Claudia Blais

Impact of Valve Prosthesis-Patient Mismatch on Short-Term Mortality After Aortic Valve Replacement

Background—The prosthesis used for aortic valve replacement (AVR) can be too small in relation to body size, thus causing valve prosthesis-patient mismatch (PPM) and abnormally high transvalvular pressure gradients. This study examined if there is a relation between PPM and short-term mortality after operation. Methods and Results—The indexed valve effective orifice area (EOA) was estimated for each type and size of prosthesis being implanted in 1266 consecutive patients and used to define PPM as not clinically significant if >0.85 cm2/m2, as moderate if >0.65 cm2/m2 and ≤0.85 cm2/m2, and as severe if ≤0.65 cm2/m2; it was correlated with 30-day mortality and compared with other relevant variables. Moderate or severe PPM was present in 38% of patients. Thirty-day mortality was 4.6% (58/1266 patients) and the strongest independent predictors in multivariate analysis were left ventricular ejection fraction <40% (P =0.007), infectious endocarditis (P =0.002), emergent/salvage operation (P =0.002), cardiopulmonary bypass time >120 minutes (P =0.001), and PPM (P =0.003). Relative risk of mortality was increased 2.1-fold (95% confidence interval, 1.2 to 3.7) in patients with moderate PPM and 11.4-fold (4.4 to 29.5) in those with severe PPM. Moreover, risk of mortality for every category of PPM was higher in patients with a left ventricular ejection fraction <40% as compared with ≥40% (nonsignificant PPM, 2.7 versus 1.0; moderate PPM, 7.1 versus 1.8; severe PPM, 77.1 versus 11.3). Conclusion—PPM is a strong and independent predictor of short-term mortality among patients undergoing AVR, and its impact is related both to its degree of severity and the status of left ventricular function. In contrast to other risk factors, moderate-severe PPM can be largely avoided with the use of a prospective strategy at the time of operation.

Projected Valve Area at Normal Flow Rate Improves the Assessment of Stenosis Severity in Patients With Low-Flow, Low-Gradient Aortic Stenosis The Multicenter TOPAS (Truly or Pseudo-Severe Aortic Stenosis) Study

Background— We sought to investigate the use of a new parameter, the projected effective orifice area (EOAproj) at normal transvalvular flow rate (250 mL/s), to better differentiate between truly severe (TS) and pseudo-severe (PS) aortic stenosis (AS) during dobutamine stress echocardiography (DSE). Changes in various parameters of stenosis severity have been used to differentiate between TS and PS AS during DSE. However, the magnitude of these changes lacks standardization because they are dependent on the variable magnitude of the transvalvular flow change occurring during DSE. Methods and Results— The use of EOAproj to differentiate TS from PS AS was investigated in an in vitro model and in 23 patients with low-flow AS (indexed EOA <0.6 cm2/m2, left ventricular ejection fraction ≤40%) undergoing DSE and subsequent aortic valve replacement. For an individual valve, EOA was plotted against transvalvular flow (Q) at each dobutamine stage, and valve compliance (VC) was derived as the slope of the regression line fitted to the EOA versus Q plot; EOAproj was calculated as EOAproj=EOArest+VC×(250−Qrest), where EOArest and Qrest are the EOA and Q at rest. Classification between TS and PS was based on either response to flow increase (in vitro) or visual inspection at surgery (in vivo). EOAproj was the most accurate parameter in differentiating between TS and PS both in vitro and in vivo. In vivo, 15 of 23 patients (65%) had TS and 8 of 23 (35%) had PS. The percentage of correct classification was 83% for EOAproj and 91% for indexed EOAproj compared with percentages of 61% to 74% for the other echocardiographic parameters usually used for this purpose. Conclusions— EOAproj provides a standardized evaluation of AS severity with DSE and improves the diagnostic accuracy for distinguishing TS and PS AS in patients with low-flow, low-gradient AS.

Diagnosed hypertension in Canada: incidence, prevalence and associated mortality

Background: Hypertension is a leading risk factor for cardiovascular diseases. Our objectives were to examine the prevalence and incidence of diagnosed hypertension in Canada and compare mortality among people with and without diagnosed hypertension. Methods: We obtained data from linked health administrative databases from each province and territory for adults aged 20 years and older. We used a validated case definition to identify people with hypertension diagnosed between 1998/99 and 2007/08. We excluded pregnant women from the analysis. Results: This retrospective population-based study included more than 26 million people. In 2007/08, about 6 million adults (23.0%) were living with diagnosed hypertension and about 418 000 had a new diagnosis. The age-standardized prevalence increased significantly from 12.5% in 1998/99 to 19.6% in 2007/08, and the incidence decreased from 2.7 to 2.4 per 100. Among people aged 60 years and older, the prevalence was higher among women than among men, as was the incidence among people aged 75 years and older. The prevalence and incidence were highest in the Atlantic region. For all age groups, all-cause mortality was higher among adults with diagnosed hypertension than among those without diagnosed hypertension. Interpretation: The overall prevalence of diagnosed hypertension in Canada from 1998 to 2008 was high and increasing, whereas the incidence declined during the same period. These findings highlight the need to continue monitoring the effectiveness of efforts for managing hypertension and to enhance public health programs aimed at preventing hypertension.

B-type natriuretic peptide in low-flow, low-gradient aortic stenosis : Relationship to hemodynamics and clinical outcome: Results from the multicenter truly or pseudo-severe aortic stenosis (TOPAS) study

Background— The prognostic value of B-type natriuretic peptide (BNP) is unknown in low-flow, low-gradient aortic stenosis (AS). We sought to evaluate the relationship between AS and rest, stress hemodynamics, and clinical outcome. Methods and Results— BNP was measured in 69 patients with low-flow AS (indexed effective orifice area <0.6 cm2/m2, mean gradient ≤40 mm Hg, left ventricular ejection fraction ≤40%). All patients underwent dobutamine stress echocardiography and were classified as truly severe or pseudosevere AS by their projected effective orifice area at normal flow rate of 250 mL/s (effective orifice area ≤1.0 cm2 or >1.0 cm2). BNP was inversely related to ejection fraction at rest (Spearman correlation coefficient rs=−0.59, P<0.0001) and at peak stress (rs=−0.51, P<0.0001), effective orifice area at rest (rs=−0.50, P<0.0001) and at peak stress (rs=−0.46, P=0.0002), and mean transvalvular flow (rs=−0.31, P=0.01). BNP was directly related to valvular resistance (rs=0.42, P=0.0006) and wall motion score index (rs=0.36, P=0.004). BNP was higher in 29 patients with truly severe AS versus 40 with pseudosevere AS (median, 743 pg/mL [Q1, 471; Q3, 1356] versus 394 pg/mL [Q1, 191 to Q3, 906], P=0.012). BNP was a strong predictor of outcome. In the total cohort, cumulative 1-year survival of patients with BNP ≥550 pg/mL was only 47±9% versus 97±3% with BNP <550 (P<0.0001). In 29 patients who underwent valve replacement, postoperative 1-year survival was also markedly lower in patients with BNP ≥550 pg/mL (53±13% versus 92±7%). Conclusions— BNP is significantly higher in truly severe than pseudosevere low-gradient AS and predicts survival of the whole cohort and in patients undergoing valve replacement.

Administrative data have high variation in validity for recording heart failure

BACKGROUND Many studies have relied on administrative data to identify patients with heart failure (HF). OBJECTIVE To systematically review studies that assessed the validity of administrative data for recording HF. METHODS English peer-reviewed articles (1990 to 2008) validating International Classification of Diseases (ICD)-8, -9 and -10 codes from administrative data were included. An expert panel determined which ICD codes should be included to define HF. Frequencies of ICD codes for HF were calculated using up to the 16 diagnostic coding fields available in the Canadian hospital discharge abstract during fiscal years 2000⁄2001 and 2005⁄2006. RESULTS Between 1992 and 2008, more than 70 different ICD codes for defining HF were used in 25 published studies. Twenty-one studies validated hospital discharge abstract data; three studies validated physician claims and two studies validated ambulatory care data. Eighteen studies reported sensitivity (range 29% to 89%). Specificity and negative predictive value were greater than 70% across 17 studies. Nineteen studies reported positive predictive values (range 12% to 100%). Ten studies reported kappa values (range 0.39 to 0.84). For Canadian hospital discharge data, ICD-9 and -10 codes 428 and I50 identified HF in 5.50% and 4.80% of discharge records, respectively. Additional HF-related ICD-9 and -10 codes did not impact HF prevalence. CONCLUSION The ICD-9 and -10 codes 428 and I50 were the most commonly used to define HF in hospital discharge data. Validity of administrative data in recording HF varied across the studies and data sources that were assessed.

Comparison of Valve Resistance With Effective Orifice Area Regarding Flow Dependence

Aortic valve resistance has been proposed to represent the severity of aortic stenosis because some studies observed that it was less affected by change in flow than the valve-effective orifice area, but this issue remains controversial. The objective of this study was to systematically analyze the theoretical and practical determinants of these parameters in relation to changes in flow. Valve area and resistance in different valves were studied in vitro in a pulse duplicator system at different flow rates and in vivo in 90 subjects referred to either exercise or dobutamine infusion. Theoretical analysis and experimental results both demonstrated a unique relation between resistance (RES), valve-effective orifice area (EOA), and flow rate (Q): RES = K x (Q/EOA(2)). Accordingly, in fixed stenoses or in mechanical valves, resistance increased markedly with flow rate both in vitro (+0.88 +/- 0.26%/% of flow increase) and in vivo (mechanical valves: +2.09 +/- 4.61, fixed stenotic valves: +0.59 +/- 0.32%/%), whereas valve area did not change significantly (<0.2%/%). In contrast, in valves with a flexible orifice (bioprostheses and some patients with aortic stenosis), resistance was less increased due to the increase in valve area. Thus, both from a theoretical and a practical standpoint, valve resistance is much more flow dependent than valve area, particularly in fixed stenoses. Situations in which resistance does not increase with flow rate are unpredictable and are found in flexible valves when there is a concomitant increase in valve area.

Impact of Socioeconomic Deprivation and Area of Residence on Access to Coronary Revascularization and Mortality After a First Acute Myocardial Infarction in Québec

BACKGROUND Socioeconomic status (SES) and area of residence are known to impact access to invasive cardiac procedures. Low SES adversely affects long-term mortality after acute myocardial infarction (AMI). Most of the data were derived from private healthcare systems. Our objectives were to evaluate the effects of SES and area of residence on access to coronary angiography, revascularization and mortality after a first AMI in a publicly-funded healthcare system with a high supply of catheterization facilities. METHODS Québec administrative databases were used to identify all patients with a first AMI between 1997 and 2001. The SES was determined with the population deprivation index, which has 2 dimensions: material and social. Six-month access to angiography, revascularization and 1-year mortality were considered in proportional hazards survival regression analyses measuring the effect of deprivation and the geographical area of residence, accounting for several other covariates. RESULTS The study cohort consisted of 50,242 patients. The most materially and socially deprived patients had a 16% (95% confidence interval [CI], 1.08-1.25) and 13% (95% CI, 1.05-1.21) relative increased hazard of dying within 1 year respectively compared with the most privileged subjects. This mortality gradient could not be explained by meaningful differences in access to angiography or revascularization. Geography did not influence access to revascularization procedures. CONCLUSIONS Despite universal healthcare system, SES measured with a material and social deprivation index, had significant adverse effect on 1-year mortality after a first AMI. Such findings were not explained by lower access to coronary angiography or revascularization.

Assessing the Burden of Hospitalized and Community-Care Heart Failure in Canada

BACKGROUND The surveillance of heart failure (HF) is currently conducted using either survey or hospital data, which have many limitations. Because Canada is collecting medical information in administrative health data, the present study seeks to propose methods for the national surveillance of HF using linked population-based data. METHODS Linked administrative data from 5 Canadian provinces were analyzed to estimate prevalence, incidence, and mortality rates for persons with HF between 1996/1997 and 2008/2009 using 2 case definitions: (1) 1 hospitalization with an HF diagnosis in any field (H_Any) and (2) 1 hospitalization in any field or at least 2 physician claims within a 1-year period (H_Any_2P). One hospitalization with an HF diagnosis code in the most responsible diagnosis field (H_MR) was also compared. Rates were calculated for individuals aged ≥ 40 years. RESULTS In 2008/2009, combining the 5 provinces (approximately 82% of Canadas total population), both age-standardized HF prevalence and incidence were underestimated by 39% and 33%, respectively, with H_Any when compared with H_Any_2P. Mortality was higher in patients with H_MR compared with H_Any. The degree of underestimation varied by province and by age, with older age groups presenting the largest differences. Prevalence estimates were stable over the years, especially for the H_Any_2P case definition. CONCLUSIONS The prevalence and incidence of HF using inpatient data alone likely underestimates the population rates by at least 33%. The addition of physician claims data is likely to provide a more inclusive estimate of the burden of HF in Canada.

Type and Proximity of Green Spaces Are Important for Preventing Cardiovascular Morbidity and Diabetes—A Cross-Sectional Study for Quebec, Canada

This study aimed at determining the role of proximity to specific types of green spaces (GSes) as well as their spatial location in the relationship with the most morbid cardiovascular diseases (CVD) and diabetes. We measured the accessibility to various types of GS and used a cross-sectional approach at census Dissemination Area (DA) levels in the Montreal and Quebec City metropolitan zones for the period 2006–2011. Poisson and negative binomial regression models were fitted to quantify the relationship between distances to specific types of GS and CVD morbidity as well as some risk factors (diabetes and hypertension) while controlling for several social and environmental confounders. GSes that have sports facilities showed a significant relationship to cerebrovascular diseases: the most distant population had an 11% higher prevalence rate ratio (PRR) compared to the nearest, as well as higher diabetes risk (PRR 9%) than the nearest. However, the overall model performance and the understanding of the role of GSes with sport facilities may be substantially achieved with lifestyle factors. Significantly higher prevalence of diabetes and cerebrovascular diseases as well as lower access to GSes equipped with sports facilities were found in suburban areas. GSes can advantageously be used to prevent some CVDs and their risk factors, but there may be a need to reconsider their types and location.

Prevalence, incidence, awareness and control of hypertension in the province of Quebec: Perspective from administrative and survey data

OBJECTIVES: Hypertension is a major risk factor for cardiovascular diseases. Nearly one adult in four was diagnosed with hypertension in 2007–2008 in Canada. One of the objectives of this study was to determine whether the prevalence of hypertension in Quebec as assessed using administrative data is comparable to that specifically measured, especially for the elderly population.METHODS: Trends in prevalence, incidence and mortality were examined using the Quebec Integrated Chronic Disease Surveillance System built from grouping numerous administrative databases from 1996–1997 to 2009–2010. Blood pressure measurements, hypertension prevalence, awareness and control were obtained in 1,706 Quebecers in the combined cycles of the Canadian Health Measures Survey.RESULTS: Using administrative databases, 23.6% [95% confidence interval, 23.5–23.6] of the Quebec population (n=1,433,400) aged >20 years was diagnosed with hypertension in 2009–2010, an increase of 32.1 % compared to 2000–2001. The incidence decreased by 27.3%. Among people aged >65 years, the prevalence rose to 69.0% [95% CI: 68.8–69.2] in women and 61.7% [95% CI: 61.5–61.9] in men. For people aged 20–79 years, the prevalence of hypertension was lower with the administrative data compared to the survey (20.2% and 23.1 %, respectively). The level of awareness, treatment and control were 84.3%, 83.1% and 67.9%, respectively.CONCLUSION: The prevalence of hypertension derived from administrative data is comparable to that obtained with a health measured survey. Elderly women (>65 years) are a very high-risk subgroup. The levels of awareness, treatment and control of hypertension in Quebec are very high.RésuméOBJECTIFS: L’hypertension artérielle est un facteur de risque majeur des maladies cardiovasculaires. Près d’un adulte sur quatre a été diagnostiqué hypertendu en 2007–2008, au Canada. Un des objectifs de cette étude était de déterminer si la prévalence de l’hypertension au Québec obtenue à partir de données médico-administratives est comparable à celle mesurée, en particulier chez les personnes âgées.METHODES: Les tendances de la prévalence, de l’incidence et de la mortalité ont été examinées avec le Système Intégré de Surveillance des Maladies Chroniques du Québec regroupant de nombreuses bases de données médico-administratives de 1996–1997 à 2009–2010. Des mesures de pression artérielle, de prévalence d’hypertension, de conscience et de contrôle ont été obtenus chez 1 706 Québécois dans les cycles combinés de l’Enquête canadienne sur les mesures de la santé.RÉSULTATS: En utilisant les données médico-administratives, 23,6 % [Intervalle de confiance à 95%, 23,5–23,6] de la population du Québec (n=1 433 400) âgés de ≥20 ans a été diagnostiqué hypertendue en 2009–2010, ce qui représente une augmentation de 32,1 % comparativement à 2000–2001. L’incidence a diminué de 27,3 %. Parmi les personnes âgées de ≥65 ans, cette prévalence est passée à 69,0 % [IC à 95%, 68,8–69,2] chez les femmes et à 61,7 % [IC à 95%, 61,5–61,9] chez les hommes. Pour les personnes âgées de 20–79 ans, la prévalence de l’hypertension était inférieure avec les données médico-administratives comparativement à celles avec l’enquête (20,2 % et 23,1 %, respectivement). Les niveaux de conscience, traitement et de contrôle étaient de 84,3 %, 83,1 % et 67,9 %, respectivement.CONCLUSION: La prévalence de l’hypertension provenant des données médico-administratives est comparable à celle obtenue avec une enquête des mesures de la santé. Les femmes âgées (≥65 ans) sont un sous-groupe à risque très élevé. Les niveaux de conscience, de traitement et de contrôle de l’hypertension au Québec sont très élevés.