Atrial Cardiomyopathy Revisited - Evolution of a Concept. A Clinical Consensus Statement of the European Heart Rhythm Association (EHRA) of the ESC, the Heart Rhythm Society (HRS), the Asian Pacific Heart Rhythm Association (APHRS), and the Latin American Heart Rhythm Society (LAHRS).

Developed in partnership with the European Heart Rhythm Association (EHRA), (a registered branch of the European Society of Cardiology (ESC)) the Heart Rhythm Society (HRS), the Asia Pacific Heart Rhythm Society (APHRS), the Latin America Heart Rhythm Society (LAHRS).

European Heart Rhythm Association (EHRA) position paper on arrhythmia management and device therapies in endocrine disorders, endorsed by Asia Pacific Heart Rhythm Society (APHRS) and Latin American Heart Rhythm Society (LAHRS).

Endocrine disorders are associated with various tachyarrhythmias, including atrial fibrillation (AF), ventricular tachycardia (VT), ventricular fibrillation (VF), and bradyarrhythmias. Along with underlying arrhythmia substrate, electrolyte disturbances, glucose, and hormone levels, accompanying endocrine disorders contribute to development of arrhythmia. Arrhythmias may be life-threatening, facilitate cardiogenic shock development and increase mortality. The knowledge on the incidence of tachy- and bradyarrhythmias, clinical and prognostic significance as well as their management is limited; it is represented in observational studies and mostly in case reports on management of challenging cases. It should be also emphasized, that the topic is not covered in detail in current guidelines. Therefore, cardiologists and multidisciplinary teams participating in care of such patients do need the evidence-based, or in case of limited evidence expert-opinion based recommendations, how to treat arrhythmias using contemporary approaches, prevent their complications and recurrence in patients with endocrine disorders. In recognizing this close relationship between endocrine disorders and arrhythmias, the European Heart Rhythm Association (EHRA) convened a Task Force, with representation from Asia-Pacific Heart Rhythm Society (APHRS) and Sociedad Latinoamericana de Estimulación Cardíaca y Electrofisiología (SOLAECE), with the remit of comprehensively reviewing the available evidence and publishing a joint consensus document on endocrine disorders and cardiac arrhythmias, and providing up-to-date consensus recommendations for use in clinical practice.

The first Latin American Catheter Ablation Registry.

AIMS: To assess the results of transcatheter ablation of cardiac arrhythmias in Latin America and establish the first Latin American transcatheter ablation registry. METHODS AND RESULTS: All ablation procedures performed between 1 January and 31 December 2012 were analysed retrospectively. Data were obtained on the characteristics and resources of participating centres (public or private institution, number of beds, cardiac surgery availability, type of room for the procedures, days per week assigned to electrophysiology procedures, type of fluoroscopy equipment, availability and type of electroanatomical mapping system, intracardiac echo, cryoablation, and number of electrophysiologists) and the results of 17 different ablation substrates: atrio-ventricular node reentrant tachycardia, typical atrial flutter, atypical atrial flutter, left free wall accessory pathway, right free wall accessory pathway, septal accessory pathway, right-sided focal atrial tachycardia, left-sided focal atrial tachycardia, paroxysmal atrial fibrillation, non-paroxysmal atrial fibrillation, atrio-ventricular node, premature ventricular complex, idiopathic ventricular tachycardia, post-myocardial infarction ventricular tachycardia, ventricular tachycardia in chronic chagasic cardiomyopathy, ventricular tachycardia in congenital heart disease, and ventricular tachycardias in other structural heart diseases. Data of 15 099 procedures were received from 120 centres in 13 participating countries (Argentina, Bolivia, Brazil, Chile, Colombia, Cuba, El Salvador, Guatemala, Mexico, Peru, Dominican Republic, Uruguay, and Venezuela). Accessory pathway was the group of arrhythmias most frequently ablated (31%), followed by atrio-ventricular node reentrant tachycardia (29%), typical atrial flutter (14%), and atrial fibrillation (11%). Overall success was 92% with the rate of global complications at 4% and mortality 0.05%. CONCLUSION: Catheter ablation in Latin America can be considered effective and safe.

Impact of prophylactic corticosteroids on systemic inflammation after extensive atrial ablation in pigs.

AIMS: Prophylactic corticosteroids have been reported to attenuate the increase in C-reactive protein (CRP) and the incidence of atrial fibrillation (AF) both after heart surgery and AF ablation. We tested the impact of a single prophylactic corticosteroid dose on ultrasensitive CRP 24 h and 14 days after extensive linear atrial ablation (8 mm or 3.5 irrigated tip) guided by electroanatomical mapping (NavX) in pigs with normal hearts. METHODS AND RESULTS: Pigs (n = 19; 35 kg) were divided into three groups: corticoid (n = 7), atrial ablation with administration of 500 mg methylprednisolone intravenous at anaesthetic induction; control (n = 7), atrial ablation only; and sham (n = 5), surgical procedure without ablation. Troponin and CRP were measured before, 24 h and 14 days after the procedure. After sacrifice, lesions were analysed macroscopically and histologically. Linear lesions were created in the right (n = 23) and left (n = 21) atrium of 14 animals, with no difference between groups. In all groups there was elevation of troponin and CRP 24 h after ablation, with a return to baseline values after 14 days. However, CRP levels of the control, corticoid, and sham groups were similar at all three time points analysed (baseline P = 0.52, 24 h P = 0.21, 14 days P = 0.66). Histological analysis did not show any difference between corticoid and control groups. CONCLUSION: In this model, extensive biatrial RF ablation, per se, does not promote systemic inflammation. The use of a prophylactic single corticoid dose before ablation did not prevent systemic inflammation or alter the healing of the lesions.

Radiofrequency ablation does not induce apoptosis in the rat myocardium.

BACKGROUND: The mechanisms implicated in the genesis of delayed radiofrequency (RF) effects remain unclear, but may be related to extension of the lesion beyond the region of coagulative necrosis. The role of apoptosis in this process has not been previously reported. We assessed whether RF promotes apoptosis in the region surrounding acute ablation lesions in a rat model. METHODS: Wistar rats (n=30; weight 300 g) were anesthesized, the chest was opened, and the heart was exposed. A modified unipolar RF ablation (custom catheter 4.5-mm-tip diameter, 12 Watts, 10 seconds) was undertaken on the left ventricular anterolateral epicardial surface and the chest was closed. After 2 hours, animals were killed for histological (hematoxylin and eosin, TdT-mediated dUTP Nick End-Labeling [TUNEL] assay) and immunohistochemical (anti-BAD and anti-caspase 3 antibodies) analysis (n=18). Additional animals (n=12) were sacrificed at 2 (n=3), 24 (n=3), 48 (n=3), and 72 hours (n=3) after ablation exclusively for anti-BAD Western Blotting analysis. RESULTS: Lesions were characterized by well-defined regions of coagulative necrosis. In 18/18 (100%) animals, TUNEL assay revealed positive luminescent reaction cells in the region surrounding the lesion, extending up to 2 mm from the border zone. However, microscopic evaluation of the nuclei and immunohistochemical and anti-BAD Western Blotting analysis were negative in all (100%) rats. Thus, positive TUNEL reaction in the periphery of the ablation lesion likely reflects nonspecific DNA damage. CONCLUSION: RF ablation does not promote apoptosis in the periphery of the myocardial lesion. This finding may have implications for the elucidation of late lesion extension following RF ablation.

Sudden cardiac death in Brazil: study based on physicians' perceptions of the public health care system.

BACKGROUND: There are no available statistical data about sudden cardiac death in Brazil. Therefore, this study has been conducted to evaluate the incidence of sudden cardiac death in our population and its implications. METHODS: The research methodology was based on Thurstone's Law of Comparative Judgment, whose premise is that the more an A stimulus differs from a B stimulus, the greater will be the number of people who will perceive this difference. This technique allows an estimation of actual occurrences from subjective perceptions, when compared to official statistics. Data were collected through telephone interviews conducted with Primary and Secondary Care physicians of the Public Health Service in the Metropolitan Area of São Paulo (MASP). RESULTS: In the period from October 19, 2009, to October 28, 2009, 196 interviews were conducted. The incidence of 21,270 cases of sudden cardiac death per year was estimated by linear regression analysis of the physicians' responses and data from the Mortality Information System of the Brazilian Ministry of Health, with the following correlation and determination coefficients: r = 0.98 and r(2) = 0.95 (95% confidence interval 0.8-1.0, P < 0.05). The lack of waiting list for specialized care and socioadministrative problems were considered the main barriers to tertiary care access. CONCLUSIONS: The incidence of sudden cardiac death in the MASP is high, and it was estimated as being higher than all other causes of deaths; the extrapolation technique based on the physicians' perceptions was validated; and the most important bureaucratic barriers to patient referral to tertiary care have been identified. (PACE 2012; 35:1326-1331).

Changes in Tachycardia Cycle Length with Varying Degrees of Right Bundle Branch Block: What Is the Mechanism?

The present case contributes to understanding the mechanism and differential diagnosis of a wide QRS complex tachycardia with varying degrees of right bundle branch block morphology.

Impact of corticosteroids on late growth of radiofrequency lesions in infant pigs: histopathological and electroanatomical findings.

AIMS: Corticosteroids attenuate late growth of radiofrequency (RF) lesions in the thigh muscle of infant rats. We sought to assess the impact of these drugs on the late growth of RF lesions in immature swine myocardium and to determine the electroanatomical mapping (EAM) characteristics of these lesions. METHODS AND RESULTS: Radiofrequency (60°C; 60 s) lesions were created in the right atrium (n = 2) and ventricle (n = 2) of 14 piglets (age 65 days; weight 5 kg) and 3 adults. Piglets were divided into: controls (n = 7) and treated (n = 7), receiving hydrocortisone (10 mg/kg iv after RF) and prednisone (1 mg/kg/day) for 29 days. After 8 months, animals were sacrificed for histological analysis. In four piglets, endocardial and epicardial voltage EAM were performed. In infant groups, the dimensions of atrial (11 ± 5 vs. 13 ± 7 mm) and ventricular (12 ± 3 vs. 11 ± 3 mm) lesions were similar. In adults, atrial (6 ± 1 mm) and ventricular (6 ± 1 mm) lesions were smaller. In controls, ventricular lesions depicted dense fibrosis and multiple strands of fibrous tissue extending from the lesion into normal muscle. Treated piglets revealed scars exhibiting less dense fibrosis with predominance of fibroadipose tissue and less collagen proliferation. Large atrial and ventricular low-voltage areas corresponding to the macroscopic lesions were identified in all animals. CONCLUSION: Radiofrequency lesions in infant pigs reveal late growth and invasion of normal muscle by intense collagen proliferation. Corticosteroids do not prevent late enlargement of the lesions but modulate the fibrotic proliferation. The expressive growth of the lesion may generate low-voltage areas detectable by EAM.

Change in cycle length during pacemaker-mediated tachycardia: What is the mechanism?

A thorough understanding of advanced device algorithms designed to promote intrinsic atrioventricular conduction is mandatory to allow appropriate management of arrhythmias induced by pacing, particularly when other types of tachycardia are involved.

Left ventricle radio-frequency ablation in the rat: a new model of heart failure due to myocardial infarction homogeneous in size and low in mortality.

BACKGROUND: The purpose of the current study was to create a model of myocardial infarction (MI) that is homogeneous in size with a low immediate (24 hours) mortality. METHODS AND RESULTS: Male and female rats (n = 256) underwent left ventricle (LV) ablation (Ab) by a radiofrequency current (1000 kHz; 12 watts for 12 seconds) to promote a MI. A transmural MI occurred in all rats. Post-Ab complex arrhythmias were frequent (atrioventricular block, ventricular tachycardia, and fibrillation), which rapidly and spontaneously reverted to sinus rhythm. Among 66 male rats, immediate mortality occurred in 7.5%. Small MI size dispersion was characterized by smaller variability following Ab (x +/- SD: 45 +/- 8%) when compared with coronary occlusion (Oc; 40 +/- 19%). The histopathologic evaluations identified lesions similar to those which occurred following Oc, with scarring complete at 4 weeks. The hemodynamic and Doppler echocardiograms showed comparable increases in LV dimension, end-diastolic pressure, and pulmonary water content 1 and 4 weeks post-MI. Papillary muscle mechanics 6 weeks post-MI had matched inotropic and lusitropic dysfunction. CONCLUSIONS: LV Ab gave rise to a MI within a narrow size limit and with a low immediate mortality. LV Ab resulted in histopathologic evolution, ventricular dilation, and dysfunction, impairment in myocardial mechanics, and congestive outcome that reproduced a MI from Oc.

Effects of corticosteroid therapy on the long-term outcome of radiofrequency lesions in the Swine caval veins.

BACKGROUND: We explored the angiographic and pathological effects of corticosteroids on the long-term outcome of radiofrequency (RF) ablation lesions in the swine caval veins. METHODS: Under fluoroscopy guidance, a single linear RF lesion (4-mm tip, 60 degrees C, 180 seconds) was created in each vena cava (from +/-2 cm into the vein to the venoatrial junction) of 20 anesthetized minipigs (35+/- 2 kg). Three groups were studied: acute (n = 4), killed 1 hour after RF; control (n = 8), sacrificed 83+/- 1 days after RF; and pigs (n = 8) receiving hydrocortisone (400 mg i.v. after RF) and prednisone (25 mg po for 30 days), killed 83+/- 1 days post-RF. Angiography was performed before, immediately after ablation, and at follow-up. Then, animals were sacrificed for histological analysis. RESULTS: Mild (<40%) or moderate (41-70%) acute luminal narrowing occurred in 19/20 (95%) inferior veins and in 13/20 (65%) superior veins. Severe (>70%) stenosis and occlusions were not noted. At follow-up, in both chronic groups, mean vessel diameters returned to baseline and progression of luminal narrowing did not occur in any vein. Of note, superior and inferior vena cava angiographic diameter for control and treated pigs did not differ. The same was observed for the cross-sectional luminal area. Acute lesions displayed transmural coagulative necrosis whereas chronic lesions revealed marked fibrosis. Histological findings were similar in controls and treated pigs. CONCLUSION: In this model, mild and moderate stenosis, occurring immediately after ablation, seems to resolve over time. Corticosteroids do not affect the long-term outcome of such RF lesions in the caval veins.

Atrial fibrillation promotion in a rat model of heart failure induced by left ventricle radiofrequency ablation.

BACKGROUND: Atrial fibrillation (AF) frequently coexists with congestive heart failure (CHF). The increased susceptibility to AF in CHF has been attributed to a variety of structural and electrophysiological changes in the atria, particularly dilation and interstitial fibrosis. We evaluated atrial remodeling and AF vulnerability in a rat model of CHF induced by left ventricle (LV) radiofrequency (RF) ablation. METHODS: Wistar rats were divided into 3 groups: RF-induced CHF (Ab, n = 36), CHF animals treated with spironolactone (AbSpi, n = 20) and sham controls (Sham, n = 29). After 12 weeks, animals underwent echocardiographic and electrophysiological evaluation and were sacrificed for histological (atrial fibrosis) and Western blotting (TGF-ß1, collagen I/III, connexin 43 and CaV1.2) analysis. RESULTS: Mild LV dysfunction and marked atrial enlargement were noted in both ablated groups. AF inducibility (episodes ≥2 s) increased in the Ab group compared to sham animals (31/36, 86%; vs. 15/29, 52%; p = 0.005), but did not differ from the AbSpi group (16/20, 80%; p = NS). Sustained AF (>30 s) was also more frequent in the Ab group compared to shams (56% vs. 28%; p = 0.04). Spironolactone reduced atrial fibrosis (p < 0.01) as well as TGF-ß1 (p < 0.01) and collagen I/III (p < 0.01) expression but did not affect connexin 43 and CaV1.2 expression. CONCLUSIONS: Rats with RF-induced CHF exhibit pronounced atrial structural remodeling and enhanced AF vulnerability. This model may be useful for studying AF substrate in CHF.

Effect of atenolol pre-treatment in heart damage in a model of intestinal ischemia-reperfusion.

PURPOSE: To investigate the effects of atenolol in inflammatory mediator and oxidative stress in a myocardial injury by intestinal ischemia/reperfusion in rat model. METHODS: Adult Wistar male rats were randomly (n=8), anesthetized and divided in: Sham: submitted to operation only; group SS+IR: intravenous saline infusion following superior mesenteric artery occlusion during 60 minutes (ischemia) and open for 120 minutes (reperfusion); group AT+IR: intravenous atenolol infusion (2 mg/kg) following superior mesenteric artery occlusion during 60 minutes (ischemia) and open for 120 minutes (reperfusion); and group AT+I+AT+R: intravenous atenolol infusion following superior mesenteric artery occlusion during 60 minutes (ischemia) and in the time 45 minutes other atenolol doses were administrated and the artery was open for 120 minutes (reperfusion), all animals were submitted to muscular relaxation for mechanical ventilation. In the end of experiment the animals were euthanized and the hearts tissue were morphology analyzed by histology and malondialdehyde by ELISA, and the plasma were analyzed for tumor necrosis factor-alpha by ELISA. RESULTS: The group SS+IR demonstrated the higher malondialdehyde levels when compared with the atenolol treated-groups (p=0.001) in the heart tissue. The tumor necrosis factor-alpha level in plasma decrease in the treated groups when compared with SS+IR group (p=0.001). Histology analyses demonstrate pyknosis, edema, cellular vacuolization, presence of inflammatory infiltrate and band contraction in the heart tissue of the rats. CONCLUSION: Atenolol significantly reduce the degree of cardiac damage after intestinal ischemia-reperfusion.