Cardiomyopathy Induced by Artificial Cardiac Pacing: To Whom, When, Why, and How? Insights on Heart Failure Development.

Coordinated and harmonic (synchronous) ventricular electrical activation is essential for better left ventricular systolic function. Intraventricular conduction abnormalities, such as left bundle branch block due to artificial cardiac pacing, lead to electromechanical "dyssynchronopathy" with deleterious structural and clinical consequences. The aim of this review was to describe and improve the understanding of all the processes connecting the several mechanisms involved in the development of artificially induced ventricular dyssynchrony by cardiac pacing, most known as pacing-induced cardiomyopathy (PiCM). The chronic effect of abnormal impulse conduction and nonphysiological ectopic activation by artificial cardiac pacing is suspected to affect metabolism and myocardial perfusion, triggering regional differences in the activation/contraction processes that cause electrical and structural remodeling due to damage, inflammation, and fibrosis of the cardiac tissue. The effect of artificial cardiac pacing on ventricular function and structure can be multifactorial, and biological factors underlying PiCM could affect the time and probability of developing the condition. PiCM has not been included in the traditional classification of cardiomyopathies, which can hinder detection. This article reviews the available evidence for pacing-induced cardiovascular disease, the current understanding of its pathophysiology, and reinforces the adverse effects of right ventricular pacing, especially right ventricular pacing burden (commonly measured in percentage) and its repercussion on ventricular contraction (reflected by the impact on left ventricular systolic function). These effects might be the main defining criteria and determining mechanisms of the pathophysiology and the clinical repercussion seen on patients.

Cardiomyopathy Induced by Artificial Cardiac Pacing: To Whom, When, Why, and How? Insights on Heart Failure Development

ABSTRACT Coordinated and harmonic (synchronous) ventricular electrical activation is essential for better left ventricular systolic function. Intraventricular conduction abnormalities, such as left bundle branch block due to artificial cardiac pacing, lead to electromechanical "dyssynchronopathy" with deleterious structural and clinical consequences. The aim of this review was to describe and improve the understanding of all the processes connecting the several mechanisms involved in the development of artificially induced ventricular dyssynchrony by cardiac pacing, most known as pacing-induced cardiomyopathy (PiCM). The chronic effect of abnormal impulse conduction and nonphysiological ectopic activation by artificial cardiac pacing is suspected to affect metabolism and myocardial perfusion, triggering regional differences in the activation/contraction processes that cause electrical and structural remodeling due to damage, inflammation, and fibrosis of the cardiac tissue. The effect of artificial cardiac pacing on ventricular function and structure can be multifactorial, and biological factors underlying PiCM could affect the time and probability of developing the condition. PiCM has not been included in the traditional classification of cardiomyopathies, which can hinder detection. This article reviews the available evidence for pacing-induced cardiovascular disease, the current understanding of its pathophysiology, and reinforces the adverse effects of right ventricular pacing, especially right ventricular pacing burden (commonly measured in percentage) and its repercussion on ventricular contraction (reflected by the impact on left ventricular systolic function). These effects might be the main defining criteria and determining mechanisms of the pathophysiology and the clinical repercussion seen on patients.

Estudo das diferenças antropométricas e de comorbidades entre pacientes com insuficiência cardíaca com fração de ejeção preservada e reduzida / Study of anthropometric differences and co-morbidities among patients with heart failure with preserved and reduced ejection fraction

Introdução: As doenças cardiovasculares têm ampla prevalência e no Brasil são responsáveis pela terceira maior causa de internações do SUS sendo a a insuficiência cardíaca (IC) a principal razão. O presente estudo visa comparar as características antropométricas e presença de diferentes comorbidades em pacientes ambulatoriais com IC crônica, analisando as diferenças entre dois grupos, dicotomizados pela preservação ou comprometimento da fração de ejeção (FE). Métodos: Estudo observacional de pacientes com IC crônica atendidos na região metropolitana de Porto Alegre (RS). Os pacientes foram divididos em dois grupos de FE, preservada (FER ≥ 50 %) ou reduzida (FER ≤ 50%), de um total de 155 pacientes atendidos entre julho de 2010 e junho de 2011. Análise estatística: As variáveis contínuas foram apresentadas por média e desvio padrão e as categóricas por frequência. As diferenças entre as variáveis continuas foram aferidas pelo teste T de Student, e, entre as categóricas, pelo teste do qui-quadrado, e consideradas estatisticamente significativas quando p≤0,05. Resultados: Na amostra, 48 pacientes apresentavam FEP, sendo 60,4% do sexo feminino, com índice de massa corporal médio de 32,8 Kg/m2SC e circunferência abdominal e quadril com médias de 105,7 cm e 107,9 cm, respectivamente, que foram significativamente maiores do que no grupo com FER, além de níveis pressóricos sistólicos mais elevados. Conclusão: Os pacientes com FEP, na amostra estudada, foram significativamente mais obesos e com maior distribuição de gordura centrípeta, sem outras diferenças antropométricas, e com média de PA sistólica mais elevada, quando comparados aos pacientes com FER.

Introduction: Cardiovascular diseases are widely prevalent and in Brazil they are the third leading cause of SUS hospitalizations where heart failure (HF) is the main reason. This study aims to compare the anthropometric characteristics and presence of various co-morbidities in outpatients with chronic HF, analyzing the differences between two groups, dichotomized by preservation or impairment of the ejection fraction (EF). Methods: An observational study of patients with chronic heart failure treated in the metropolitan region of Porto Alegre (RS). The patients were divided into two groups of EF, preserved (PEF ≥ 50%) or reduced (REF ≤ 50%), from a total of 155 patients treated between July 2010 and June 2011. Statistical analysis: Continuous variables were presented as mean and standard deviation and categorical variables by frequency. Differences between continuous variables were assessed by the Student’s t test, and between categorical variables by the chi-square test, and considered statistically significant at p ≤ 0.05. Results: In the sample, 48 patients had PEF, 60.4% being females, with a mean body mass index of 32.8 Kg/m2SC and mean waist circumference and hip of 105.7 cm and 107.9 cm, respectively, which were significantly higher than in the REF group, and higher systolic blood pressure. Conclusion: In our sample, patients with PEF were significantly more obese and had more centripetal fat distribution, with no other anthropometric differences, and higher mean systolic BP than patients with REF.