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Canadian Cardiovascular Society (CCS) CCS475 Oral: Atrial Fibrillation Mechanisms and Management Monday, October 25, 2010
Abstracts RA. These results contribute to a better understanding of the consequences of rotational atherectomy for stent strut pulverization, possibly partially validating its use in clinical practice.
241
THE INFLUENCE OF INDUSTRY REPRESENTATION ON THE UTILIZATION OF CORONARY ARTERY STENTS: A SINGLE-CENTRE STUDY J Charania, A Inman, L Gula, S Lavi London, Ontario BACKGROUND: The direct effect of pharmaceutical company involvement on rates of drug administration, ease of availability, and extent of research has been previously well described. However, the influence of device company representation has been examined to a much lesser degree. We hypothesize that the presence of device company representation in the Cardiac Catheterization Laboratory influences the choice of coronary arterial stent and balloon utilization. CONCLUSION: Presence of device company representation during stent implantation influences the type of stent and balloon used. These may have ethical and budgetary consequences.
Canadian Cardiovascular Society (CCS) CCS475 Oral ATRIAL FIBRILLATION MECHANISMS AND MANAGEMENT Monday, October 25, 2010 Featured Research 244
ANXIETY SENSITIVITY PREDICTS THE IMPACT OF RHYTHM VERSUS RATE CONTROL STRATEGIES IN PATIENTS WITH ATRIAL FIBRILLATION AND CONGESTIVE HEART FAILURE N Frasure-Smith, F Lespérance, P Khairy, P Dorian, M Talajic, D Roy, on behalf of the AF-CHF Investigators Montréal, Québec BACKGROUND: Some people interpret increases in heart rate and sweaty palms as dangerous and seek medical attention. Others see these simply as unpleasant symptoms that occur in stressful situations. Anxiety sensitivity (AS) describes the personality factor reflecting the degree to which people are frightened by bodily sensations, particularly those associated with anxiety. While AS is known to predict the occurrence of panic attacks in cardiac and non-cardiac patients, and is associated with greater symptom preoccupation and worse quality of life in patients with atrial fibrillation (AF), it has not been studied as a prognostic factor. CONCLUSION: While for the majority of patients we observed no prognostic differences between Rhythm and Rate control strategies, those patients who reported that they became extremely anxious when they experienced palpitations, changes in heart rate and other physical symptoms of psychological arousal benefited more from Rhythm control than Rate control. We conclude that, based on psychological factors, there may be some AF-CHF patients for whom Rhythm control is the superior treatment option. CIHR
64D
Featured Research 245
ROLE OF VAGAL ENHANCEMENT IN EXERCISE-RELATED ATRIAL FIBRILLATION B Benito, Y Shi, P Naud, MA Gillis, E Guasch, S Heximer, G Gay, A Serrano, JC Tardif, L Mont, S Nattel Montréal, Québec BACKGROUND: Recent reports suggest that high-level exercise training (ExT) may promote atrial fibrillation (AF). We examined the effects of ExT on AF susceptibility in a rat model involving 16 weeks of 1-hour per day treadmill running, 5 days/week. We investigated the role of vagal enhancement in AF promotion and studied potential underlying molecular mechanisms. CONCLUSION: In this rat model, chronic ExT increased AF susceptibility and maintenance, compatible with clinical observations. Vagal tone was necessary for AF inducibility, implying an important mechanistic contribution. Altered regulation of vagal responses by RGS-proteins may contribute significantly to increased sensitivity to effects of cholinergic agonists and AF-promotion. Our results provide insights into the fundamental basis of an important clinical paradigm.
246
IN-HOSPITAL MANAGEMENT OF ATRIAL FIBRILLATION: THE CHADS-2 SCORE PREDICTS INCREASED COST MA Kotowycz, K Filion, D Dube, MR Reynolds, L Pilote, MJ Eisenberg, V Essebag Montréal, Québec BACKGROUND: Hospitalizations for atrial fibrillation (AF) impose a substantial burden on our healthcare system, and strategies for AF management are increasingly focused on the ability to reduce hospitalizations, in addition to reducing morbidity and mortality. However, the cost of an inpatient admission for AF in Canada is largely unknown. The goals of the present study were to document the cost of an index hospitalization for AF at a large Canadian teaching hospital and to identify the main determinants of this cost. CONCLUSION: The median cost of an AF hospitalization was $3527. Over 50% of the cost was attributable to nursing unit costs, which are directly proportional to length of hospitalization. The main clinical determinants of increased cost and of increased length of stay were the CHADS-2 score and warfarin use. Strategies for reducing AF-related costs should include preventing or decreasing length of hospitalization in patients with high CHADS-2 scores and finding alternatives to the inpatient use of warfarin. CIHR Clinician Scientist Award
247
ATRIAL FIBRILLATION IN THE EMERGENCY DEPARTMENT: A POPULATION-BASED DESCRIPTION CL Atzema, L Yun, P Dorian Toronto, Ontario BACKGROUND: Atrial fibrillation (AF) is the most common arrhythmia seen in the emergency department (ED). The frequency of ED visits for AF in a contemporary, unselected, geographically large and defined population is not known, nor are their outcomes, including mortality, strokes, and return ED visits for AF. ED visits for AF are increasing, and return ED visits are common in these patients. While the proportion of patients discharged from the ED are increasing, rates of return ED visits, hospitalizations for stroke, and mortality have remained unchanged. The mortality rate following an ED visit by these commonly-encountered patients is substantial. HSFO
Can J Cardiol Vol 26 Suppl D October 2010
Abstracts
248
MECHANISMS OF ATRIAL FIBRILLATION ASSOCIATED WITH OBESITY AND OBSTRUCTIVE SLEEP APNEA Y Iwasaki, B Benito, MA Gillis, A Maguy, S Nattel Montréal, Québec BACKGROUND: Obesity and obstructive sleep apnea are independent risk factors for atrial fibrillation (AF). Obesity and obstructive sleep apnea are associated with multiple pathophysiological mechanisms like hypoxia, autonomic tone changes and intrathoracic pressure alterations, that may be directly implicated in the pathogenesis of AF. Consequently, the pathogenesis of AF in obesity and sleep apnea is still uncertain. The purpose of this study was to assess the AF-substrate in relation to obesity and sleep apnea in a rat model. CONCLUSION: Zucker obese rats show substantially-increased AF inducibility during obstructive apnea vs. lean rats, but there are no differences (AF non-inducible in either group) during non-obstructive apnea These results suggest that, in addition to hypoxia, increased negative intrathoracic pressure is an important factor in AF development in the obstructive sleep apnea syndrome. Repetitive forced respiration against closed upper respiratory airways, which generates substantial negative pressures in the chest cavity, might cause atrial stretch and autonomic changes leading to increased AF susceptibility. Our results point to an important AF-promoting interaction between obesity and obstructive sleep apnea that requires further investigation.
249
SEX DIFFERENCES IN THE EMERGENCY DEPARTMENT PRESENTATION OF ATRIAL FIBRILLATION: HOW ARE WOMEN AND MEN DIFFERENT? Z Mariano, M Trivieri, CL Atzema, P Dorian Toronto, Ontario BACKGROUND: Few studies have examined gender-related differences in common arrhythmias such as atrial fibrillation (AF) and atrial flutter (AFL). We examined gender in relation to frequency of presentation, treatment, and outcome of patients presenting to the emergency department (ED) with AF/AFL. CONCLUSION: Relative to the males presenting to our ED with AF/ AFL, the females were older, a greater proportion had a CHADS2 score = 2, and they had fewer contraindications to warfarin. However they were less likely to be on warfarin or rhythm control at ED arrival or at ED/hospital discharge and they were more likely to be hospitalized.
Canadian Cardiovascular Society (CCS) CCS480 Oral IMAGING: RELATED RISKS AND APPROACHES TO IMPROVE PATIENT CARE Monday, October 25, 2010 252
REAL WORLD RADIATION DOSES FROM COMMONLY USED CARDIAC TESTING AND PROCEDURAL MODALITIES J Yang, A Scott-Moncrieff, CM Taylor, J Leipsic, B Heilbron Vancouver, British Columbia BACKGROUND: The volume of cardiac diagnostic tests performed has increased significantly in recent years. The benefits of these tests should be weighed against the risks, including those imposed by exposure to ionizing radiation. Multiple dose reduction strategies exist, but these are often underutilized in clinical practice. CONCLUSION: In this retrospective single-centre study of all patients who underwent clinically indicated CCTA, MPI and CCA in 2009 there was a wide range in effective radiation dose. These tests provide different clinical information and the appropriate test must be chosen with its resultant effective radiation dose in mind. The implementation of dose reduction strategies has the potential to significantly reduce these doses.
Can J Cardiol Vol 26 Suppl D October 2010
Featured Research 253
THE CARCINOGENIC EFFECTS OF IONIZING RADIATION FROM CARDIAC IMAGING PROCEDURES AFTER ACUTE MYOCARDIAL INFARCTION: A POPULATION-BASED LONGITUDINAL STUDY J Afilalo, PR Lawler, L Pilote, H Richard, MJ Eisenberg Montréal, Québec BACKGROUND: Patients with acute myocardial infarction (AMI) are exposed to increasing levels of low-dose ionizing radiation (LDIR) from diagnostic and therapeutic cardiac imaging procedures, during both the acute hospitalization and subsequent follow-up. Exposure to LDIR has been associated with a linear risk of cancer in atomic bomb survivors and nuclear workers, but the risk in medical patients remains uncertain. CONCLUSION: In this population-based cohort of AMI patients, LDIR from cardiac imaging procedures was associated with a graded increase in risk of cancer. These findings underscore the need for judicious use of cardiac imaging procedures, consideration of imaging modalities without LDIR when clinically appropriate, and development of protocols and technologies to reduce the dose of radiation delivered to patients.
Featured Research 254
AGE AND SEX DIFFERENCES IN RISK OF CANCER WITH LOW-DOSE IONIZING RADIATION FROM CARDIAC IMAGING PROCEDURES AFTER ACUTE MYOCARDIAL INFARCTION J Afilalo, PR Lawler, MJ Eisenberg, H Richard, L Pilote Montréal, Québec WITHDRAWN
255
RATES OF DOWNSTREAM INVASIVE CORONARY ANGIOGRAPHY AND REVASCULARIZATION: COMPUTED TOMOGRAPHIC CORONARY ANGIOGRAPHY VERSUS TC-99M SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY V Tandon, D Hall, Y Yam, L Chen, T Ruddy, BJ Chow Ottawa, Ontario BACKGROUND: Computed tomographic coronary angiography (CTA) appears to be a useful modality for the detection of obstructive coronary artery disease (CAD). Recent data suggests that CTA has a positive impact upon referrals to invasive coronary angiography (ICA) and revascularization. However, there remains concern that the implementation of CTA could increase referrals to ICA. We followed a large cohort of CTA patients and a matched cohort of Tc-99m single photon emission computed tomography (SPECT) patients to determine downstream referrals for ICA and revascularization. CONCLUSION: Compared to SPECT, CTA had similar referrals for ICA, revascularization and false positive rates. CTA appears to be a viable non-invasive diagnostic modality and does not appear to negatively impact upon ICA resources.
256
PREVALENCE, APPROPRIATENESS AND TIMING OF TRANSTHORACIC ECHOCARDIOGRAPHY IN THE CORONARY CARE UNIT: A QUALITY ASSURANCE AUDIT KM Bhagirath, RA Ducas, JW Tam Winnipeg, Manitoba BACKGROUND: In an era of spiraling health care costs, the appropriate use of medical technologies such as imaging services is of major importance. In this quality assurance investigation, we sought to determine the
65D
241
THE INFLUENCE OF INDUSTRY REPRESENTATION ON THE UTILIZATION OF CORONARY ARTERY STENTS: A SINGLE-CENTRE STUDY J Charania, A Inman, L Gula, S Lavi London, Ontario BACKGROUND: The direct effect of pharmaceutical company involvement on rates of drug administration, ease of availability, and extent of research has been previously well described. However, the influence of device company representation has been examined to a much lesser degree. We hypothesize that the presence of device company representation in the Cardiac Catheterization Laboratory influences the choice of coronary arterial stent and balloon utilization. CONCLUSION: Presence of device company representation during stent implantation influences the type of stent and balloon used. These may have ethical and budgetary consequences.
Canadian Cardiovascular Society (CCS) CCS475 Oral ATRIAL FIBRILLATION MECHANISMS AND MANAGEMENT Monday, October 25, 2010 Featured Research 244
ANXIETY SENSITIVITY PREDICTS THE IMPACT OF RHYTHM VERSUS RATE CONTROL STRATEGIES IN PATIENTS WITH ATRIAL FIBRILLATION AND CONGESTIVE HEART FAILURE N Frasure-Smith, F Lespérance, P Khairy, P Dorian, M Talajic, D Roy, on behalf of the AF-CHF Investigators Montréal, Québec BACKGROUND: Some people interpret increases in heart rate and sweaty palms as dangerous and seek medical attention. Others see these simply as unpleasant symptoms that occur in stressful situations. Anxiety sensitivity (AS) describes the personality factor reflecting the degree to which people are frightened by bodily sensations, particularly those associated with anxiety. While AS is known to predict the occurrence of panic attacks in cardiac and non-cardiac patients, and is associated with greater symptom preoccupation and worse quality of life in patients with atrial fibrillation (AF), it has not been studied as a prognostic factor. CONCLUSION: While for the majority of patients we observed no prognostic differences between Rhythm and Rate control strategies, those patients who reported that they became extremely anxious when they experienced palpitations, changes in heart rate and other physical symptoms of psychological arousal benefited more from Rhythm control than Rate control. We conclude that, based on psychological factors, there may be some AF-CHF patients for whom Rhythm control is the superior treatment option. CIHR
64D
Featured Research 245
ROLE OF VAGAL ENHANCEMENT IN EXERCISE-RELATED ATRIAL FIBRILLATION B Benito, Y Shi, P Naud, MA Gillis, E Guasch, S Heximer, G Gay, A Serrano, JC Tardif, L Mont, S Nattel Montréal, Québec BACKGROUND: Recent reports suggest that high-level exercise training (ExT) may promote atrial fibrillation (AF). We examined the effects of ExT on AF susceptibility in a rat model involving 16 weeks of 1-hour per day treadmill running, 5 days/week. We investigated the role of vagal enhancement in AF promotion and studied potential underlying molecular mechanisms. CONCLUSION: In this rat model, chronic ExT increased AF susceptibility and maintenance, compatible with clinical observations. Vagal tone was necessary for AF inducibility, implying an important mechanistic contribution. Altered regulation of vagal responses by RGS-proteins may contribute significantly to increased sensitivity to effects of cholinergic agonists and AF-promotion. Our results provide insights into the fundamental basis of an important clinical paradigm.
246
IN-HOSPITAL MANAGEMENT OF ATRIAL FIBRILLATION: THE CHADS-2 SCORE PREDICTS INCREASED COST MA Kotowycz, K Filion, D Dube, MR Reynolds, L Pilote, MJ Eisenberg, V Essebag Montréal, Québec BACKGROUND: Hospitalizations for atrial fibrillation (AF) impose a substantial burden on our healthcare system, and strategies for AF management are increasingly focused on the ability to reduce hospitalizations, in addition to reducing morbidity and mortality. However, the cost of an inpatient admission for AF in Canada is largely unknown. The goals of the present study were to document the cost of an index hospitalization for AF at a large Canadian teaching hospital and to identify the main determinants of this cost. CONCLUSION: The median cost of an AF hospitalization was $3527. Over 50% of the cost was attributable to nursing unit costs, which are directly proportional to length of hospitalization. The main clinical determinants of increased cost and of increased length of stay were the CHADS-2 score and warfarin use. Strategies for reducing AF-related costs should include preventing or decreasing length of hospitalization in patients with high CHADS-2 scores and finding alternatives to the inpatient use of warfarin. CIHR Clinician Scientist Award
247
ATRIAL FIBRILLATION IN THE EMERGENCY DEPARTMENT: A POPULATION-BASED DESCRIPTION CL Atzema, L Yun, P Dorian Toronto, Ontario BACKGROUND: Atrial fibrillation (AF) is the most common arrhythmia seen in the emergency department (ED). The frequency of ED visits for AF in a contemporary, unselected, geographically large and defined population is not known, nor are their outcomes, including mortality, strokes, and return ED visits for AF. ED visits for AF are increasing, and return ED visits are common in these patients. While the proportion of patients discharged from the ED are increasing, rates of return ED visits, hospitalizations for stroke, and mortality have remained unchanged. The mortality rate following an ED visit by these commonly-encountered patients is substantial. HSFO
Can J Cardiol Vol 26 Suppl D October 2010
Abstracts
248
MECHANISMS OF ATRIAL FIBRILLATION ASSOCIATED WITH OBESITY AND OBSTRUCTIVE SLEEP APNEA Y Iwasaki, B Benito, MA Gillis, A Maguy, S Nattel Montréal, Québec BACKGROUND: Obesity and obstructive sleep apnea are independent risk factors for atrial fibrillation (AF). Obesity and obstructive sleep apnea are associated with multiple pathophysiological mechanisms like hypoxia, autonomic tone changes and intrathoracic pressure alterations, that may be directly implicated in the pathogenesis of AF. Consequently, the pathogenesis of AF in obesity and sleep apnea is still uncertain. The purpose of this study was to assess the AF-substrate in relation to obesity and sleep apnea in a rat model. CONCLUSION: Zucker obese rats show substantially-increased AF inducibility during obstructive apnea vs. lean rats, but there are no differences (AF non-inducible in either group) during non-obstructive apnea These results suggest that, in addition to hypoxia, increased negative intrathoracic pressure is an important factor in AF development in the obstructive sleep apnea syndrome. Repetitive forced respiration against closed upper respiratory airways, which generates substantial negative pressures in the chest cavity, might cause atrial stretch and autonomic changes leading to increased AF susceptibility. Our results point to an important AF-promoting interaction between obesity and obstructive sleep apnea that requires further investigation.
249
SEX DIFFERENCES IN THE EMERGENCY DEPARTMENT PRESENTATION OF ATRIAL FIBRILLATION: HOW ARE WOMEN AND MEN DIFFERENT? Z Mariano, M Trivieri, CL Atzema, P Dorian Toronto, Ontario BACKGROUND: Few studies have examined gender-related differences in common arrhythmias such as atrial fibrillation (AF) and atrial flutter (AFL). We examined gender in relation to frequency of presentation, treatment, and outcome of patients presenting to the emergency department (ED) with AF/AFL. CONCLUSION: Relative to the males presenting to our ED with AF/ AFL, the females were older, a greater proportion had a CHADS2 score = 2, and they had fewer contraindications to warfarin. However they were less likely to be on warfarin or rhythm control at ED arrival or at ED/hospital discharge and they were more likely to be hospitalized.
Canadian Cardiovascular Society (CCS) CCS480 Oral IMAGING: RELATED RISKS AND APPROACHES TO IMPROVE PATIENT CARE Monday, October 25, 2010 252
REAL WORLD RADIATION DOSES FROM COMMONLY USED CARDIAC TESTING AND PROCEDURAL MODALITIES J Yang, A Scott-Moncrieff, CM Taylor, J Leipsic, B Heilbron Vancouver, British Columbia BACKGROUND: The volume of cardiac diagnostic tests performed has increased significantly in recent years. The benefits of these tests should be weighed against the risks, including those imposed by exposure to ionizing radiation. Multiple dose reduction strategies exist, but these are often underutilized in clinical practice. CONCLUSION: In this retrospective single-centre study of all patients who underwent clinically indicated CCTA, MPI and CCA in 2009 there was a wide range in effective radiation dose. These tests provide different clinical information and the appropriate test must be chosen with its resultant effective radiation dose in mind. The implementation of dose reduction strategies has the potential to significantly reduce these doses.
Can J Cardiol Vol 26 Suppl D October 2010
Featured Research 253
THE CARCINOGENIC EFFECTS OF IONIZING RADIATION FROM CARDIAC IMAGING PROCEDURES AFTER ACUTE MYOCARDIAL INFARCTION: A POPULATION-BASED LONGITUDINAL STUDY J Afilalo, PR Lawler, L Pilote, H Richard, MJ Eisenberg Montréal, Québec BACKGROUND: Patients with acute myocardial infarction (AMI) are exposed to increasing levels of low-dose ionizing radiation (LDIR) from diagnostic and therapeutic cardiac imaging procedures, during both the acute hospitalization and subsequent follow-up. Exposure to LDIR has been associated with a linear risk of cancer in atomic bomb survivors and nuclear workers, but the risk in medical patients remains uncertain. CONCLUSION: In this population-based cohort of AMI patients, LDIR from cardiac imaging procedures was associated with a graded increase in risk of cancer. These findings underscore the need for judicious use of cardiac imaging procedures, consideration of imaging modalities without LDIR when clinically appropriate, and development of protocols and technologies to reduce the dose of radiation delivered to patients.
Featured Research 254
AGE AND SEX DIFFERENCES IN RISK OF CANCER WITH LOW-DOSE IONIZING RADIATION FROM CARDIAC IMAGING PROCEDURES AFTER ACUTE MYOCARDIAL INFARCTION J Afilalo, PR Lawler, MJ Eisenberg, H Richard, L Pilote Montréal, Québec WITHDRAWN
255
RATES OF DOWNSTREAM INVASIVE CORONARY ANGIOGRAPHY AND REVASCULARIZATION: COMPUTED TOMOGRAPHIC CORONARY ANGIOGRAPHY VERSUS TC-99M SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY V Tandon, D Hall, Y Yam, L Chen, T Ruddy, BJ Chow Ottawa, Ontario BACKGROUND: Computed tomographic coronary angiography (CTA) appears to be a useful modality for the detection of obstructive coronary artery disease (CAD). Recent data suggests that CTA has a positive impact upon referrals to invasive coronary angiography (ICA) and revascularization. However, there remains concern that the implementation of CTA could increase referrals to ICA. We followed a large cohort of CTA patients and a matched cohort of Tc-99m single photon emission computed tomography (SPECT) patients to determine downstream referrals for ICA and revascularization. CONCLUSION: Compared to SPECT, CTA had similar referrals for ICA, revascularization and false positive rates. CTA appears to be a viable non-invasive diagnostic modality and does not appear to negatively impact upon ICA resources.
256
PREVALENCE, APPROPRIATENESS AND TIMING OF TRANSTHORACIC ECHOCARDIOGRAPHY IN THE CORONARY CARE UNIT: A QUALITY ASSURANCE AUDIT KM Bhagirath, RA Ducas, JW Tam Winnipeg, Manitoba BACKGROUND: In an era of spiraling health care costs, the appropriate use of medical technologies such as imaging services is of major importance. In this quality assurance investigation, we sought to determine the
65D