Cardiotoxic Effects of Micrurus surinamensis (Cuvier, 1817) Snake Venom.

Micrurus surinamensis is a coral snake from the Elapidae family of wide distribution in Amazonia Forest. Its venom contains neurotoxins that induce muscular and respiratory paralysis; however, its cardiovascular action is not yet characterized. The aim of this study was to investigate the cardiotoxic effects caused by M. surinamensis poisoning in rodents. Twelve guinea pigs (Cavia porcellus) were distributed in two groups (n = 6) named as control and envenomed. The control group received 0.2 ml of PBS/BSA via intramuscular injection (IM), while envenomed animals received 0.75 µg of venom per g of body weight, also via IM. Electrocardiographic examination (ECG) and biochemical serum tests were conducted before and 2 h after inoculation. ECG of the envenomed animals revealed severe progressive arrhythmias including atrioventricular block, supraventricular, and ventricular extrasystoles. Serum biochemistry showed significant increase in CK, CK-MB, and LDH enzymes corroborating the skeletal and cardiac muscle damage. Myonecrosis and degeneration were observed in both skeletal and heart muscle; nevertheless, transmission electron microscopy revealed cardiac muscle fibers fragmentation. In conclusion, M. surinamensis venom has a potent cardiotoxic activity eliciting arrhythmogenic effects and heart damage after only 2 h of envenomation.

Ventricular arrhythmias in the Chagas disease are not random phenomena: Long-term monitoring in Chagas arrhythmias.

BACKGROUND: Variability of ventricular arrhythmias among days in patients with Chagas disease is not detected by 24 hours of Holter monitoring. OBJECTIVE: To analyze whether ventricular arrhythmias are a random phenomenon or have a reproducible behavior in patients with Chagas cardiomyopathy. METHOD: Holter monitoring was recorded in 16 subjects with a mean age of 52 ± 8 years. They were clinically stable and had ventricular couplets, isolated premature ventricular contractions (PVCs), and nonsustained ventricular tachycardia (NSVT). The recordings occurred for 7 days. Hurst exponent (HE) evaluated randomness and predictability index (PI) and repeated analysis of variance (ANOVA) assessed reproducibility. RESULTS: The HE was significantly greater than 0.5 in all 16 patients, which confirms the nonrandomness of arrhythmias in this Chagas sample. The PI for ventricular couplets and isolated PVCs was, on average, 38% and 54%, respectively. ANOVA with repeated measurement showed significant differences in the daily frequency of ventricular couplets (n = 15, P ≤ .05), isolated PVC (n = 12, P ≤ .05), and NSVT (n = 7, P ≤ .05). CONCLUSION: Ventricular arrhythmias in Chagas cardiomyopathy are not random. Dissimilarities in arrhythmias frequency make unlikely that 24 hours of Holter recording can capture this variability.

When and how does a single ventricular premature beat initiate and terminate supraventricular tachycardia?

BACKGROUND: The differential diagnosis of a supraventricular tachycardia (SVT) is accomplished using a number of pacing maneuvers. The incidence and mechanism of a single ventricular premature beat (VPB) on initiation and termination of tachycardia were evaluated during programmed electrical stimulation (PES) of the heart in patients with the two most common regular SVTs: atrioventricular re-entrant tachycardia (AVNRT) and orthodromic atrioventricular tachycardia (AVRT). METHODS: Three hundred and thirty-seven consecutive patients aged above 18 years with an inducible sustained AVNRT or AVRT were prospectively enrolled. Patients with more than one tachyarrhythmia mechanism were excluded. Two hundred and seventeen patients (64.4%) had typical slow/fast AVNRT and 120 (35.6%) had an orthodromic AVRT using a rapidly conducting accessory pathway for V-A conduction. In this cross-sectional study, we specifically report the analysis of tachycardia induction and termination by a single VPB. RESULTS: Tachycardia induction with a single VPB during sinus rhythm was seen in 7 of 120 AVRT and in only one of the 217 patients with AVNRT, (5.8% vs. 0.3%, p < 0.05). When a single VPB was delivered during basic ventricular pacing these values were 28% versus 4%, respectively, (p < 0.001). Termination of tachycardia by a single VPB was observed in nine (4.1%) patients with AVNRT and in 57 (47.5%) with AVRT (p < 0.001). CONCLUSION: Initiation of SVT by a single VPB during sinus rhythm was uncommon and favored AVRT. Termination of SVT by a single VPB was commonly seen in AVRT but rarely in AVNRT. These findings can be of help when interpreting a noninvasive arrhythmia event recording.

An unusual ectopic ventricular rhythm in a young woman.

A case of a 22-year-old young pregnant woman with palpitations and near syncope is presented. Holter monitoring showed very frequent premature beats and runs of wide complex tachycardia, refractory to antiarrhythmic drugs. Electrophysiologic evaluation disclosed spontaneous automatism arising in an atriofascicular pathway. Differential diagnosis is discussed.

Is There any Relationship Between Myocardial Repolarization Parameters and the Frequency of Ventricular Premature Contractions?

BACKGROUND: Ventricular premature contractions (VPCs) may trigger lethal ventricular arrhythmias in patients with structural heart disease. However, this role of VPCs in healthy people remains controversial once that not enough clinical trials are available. Recently, some myocardial repolarization markers, such as Tp-e interval, Tp-e/QT, and Tp-e/QTc ratios, have been reported to be useful for predicting lethal ventricular arrhythmias in various clinical disorders without structural heart disease. OBJECTIVE: In this study, we aimed to investigate the relation between VPC frequent and myocardial repolarization markers in individuals without structural heart disease. METHODS: This study included 100 patients who had complaints of dizziness and palpitations. Twelve-lead electrocardiography and 24-hour ambulatory Holter recordings were obtained from all patients. VPC burden was calculated as the total number of VPCs divided by the number of all QRS complexes in the total recording time. P-values < 0.05 were considered significant. RESULTS: Tp-e interval and Tp-e/QTc ratio were significantly higher in patients with higher VPC burden than in patients with lower VPC burden, and a positive correlation was found between these markers and VPC burden. Tp-e (ß = 1.318, p = 0.043) and Tp-e/QTc (ß = -405.136, p = 0.024) in the lead V5 were identified as independent predictors of increased VPC burden. CONCLUSIONS: Tp-e interval and Tp-e/QTc ratio increased in patients with high VPC number. Our study showed that VPCs may have a negative effect on myocardial repolarization. This interaction may lead to an increased risk of malignant arrhythmias.

Premature atrial and ventricular complexes in outpatients referred from a primary care facility.

BACKGROUND: Premature complexes are common electrocardiographic findings in daily clinical practice that require further evaluation. Investigation may sometimes be complex and expensive. The aim of our study was to analyze variables associated with premature beats identified in outpatients referred from a primary care facility. MATERIALS AND METHODS: We performed a cross-sectional study of 407 outpatients (aged 55.8±11years; 56% women) who were followed by general practitioners and were referred for resting 12-lead electrocardiograms for a routine clinical follow-up. After signing informed consent, patients answered a questionnaire and underwent physical examinations, laboratory diagnostics, transthoracic echocardiograms and 24-hour Holter monitoring to evaluate for the presence of premature complexes. After the univariate analyses, logistic regression analyses were performed with adjustment for age, sex, and cardiovascular diseases. RESULTS: Premature complexes distribution revealed that they were frequent but with low density. Premature atrial complexes (≥ 4/hours) were associated with age (Odds Ratio (OD) = 1.030, Confidence Interval (CI) 95% = 1.002 ─ 1.059, p = 0.029), brain natriuretic peptide (BNP) levels > 20mg/dL (OR = 4.489, 95%CI = 1.918 ─ 10.507, p = 0.0005), intraventricular blocks (OR = 4.184, 95%CI = 1.816 ─ 9.406, p = 0.0005) and left atrial diameter (OR = 1.065, 95%CI = 1.001 ─ 1.134, p = 0.046). Premature ventricular complexes (≥ 5/hour) were related to age (OR = 1.032, 95%CI = 1.010 ─ 1.054, p = 0.004), the use of calcium channel blockers (OR = 2.248, 95%CI = 1.019 ─ 4.954, p = 0.045), HDL-cholesterol levels (OR = 0.971, 95%CI = 0.951 ─ 0.992, p = 0.007), BNP levels > 20mg/dL (OR = 2.079, 95%CI = 0.991 ─ 0.998, p = 0.033), heart rate (OR = 1.019, 95%CI = 1.001 ─ 1.038, p = 0.041), left ventricular hypertrophy (OR = 2.292, 95%CI = 1.402 ─ 3.746, p = 0.001) and left ventricular ejection fraction (OR = 0.938, 95%CI = 0.900 ─ 0.978, p = 0.002). CONCLUSIONS: Premature complexes had low density and were associated with BNP levels > 20mg/dL, lower levels of HDL-cholesterol, left atrial enlargement and ventricular hypertrophy. The identification of premature complexes on 24-hour Holter monitor recordings of outpatients in a primary public healthcare setting was associated with uncontrolled cardiovascular risk factors that may be addressed with medical advice and therapy in a primary care setting.

Is There any Relationship Between Myocardial Repolarization Parameters and the Frequency of Ventricular Premature Contractions? / Há Alguma Relação entre os Parâmetros de Repolarização do Miocárdio e a Frequência de Contrações Ventriculares Prematuras?

Abstract Background: Ventricular premature contractions (VPCs) may trigger lethal ventricular arrhythmias in patients with structural heart disease. However, this role of VPCs in healthy people remains controversial once that not enough clinical trials are available. Recently, some myocardial repolarization markers, such as Tp-e interval, Tp-e/QT, and Tp-e/QTc ratios, have been reported to be useful for predicting lethal ventricular arrhythmias in various clinical disorders without structural heart disease. Objective: In this study, we aimed to investigate the relation between VPC frequent and myocardial repolarization markers in individuals without structural heart disease. Methods: This study included 100 patients who had complaints of dizziness and palpitations. Twelve-lead electrocardiography and 24-hour ambulatory Holter recordings were obtained from all patients. VPC burden was calculated as the total number of VPCs divided by the number of all QRS complexes in the total recording time. P-values < 0.05 were considered significant. Results: Tp-e interval and Tp-e/QTc ratio were significantly higher in patients with higher VPC burden than in patients with lower VPC burden, and a positive correlation was found between these markers and VPC burden. Tp-e (β = 1.318, p = 0.043) and Tp-e/QTc (β = -405.136, p = 0.024) in the lead V5 were identified as independent predictors of increased VPC burden. Conclusions: Tp-e interval and Tp-e/QTc ratio increased in patients with high VPC number. Our study showed that VPCs may have a negative effect on myocardial repolarization. This interaction may lead to an increased risk of malignant arrhythmias.

Resumo Fundamento: As contrações ventriculares prematuras (CVPs) podem provocar arritmias ventriculares letais em pacientes com doença cardíaca estrutural, no entanto o papel das CVPs em indivíduos saudáveis permanece controverso, já que não há muitos estudos clínicos disponíveis. Recentemente, alguns marcadores de repolarização do miocárdio, tais como o intervalo Tp-e e as relações Tp-e/QT e Tp-e/QTc, foram relatados como úteis para prognosticar arritmias ventriculares letais em diversos transtornos clínicos sem doença cardíaca estrutural. Objetivo: Neste estudo, o objetivo foi investigar a relação entre os marcadores de repolarização do miocárdio e as CVPs frequentes em indivíduos sem doença cardíaca estrutural. Métodos: Este estudo incluiu 100 pacientes com queixas de tonturas e palpitações. Eletrocardiografia de 12 derivações e registros de Holter ambulatorial de 24 horas foram obtidos de todos os pacientes. A carga de CVP foi calculada como o número total de CVPs dividido pelo número de todos os complexos de QRS no tempo de registro total. Foram considerados significativos valores p < 0,05. Resultados: O intervalo Tp-e e a relação Tp-e/QTc foram significativamente mais altos em pacientes com carga de CVP mais alta do que nos pacientes com carga de CVP inferior, e encontrou-se correlação positiva entre esses marcadores e a carga de CVP. Tp-e (β = 1,318, p = 0,043) e Tp-e/QTc (β = -405,136, p = 0,024) na derivação V5 foram identificados como preditores independentes da carga de CVP aumentada. Conclusões: O intervalo Tp-e e a razão Tp-e/QTc foram mais altos em pacientes com um valor mais alto de CVP. Nosso estudo mostrou que CVPs podem ter um efeito negativo na repolarização do miocárdio. Essa interação pode resultar em risco aumentado de arritmias malignas.

Association between premature ventricular complexes during exercise, long-term occurrence of life-threatening arrhythmia and mortality.

OBJECTIVE: Exercise-induced premature ventricular complexes (EiPVCs) are often considered as benign arrhythmias, although they are associated with a high risk of all-cause death in the general healthy population. However, an intermediate pathophysiological process remains unclear, particularly in patients with known cardiovascular disease. The aim of this study was to find an association between EiPVCs, the occurrence of life-threatening ventricular arrhythmias (LACO), and all-cause mortality in patients with cardiovascular disease. METHODS: This was an observational study of a cohort of patients with coronary artery disease (CAD) or idiopathic cardiomyopathy (ICM). Stress testing was performed as a part of the routine cardiovascular evaluation. The occurrence of EiPVCs was evaluated during exercise testing (ET). At follow-up, long-term occurrence of LACO was evaluated. A bivariate and multivariate analysis was performed. RESULTS: Out of the total of 1442 patients analysed, 700 (49%) had EiPVCs. During 14 years of following-up after ET, 106 LACO outcomes were observed. Long-term all-cause mortality was 4% (n=61). A bivariate analysis showed that patients with EiPVCs had an increased risk for LACO (RR=2.81, 95% CI; 1.9-4.3, P<.001), and for mortality (RR=2.1, CI95% 1.2-3.4, P<.01). Occurrence of LACO was also associated with a higher mortality risk (RR=5.7, 95% CI; 3.4-9.4, P<.001). After a post hoc analysis, LACO remained as a highly predictive variable for mortality. CONCLUSION: Patients with EiPVCs have a high risk of LACO and all-cause mortality. The presence of LACO could be an intermediate stage between EiPVCs and mortality in subjects with cardiovascular disease.

Accuracy of the pacemaker event recorder versus Holter-ECG to detect both symptomatic and asymptomatic ventricular arrhythmias.

BACKGROUND: Although new pacemakers can register cardiac rhythm, few studies were performed evaluating their accuracy in diagnosing ventricular arrhythmias (VA). This study aimed to assess the correlation and agreement between the pacemaker's monitor and the ambulatory Holter in detecting VA. METHODS AND RESULTS: We studied 129 patients with pacemakers, mean age 68.6 ± 19.1 years, 54.8% female. Once Holter monitoring was connected, the pacemakers' event counters were reset and clocks of both systems were synchronized to register electrocardiograms (ECG) simultaneously. Pacemakers were programmed to detect the lowest ventricular rate and lowest number of sequential beats allowed in their event monitors. After 72 hours, Holter and pacemakers records were analyzed. VA was defined in Holter and event monitor, respectively, as: isolated premature ventricular complexes: "PVC"; pairs: "couplets"; nonsustained ventricular tachycardia (NSVT): "triplets"-3 beats; "runs"-4-8 or > 8 beats, and high ventricular rates ("HVR")-3-4 beats. Spearman correlations evaluated whether pacemaker and Holter identified the same parameters. Intraclass correlation coefficients (ICCs) and respective 95% confidence intervals were calculated to assess the concordance between methods. The agreement between both systems was low, except for "triplet" and three beats NSVT (ICC = 0.984). The correlation for more than 10 PVC/h was moderate (Kappa = 0.483). When the pacemaker was programmed to detect HVR sequences of three beats lower than 140 bpm (< 140/3), the correlation with NSVT was perfect (r = 1) and agreement was also quite high (ICC = 0.800). CONCLUSIONS: Pacemakers' event monitors underestimate the occurrence of ventricular arrhythmias detected by Holter. Standardization of pacemakers' algorithms is required before using this function for patients' clinical follow-up.

Association between premature ventricular complexes during exercise, long-term occurrence of life-threatening arrhythmia and mortality / Asociación entre ectopia ventricular en ejercicio, la ocurrencia de arritmias potencialmente mortales y mortalidad a largo plazo

Abstract Objective: Exercise-induced premature ventricular complexes (EiPVCs) are often considered as benign arrhythmias, although they are associated with a high risk of all-cause death in the general healthy population. However, an intermediate pathophysiological process remains unclear, particularly in patients with known cardiovascular disease. The aim of this study was to find an association between EiPVCs, the occurrence of life-threatening ventricular arrhythmias (LACO), and all-cause mortality in patients with cardiovascular disease. Methods: This was an observational study of a cohort of patients with coronary artery disease (CAD) or idiopathic cardiomyopathy (ICM). Stress testing was performed as a part of the routine cardiovascular evaluation. The occurrence of EiPVCs was evaluated during exercise testing (ET). At follow-up, long-term occurrence of LACO was evaluated. A bivariate and multivariate analysis was performed. Results: Out of the total of 1442 patients analysed, 700 (49%) had EiPVCs. During 14 years of following-up after ET, 106 LACO outcomes were observed. Long-term all-cause mortality was 4% (n = 61). A bivariate analysis showed that patients with EiPVCs had an increased risk for LACO (RR = 2.81, 95% CI; 1.9---4.3, P < .001), and for mortality (RR = 2.1, CI95% 1.2---3.4, P < .01). Occurrence of LACO was also associated with a higher mortality risk (RR = 5.7, 95% CI; 3.4---9.4, P < .001). After a post hoc analysis, LACO remained as a highly predictive variable for mortality. Conclusion: Patients with EiPVCs have a high risk of LACO and all-cause mortality. The presence of LACO could be an intermediate stage between EiPVCs and mortality in subjects with cardiovascular disease.

Resumen Objetivo: La extrasistolia ventricular inducida por ejercicio (EVIE) suele considerarse una arritmia benigna, sin embargo, ha sido asociada a mayor mortalidad en población general. Hasta hoy no se ha encontrado el proceso fisiopatológico involucrado, particularmente en pacientes con enfermedad cardiovascular. El objetivo del estudio fue establecer una asociación entre EVIE con la ocurrencia de arritmias ventriculares potencialmente malignas (APM) y letalidad a largo plazo, en sujetos con enfermedad cardiovascular. Método: Estudiamos una cohorte de pacientes con enfermedad coronaria o miocardiopatía dilatada, que realizaron una prueba de ejercicio al inicio del estudio. Inicialmente evaluamos la ocurrencia de EVIE, APM y letalidad a largo plazo y posteriormente se realizó un estudio bivariable y multivariable. Resultados: Se incluyeron 1,442 pacientes de los cuales 700 presentaron EVIE (49%). Durante 14 an˜os de seguimiento, 106 sujetos presentaron APM y la mortalidad total fue de 61 casos (4%). El estudio bivariable mostró que aquellos pacientes con EVIE tuvieron un riesgo de presentar APM de 2.81 (IC95% de 1.9 a 4.3, p < 0.001) y de mortalidad de 2.1 (IC95% de 1.2 a 3.4, p < 0.01). Los individuos con APM tuvieron mayor riesgo de mortalidad (RR= 5.7, IC95% de 3.4 a 9.4, p < 0.001). Después de un análisis multivariable, la APM continuó siendo una variable altamente predictiva de mortalidad. Conclusión: Los pacientes con EVIE tienen un riesgo elevado de presentar APM y de mortalidad a largo plazo. Los resultados sugieren que las APM podrían representar un estado intermedio entre la presencia de EVIE y la mortalidad en pacientes con enfermedad cardiovascular.

Cholinesterase inhibition reduces arrhythmias in asymptomatic Chagas disease.

INTRODUCTION: Parasympathetic dysfunction may play a role in the genesis of arrhythmias in Chagas disease. AIM: This study evaluates the acute effects of pyridostigmine (PYR), a reversible cholinesterase inhibitor, on the occurrence of arrhythmias in patients with Chagas cardiac disease. METHOD: Following a double-blind, randomized, placebo-controlled, cross-over protocol, 17 patients (age 50±2 years) with Chagas cardiac disease type B underwent 24-hour Holter recordings after oral administration of either pyridostigmine bromide (45 mg, 3 times/day) or placebo (PLA). RESULTS: Pyridostigmine reduced the 24-hours incidence (median [25%-75%]) of premature ventricular beats-PLA: 2998 (1920-4870), PYR: 2359 (940-3253), P=.044; ventricular couplets-PLA: 84 (15-159), PYR: 33 (6-94), P=.046. Although the total number of nonsustained ventricular tachycardia in the entire group was not different (P=.19) between PLA (1 [0-8]) and PYR (0 [0-4]), there were fewer episodes under PYR in 72% of the patients presenting this type of arrhythmia (P=.033). CONCLUSION: Acute administration of pyridostigmine reduced the incidence of nonsustained ventricular arrhythmias in patients with Chagas cardiac disease. Further studies that address the use of pyridostigmine by patients with Chagas cardiac disease under a more prolonged follow-up are warranted.

Premature ventricular contractions associated with isotretinoin use

Abstract Isotretinoin has been considered a unique drug for acne treatment. However, it is associated with numerous adverse effects. Isotretinoin can trigger premature ventricular contractions. This report describes a 33-year-old-woman who presented with palpitations for 1 week while undergoing 1-month isotretinoin treatment for mild-moderate facial acne. An electrocardiogram and Holter monitoring showed premature ventricular contractions during isotretinoin (Roaccutane, Roche) treatment. Isotretinoin-related premature ventricular contractions were strongly suggested in this case due to the existence of documented premature ventricular contractions on electrocardiograms and the disappearance of these premature ventricular contractions two weeks after termination of the treatment To the authors' knowledge, there has been 1 reported case of premature ventricular contractions linked to isotretinoin use; this report describes a second such case.

Quantitative analysis of ventricular ectopic beats in short-term RR interval recordings to predict imminent ventricular tachyarrhythmia.

BACKGROUND: Most approaches to predict ventricular tachyarrhythmias which are based on RR intervals consider only sinus beats, excluding premature ventricular complexes (PVCs). The method known as heartprint, which analyses PVCs and their characteristics, has prognostic value for fatal arrhythmias on long recordings of RR intervals (>70,000 beats). OBJECTIVE: To evaluate characteristics of PVCs from short term recordings (around 1000 beats) and their prognostic value for imminent sustained tachyarrhythmia. MATERIALS AND METHODS: We analyzed 132 pairs of short term RR interval recordings (one before tachyarrhythmia and one control) obtained from 78 patients. Patients were classified into two groups based on the history of accelerated heart rate (HR) (HR>90bpm) before a tachyarrhythmia episode. Heartprint indexes, such as mean coupling interval (meanCI) and the number of occurrences of the most prevalent form of PVCs (SNIB) were calculated. The predictive value of all the indexes and of the combination of different indexes was calculated. RESULTS: MeanCI shorter than 482ms and the occurrence of more repetitive arrhythmias (sNIB≥2.5), had a significant prognostic value for patients with accelerated heart rate: adjusted odds ratio of 2.63 (1.33-5.17) for meanCI and 2.28 (1.20-4.33) for sNIB. Combining these indexes increases the adjusted odds ratio: 10.94 (3.89-30.80). CONCLUSIONS: High prevalence of repeating forms of PVCs and shorter CI are potentially useful risk markers of imminent ventricular tachyarrhythmia. Knowing if a patient has history of VT/VF preceded by accelerated HR, improves the prognostic value of these risk markers.

Short-term Effects of High-Dose Caffeine on Cardiac Arrhythmias in Patients With Heart Failure: A Randomized Clinical Trial.

IMPORTANCE: The presumed proarrhythmic action of caffeine is controversial. Few studies have assessed the effect of high doses of caffeine in patients with heart failure due to left ventricular systolic dysfunction at high risk for ventricular arrhythmias. OBJECTIVE: To compare the effect of high-dose caffeine or placebo on the frequency of supraventricular and ventricular arrhythmias, both at rest and during a symptom-limited exercise test. DESIGN, SETTING, AND PARTICIPANTS: Double-blinded randomized clinical trial with a crossover design conducted at the heart failure and cardiac transplant clinic of a tertiary-care university hospital. The trial included patients with chronic heart failure with moderate-to-severe systolic dysfunction (left ventricular ejection fraction <45%) and New York Heart Association functional class I to III between March 5, 2013, and October 2, 2015. INTERVENTIONS: Caffeine (100 mg) or lactose capsules, in addition to 5 doses of 100 mL decaffeinated coffee at 1-hour intervals, for a total of 500 mg of caffeine or placebo during a 5-hour protocol. After a 1-week washout period, the protocol was repeated. MAIN OUTCOMES AND MEASURES: Number and percentage of ventricular and supraventricular premature beats assessed by continuous electrocardiographic monitoring. RESULTS: We enrolled 51 patients (37 [74%] male; mean [SD] age, 60.6 [10.9] years) with predominantly moderate-to-severe left ventricular systolic dysfunction (mean [SD] left ventricular ejection fraction, 29% [7%]); 31 [61%] had an implantable cardioverter-defibrillator device. No significant differences between the caffeine and placebo groups were observed in the number of ventricular (185 vs 239 beats, respectively; P = .47) and supraventricular premature beats (6 vs 6 beats, respectively; P = .44), as well as in couplets, bigeminal cycles, or nonsustained tachycardia during continuous electrocardiographic monitoring. Exercise test-derived variables, such as ventricular and supraventricular premature beats, duration of exercise, estimated peak oxygen consumption, and heart rate, were not influenced by caffeine ingestion. We observed no increases in ventricular premature beats (91 vs 223 vs 207 beats, respectively) in patients with higher levels of plasma caffeine concentration compared with lower plasma levels (P = .91) or with the placebo group (P = .74). CONCLUSIONS AND RELEVANCE: Acute ingestion of high doses of caffeine did not induce arrhythmias in patients with systolic heart failure and at high risk for ventricular arrhythmias. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT02045992.

Premature ventricular contractions associated with isotretinoin use.

Isotretinoin has been considered a unique drug for acne treatment. However, it is associated with numerous adverse effects. Isotretinoin can trigger premature ventricular contractions. This report describes a 33-year-old-woman who presented with palpitations for 1 week while undergoing 1-month isotretinoin treatment for mild-moderate facial acne. An electrocardiogram and Holter monitoring showed premature ventricular contractions during isotretinoin (Roaccutane, Roche) treatment. Isotretinoin-related premature ventricular contractions were strongly suggested in this case due to the existence of documented premature ventricular contractions on electrocardiograms and the disappearance of these premature ventricular contractions two weeks after termination of the treatment To the authors' knowledge, there has been 1 reported case of premature ventricular contractions linked to isotretinoin use; this report describes a second such case.

Effect of caffeine on ventricular arrhythmia: a systematic review and meta-analysis of experimental and clinical studies.

AIMS: The relationship between caffeine consumption and the occurrence of arrhythmias remains controversial. Despite this lack of scientific evidence, counselling to reduce caffeine consumption is still widely advised in clinical practice. We conducted a systematical review and meta-analysis of interventional studies of the caffeine effects on ventricular arrhythmias. METHODS AND RESULTS: The search was performed on Pubmed, Embase, and Cochrane database, and terms related to coffee, caffeine, and cardiac arrhythmias were used. Methodological quality was assessed based on The Cochrane Collaboration recommendations and the ARRIVE guidelines. There were 2016 citations retrieved on the initial research. After full-text assessment, seven human and two animal studies were included in the meta-analysis. In animal studies, the main outcome reported was the ventricular fibrillation threshold. We observed a significant mean difference of -2.15 mA (95% CI -3.43 to -0.87; I(2) 0.0%, P for heterogeneity = 0.37). The main outcome evaluated in human studies was the rate of ventricular premature beats (VPBs). The overall relative risk for occurrence of VPBs in 24 h attributed to caffeine exposure was 1.00 (95% CI 0.94-1.06; I(2) 13.5%, P for heterogeneity = 0.32). Sensitivity analysis for caffeine dose, different designs, and subject profile was performed and no major differences were observed. CONCLUSION: Our meta-analysis demonstrates that data from human interventional studies do not show a significant effect of caffeine consumption on the occurrence of VBPs. The effects observed in animal studies are most probably the result of very high caffeine doses that are not regularly consumed in a daily basis by humans.

Radiofrequency catheter ablation of frequent premature ventricular contractions using ARRAY multi-electrode balloon catheter.

BACKGROUND: The noncontact mapping system facilitates the mapping of premature ventricular contractions (PVCs) and ventricular tachycardia (VT) using a 64-electrode expandable balloon catheter (ARRAY, St. Jude Medical). The aim of this study is to analyze the results and follow-up of the PVC ablation using this system. METHODS AND RESULTS: Prospective and consecutive patients with frequent PVCs (6,000 or more) or monomorphic VT, suspected to be originated on the right ventricular outflow tract (RVOT), were included. The balloon catheter was positioned in the RVOT. Eighteen patients, 9 women, mean age 48 years (youngest/oldest 19-65) were included. Sixteen patients presented no structural heart disease. The origin of the arrhythmia was RVOT (n = 15), right ventricular inflow tract (n = 1), and left ventricular outflow tract (n = 2). Acute success was achieved in 15 patients; in 2 patients radiofrequency was not applied due to security reasons (origin site close to left coronary artery origin). The mean follow-up was 15 months (min. 4, max. 26); 13 patients presented abolition of the arrhythmia without drugs and 1 patient required antiarrhythmic drugs for arrhythmia control (previously ineffective). As an only complication, a femoral artery-venous fistula was observed. CONCLUSIONS: The noncontact mapping system using a multielectrode balloon allows right ventricular arrhythmia treatment with a high rate of efficacy and safety.

Electrocardiographic and echocardiographic abnormalities in Chagas disease: findings in residents of rural Bolivian communities hyperendemic for Chagas disease.

BACKGROUND: Chagas disease is a neglected and preventable tropical disease that causes significant cardiac morbidity and mortality in Latin America. OBJECTIVES: This study sought to describe cardiac findings among inhabitants of rural communities of the Bolivian Chaco. METHODS: The cardiac study drew participants from an epidemiologic study in 7 indigenous Guarani communities. All infected participants 10 years or older were asked to undergo a brief physical examination and 12-lead electrocardiogram (ECG). A subset had echocardiograms. ECG and echocardiograms were read by 1 or more cardiologists. RESULTS: Of 1,137 residents 10 years or older, 753 (66.2%) had Trypanosoma cruzi infection. Cardiac evaluations were performed for 398 infected participants 10 years or older. Fifty-five participants (13.8%) had 1 or more ECG abnormalities suggestive of Chagas cardiomyopathy. The most frequent abnormalities were bundle branch blocks in 42 (11.3%), followed by rhythm disturbances or ventricular ectopy in 13 (3.3%), and atrioventricular blocks (AVB) in 10 participants (2.6%). The prevalence of any abnormality rose from 1.1% among those 10 to 19 years old to 14.2%, 17.3%, and 26.4% among those 20 to 39, 40 to 59, and older than 60 years, respectively. First-degree AVB was seen most frequently in participants 60 years or older, but the 4 patients with third-degree AVB were all under 50 years old. Eighteen and 2 participants had a left ventricular ejection fraction of 40% to 54% and <40%, respectively. An increasing number of ECG abnormalities was associated with progressively larger left ventricular end-diastolic dimensions and lower left ventricular ejection fraction. CONCLUSIONS: We found a high prevalence of ECG abnormalities and substantial evidence of Chagas cardiomyopathy. Programs to improve access to basic cardiac care (annual ECG, antiarrhythmics, pacemakers) could have an immediate impact on morbidity and mortality in these highly endemic communities.

Ventricular ectopy in children without known heart disease.

OBJECTIVE: To describe the presentation and clinical course of patients with ventricular ectopy (VE) without known heart disease seen at a single institution. STUDY DESIGN: Patients with VE were identified from the cardiology database. Patients with known hemodynamically significant heart disease or systemic diseases were excluded. RESULTS: A total of 219 patients constitute the study population, with 59% male and median age of diagnosis 11.3 years. A total of 138 patients had follow-up data. Median duration of follow-up was 3.1 years (n = 138, range 0-21 years) for a total of 587 patient-years. Simple VE was found in 83%, and 17% had ventricular tachycardia. Most patients were asymptomatic at presentation (77%) At presentation, echocardiograms were performed in 164 patients, with 98% normal. Of the 36 patients with sequential echocardiograms, 32 (88%) remained normal, 3 (9%) had abnormal echocardiograms which normalized, and 1 (3%) had progressive left ventricular dysfunction. On sequential Holter data (n = 48), 54% showed stable or decreased VE, 40% showed resolution, and 6% showed worsening. No cases of death or resuscitated sudden death occurred. CONCLUSIONS: Most patients were asymptomatic. There were rare cases of progression of VE and development of left ventricular dysfunction but the majority had stable findings. No deaths occurred.