decubitus position and 85.1 (15.4) bpm during the first 6 min of tilting. There was strong inverse correlation between the heart rate increase induced by tilting and age (r=‐0.63; P

Publicado en la Revista Española de Cardiología 2005;58(1):41-47. Introduction and objectives. Mathematical models of cardiac electrical activity may help to elucidate the electrophysiological mechanisms involved in the genesis of arrhythmias. The most realistic simulations are based on reaction-diffusion models and involve a considerable computational burden. The aim of this study was to develop a computer model of cardiac electrical activity able to simulate complex electrophysiological phenomena but free of the large computational demands required by other commonly used models. Material and method. A cellular automata system was used to model the cardiac tissue. Each individual unit had several discrete states that changed according to simple rules as a function of the previous state and the state of the neighboring cells. Activation was considered as a probabilistic process and was adjusted using restitution curves. In contrast, repolarization was modeled as a deterministic phenomenon. Cell currents in the model were calculated with a prototypical action potential that allowed virtual monopolar and bipolar electrograms to be simulated at any point in space. Results. Reproducible flat activation fronts, propagation from a focal stimulus, and reentry processes that were stable and unstable in two dimensions (with their corresponding electrograms) were obtained. The model was particularly suitable for the simulation of the effects observed in curvilinear activation fronts. Fibrillatory conduction and stable rotors in two- and three-dimensional substrates were also obtained. Conclusions. The probabilistic cellular automata model was simple to implement and was not associated with a high computational burden. It provided a realistic simulation of complex phenomena of interest in electrophysiology. Introducción y objetivos. La utilización de modelos matemáticos de activación y propagación del impulso ha mejorado la comprensión de diversos mecanismos electrofisiológicos involucrados en la génesis de las arritmias. Las simulaciones más realistas se basan en los modelos de reacción-difusión e implican una carga computacional muy elevada. El objetivo del estudio es desarrollar un modelo de activación eléctrica cardíaca por ordenador que permita simular fenómenos electrofisiológicos complejos y que no requiera la carga computacional necesaria en otros modelos habitualmente empleados. Material y método. Se ha modelado el tejido cardíaco como un autómata celular, cada uno de cuyos elementos adopta estados discretos en función de su estado previo y del de las células vecinas siguiendo unas reglas sencillas. La activación se contempla como un proceso probabilístico y se ajusta mediante el fenómeno de restitución, mientras la repolarización se modela como un proceso determinista. Finalmente, las corrientes celulares se calculan utilizando un potencial de acción prototipo, lo que permite simular los electrogramas virtuales monopolares y bipolares en cualquier punto del espacio. Resultados. Se ha conseguido reproducir frentes planos de activación, propagación de un estímulo focal y reentradas estables e inestables en 2 dimensiones, con sus electrogramas correspondientes. El modelo es particularmente adecuado para simular los fenómenos asociados a la curvatura de los frentes, y permite reproducir la conducción fibrilatoria y los rotores estables en 2 y 3 dimensiones. Conclusiones. Aunque el modelo de autómata celular probabilístico desarrollado es sencillo y no requiere cargas computacionales elevadas, es capaz de simular de forma realista fenómenos complejos de gran interés en electrofisiología. Teoría de la Señal y Comunicaciones

Introduccion y objetivos. El incremento acentuado de la frecuencia cardiaca en los primeros minutos de la prueba de basculacion ha sido utilizado como predictor del resultado final de esta, en protocolos sin potenciacion farmacologica o con isoproterenol. El objetivo del estudio es evaluar si este incremento se relaciona con la aparicion de sincope durante la prueba de basculacion potenciada con nitroglicerina. Pacientes y metodo. Analisis retrospectivo de 158 pacientes consecutivos sometidos a prueba de basculacion potenciada con nitroglicerina por sincope, sin cardiopatia y en ritmo sinusal. Se calculo el incremento de la frecuencia cardiaca secundario a la basculacion y el debido a la nitroglicerina, relacionandolos con las variables clinicas y el resultado de la prueba. Resultados. La prueba de basculacion fue positiva en 117 pacientes (74%). La frecuencia cardiaca paso de 68,7 ± 11,3 lat/min en decubito a 85,1 ± 15,4 lat/min en los primeros 6 min posbasculacion. El incremento de frecuencia presento una fuerte correlacion negativa con la edad (r = ­-0,63; p < 0,001), pero no se relaciono significativamente con el resultado (16,8 ± 9,3 lat/min en el grupo con prueba positiva frente a 14,9 ± 11,3 en el negativo; p = 0,3). El aumento de la frecuencia cardiaca inducido por la nitroglicerina (27,3 ± 12,6 y 26,7 ± 13,4 lat/min, respectivamente; p = 0,8) tampoco predijo el resultado del test durante la fase farmacologica. Conclusiones. Los incrementos de frecuencia cardiaca en los primeros minutos despues de la basculacion y la administracion del farmaco se relacionan fundamentalmente con la edad y no tienen utilidad para predecir el resultado de la prueba de basculacion potenciada con nitroglicerina.

Introduction and objectives Few data are available on the prognosis of presyncope in patients with structural heart disease. The aim of this study was to compare the clinical characteristics and long-term prognosis of patients with structural heart disease admitted for presyncope or syncope in the cardiology department of a tertiary hospital. Methods We reviewed the medical records of 449 patients (65% men, mean age 66.8 [13.1] years) with structural heart disease admitted because of syncope (n = 272) or presyncope (n = 177) during the period from 1992 to 1998. Clinical and demographic variables were analyzed and the final diagnosis was classified according to European Society of Cardiology criteria. The follow-up (available in 97.1% of patients) consisted of a personal interview with the patient or a review of the medical records and an interview with the relatives of the patients who had died. Results Both groups had similar demographic and clinical characteristics, except for the presence of atrial fibrillation on admission, which was more common in the presyncope group. Previous syncopal episodes were more frequent in patients admitted for syncope. The mechanism of the episode was considered arrhythmic in 25.7% of the patients with syncope and 22.0% of those in the presyncope group (P = .37). After a mean follow-up of 57.4 [30.5 months the survival curves were similar for both groups and no significant differences were found regarding the causes of death or the rate of sudden death. Conclusions The clinical characteristics and the long-term prognosis in patients with structural heart disease admitted to a cardiology department for presyncope are similar to those of patients admitted for syncope. This suggests that the approach to diagnosis and risk stratification should be similar in both groups of patients.