- [Show abstract] [Hide abstract] ABSTRACT: Background Atrioventricular reentrant tachycardias account for approximately one third of cases referred for electrophysiological study (EPS). The anatomical substrate responsible for the reentry is an accessory pathway (AP) able to conduct the electrical stimulus in an anterograde, retrograde or bidirectional manner. Objective To evaluate the correlation of AP location with the male and female genders and AP clinical presentation, whether manifest or concealed. Methods Retrospective observational study including 942 consecutive patients, all diagnosed with EPS-confirmed AP from January1994 to December2008. AP were classified into eight anatomical groups: left lateral (LL), left posterior (LP), left posteroseptal (LPS), right posteroseptal (RPS), right midseptal (RMS), right anteroseptal (RAS), right lateral (RL), and right posterior (RP). Results Of the 942 patients, 52.6% were males. The mean age was 31.2 ± 13.8 years. As regards gender, AP were more prevalent among men. However, a statistically significant difference was observed only in the LPS (p = 0.029) and RL (p = 0.003) regions. In relation to the form of presentation of AP, the manifest form was more frequent than the concealed form in six of the eight regions studied, except for the LL and LPS regions. Conclusion AP predominated in males and the manifest form was more frequent than the concealed form in most of the regions studied.
- [Show abstract] [Hide abstract] ABSTRACT: Background: Studies have shown the impact of atrial fibrillation (AF) on the patients' quality of life. Specific questionnaires enable the evaluation of relevant events. We previously developed a questionnaire to assess the quality of life of patients with AF (AFQLQ version 1), which was reviewed in this study, and new domains were added. Objective: To demonstrate the reproducibility of the AFQLQ version 2 (AFQLQ v.2), which included the domains of fatigue, illness perception and well-being. Methods: We applied 160 questionnaires (AFQLQ v.2 and SF-36) to 40 patients, at baseline and 15 days after, to measure inter- and intraobserver reproducibility. The analysis of quality of life stability was determined by test-retest, applying the Bartko intraclass correlation coefficient (ICC). Internal consistency was assessed by Cronbach's alpha test. Results: The total score of the test-retest (n = 40) had an ICC of 0.98 in the AFQLQ v.2, and of 0.94 in the SF36. In assessing the intra- and interobserver reproducibility of the AFQLQ v.2, the ICC reliability was 0.98 and 0.97, respectively. The internal consistency had a Cronbach's alpha coefficient of 0.82, compatible with good agreement of the AFQLQ v.2. Conclusion: The AFQLQ v.2 performed better than its previous version. Similarly, the domains added contributed to make it more comprehensive and robust to assess the quality of life of patients with AF.
- [Show abstract] [Hide abstract] ABSTRACT: Background Atrial fibrillation (AF) is an important and growing public health problem worldwide, but data about its actual prevalence, therapeutic management, and clinical outcomes in middle- to low-income countries are scarce. Design The First Brazilian Cardiovascular Registry of Atrial Fibrillation (the RECALL study) will assess demographic characteristics and evidence-based practice of a representative sample of patients with AF in Brazil. The prospective, multicenter registry has a planned sample size of around 5,000 patients at approximately 80 sites. Eligibility criteria include age >18 years and permanent, paroxysmal, or persistent AF documented by electrocardiogram, 24-hour Holter monitoring, or device interrogation. Patients will be followed up through 1 year after enrollment. Information on laboratory tests, echocardiographic data, medication use, and clinical outcomes will be obtained. Various aspects of the population will be described, including demographic characteristics; antithrombotic therapies; antiarrhythmic agents; level of control of international normalized ratio (by average time within the therapeutic range) among patients using vitamin K antagonists; rates of warfarin discontinuation; outcomes such as death, stroke, systemic embolism, and major bleeding within 1 year after enrollment in the study; and rates of electrical cardioversion, percutaneous ablation of AF, ablation of the atrioventricular junction, and pacemaker/cardioverter-defibrillator implantation. Summary RECALL is the first prospective, multicenter registry of AF in Brazil. This study will provide important information about demographics, practice patterns, treatments, and associated outcomes in patients with AF. The results of this registry will also allow Brazilian data to be put in perspective with other AF registries across the world and provide opportunities to improve care of patients with AF in Brazil.
- [Show abstract] [Hide abstract] ABSTRACT: The sleep of patients admitted to coronary care unit (CCU) may be compromised. A feasible and cost-effective tool to evaluate sleep in this scenario could provide important data. The aim of this study was to evaluate sleep with a questionnaire developed specifically for the CCU and to validate it with polysomnography (PSG). Ninety-nine patients (68% male; 56 ± 10 years old) with acute coronary syndrome were included. PSG was performed within 36 h of admission. A specific 18-question questionnaire (CCU questionnaire) was developed and applied after the PSG. Cronbach's alpha test was used to validate the questionnaire. The Spearman test was used to analyze the correlation between the PSG variables and the questionnaire, and the Kruskal-Wallis test was used to compare the PSG variables among patients with good, regular, or poor sleep. The total sleep time was 265 ± 81 min, sleep efficiency 62 ± 18%, REM sleep 10 ± 7%, apnea/hypopnea index 15 ± 23, and the arousal index 24 ± 15. Cronbach's alpha test was 0.69. The CCU questionnaire showed correlation with the sleep efficiency evaluated by PSG (r: 0.52; p < 0.001). Sleep quality was divided into three categories according to the CCU questionnaire: patients with good sleep had a sleep efficiency of 72 ± 9%, better than those with a regular or poor sleep (60 ± 16% and 53 ± 20%, respectively; p < 0.01). The CCU questionnaire is a feasible and reliable tool to evaluate sleep in the CCU, showing correlation with the PSG sleep efficiency. Copyright © 2015 Elsevier B.V. All rights reserved.
- [Show abstract] [Hide abstract] ABSTRACT: Training requirements for general cardiologists without echocardiographic expertise to perform focused cardiac ultrasound (FCU) with portable devices have not yet been defined. The objective of this study was to evaluate a training program to instruct cardiology residents to perform FCU with a hand-carried device (HCD) in different clinical settings. Twelve cardiology residents were subjected to a 50-question test, 4 lectures on basic echocardiography and imaging interpretation, the supervised interpretation of 50 echocardiograms and performance of 30 exams using HCD. After this period, they repeated the written test and were administered a practical test comprising 30 exams each (360 patients) in different clinical settings. They reported on 15 parameters and a final diagnosis; their findings were compared to the HCD exam of a specialist in echocardiography. The proportion of correct answers on the theoretical test was higher after training (86%) than before (51%; P = 0.001). The agreement was substantial among the 15 parameters analyzed (kappa ranging from 0.615 to 0.891; P < 0.001). The percentage of correct interpretation was lower for abnormal (75%) than normal (95%) items, for valve abnormalities (85%) compared to other items (92%) and for graded scale (87%) than for dichotomous (95%) items (P < 0.0001, for all). For the final diagnoses, the kappa value was higher than 0.941 (P < 0.001; 95% CI [0.914, 0.955]). The training proposed enabled residents to perform FCU with HCD, and their findings were in good agreement with those of a cardiologist specialized in echocardiography. © 2015, Wiley Periodicals, Inc.
- [Show abstract] [Hide abstract] ABSTRACT: Atrial fibrillation (AF) is a supraventricular arrhythmia, usually tachycardic, where in irregular atrial activation occurs, almost always leading to the loss of 20–25 % of cardiac output. These values may be higher in cases of hypertrophic myocardium resulting from hypertension or hypertrophic cardiomyopathy .
- [Show abstract] [Hide abstract] ABSTRACT: Background: The mechanisms associated with the cardiovascular consequences of obstructive sleep apnea include abrupt changes in autonomic tone, which can trigger cardiac arrhythmias. The authors hypothesized that nocturnal cardiac arrhythmia occurs more frequently in patients with obstructive sleep apnea. Objective: To analyze the relationship between obstructive sleep apnea and abnormal heart rhythm during sleep in a population sample. Methods: Cross-sectional study with 1,101 volunteers, who form a representative sample of the city of São Paulo. The overnight polysomnography was performed using an EMBLA® S7000 digital system during the regular sleep schedule of the individual. The electrocardiogram channel was extracted, duplicated, and then analyzed using a Holter (Cardio Smart®) system. Results: A total of 767 participants (461 men) with a mean age of 42.00 ± 0.53 years, were included in the analysis. At least one type of nocturnal cardiac rhythm disturbance (atrial/ventricular arrhythmia or beat) was observed in 62.7% of the sample. The occurrence of nocturnal cardiac arrhythmias was more frequent with increased disease severity. Rhythm disturbance was observed in 53.3% of the sample without breathing sleep disorders, whereas 92.3% of patients with severe obstructive sleep apnea showed cardiac arrhythmia. Isolated atrial and ventricular ectopy was more frequent in patients with moderate/severe obstructive sleep apnea when compared to controls (p < 0.001). After controlling for potential confounding factors, age, sex and apnea-hypopnea index were associated with nocturnal cardiac arrhythmia. Conclusion: Nocturnal cardiac arrhythmia occurs more frequently in patients with obstructive sleep apnea and the prevalence increases with disease severity. Age, sex, and the Apnea-hypopnea index were predictors of arrhythmia in this sample.
- [Show abstract] [Hide abstract] ABSTRACT: Background: Left Atrial (LA) dilation is associated with a worse prognosis in various clinical situations, including chronic Non-Ischemic Mitral Regurgitation (NIMR). Real time Three-Dimensional Echocardiography (3DE) has allowed a better assessment of LA volume and function. Although LA reverse remodeling has been observed in long-term outcome after surgery in NIMR, little is known about the behavior of LA structure and function in an early post-operative period. We aimed to analyze these aspects with 3DE. Methods: We prospectively studied 43 patients with symptomatic chronic NIMR who underwent valve repair or bioprosthetic valve replacement. LA volumes and function were analyzed before and 30 days after surgery by means of 3DE in all patients, and in a control group of 20 healthy subjects. We studied maximum, minimum and pre-atrial contraction volumes, and calculated total, passive and active LA emptying fractions. Results: Before surgery patients had higher LA volumes (p<0.001), but smaller LA emptying fractions than controls (p<0.01). After surgery, all three LA volumes reduced in both groups. Postoperative increase in active LA emptying fraction also occurred in both groups. Independent predictors of early postoperative LA reverse remodeling were diastolic blood pressure before surgery (Coefficient= - 0.004; p= 0.02), lateral mitral annulus early diastolic velocity (e') (Coefficient=0.02; p=0.008), and a mean transmitral diastolic gradient increment (Coefficient= - 0.035; p < 0.001), but not the surgical technique. Besides, e' was the only variable independently associated with the early recovery of active LA emptying fraction (OR= 1.664, P=0.027). Conclusion: LA reverse remodeling and functional improvement occur soon after surgery of symptomatic chronic NIMR patients, regardless of the surgical technique. Those changes are related to preoperative diastolic blood pressure and an echocardiographic marker of left ventricular diastolic function.
- [Show abstract] [Hide abstract] ABSTRACT: Purpose: Left Atrial Volume Index (LAVi) evaluated by echocardiography has prognostic value in patients with heart failure. The aim of this study was to evaluate the determinants of the LAVi in patients with non-ischemic Dilated Cardiomyopathy (DCM) and Left Ventricular (LV) systolic dysfunction. Methods: Ninety patients with DCM, LV ejection fraction ≤ 0.50, sinus rhythm and optimized medical therapy for heart failure were included. LAVi was measured with three-dimensional echocardiography. With real-time three-dimensional echocardiography, Doppler and tissue Doppler, the following variables were evaluated: LV end-diastolic and end-systolic volumes, LV ejection fraction, mitral inflow E wave, tissue Doppler (TDI) e' wave, E/e' ratio, intraventricular delay at TDI, 3D dyssynchrony index and mitral regurgitation vena contracta. Heart rate and systolic blood pressure were also evaluated. The Pearson's coefficient was used to identify the correlation of the LAVi with the variables evaluated. A multiple linear regression model was developed that included LAVi as the dependent variable and the variables correlated with it as the predictive variables. Results: Mean age was 52±11 years old, mean functional class: 2.1±0.5, LV ejection fraction: 32.3±8.9% (16-50%) and the LAVi: 39.2±15.7 ml/m2. The variables that correlated with LAVi were: LV end-diastolic volume (r=0.38; p<0.01), LV end-systolic volume (r=0.427; p<0.001), LV ejection fraction (r= -0.362; p<0.01), E wave (r=0.50; p<0.01), E/e' ratio (r=0.510; p<0.01) and mitral regurgitation vena contracta (r=0.528; p<0.01). A multivariate analysis identified the E/e' ratio (p=0.02) and the mitral regurgitation vena contracta (p=0.02) as the only independent variables associate with the LAVi increase. Conclusion: The LAVi is independently determined by the LV filling pressures (E/e' ratio) and the mitral regurgitation in patients with dilated cardiomyopathy.
- [Show abstract] [Hide abstract] ABSTRACT: BACKGROUND: EnSiteNavx electroanatomic mapping system is widely used in radiofrequency (RF) atrial fibrillation ablation, helping the creation of linear lesions. However, the correspondence of the virtual line created by EnSite with the pathological lesion has not yet been evaluated. OBJECTIVE: to assess the continuousness of Ensite-guided virtual lines in a swine model. METHODS: we performed RF ablation linear lesions (8mm and irrigated catheters tips) in both atria of 14 pigs (35Kg) guided by the EnSite. The animals were sacrificed 14 days post-ablation for macroscopic and histological analysis. RESULTS: a total of 23 lines in the right atrium and 21 lines in the left atrium were created in 14 animals. The medium power, impedance and temperature applications were 56 W, 54 ºC and 231 Ω for the 8mm tip, and 39W, 37ºC, 194 Ω for the irrigated tip catheter, respectively. All (100%) lines were identified on the epicardial and endocardial surfaces, denoting transmurality. At macroscopic examination, lesions were extensive and pale, continuous, with 3.61 cm long and 0.71 cm deep. The transmurality of the lesions was confirmed by microscopy. There was a correlation in the location of the lines at the virtual map and the anatomical lesions in 21 of 23 (91.3%) of the right atrium and 19/21 (90.4%) of the left atrium. CONCLUSION: In this model, the lines created in the virtual map by EnSiteNavX system correspond to continuous transmural linear lesions in anatomical specimen, suggesting that this method is suitable for linear ablation of atrial fibrillation.
- [Show abstract] [Hide abstract] ABSTRACT: Purpose: Obstructive sleep apnea (OSA) is a risk factor for cardiovascular disease. Strong associations have been reported among sleep duration, hypertension, obesity, and cardiovascular mortality. The authors hypothesize that sleep duration may play a role in OSA severity. The aim of this study is to analyze sleep duration in OSA patients. Methods: Patients who underwent overnight polysomnography were consecutively selected from the Sleep Clinic of Universidade Federal de São Paulo database between March 2009 and December 2010. All subjects were asked to come to the Sleep Clinic at 8:00 a.m. for a clinical evaluation and actigraphy. Anthropometric parameters such as weight, height, hip circumference, abdominal circumference, and neck circumference were also measured. Results: One hundred thirty-three patients were divided into four groups based on total sleep time, sleep efficiency, sleep latency, and wake after sleep onset: very short sleepers (n = 11), short sleepers (n = 21), intermediate sleepers (n = 56), and sufficient sleepers (n = 45). Apnea-hypopnea index (AHI) was higher in very short sleepers (50.18 ± 30.86 events/h) compared with intermediate sleepers (20.36 ± 14.68 events/h; p = 0.007) and sufficient sleepers (23.21 ± 20.45 events/h; p = 0.02). Minimal and mean arterial oxygen saturation and time spent below 90 % oxygen saturation exhibited worse values in very short sleepers. After adjustment for gender, age, AHI, and body mass index, mean oxygen saturation was significantly associated to total sleep time (p = 0.01). Conclusions: In conclusion, the present study suggests that sleep duration may be associated to low mean oxygen saturation in OSA patients.
- [Show abstract] [Hide abstract] ABSTRACT: Purpose: Late lesion extension may be involved in the genesis of delayed radiofrequency (RF) effects. Because RF lesion is thermally mediated, we hypothesized that induction of heat shock response (thermotolerance) would modulate lesion healing. We evaluated the effects of thermotolerance on the dimensions and remodeling of RF lesions in a rat model of heart failure. Methods: Wistar rats (weight 300 g) subjected to heat stress (n = 22, internal temperature of 42 °C for 10 min) were compared to controls (n = 22, internal temperature of 37 °C for 10 min). After 48 h (peak of HSP70 myocardial concentration), a modified unipolar RF lesion (customized catheter, tip 4.5 mm in diameter; 12 W; 10 s) was created on the left ventricular free wall. Animals were sacrificed 2 h (n = 10 per group) and 4 weeks (n = 12 per group) after ablation for lesion analysis. An echocardiogram was obtained at 4 weeks. Results: There was no difference between groups regarding the size of acute (controls 27 ± 2 vs. treated 27 ± 3 mm(2)) and chronic lesions (controls 17 ± 1 vs. treated 19 ± 1 mm(2)). Histology of lesions did not differ between groups. The echocardiogram revealed dilation of the cavities and moderate systolic dysfunction without difference between groups. Acute lesion dimensions were similar between control and treated animals over time (ablation undertaken 3, 12, 24, 48, and 72 h after hyperthermia) and also using a conventional ablation catheter (50 °C; 15 W; 10 s). Conclusion: Thermotolerance does not reduce the size or remodeling of RF lesions in the rat myocardium.
- [Show abstract] [Hide abstract] ABSTRACT: Sleep is an important factor in the maintenance of cardiovascular integrity. It seems that cardiovascular injury and sleep impairment is another chicken or egg puzzle and we hypothesized that the higher the cardiovascular risk factors the higher the sleep impairment. Therefore, the goal of this study is to analyze the sleep profile of a general population based on cardiovascular risk stratification. This population-based survey used a probabilistic three-stage cluster sample of Sao Paulo inhabitants to represent the population. A sample size of 1056 volunteers was defined in order to allow for prevalence estimates with 3% precision. From the 1101 selected and interviewed participants, a complete full-night polysomnogram (PSG) was performed in 1042 participants as well as clinical evaluation and blood samples analyses to assess Framingham risk score. Nine hundred four subjects were classified according the Framingham score and were included in the analyses. A total of 91.7% were classified as a low risk, 5.8% in the intermediate, and 2.4% in the high risk groups according to Framingham score. All polisomnographic parameters were different between groups, except those related to REM sleep parameters. AHI were greater in the high risk compared to the intermediate and low risk groups (23.9 ± 2.8; 17.7 ± 1.8; 7.2 ± 0.5, respectively, p<0.001), as well as a lower total sleep time in minutes (295.3 ± 16.2; 338.4 ± 10.2; 347.4 ± 2.6, respectively, p=0.01). Sleep efficiency in percentage also exhibits a reduction between groups (67.6 ± 2.5; 78.4 ± 1.6; 82.9 ± 0.4, respectively, p<0.001). After adjustment for confounder factors age (p<0.001) and sleep efficiency (p=0.06) remained strongly associated with high risk population. High Framingham risk score was associated with poor sleep efficiency and aging.
- [Show abstract] [Hide abstract] ABSTRACT: Invasive and non-invasive tests have been used to identify the risk of ventricular tachycardia (VT) in patients with chronic Chagas' heart disease (CCHD). Cardiac magnetic resonance imaging (CMRI) using the delayed enhancement (DE) technique can be useful to select patients with global or segmentary ventricular dysfunction, with high degree of fibrosis and at higher risk for clinical VT. To improve the identification of predictors of VT in patients with CCHD. This study assessed 41 patients with CCHD [30 (72%) males; mean age, 55.1 ± 11.9 years]. Twenty-six patients had history of VT (VT group), and 15 had no VT (NVT group). All patients enrolled had DE and segmentary ventricular dysfunction. In each case, the following variables were determined: left ventricular volume; percentage of ventricular wall thickness impairment in each segment; and DE distribution. No statistical difference regarding the DE volume between both groups was observed: VT group = 30.0 ± 16.2%; NVT group = 21.7 ± 15.7%; p = 0.118. The probability of VT was greater in the presence of two or more contiguous transmural fibrosis areas, and that was a predictive factor of clinical VT (RR 4.1; p = 0,04). Agreement between observers was 100% regarding that criterion (p < 0.001). The identification of two or more segments of transmural DE by use of CMRI is associated with the occurrence of clinical VT in patients with CCHD. Thus, CMRI improved risk stratification in the population studied.
- [Show abstract] [Hide abstract] ABSTRACT: To evaluate respiratory muscle strength, oxygenation and chest pain in patients undergoing off-pump coronary artery bypass (OPCAB) using internal thoracic artery grafts comparing pleural drain insertion site at the subxyphoid region versus the lateral region. Forty patients were randomized into two groups in accordance with the pleural drain site. Group II (n = 19) -pleural drain exteriorized in the intercostal space; group (SI) (n = 21) chest tube exteriorized at the subxyphoid region. All patients underwent assessment of respiratory muscle strength (inspiratory and expiratory) on the pre, 1, 3 and 5 postoperative days (POD). Arterial blood gas analysis was collected on the pre and POD1. The chest pain sensation was measured 1, 3 and 5 POD. A significant decrease in respiratory muscle strength (inspiratory and expiratory) was seen in both groups until POD5 (P <0.05). When compared, the difference between groups remained significant with greater decrease in the II (P <0.05). The blood arterial oxygenation fell in both groups (P <0.05), but the oxygenation was lower in the II (P <0.05). Referred chest pain was higher 1, 3 and 5 POD in the II group (P <0.05). The orotracheal intubation time and postoperative length of hospital stay were higher in the II group (P <0.05). Patients submitted to subxyphoid pleural drainage showed less decrease in respiratory muscle strength, better preservation of blood oxygenation and reduced thoracic pain compared to patients with intercostal drain on early OPCAB postoperative.
- [Show abstract] [Hide abstract] ABSTRACT: 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. 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. 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. 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.
- [Show abstract] [Hide abstract] ABSTRACT: We sought to assess the effect of naproxen versus placebo on prevention of atrial fibrillation after coronary artery bypass graft (CABG) surgery. In this randomized, double-blind, placebo-controlled, single-center trial of 161 consecutive patients undergoing CABG surgery, patients received naproxen 275 mg every 12 hours or placebo at the same dosage and interval over 120 hours immediately after CABG surgery. The primary outcome was the occurrence of atrial fibrillation in the first 5 postoperative days. The incidence of postoperative atrial fibrillation was 15.2% (12/79) in the placebo versus 7.3% (6/82) in the naproxen group (P=.11). The duration of atrial fibrillation episodes was significantly lower in the naproxen (0.35 hours) versus placebo group (3.74 hours; P=.04). There was no difference in the overall days of hospitalization between placebo (17.23±7.39) and naproxen (18.33±9.59) groups (P=.44). Intensive care unit length of stay was 4.0±4.57 days in the placebo and 3.23±1.25 days in the naproxen group (P=.16). The trial was stopped by the data monitoring committee before reaching the initial target number of 200 patients because of an increase in renal failure in the naproxen group (7.3% vs 1.3%; P=.06). Postoperative use of naproxen did not reduce the incidence of atrial fibrillation but decreased its duration, in a limited sample of patients after CABG surgery. There was a significant increase in acute renal failure in patients receiving naproxen 275 mg twice daily. Our study does not support the routine use of naproxen after CABG surgery for the prevention of atrial fibrillation.
- [Show abstract] [Hide abstract] ABSTRACT: Rate control is an acceptable alternative to rhythm control in patients with chronic atrial fibrillation (AF). The aim of this study of AF patients was to understand the correlation between their exercise capacity and both heart rate (HR) and HR variation index during exercise. The exercise capacity of 85 male patients with chronic AF was measured using a cardiopulmonary exercise test (CPX). Within this population, we compared the exercise tolerance of patients with a normal chronotropic response (maximal HR 85%-115% that of the maximal age-predicted HR during CPX) to those whose HR response exceeded this range. Two similar comparisons were made by dividing the subject population according to (1) whether or not their HR variation index (HRVI) during CPX exceeded 10 bpm/min, and (2) whether their HR during the 6-minute walk test exceeded 110 bpm. Patients with an HRVI not over 10 bpm/min showed higher maximal oxygen uptake compared to patients with a higher HRVI (26.7 ± 6.1 vs 22.8 ± 4.8 mL O(2) /kg/min, P = 0.002) and a longer distance walked during CPX (705.6 ± 200.3 vs 520.9 ± 155.5 m, P<0.001). No other significant influence on exercise capacity was seen. Multivariate regression analysis revealed that both the body mass index and the HRVI during CPX were independent predictors of the maximal oxygen uptake. Better HRVI control on CPX was correlated with better exercise capacity in patients with chronic AF.
Rio de Janeiro State University
Rio de Janeiro, Rio de Janeiro, Brazil
- Faculdade de Ciências Médicas (FCM)
Cleveland ClinicCleveland, Ohio, United States