Development and evolution of nuclear cardiology and cardiac PET in Canada.

Gated radionuclide angiography and myocardial perfusion imaging were developed in the United States and Europe in the 1970's and soon adopted in Canadian centers. Much of the early development of nuclear cardiology in Canada was in Toronto, Ontario and was quickly followed by new programs across the country. Clinical research in Canada contributed to the further development of nuclear cardiology and cardiac PET. The Canadian Nuclear Cardiology Society (CNCS) was formed in 1995 and became the Canadian Society of Cardiovascular Nuclear and CT Imaging (CNCT) in 2014. The CNCS had a major role in education and advocacy for cardiovascular nuclear medicine testing. The CNCS established the Dr Robert Burns Lecture and CNCT named the Canadian Society of Cardiovascular Nuclear and CT Imaging Annual Achievement Award for Dr Michael Freeman in memoriam of these two outstanding Canadian leaders in nuclear cardiology. The future of nuclear cardiology in Canada is exciting with the expanding use of SPECT imaging to include Tc-99m-pyrophosphate for diagnosis of transthyretin cardiac amyloidosis and the ongoing introduction of cardiac PET imaging.

Pregnancy related changes in Doppler gradients and left ventricular mechanics in women with sub-valvular or valvular aortic stenosis.

BACKGROUND: The aim of our study was to characterize echocardiographic changes during pregnancy in women with known LVOT obstruction or AS compared to the healthy pregnancy controls, and to assess the relationship with pregnancy outcomes. METHODS: We retrospectively studied 34 pregnant patients with congenital LVOT obstruction or AS with healthy age-matched pregnant controls. Patients with other significant valvular lesions, structural heart disease (LVEF < 40%), or prior valve surgery were excluded. All LVOTO/AS patients underwent a minimum of two consecutive echocardiograms between 1 year pre-conception and 1 year postpartum, with at least two studies during the pregnancy. Comprehensive echocardiographic evaluation was performed including speckle-tracking LV global longitudinal strain. RESULTS: A total of 83 echocardiograms from the study group and 34 echocardiograms from the control group were evaluated. Over the range of LVOTO/AS, a significantly greater increase in the AV gradients and LV and LA volumes were observed as compared with the controls. In the sub-group of LVOTO/AS pregnant women with ≥ moderate (n = 8) versus < moderate LVOTO/AS (n = 26), averaged 2nd /3rd trimester LVEF was lower (51 ± 12)% versus (58 ± 4)%, (p = 0.02) and GLS was lower (-19.5 ± 2.8) versus (21.2 ± 2.4), (p = 0.06). Pregnancy was well tolerated despite these changes. CONCLUSION: Among pregnant women with even milder forms of LVOTO/AS, increases in cardiac volumes and AV gradients can be expected over the course of pregnancy. Significant decreases in LV function and mechanics were only observed in women with moderate or greater LVOTO/AS, although still remained in normal range.

Cardiac Risk Score to Predict Small for Gestational Age Infants in Pregnant Women With Heart Disease.

BACKGROUND: One of the most common fetal complications in pregnant women with cardiovascular disease is a small for gestational age (SGA) neonate, which is associated with a higher risk of perinatal morbidity/mortality and poor long-term health outcomes. The objective of this study was to identify cardiac determinants and derive a risk score for clinically relevant SGA < 5th percentile (SGA-5th). METHODS: A prospective cohort of 1812 pregnancies in women with heart disease were studied. SGA-5th was the outcome of interest, defined as birth weight < 5th percentile for gestational age and sex. Multivariable logistic regression analysis was used to identify predictors for SGA-5th. Based on the regression coefficients, a weighted risk score was created. RESULTS: SGA-5th complicated 10% of pregnancies, 11 predictors of SGA-5th were identified, and each was assigned a weighted score: maternal cyanosis (8), Fontan palliation (7), smoking (3), moderate or severe valvular regurgitation (3), ß-blocker use throughout pregnancy (4) or only in the 2nd and 3rd trimesters (2), high baseline ß-blocker dose (4), body mass index < 18.5 kg/m2 (3) or 18.5-24.9 kg/m2 (1), Asian/other ethnicity (2), and significant outflow tract obstruction (1). In the absence of these identified risk factors, the risk of SGA-5th was approximately 4%. Pregnancies with risk scores of 1 had a rate of 5%; 2, 7%; 3, 9%; 4, 12%; 5, 14%; 6, 18%; 7, 23%; 8, 28%; and ≥ 9, 34%. CONCLUSIONS: There are a number of cardiac predictors that are associated with increased risk of SGA-5th. This is a prognostically important outcome, and consideration should be given to routinely predicting and modifying the risk whenever possible.

Atrial arrhythmias and thromboembolic complications in adults post Fontan surgery.

OBJECTIVE: Patients with Fontan surgery experience late complications in adulthood. We studied the factors associated with the development and maintenance of atrial arrhythmias and thromboembolic complications in an adult population with univentricuar physiology post Fontan surgery. METHODS: Single centre retrospective cohort study of patients ≥18 years of age with Fontan circulation followed at our quaternary care centre for more than 1 year were included. Univariate and multivariate regression models were used where applicable to ascertain clinically significant associations between risk factors and complications. RESULTS: 93 patients were included (age 30.2±8.8 years, 58% men). 28 (30%) had atriopulmonary Fontan connection, 35 (37.6%) had lateral tunnel Fontan and 29 (31.1%) had extracardiac Fontan pathway. After a mean of 7.27±5.1 years, atrial arrhythmia was noted in 37 patients (39.8%), of which 13 developed had atrial fibrillation (14%). The presence of atrial arrhythmia was associated with the number of prior cardiac surgeries/procedures, increasing age and prior atriopulmonary Fontan operation. Thromboembolic events were present in 31 patients (33%); among them 14 had stroke (45%), 3 had transient ischaemic attack (9.7%), 7 had pulmonary embolism (22.6%) and 5 had atrial thrombus with imaging (16.1%). The presence of thromboembolic events was only associated with age and the presence of cirrhosis in multivariate analysis. CONCLUSIONS: Atrial arrhythmias are common in adults with Fontan circulation at an early age, and are associated with prior surgical history and increasing age. Traditional risk factors may not be associated with atrial arrhythmia or thromboembolism in this cohort.

Tricuspid Intervention Following Pulmonary Valve Replacement in Adults With Congenital Heart Disease.

BACKGROUND: Tricuspid regurgitation (TR) is common among adults with corrected tetralogy of Fallot (TOF) or pulmonary stenosis (PS) referred for pulmonary valve replacement (PVR). Yet, combined valve surgery remains controversial. OBJECTIVES: This study sought to evaluate the impact of concomitant tricuspid valve intervention (TVI) on post-operative TR, length of hospital stay, and on a composite endpoint consisting of 7 early adverse events (death, reintervention, cardiac electronic device implantation, infection, thromboembolic event, hemodialysis, and readmission). METHODS: The national Canadian cohort enrolled 542 patients with TOF or PS and mild to severe TR who underwent isolated PVR (66.8%) or PVR+TVI (33.2%). Outcomes were abstracted from charts and compared between groups using multivariable logistic and negative binomial regression. RESULTS: Median age at reintervention was 35.3 years. Regardless of surgery type, TR decreased by at least 1 echocardiographic grade in 35.4%, 66.9%, and 92.8% of patients with pre-operative mild, moderate, and severe insufficiency. In multivariable analyses, PVR+TVI was associated with an additional 2.3-fold reduction in TR grade (odds ratio [OR]: 0.44; 95% confidence interval [CI]: 0.25 to 0.77) without an increase in early adverse events (OR: 0.85; 95% CI: 0.46 to 1.57) or hospitalization time (incidence rate ratio: 1.17; 95% CI: 0.93 to 1.46). Pre-operative TR severity and presence of transvalvular leads independently predicted post-operative TR. In contrast, early adverse events were strongly associated with atrial tachyarrhythmia, extracardiac arteriopathy, and a high body mass index. CONCLUSIONS: In patients with TOF or PS and significant TR, concomitant TVI is safe and results in better early tricuspid valve competence than isolated PVR.

Stress Echocardiographic Evaluation for D-Transposition of the Great Arteries after Atrial Redirection: Unmasking Early Signs of Myocardial Dysfunction and Baffle Stenosis.

BACKGROUND: The authors used semisupine cycle ergometry stress echocardiography to assess cardiac function and unmask baffle stenosis in patients with d-transposition of the great arteries after atrial redirection surgery. METHODS: This was a retrospective review of semisupine cycle ergometry stress echocardiography performed in 53 patients (64% male; mean age, 24.0 years; 90% Mustard procedure) and 56 healthy control subjects. Incremental exercise to volitional fatigue was performed. Hemodynamic data, echocardiographic cardiac dimensions, area change, tissue Doppler velocities, strain, ventricular synchronization, and superior vena cava flow velocities before and immediately after exercise are reported. RESULTS: Patients had lower exercise capacity (870 vs 1,854 J/kg, P < .001) and peak heart rates (132 vs 167 beats/min, P < .001). Stroke volume index did not increase with exercise (45 vs 47 mL/m2, P = .400). Cardiac index increased in both groups with exercise (3.0 vs 6.1 and 2.9 vs 7.0 L/min/m2, P < .001) and was higher in control subjects (P = .006). Right ventricular diastolic and systolic areas decreased significantly with exercise in both the short-axis and four-chamber views. Right and left ventricular contraction time shortened with exercise (405 vs 247 and 338 vs 217 msec, P < .001) and remained synchronous (ratio of right ventricular to left ventricular contraction time = 0.080). Doppler velocities in patients with baffle obstruction were higher in the lower superior vena cava with exercise compared with nonobstructed patients (1.87 vs 1.46 m/sec, P = .020) and normalized after catheter intervention (1.49 vs 1.46 m/sec, P = .800). CONCLUSIONS: Patients with d-transposition of the great arteries have lower exercise capacity and peak heart rates. The systemic right ventricle presents a lesser but qualitatively normal systolic response and decreased diastolic filling. Semisupine cycle ergometry stress echocardiography unmasked SVC obstruction.

Meta-Analysis of the Effectiveness of Heart Transplantation in Patients With a Failing Fontan.

The Fontan procedure is increasingly being used to palliate univentricular physiology. It is a complex anatomic and physiologic repair that can fail at any age, often leaving heart transplantation as the only remaining solution. A meta-analysis was performed to achieve the aim of systematically evaluating the existing evidence for survival after heart transplantation in patients who have undergone a Fontan palliation. MEDLINE, Embase, PubMed, and Web of Science were searched for original research studies. The primary outcome was mortality at 1 and 5 years after transplantation. Five hundred eighty-two records were screened, after the removal of duplicates, 12 retrospective observational studies were selected for inclusion in our meta-analysis. This encompassed a total of 351 Fontan patients undergoing heart transplantation. Mean age was 14 years (range 7 to 24 years) and 65% were men. One- and 5-year survival rates after heart transplantation were found to be 80.3% (95% CI 75.9% to 84.2%) and 71.2% (95% CI 66.3% to 75.7%), respectively. No significant association was found between age, gender, and pulmonary pressures and 1-year mortality. In conclusion, in the largest analysis to date, we found that heart transplantation in younger patients after Fontan procedure has an acceptable early and mid-term mortality. It is comparable to published mortality data of heart transplantation for other forms of congenital heart disease. Heart transplantation in the younger failing Fontan population appears to be a reasonable option when all other avenues have been exhausted and appropriate screening has taken place.

Right ventricle to pulmonary artery conduit reoperations in patients with tetralogy of fallot or pulmonary atresia associated with ventricular septal defect.

The short lifespan of right ventricle-to-pulmonary artery (RV-PA) conduits used in repairs of complex congenital heart defects makes future surgical replacement inevitable. Percutaneous pulmonary valve implantation (PPVI) now offers an attractive alternative to surgery in some patients. The objectives of this study were to examine the pattern of conduit reoperations, the factors affecting conduit longevity, and to discuss the role of PPVI in these patients. Forty-nine patients (mean age 27 ± 8 years) with pulmonary atresia or pulmonary stenosis with tetralogy of Fallot who underwent surgery for RV-PA conduits from September 1974 to October 2011 were reviewed. A total of 106 RV-PA conduits were implanted, 57 of which were replacements. Second, third, and fourth conduits were required during the follow-up period in 39, 16, and 2 patients, respectively. Freedom from reoperation at 10 years for the first, second, and third conduits was 50%, 74%, and 86%, respectively. Significant independent predictors of shorter conduit longevity included smaller conduit and conduit type (homograft and other vs Dacron). Furthermore, a significant proportion (32 of 57 [56%]) of conduit replacements took place from ages 9 to 18 years. There were 37 adults whose current existing conduits had not yet failed, with 73% (27 of 37) potentially suitable in the future for PPVI on the basis of conduit size of 16 to 27 mm. In conclusion, multiple RV-PA conduit revisions were required in patients who survived to adulthood, with many replacements taking place during adolescence. Most conduits in this adult cohort met size criteria for PPVI, thereby offering these patients a potential alternative to surgical intervention for conduit failure.

Evaluation of silent thrombus after the Fontan operation.

BACKGROUND: Thromboembolic complications have been noted after the Fontan operation. However, the prevalence of silent events among an adult contemporary population is not known. Noninvasive screening by any method including computed tomography (CT) has been technically limited to date. OBJECTIVES: The objective of this study was to evaluate a novel dual-energy CT (DECT) protocol in determining the prevalence of "silent" intracardiac thrombus and thrombus in the Fontan and pulmonary circulations among adults after the Fontan operation. METHODS: All post-Fontan patients attending the Pacific Adult Congenital Heart Clinic were approached for study participation. Those agreeable underwent a full clinical assessment, cardiopulmonary stress testing, transthoracic echocardiogram, and DECT low kilovoltage imaging protocol. RESULTS: Twenty-three patients were included in the study (30 ± 10 years, 26% women). Three (13%) patients had evidence of silent thrombi detected on DECT. All three of these patients had an extracardiac conduit and mural thrombus was found within the conduit. Older age at the time of the Fontan operation was associated with the presence of thrombus (21 ± 14 vs. 11 ± 6 years, P =.05). CONCLUSIONS: Thirteen percent of adult patients post-Fontan procedure have clinically silent thrombi. These were all found among patients with an extracardiac conduit traditionally thought to be at low risk for thromboembolism. Given the significant risk of thromboembolic complications, large randomized prospective studies looking at anticoagulation therapy in all Fontan patients are urgently needed. In the meanwhile, given the important rate of silent thrombi, a systematic robust screening protocol that includes noninvasive low radiation methods such as DECT methods should be considered.

A case of Starr-Edwards valve thrombosis in pregnancy.

Starr-Edwards ball-in-cage prosthetic heart valves, although durable, are associated with a particularly high rate of thromboembolic complications. This valve is seldom used in North America, and is certainly not the valve of choice in a woman of childbearing age. Few reports exist from the 1970s of thrombotic complications in pregnant women with Starr-Edwards prostheses, and the optimal management strategy for such valves is unclear. Here, the case is reported of a 31-year-old woman with a Starr-Edwards prosthesis in the mitral position who was transferred to the authors' center at six weeks' gestation with pulmonary edema. Transthoracic echocardiography demonstrated thrombosis of the prosthetic valve, with a mean gradient of 23 mmHg. When treated initially with intravenous heparin and furosemide the patient improved significantly; however, the optimal management going forward was unclear. Here, the options for anticoagulation during pregnancy and for management in the event of valve thrombosis are reviewed. In the absence of any clear guidelines, a thorough discussion of the various risks and benefits with the patient is necessary, but ultimately any consideration of the risk to the mother is paramount.

Structure and process measures of quality of care in adult congenital heart disease patients: a pan-Canadian study.

BACKGROUND: There are more adults than children with congenital heart disease. Of over 96,000 ACHD patients in Canada, approximately 50% require ongoing expert care. In spite of published recommendations, data on the quality of care for ACHD patients are lacking. METHODS: Survey methodology targeted all Canadian Adult Congenital Heart (CACH) network affiliated ACHD centers. Clinics were asked to prospectively collect outpatient and procedural volumes for 2007. In 2008, centers were surveyed regarding infrastructure, staffing, patient volumes and waiting times. RESULTS: All 15 CACH network registered centers responded. The total number of patients followed in ACHD clinics was 21,879 (median per clinic=1132 (IQR: 585, 1816)). Of the total 80 adult and pediatric cardiologists affiliated to an ACHD clinic, only 27% had received formal ACHD training. Waiting times for non-urgent consultations were 4 ± 2 months, and 4 ± 3 months for percutaneous and surgical procedures. These were beyond Canadian recommended targets at 11 sites (73%) for non-urgent consultations, at 8 sites (53%) for percutaneous interventions and 13 sites (87%) for surgery. CONCLUSIONS: Of a minimum number of 96,000 ACHD patients in Canada, only 21,879 were being regularly followed in 2007. At most sites waiting times for ACHD services were beyond Canadian recommended targets. In spite of universal health care access, published guidelines for ACHD patient structure and process measures of health care quality are not being met.

Canadian Cardiovascular Society 2009 Consensus Conference on the management of adults with congenital heart disease: executive summary.

With advances in pediatric cardiology and cardiac surgery, the population of adults with congenital heart disease (CHD) has increased. In the current era, there are more adults with CHD than children. This population has many unique issues and needs. They have distinctive forms of heart failure, and their cardiac disease can be associated with pulmonary hypertension, thromboemboli, complex arrhythmias and sudden death.Medical aspects that need to be considered relate to the long-term and multisystemic effects of single-ventricle physiology, cyanosis, systemic right ventricles, complex intracardiac baffles and failing subpulmonary right ventricles. Since the 2001 Canadian Cardiovascular Society Consensus Conference report on the management of adults with CHD, there have been significant advances in the understanding of the late outcomes, genetics, medical therapy and interventional approaches in the field of adult CHD. Therefore, new clinical guidelines have been written by Canadian adult CHD physicians in collaboration with an international panel of experts in the field. The present executive summary is a brief overview of the new guidelines and includes the recommendations for interventions. The complete document consists of four manuscripts that are published online in the present issue of The Canadian Journal of Cardiology, including sections on genetics, clinical outcomes, recommended diagnostic workup, surgical and interventional options, treatment of arrhythmias, assessment of pregnancy and contraception risks, and follow-up requirements. The complete document and references can also be found at www.ccs.ca or www.cachnet.org.

Canadian Cardiovascular Society 2009 Consensus Conference on the management of adults with congenital heart disease: outflow tract obstruction, coarctation of the aorta, tetralogy of Fallot, Ebstein anomaly and Marfan's syndrome.

With advances in pediatric cardiology and cardiac surgery, the population of adults with congenital heart disease (CHD) has increased. In the current era, there are more adults with CHD than children. This population has many unique issues and needs. Since the 2001 Canadian Cardiovascular Society Consensus Conference report on the management of adults with CHD, there have been significant advances in the field of adult CHD. Therefore, new clinical guidelines have been written by Canadian adult CHD physicians in collaboration with an international panel of experts in the field. Part II of the guidelines includes recommendations for the care of patients with left ventricular outflow tract obstruction and bicuspid aortic valve disease, coarctation of the aorta, right ventricular outflow tract obstruction, tetralogy of Fallot, Ebstein anomaly and Marfan's syndrome. Topics addressed include genetics, clinical outcomes, recommended diagnostic workup, surgical and interventional options, treatment of arrhythmias, assessment of pregnancy risk and follow-up requirements. The complete document consists of four manuscripts that are published online in the present issue of The Canadian Journal of Cardiology. The complete document and references can also be found at www.ccs.ca or www.cachnet.org.

The Extensive Lifestyle Management Intervention (ELMI) after cardiac rehabilitation: a 4-year randomized controlled trial.

BACKGROUND: Previous reports indicate risk factors and lifestyle behaviors may deteriorate early after completion of a cardiac rehabilitation program (CRP). We hypothesized that a modest risk factor and lifestyle management intervention after a CRP would significantly reduce overall cardiovascular risk using the Framingham risk score compared with usual care after 4 years. METHODS: Patients with ischemic heart disease (n = 302) were randomized after a CRP to either usual care or intervention (exercise sessions, telephone follow-ups, counseling sessions, and reports to the participants' family physicians). The Framingham risk score, risk factors, and lifestyle behaviors were compared after 4 years. RESULTS: Data were available for 130 intervention and 119 usual care participants. The intervention resulted in 15.5 hours of direct participant contact. Framingham score, total cholesterol, low-density lipoprotein cholesterol, and systolic blood pressure were significantly improved in the intervention group after adjusting for baseline factors. There were no significant differences with respect to lifestyle factors between the groups. CONCLUSIONS: A modest risk factor and lifestyle management intervention resulted in a significant reduction to global risk compared with usual care and should be considered after CRP.

The Extensive Lifestyle Management Intervention (ELMI) following cardiac rehabilitation trial.

AIM: Previous studies have reported lifestyle and risk factor deterioration following completion of a cardiac rehabilitation program (CRP). We report the results of a one-year Extensive Lifestyle Management Intervention (ELMI) aimed at preventing these adverse changes. METHODS AND RESULTS: A total of 302 men and women with ischaemic heart disease were recruited following completion of a CRP and randomized to either the ELMI (consisting of exercise sessions, telephone follow-ups and risk factor and lifestyle counselling) or usual care. The primary outcome was global cardiovascular risk using the Framingham and Procam risk scores. Secondary outcomes included risk factors and lifestyle behaviours. Baseline characteristics were similar between the two groups. Adherence to the ELMI was high. There was a non-significant trend in favour of the ELMI between for both the Framingham (6.6+/-3.1 to 6.2+/-2.9 vs 6.6+/-3.2 to 6.7+/-3.2, P=0.138) and Procam (20.0+/-20.0 to 20.6+/-19.5 vs 19.1+/-18.7 to 21.8+/-19.1, P=0.089) scores. There were no differences in secondary outcomes. CONCLUSIONS: A one-year multi-factorial post-CRP intervention results in modest, non-significant benefits to global risk compared to usual care. The absence of deterioration in the usual care group may be due to improved practices in usual care.