The number of articles published each year in this discipline is so colossal that any attempt to summarize them might even prove to be foolhardy. Therefore, the reader should consider the present article as a mere outline of a selection of the relevant information published in this field.

There are 2 interesting reports that take fuller advantage of the information obtained from the surface electrocardiogram. González-Torrecilla et al1 differentiate preexcitation syndromes with strictly para-Hisian accessory pathways from other anteroseptal or midseptal pathways and show that the sensitivity of the negative delta wave in leads V1-V2 for the identification of these accessory pathways is very low (25%), but that the specificity is very high (92%), and that the sum of the R-wave amplitudes in those leads (< 0.5mV) enables their identification with a sensitivity and specificity of 85.5% and 75.5%, respectively.

Haghjoo et al2 propose the presence of a “pseudo-r”’ in aVR to identify atrioventricular nodal reentrant tachycardia; it has a better statistical performance compared with the standard electrocardiographic criteria (pseudo-r’ in V1-V2 and pseudo-S in inferior leads).

Regarding electrophysiological tools for differentiating between atrioventricular nodal reentrant tachycardia and orthodromic tachycardia, previous studies have demonstrated the value of return cycles after entrainment with ventricular pacing trains from the right ventricular (RV) apex and the determination of the ventriculoatrial interval during pacing minus the ventriculoatrial interval during tachycardia. However, in 15% of patients, these measurements cannot be carried out because the tachycardia is interrupted by ventricular pacing trains. The validity of determining these same measurements after the introduction of single or double ventricular extrastimuli during tachycardia has been reported,3 with the advantage of its being applicable to practically all tachycardias.

The strong association between obstructive sleep apnea syndrome and atrial fibrillation (AF) has been recognized for years. Bazan et al4 report that, in their series, 82% of the patients with typical atrial flutter who underwent ablation had sleep apnea. During follow-up, AF developed in 38% of these patients; protective factors were the absence of previous AF and the use of continuous positive airway pressure in the patients with no history of AF. These findings are truly interesting, indicating that it may be useful to examine patients with atrial flutter for sleep apnea, because the early diagnosis of this syndrome and initiation of treatment with continuous positive airway pressure can reduce the high risk of developing AF that exists in this group.

After 1 year of follow-up of patients who had undergone ablation for typical atrial flutter, García-Seara et al5 observed improvements in left ventricular ejection fraction and diastolic function and reduced pulmonary pressure, findings that indicated reverse functional and structural remodeling after the restoration of sinus rhythm.

The literature provides a number of articles reporting contradictory findings on the use of adenosine to unmask dormant conduction following cavotricuspid isthmus ablation, like that observed in pulmonary veins. Finally, in a prospective study6 of 81 patients with a mean (standard deviation) follow-up of 12 (8) months, the authors observed that the group with transient resumption of conduction with adenosine had a higher risk of recurrence (relative risk = 31.7) and, thus, that the procedure cannot be considered to be concluded if this reconnection occurs.

In an attempt to reduce the fluoroscopy time and radiation dose without increasing total ablation time, as recently demonstrated in paroxysmal supraventricular tachycardia and atrial flutter, a new technological platform has been introduced (Mediguide Technology MG, St. Jude Medical Inc.) (Figure 1). This platform consists of creating a 3-dimensional electromagnetic field to locate sensors in medical devices (sheaths, catheters, guide wires, etc.) that enables real-time catheter tracking using prerecorded fluoroscopic images.

Figure 1.

Image acquired using MediguideTM Technology during implantation of a cardiac resynchronization therapy device. Reproduced with permission of St. Jude Medical, 2013.

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Certain ventricular arrhythmias can have fatal consequences for the patient. Thus, it is important to correctly identify the specific diagnosis, optimize treatment, and establish prognosis. Thus, Della Bella et al14 described the creation of a multidisciplinary dedicated unit for patients with ventricular tachycardia, in which ablation played an important role. In addition to presenting a large series of patients (n = 528), the authors carried out comprehensive procedures, and the acute outcomes were very good (noninducible clinical arrhythmia in > 77% of patients following the procedure), conferring an important prognostic role to electrophysiological study following ablation. The patients who continued to have inducible arrhythmias after ablation had a poorer course during follow-up due to both arrhythmia recurrence and death.

To improve diagnostic accuracy, Hoffmayer et al15 proposed a scoring system for use in the always difficult differentiation between patients with idiopathic outflow tract ventricular arrhythmia and those with arrhythmogenic RV dysplasia. This system evaluates T wave inversion in leads V1-V3 during sinus rhythm (3 points) and, during ventricular arrhythmia, a QRS duration in lead V1 > 120ms (2 points), QRS notching in several leads (2 points), and precordial transition in V5 or V6 (1 point). A score of ≥ 5 identified patients with arrhythmogenic RV dysplasia 93% of the time.

Imaging techniques, used to aid the characterization of ventricular scars, have again been the subject of a number of publications. Fernández-Armenta et al16 employed high-resolution 3-dimensional magnetic resonance in postinfarction patients and observed a larger scar area in the epicardium than in the endocardium but nevertheless detected more channels along the border of the endocardial scar than in the epicardial scar. Moreover, these channels, observed using a noninvasive technique, correlated very closely with those obtained from electroanatomic mapping.

Many postinfarction patients with ventricular arrhythmias have implantable cardioverter defibrillator (ICD) devices, which could limit the performance of magnetic resonance. Thus, Komatsu et al17 used multidetector computed tomography, correlating the areas of myocardial thinning to < 5mm with areas of low voltage and late potentials obtained by electroanatomic mapping. Despite the strong correlation, the area of thinning to < 5mm was slightly smaller than the low voltage area. In contrast, all the late potentials were found in the thinned area and the very late potentials (> 100ms post-QRS), in portions that were even thinner (< 3mm). All these findings may prove to be an aid for delimiting the area of interest in patients scheduled to undergo ventricular tachycardia ablation.

Once again, the possibility of reversing dilated cardiomyopathies following ablation of premature ventricular complexes has prompted the publication of several articles. Campos et al18 used unipolar voltage mapping to identify patients with reversible cardiomyopathy after ablation of their premature ventricular complexes when the area of unipolar amplitude abnormality (< 8.27mV) was < 32% of the total left ventricular surface (Figure 2).

Figure 2.

Electroanatomic map of the left ventricles of 2 patients with nonischemic dilated cardiomyopathy, whose unipolar voltage maps show a higher probability of reversibility (top) or irreversibility (bottom) of cardiomyopathy following ablation of premature ventricular complexes. LPO, left posterior oblique; RAO, right anterior oblique. Adapted with permission from Campos et al.18.

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During 2012, the Task Force for the Diagnosis and Treatment of Acute and Chronic Heart Failure of the ESC/EHRA (European Society of Cardiology/European Heart Rhythm Association) and the ACCF/AHA/HRS (American College of Cardiology Foundation/American Heart Association/Heart Rhythm Society) published new guidelines with recommendations on CRT.23,24 The update of the ACCF/AHA/HRS guidelines that incorporates innovations in CRT was presented in January 2013,25 and the task force on cardiac pacing and CRT of the ESC/EHRA published the update of their guidelines on cardiac pacing and CRT in August of the same year.26 Some of the modifications in the recommendations are common to both guidelines, but we can also observe certain differences (Table 2 and Figures 4 and 5). For the first time, the 2013 ESC/EHRA guidelines include recommendations on the choice between CRT alone and CRT with ICD, In candidates for CRT, clinical data favoring implantation of a CRT device alone are considered (advanced HF, severe renal failure or dialysis, comorbidities, frailty or cachexia) vs clinical data that favor CRT with ICD (stable HF in New York Heart Association functional class II, life expectancy > 1 year, ischemic heart disease with a low or intermediate MADIT risk score, and absence of comorbidities). In candidates for ICD implantation, a CRT with ICD device should be implanted, provided it is indicated.26

Figure 4.

Diagram showing the indications for cardiac resynchronization therapy in patients in sinus rhythm (A) and in those with atrial fibrillation (B), according to the 2013 update of the European Society of Cardiology/European Heart Rhythm Association guidelines. AVN, atrioventricular node; HF, heart failure; LBBB, left bundle branch block; LVEF, left ventricular ejection fraction: NYHA, New York Heart Association.

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Figure 5.

Diagram showing the indications for cardiac resynchronization therapy in patients in sinus rhythm (A) and in those with atrial fibrillation (B), according to the 2013 update of the American College of Cardiology Foundation/American Heart Association/Heart Rhythm Society guidelines. AVN, atrioventricular node; CRT, cardiac resynchronization therapy; HF, heart failure; LBBB, left bundle branch block; LVEF, left ventricular ejection fraction: NYHA, New York Heart Association.

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The purpose of optimizing the response to CRT is to reduce the rate of nonresponders.27 The recommended program includes simultaneous stimulation of both ventricles, with an atrioventricular interval programmed at 100ms to 120ms. In addition, it is recommended that the left ventricular pacing lead be implanted in a lateral or posterolateral vein to improve the response to CRT. During follow-up, the recommendation is to maintain biventricular pacing as close as possible to 100% (at least > 93%), to program the optimal atrioventricular interval to achieve the greatest possible contribution of left atrial contraction to left ventricular filling, and to program an optimal interventricular interval to reduce residual left ventricular asynchrony (even with pacing of the left ventricle alone).27,28 Standard exercise testing enables the evaluation of the loss of biventricular pacing during exercise and facilitates decision-making on drug therapy, device programming, and the need for atrioventricular node ablation in patients with CRT.29 There is increasing interest in determining the influence of structural RV changes on predicting the response to CRT, as well as the influence of remodeling of that chamber on the clinical course and incidence of ventricular arrhythmias in patients treated with CRT.30,31

A number of interesting technological advances have been introduced over the past year. One of the most notable innovations is the use of quadripolar leads with different fixation mechanisms and different distances between left ventricular pacing leads, with the accompanying development of software that enables multisite left ventricular pacing.32 Another novelty is the implantation of the first leadless left ventricular epicardial pacing system33 and CRT devices that deliver left ventricular endocardial pacing stimuli via the interventricular septum,34 a technique that will help to overcome the challenges of the coronary venous anatomy.

In recent years, remote monitoring (RM) has been gaining ground as an efficient method that is well accepted by patients with cardiac pacing systems and provides information that is similar to that provided by office visits. In recent months, several aspects of this technique have become consolidated and thus RM should be considered the monitoring system of choice, even superior to office visits. A few brief comments on some of these aspects are discussed below.

Of the articles published over the past year, 1003 included the term “cardiac pacing” as a key word. Here, we summarize those of greatest interest.

An analysis from the ASSERT trial52 compared the positive predictive value of events catalogued as atrial high-rate episodes, retrieved in a review of stored electrograms, for several atrial rate cutoff points and episode durations. The authors concluded that reviewing electrograms is crucial to interpret episodes of shorter duration. Along the lines of the results of the ASSERT trial, a prospective study involving 560 HF patients with CRT devices demonstrated that, in this group of high-risk patients, the presence of atrial arrhythmias detected by the device and reviewed by RM was associated with an increase in the risk of thromboembolic events.53 A substudy of the TRENDS trial,54 carried out in patients with implantable devices and a CHADS2 (congestive heart failure, hypertension, age, diabetes, stroke [doubled]) score ≥ 1 and no history of clinical AF, called attention to the high incidence of atrial tachycardia or AF, detected with continuous monitoring, in this group of patients (30%), which was of longer duration in patients with multiple risk factors. A substudy of the ASSERT trial55 evaluated the utility of an algorithm for atrial overdrive pacing in the prevention of AF of > 6 minutes’ duration. There were no differences between the group of patients in which the algorithm was enabled (ON) and the group in which it was not (OFF) in the incidence of AF and thromboembolic events.

This subject continues to be controversial. Two meta-analyses published in 2013 highlighted the advantages of continuing oral anticoagulation therapy over heparin administration in terms of a lower incidence of bleeding, with no difference in the rate of thromboembolic events.56,57 The BRUISE CONTROL study,58 a randomized clinical trial involving patients at moderate to high risk for embolic events undergoing device implantation, confirmed the data available to date demonstrating a lower incidence of clinically significant hematoma in those patients who continued to receive oral anticoagulation therapy compared with those treated with heparin (3.5% vs 16.0%; relative risk = 0.19; P < .001) This study will probably change the management of anticoagulation therapy in device implantation.

Significant reports dealing with syncope have appeared over the past year.

The implantable loop recorder is considered essential in the diagnosis of syncope. A Spanish study reinforced this concept. The Spanish RevealTM Registry developed by Lacunza-Ruiz et al59 was a prospective multicenter registry in which 40 centers agreed to participate. It is the largest study to evaluate implantable loop recorders to date (743 patients, 91% of them due to syncope). The results were similar to those of previous studies, with a final diagnosis for one third of the patients with a follow-up of ≥ 1 year. There were no differences in the diagnostic yield for groups that had been specified previously (bundle branch block and structural heart disease) compared with a group with no heart disease, but the authors did observe that this yield was higher in patients with recurrent syncope than in the subgroup of patients with isolated syncope or palpitations.

The treatment of vasovagal syncope is a challenge. In 2012, there were 2 significant reports in this field. After the initial enthusiasm, the use of β-blockers as treatment had been abandoned in recent years. However, a study by Sheldon et al60 has restored some of their previous prominence. The role of age in the effectiveness of metoprolol in 2 earlier studies (one observational and the other, the POST study [Prevention of Syncope Trial], was randomized), involving a total of 361 patients. Surprisingly, β-blockers were seen to increase the risk of recurrence by 58% in patients < 42 years, but beyond that age, they reduced it by 48%. Although a randomized study in patients > 40 years of age will be necessary to confirm the validity of these results, for the time being, they support their use in a population of more advanced age.

For refractory vasovagal syncope, there are very few alternatives; the pacemaker continues to be a class IIb recommendation in the most recent European guidelines26 and, thus, new therapeutic alternatives will be welcome. Autonomic modulation is gaining weight in cardiology; such is the case of renal denervation for hypertension or vagal stimulation for HF. In this context, Yao et al61 reported that denervation by radiofrequency limited to the left atrium served to treat—with excellent results over the long term (mean, 30 months)—a group of 10 highly symptomatic patients (median, 3.5 syncopal episodes during the preceding year) and positive head-up tilt test (not necessarily with a cardioinhibitory response). In this approach, the ganglionated plexi were located by high-frequency stimulation and vagal responses were observed (Figure 6). The main objective was the inhibition of these responses following radiofrequency. Ablation of left superior ganglionated plexi was achieved in 10 patients, of right superior ganglionated plexi in 5, and of left inferior ganglionated plexi in 3 (2 ganglionated plexi were ablated in 6 patients and all 3 in only 1 patient). There were no acute or denervation-related complications (such as sinus tachycardia, gastric paresis, etc), nor were there any recurrences during the follow-up period, although episodes of presyncope did occur. Conceptually, it is a very interesting study and, given the extensive experience in AF ablation, many centers could add this approach to their therapeutic arsenal for patients with refractory disease; however, it still is an aggressive treatment that can result in complications, and a more extensive study will be necessary to determine its true effectiveness.

Figure 6.

Anatomic reconstruction of the left atrium using the Ensite-NavX®. navigation system. A vagal response with significant node arrest can be observed during the application of radiofrequency to the region of the left superior ganglionated plexi (lesions marked in red) in a patient with persistent atrial fibrillation.

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A Danish report by Ruwald et al62 has raised doubts about the good prognosis of syncope in apparently healthy patients. These authors studied 37 017 patients with a first syncopal episode between 2001 and 2009, which was recorded in a nationwide database (median age, 47 years). Forty percent of these patients were selected because they had no heart disease or comorbidities, and they were followed for a mean period of 4.5 years. They were compared with a control sample of > 185 085 individuals. The all-cause mortality at 1 year was low and was identical in the 2 groups (≈ 2%), but in the subgroup of intermediate age, defined as 25 years to 74 years, the all-cause mortality was higher among patients with syncope (hazard ratio = 1.3-2.0). Over the long term, the all-cause mortality was higher in all the age groups, except the group aged > 75 years. These surprising results implied an increase in hospital admissions for cardiac causes, recurrent syncope and stroke, and a higher incidence of device implantations (pacemakers and defibrillators). Although the report has limitations (the definition of comorbidities may be vague, the lack of the electrocardiogram from the index episode, and scarce data on the type of death), it raises doubts about the prognosis of syncope in an apparently healthy population, at least in the subgroup of individuals of intermediate age, which new epidemiological studies will have to substantiate or refute.

None declared.