CanCHD Study of Hematopoietic Cancers in Children With and Without Genetic Syndromes.

BACKGROUND: Individuals with genetic syndromes can manifest both congenital heart disease (CHD) and cancer attributable to possible common underlying pathways. To date, reliable risk estimates of hematopoietic cancer (HC) among children with CHD based on large population-based data remain scant. This study sought to quantify the risk of HC by the presence of genetic syndrome among children with CHD. METHODS AND RESULTS: Data sources were the Canadian CHD database, a nationwide database on CHD (1999-2017), and the CCR (Canadian Cancer Registry). Standardized incidence ratios were calculated for comparing HC incidences in children with CHD with the general pediatric population. A modified Kaplan-Meier curve was used to estimate the cumulative incidence of HC with death as a competing risk. A total of 143 794 children (aged 0-17 years) with CHD were followed up from birth to age 18 years for 1 314 603 person-years. Of them, 8.6% had genetic syndromes, and 898 HC cases were observed. Children with known syndromes had a substantially higher risk of incident HC than the general pediatric population (standardized incidence ratio, 13.4 [95% CI, 11.7-15.1]). The cumulative incidence of HC was 2.44% (95% CI, 2.11-2.76) among children with a syndrome and 0.79% (95% CI, 0.72-0.87) among children without a syndrome. Acute myeloid leukemia had a higher cumulative incidence during early childhood than acute lymphoblastic leukemia. CONCLUSIONS: This is the first large population-based analysis documenting that known genetic syndromes in children with CHD are a significant predictor of HC. The finding could be essential in informing risk-stratified policy recommendations for cancer surveillance in children with CHD.

Neurocognitive disorders amongst patients with congenital heart disease undergoing procedures in childhood.

BACKGROUND: Amongst children with congenital heart disease (CHD), earlier age of repair improves cardiovascular outcomes. The effects of early intervention on neurodevelopment remains unclear. We assessed the association between early life repair, cardiopulmonary bypass (CPB) and the incidence of neurocognitive disorders (NCD) amongst CHD patients. METHODS: We created two retrospective cohorts from the Quebec CHD Database; with data from 1988 to 2010. Complexity of reparative procedures for CHD lesions were used as the proxy of CPB exposure with more complex procedure means longer exposure to CPB. Study Population 1 included pediatric patients with a single reparative procedure and compared patients with complex (long CBP) versus isolated shunt (short CBP) lesions. To assess the effects of CPB alone in Study Population 2 we compared patients with isolated atrial septal defects (ASD) who had surgical (short CBP) versus percutaneous (no CBP) repairs. The primary endpoint for both cohorts was development of an NCD. RESULTS: In Study population 1, 1174 patients underwent complex surgical repair and 1620 had a shunt closure. The incidence of NCDs was 2.45/100 person-years in the complex surgery group, and 2.08/100 person-years in the shunt closure group. The following were associated with increased risk of developing a NCD: surgical complexity (Hazard Ratio [HR] = 1.20, 95% Confidence Interval [CI]: 1.01-1.42), younger age at intervention (AAI) (HR = 1.20, 95% CI: 1.16-1.25), male sex (HR = 1.91, 95% CI: 1.61-2.27), and later calendar year at intervention (HR = 1.06, 95% CI: 1.04-1.07). Study population 2 had 527 isolated ASD patients; 202 underwent surgical repair and 325 had percutaneous closure. The incidence of NCDs was not statistically different between groups. Male sex (HR = 1.77, 95% CI: 1.08-2.89) and younger AAI (HR = 1.15, 95% CI: 1.06-1.25) were associated with increased NCD risk. CONCLUSION: Increased surgical complexity, male sex and younger AAI were associated with increased risk of NCDs in pediatric CHD patients. Surveillance protocols should be considered to identify NCDs in CHD patients after cardiac intervention.

Risk prediction models for heart failure admissions in adults with congenital heart disease.

BACKGROUND: Heart failure (HF) is the leading cause of death in adult patients with congenital heart disease (ACHD). No risk prediction model exists for HF hospitalization (HFH) for ACHD patients. We aimed to develop a clinically relevant one-year risk prediction system to identify ACHD patients at high risk for HFH. METHODS: Data source was the Quebec CHD Database. A retrospective cohort including all ACHD patients aged 18-64 (1995-2010) was constructed for assessing the cumulative risk of HFH adjusting for competing risk of death. To identify one-year predictors of incident HFH, multivariable logistic regressions were employed to a nested case-control sample of all ACHD patients aged 18-64 in 2009. The final model was used to create a risk score system based on adjusted odds ratios. RESULTS: The cohort included 29,991 ACHD patients followed for 648,457 person-years. The cumulative HFH risk by age 65 was 12.58%. The case-control sample comprised 26,420 subjects, of whom 189 had HFHs. Significant one-year predictors were age ≥ 50, male sex, CHD lesion severity, recent 12-month HFH history, pulmonary arterial hypertension, chronic kidney disease, coronary artery disease, systemic arterial hypertension, and diabetes mellitus. The created risk score ranged from 0 to 19. The corresponding HFH risk rose rapidly beyond a score of 8. The risk scoring system demonstrated excellent prediction performance. CONCLUSIONS: One eighth of ACHD population experienced HFH before age 65. Age, sex, CHD lesion severity, recent 12-month HFH history, and comorbidities constructed a risk prediction model that successfully identified patients at high risk for HFH.

Transition and Transfer From Pediatric to Adult Congenital Heart Disease Care in Canada: Call For Strategic Implementation.

Dramatic increases in survival to adulthood for persons born with congenital heart disease (CHD) have led rise to a corresponding need to provide age-appropriate and developmentally appropriate care across the lifespan. Health care transition is a multidimensional process that ideally begins in early adolescence in the pediatric setting and continues through young adulthood with input from both pediatric and adult CHD providers. Preparation for transition includes the fostering of adolescents' knowledge of their CHD and of self-management and self-advocacy skills needed for lifelong management of chronic disease. Transfer is the event in time when a patient's care and ownership of health records is taken over by the adult health care team; this is just one element of the broader transition process. Transfer typically occurs by age 18 throughout much of Canada. Successful transition is a shared responsibility, requiring engaged pediatric and adult providers and partnership with both young adults and their parents, all of whom may struggle with this process. An interdisciplinary approach to transition is recommended, given that health care transition is a complex process that occurs within the broader context of young adults' lives. This review summarizes existing evidence regarding transition and transfer, offers perspectives from multiple stakeholders, and proposes a transition curriculum of development of CHD education and self-management and self-advocacy skills. Specific recommendations to improve implementation of transition and transfer care within the Canadian context are provided. This review sheds light on the current capacity and challenges of adult CHD providers and proposes directions to move this field forward.

Cancer Risk in Congenital Heart Disease-What Is the Evidence?

As life expectancy in patients with congenital heart disease (CHD) has improved, the risk for developing noncardiac morbidities is increasing in adult patients with CHD (ACHD). Among these noncardiac complications, malignancies significantly contribute to the disease burden of ACHD patients. Epidemiologic studies of cancer risk in CHD patients are challenging because they require large numbers of patients, extended follow-up, detailed and validated clinical data, and appropriate reference populations. However, several observational studies suggest that cancer risks are significantly elevated in patients with CHD compared with the general population. CHD and cancer share genetic and environmental risk factors. An association with exposure to low-dose ionizing radiation secondary to medical therapeutic or diagnostic procedures has been reported. Patients with Down syndrome, as well as, to a lesser extent, deletion of 22q11.2 and renin-angiotensin system pathologies, may manifest both CHD and a predisposition to cancer. Such observations suggest that carcinogenesis and CHD may share a common basis in some cases. Finally, specific conditions, such as Fontan circulation and cyanotic CHD, may lead to multisystem consequences and subsequently to cancer. Nonetheless, there is currently no clear consensus regarding appropriate screening for cancer and surveillance modalities in CHD patients. Physicians caring for patients with CHD should be aware of this potential predisposition and meet screening recommendations for the general population fastidiously. An interdisciplinary and global approach is required to bridge the knowledge gap in this field.

Heart failure risk predictions in adult patients with congenital heart disease: a systematic review.

To summarise existing heart failure (HF) risk prediction models and describe the risk factors for HF-related adverse outcomes in adult patients with congenital heart disease (CHD). We performed a systematic search of MEDLINE, EMBASE and Cochrane databases from January 1996 to December 2018. Studies were eligible if they developed multivariable models for risk prediction of decompensated HF in adult patients with CHD (ACHD), death in patients with ACHD-HF or both, or if they reported corresponding predictors. A standardised form was used to extract information from selected studies. Twenty-five studies met the inclusion criteria and all studies were at moderate to high risk of bias. One study derived a model to predict the risk of a composite outcome (HF, death or arrhythmia) with a c-statistic of 0.85. Two studies applied an existing general HF model to patients with ACHD but did not report model performance. Twenty studies presented predictors of decompensated HF, and four examined patient characteristics associated with mortality (two reported predictors of both). A wide variation in population characteristics, outcome of interest and candidate risk factors was observed between studies. Although there were substantial inconsistencies regarding which patient characteristics were predictive of HF-related adverse outcomes, brain natriuretic peptide, New York Heart Association class and CHD lesion characteristics were shown to be important predictors. To date, evidence in the published literature is insufficient to accurately profile patients with ACHD. High-quality studies are required to develop a unique ACHD-HF prediction model and confirm the predictive roles of potential risk factors.

Flexible Modeling of the Association Between Cumulative Exposure to Low-Dose Ionizing Radiation From Cardiac Procedures and Risk of Cancer in Adults With Congenital Heart Disease.

Adults with congenital heart disease are increasingly being exposed to low-dose ionizing radiation (LDIR) from cardiac procedures. In a recent study, Cohen et al. (Circulation. 2018;137(13):1334-1345) reported an association between increased LDIR exposure and cancer incidence but did not explore temporal relationships. Yet, the impact of past exposures probably accumulates over years, and its strength may depend on the amount of time elapsed since exposure. Furthermore, LDIR procedures performed shortly before a cancer diagnosis may have been ordered because of early symptoms of cancer, raising concerns about reversal causality bias. To address these challenges, we combined flexible modeling of cumulative exposures with competing-risks methodology to estimate separate associations of time-varying LDIR exposure with cancer incidence and all-cause mortality. Among 24,833 patients from the Quebec Congenital Heart Disease Database, 602 had incident cancer and 500 died during a follow-up period of up to 15 years (1995-2010). Initial results suggested a strong association of cancer incidence with very recent LDIR exposures, likely reflecting reverse causality bias. When exposure was lagged by 2 years, an increased cumulative LDIR dose from the previous 2-6 years was associated with increased cancer incidence, with a stronger association for women. These results illustrate the importance of accurate modeling of temporal relationships between time-varying exposures and health outcomes.

Historical investigation of medical treatment for adult congenital heart disease: A Canadian perspective.

OBJECTIVE: The number of adults with congenital heart disease (CHD) has increased substantially because of medical advances that are extending life expectancy beyond childhood. A historical investigation is timely not only because of this significant demographic shift, but also because stakeholder engagement is increasingly important in shaping research directions. The study questions were: From the perspective of stakeholders, what is known about the medical treatment for the adult CHD cohort in Canada and how has it changed over time? DESIGN/METHODS: We harnessed the use of historical research methods and conducted interviews with 21 key informants in order to articulate a contextualized understanding of the evolution of adult CHD treatment in Canada. The informants recruited were currently or previously located in and/or involved in treatment in seven provinces and two territories across Canada including patients, families, advocates, researchers, and practitioners located in disciplines that included cardiology, cardiovascular surgery, nursing, psychology, dietetics, and kinesiology. RESULTS: Alongside findings that highlighted the significant demographic shift, the findings highlight key themes related to temporal shifts in treatment, emergence of organizational structures and use of evidence, comprehensive approaches to care, and future directions. A critical finding that requires immediate attention is the significantly disproportionate resources to the number of adults living with CHD, and as a result, the real risk of premature death for this population. CONCLUSIONS: The insights provided behoove the community of stakeholders to think creatively on how to draw attention to the inadequacy of resources and the unique and diverse needs of this population.

Rationale and Design of the FREQUENCY Study: The Fetal Cardiac Registry of Québec to Improve Resource Utilization in Fetal Cardiology.

OBJECTIVE: Prenatal detection of congenital heart diseases (CHD) decreases morbidity and cost. To improve detections rates, most physicians refer pregnant women with high-risk pregnancies to fetal cardiologists even when there is no suspicion of CHD at the second trimester screening. This paper presents the rationale and detailed method of the Fetal Cardiac Registry of Québec to Improve Resource Utilization in Fetal Cardiology (FREQUENCY) study. The overall objective is to assess the impact of second trimester ultrasound screening (U/S) and referral pattern in fetal cardiology on detection rates, health care costs, and resource utilization, as well as perinatal morbidity and mortality. METHODS: This multicentre retrospective population-based cohort study will link fetal echocardiography data from all centres performing fetal echocardiography in Québec with administrative health care data. This data linking will allow the determination of a true denominator (all women in Québec who underwent second trimester U/S) with complete follow-up of up to 2 years for offspring. This protocol meets Canadian Task Force Classification II-2. RESULTS: The study investigators have collected and cleaned fetal echocardiography data for 24 259 eligible pregnancies referred to fetal cardiology. These data will be matched to approximately 860 000 pregnancies between 2007 and 2015. CONCLUSION: The results of the FREQUENCY study will shed light on the impact of the current prenatal CHD screening strategy in Canada.

Improving Quality of Congenital Heart Disease Research in Canada: Standardizing Nomenclature Across Canada.

In an effort to improve the quality of interinstitutional and nation-wide research into congenital heart disease (CHD) in Canada, the authors propose the national implementation of a single nomenclature list for CHD as a first step towards achieving a common disease classification system in all Canadian institutions that deal with congenital heart malformations. The authors offer a brief overview of the history and state of nomenclature for CHD in Canada and recommend the national use of the CHD diagnostic list that was recently finalized by the International Society for Nomenclature of Paediatric and Congenital Heart Disease. This list was submitted to the World Health Organization for incorporation into the 11th iteration of the International Classification of Diseases and was recently translated into French by members of the International Society for Nomenclature of Paediatric and Congenital Heart Disease. The bilingual list of the 11th iteration of the International Classification of Diseases CHD terms is published online in this issue of the Canadian Journal of Cardiology. The national standardization of the nomenclature pertaining to CHD using the bilingual list of terms published herein will optimize national efforts to establish longitudinal CHD cohorts, capitalizing on Canada's health care infrastructure and solidifying Canadian leadership in CHD research.

Administrative health databases for addressing emerging issues in adults with CHD: a systematic review.

The need for population-based studies of adults with CHD has motivated the growing use of secondary analyses of administrative health data in a variety of jurisdictions worldwide. We aimed at systematically reviewing all studies using administrative health data sources for adult CHD research from 2006 to 2016. Using PubMed and Embase (1 January, 2006 to 1 January, 2016), we identified 2217 abstracts, from which 59 studies were included in this review. These comprised 12 different data sources from six countries. Of these, 55% originated in the United States of America, 28% in Canada, and 17% in Europe and Asia. No study was published before 2007, after which the number of publications grew exponentially. In all, 41% of the studies were cross-sectional and 25% were retrospective cohort studies with a wide variation in the availability of patient-level compared with hospitalisation-level episodes of care; 58% of studies from eight different data sources linked administrative data at a patient level; and 37% of studies reported validation procedures. Assessing resource utilisation and temporal trends of relevant epidemiological and outcome end points were the most reported objectives. The median impact factor of publication journals was 4.04, with an interquartile range of 3.15, 7.44. Although not designed for research purposes, administrative health databases have become powerful data sources for studying adult CHD populations because of their large sample sizes, comprehensive records, and long observation periods, providing a useful tool to further develop quality of care improvement programmes. Data linkage with electronic records will become important in obtaining more granular life-long adult CHD data. The health services nature of the data optimises the impact on policy and public health.

Exposure to Low-Dose Ionizing Radiation From Cardiac Procedures and Malignancy Risk in Adults With Congenital Heart Disease.

BACKGROUND: Adults with congenital heart disease (CHD) are exposed to increasing amounts of low-dose ionizing radiation (LDIR) from cardiac procedures. Cancer prevalence in this population is higher than in the general population. This study estimates the association between LDIR exposure from cardiac procedures and incident cancer in adult patients with CHD. METHODS: The study population derived from the Quebec Congenital Heart Disease Database. We measured cumulative numbers of LDIR-related cardiac procedures for each patient until 1 year before the time of cancer diagnosis or administrative censoring. To assess the association between LDIR exposure and cancer risk, we conducted a nested case-control study and matched cancer cases with controls on sex, CHD severity, birth year, and age. RESULTS: The study included 24 833 adult patients with CHD aged 18 to 64 years from 1995 to 2009. In >250 791 person-years of follow-up, 602 cancer cases were observed (median age, 55.4 years). The cumulative incidence of cancer estimated up to 64 years of age was 15.3% (95% confidence interval [CI], 14.2-16.5). Cases had more LDIR-related cardiac procedures than controls (1410 versus 921 per 1000 adult patients with CHD, P<0.0001). Cumulative LDIR exposure was independently associated with cancer (odds ratio [OR], 1.08 per procedure; 95% CI, 1.04-1.13). Similar results were obtained by using dose estimates for LDIR exposure (OR, 1.10 per 10 mSv; 95% CI, 1.05-1.15) with a possible dose-related response. The effect measure was in the same direction, and the association was persistent for exposure from ≥6 procedures in all sensitivity analyses: after excluding most smoking-related cancer cases (OR, 1.10 per procedure; 95% CI, 1.05-1.16 and OR when exposure from ≥6 procedures, 3.08; 95% CI, 1.77-5.37), and after applying a 3-year lag period (OR, 1.09 per procedure; 95% CI, 1.03-1.14 and OR when exposure from ≥6 procedures: 2.58; 95% CI, 1.43-4.69). CONCLUSIONS: To our knowledge, this is the first large population-based study to analyze and document the association between LDIR-related cardiac procedures and incident cancer in the population of adults with CHD. Confirmations of these findings by prospective studies are needed to reinforce policy recommendations for radiation surveillance in patients with CHD where no regulation currently exists. Physicians ordering and performing cardiac imaging should ensure that exposure is as low as reasonably achievable without sacrificing quality of care.

Cost of Congenital Heart Disease Hospitalizations in Canada: A Population-Based Study.

BACKGROUND: The prevalence of congenital heart disease (CHD) is rising, and late complications are common. The impact of these factors on health-care costs is not well understood. We sought to describe inpatient CHD costs in Canada. METHODS: We conducted an observational retrospective cohort study. The Canadian Institute for Health Information (CIHI) Discharge Abstract Database was used for all Canadian provinces, except Quebec, between April 2004 and March 2014. We included hospitalizations with a main diagnosis of CHD (International Classification of Diseases, 10th revision, codes Q20.0-26.9) and hospitalizations having CHD as a secondary diagnosis if the main diagnosis was a comorbid condition related to CHD. CIHI patient cost estimates were used to provide dollar values. Costs were inflated to 2016 Canadian dollars. RESULTS: Among 59,917 hospitalizations, annual CHD costs increased by 21.6% from CAD$99.7 million (95% confidence interval [CI], $89.4-$110.1 million) in 2004 to $121.2 million (95% CI, $112.8-$129.6 million) in 2013 (P < 0.001). Costs were higher for children compared with adults. However, the cost increase was greater in adults (4.5%/y; P < 0.001) than in children (0.7%/y; P = 0.006). Adults accounted for 38.2% of costs in 2004 vs 45.8% in 2013 (P = 0.002). Costs increased most among adults with complex CHD (7.2%/y; P = 0.001). Adult men accounted for greater increases in costs relative to women (P < 0.001). Length of stay was unchanged over time. CONCLUSIONS: Inpatient CHD costs are increasing independent of inflation, particularly among adults with complex lesions. Although children still account for greater inpatient CHD costs, a larger increase was observed among adults. These data are important in allocating inpatient resources for adults with CHD.

Prevalence of Cancer in Adults With Congenital Heart Disease Compared With the General Population.

The prevalence rate of cancer among adult patients with congenital heart disease (CHD) in North America has not been previously described. The Quebec adult CHD database was used to determine the prevalence rate of cancer among adult patients with CHD measured as the number of adults with CHD and cancer alive in 2005 per 1,000 adults with CHD. This prevalence rate was compared with the prevalence rate of cancer in the general population of adults in Canada. Types of cancer among the CHD group were described by gender and age. Adult patients with CHD had a 1.6 to 2 times higher prevalence of cancer at 2, 5, and 10 years for both men and women. Overall, men had a greater prevalence of total cancers in all-time durations than did women. Breast, colon, and prostate cancer were the most common cancers reported in adults with CHD. In conclusion, we observed an increased prevalence of cancer among the adult CHD population of Quebec compared with the general Canadian population.

Congenital Heart Defects in the United States: Estimating the Magnitude of the Affected Population in 2010.

BACKGROUND: Because of advancements in care, there has been a decline in mortality from congenital heart defects (CHDs) over the past several decades. However, there are no current empirical data documenting the number of people living with CHDs in the United States. Our aim was to estimate the CHD prevalence across all age groups in the United States in the year 2010. METHODS: The age-, sex-, and severity-specific observed prevalence of CHDs in Québec, Canada, in the year 2010 was assumed to equal the CHD prevalence in the non-Hispanic white population in the United States in 2010. A race-ethnicity adjustment factor, reflecting differential survival between racial-ethnic groups through 5 years of age for individuals with a CHD and that in the general US population, was applied to the estimated non-Hispanic white rates to derive CHD prevalence estimates among US non-Hispanic blacks and Hispanics. Confidence intervals for the estimated CHD prevalence rates and case counts were derived from a combination of Taylor series approximations and Monte Carlo simulation. RESULTS: We estimated that ≈2.4 million people (1.4 million adults, 1 million children) were living with CHDs in the United States in 2010. Nearly 300 000 of these individuals had severe CHDs. CONCLUSIONS: Our estimates highlight the need for 2 important efforts: planning for health services delivery to meet the needs of the growing population of adults with CHD and the development of surveillance data across the life span to provide empirical estimates of the prevalence of CHD across all age groups in the United States.

Cardiac output as a predictor in congenital heart disease: Are we stating the obvious?

BACKGROUND: Significant pulmonary regurgitation, declining right-sided ejection fraction, increased right ventricular (RV) volumes as well as left ventricular (LV) dysfunction have all been identified as predictors of poor outcomes in patients with congenital heart disease (CHD). The prognostic value of the cardiac output (CO) in these patients however has never been studied. METHODS: All consecutive ambulatory adult patients with CHD referred for magnetic resonance imaging (MRI) at the Montreal Children's Hospital between June 2007 and May 2009 were included. Right ventricular (RV) and left ventricular (LV) variables including end diastolic and end systolic volumes (EDV, ESV respectively), ejection fractions (EF) and regurgitant volumes were obtained. Cardiac index (CI) was calculated. Patients were followed for cardiac-related hospitalizations and cardiac interventions. RESULTS: Ninety-six patients were included. Median follow up was 3.9 ± 1.4 years. Nineteen percent of patients had a systemic CI<2.4 l/min/m(2). LVEDV, LVEF and RVEF were significantly diminished in the low CI group with a significant increase in RVESV and total regurgitant volume. Best predictors of low CI were LVEF (AUC=0.74), RVEF (AUC=0.71), total RV regurgitant volume (AUC=0.64) and RVESV (AUC=0.563). Low systemic CI was the best predictor of cardiac-related hospitalizations (hazard ratio 3.5, 95% confidence interval 1.5-8.5) and cardiac interventions (hazard ratio 2.2, 95% confidence interval 1.3-4.0), superior to LVEF, RVEF, total regurgitant volume and RVESV parameters. CONCLUSIONS: In patients with congenital heart disease, cardiac index is the best predictor of cardiac hospitalizations and cardiac interventions.

Infective Endocarditis Hospitalizations Before and After the 2007 American Heart Association Prophylaxis Guidelines.

BACKGROUND: In 2007, the American Heart Association (AHA) published revised guidelines for infective endocarditis (IE) prophylaxis. Population-based data with respect to the potential impact of these revised guidelines are lacking. METHODS: The Canadian Institute for Health Information Discharge Abstract Database was used to identify all hospitalizations between April 2002 and March 2013 having IE as a primary diagnosis. Hospitalization rates were determined using age-specific population data from Statistics Canada. Interrupted time series analysis was used to evaluate changes in the slope of hospitalization rates after the AHA guidelines were published. RESULTS: There were 9431 hospitalizations during the study period among 8055 patients (63% male patients). Time trend analysis showed an increase of 0.05 IE hospitalizations per 10 million population per month (95% confidence interval, 0.005-0.09; P = 0.029) from April 2002-March 2007 and an increase of 0.07 IE hospitalizations per 10 million population per month from April 2007-March 2013 (interaction P = 0.5213). Change-point analysis showed that a change in the slope occurred in April 2011, 4 years after publication of the revised AHA guidelines. Staphylococcus aureus was the most commonly reported organism (29.4%). Streptococcal infections decreased over time, beginning before the 2007 guidelines (P < 0.0001). The presence of a pacemaker or defibrillator was an increasingly prevalent risk factor over time (4% increase per year; P = 0.0178). CONCLUSIONS: The rate of IE hospitalizations increased in Canada before and after the publication of the 2007 AHA guidelines, with no significant change in slope after 2007. These guidelines had no impact on the incidence of IE hospitalizations.