Drospirenone and non-fatal venous thromboembolism: is there a risk difference by dosage of ethinyl-estradiol?

BACKGROUND

Previous studies concluded that there was an increased risk of non-fatal venous thromboembolism (VTE) with drospirenone. It is unknown whether the risk is differential by ethinyl-estradiol dosage.

OBJECTIVES

To assess the risk of VTE with drospirenone and to determine whether drospirenone and ethinyl-estradiol 20 μg (DRSP/EE20) has a lower VTE risk than drospirenone and ethinyl-estradiol 30 μg (DRSP/EE30).

METHODS

Our cohort included women aged 18-46 years taking drospirenone or levonorgestrel (LNG)-containing combined oral contraceptives (COCs) in the IMS claims database between 2001 and 2009. VTE was defined using ICD-9-CM coding and anticoagulation. The hazard ratio (HR) from Cox proportional hazards models was used to assess the VTE relative risk (RR) with drospirenone compared with levonorgestrel, adjusted by a propensity score used to control for baseline co-morbidity and stratified by EE dosage and user-type (new/current).

RESULTS

The study included 238 683 drospirenone and 193,495 levonorgestrel users. Among new and current users, a 1.90-fold (95% CI, 1.51-2.39) increased VTE relative risk was observed for drospirenone (18.0 VTE/10,000 women-years) vs. levonorgestrel (8.9 VTE/10,000 women-years). In analysis of new users, DRSP/EE20 had a 2.35-fold (95% CI, 1.44-3.82) VTE RR versus LNG/EE20. New users of DRSP/EE30 observed an increased RR versus LNG/EE30 among women starting to use COCs between 2001 and 2006 (2.51, 95% CI, 1.12-5.64) but not between 2007 and 2009 (0.76, 95% CI, 0.42-1.39), attributable to an increased incidence rate with LNG/EE30 from 2007 to 2009. In direct comparison, DRSP/EE20 had an elevated risk of VTE compared with DRSP/EE30 (RR, 1.55; 95% CI, 0.99-2.41).

CONCLUSIONS

We observed a modestly elevated risk of VTE with drospirenone, compared with levonorgestrel. The larger VTE incidence rate observed in DRSP/EE20 than in DRSP/EE30 and the increasing VTE incidence rate with levonorgestrel between 2007 and 2009 were unexpected.

Risk of upper gastrointestinal bleeding with oral bisphosphonates and non steroidal anti-inflammatory drugs: a case-control study

BACKGROUND

Gastrointestinal injuries including gastric ulcers have been reported with oral bisphosphonate therapy. However, the risk of the more serious upper gastrointestinal bleeding (UGB) especially in the community setting with these drugs remains unknown. Similarly, the risk of UGB among users of both bisphosphonates and non steroidal anti-inflammatory drugs (NSAIDs) in the community is also unknown.

AIM

To explore the risk of more serious UGB among users of bisphosphonates and the risk of UGB among users of both bisphosphonates and NSAIDs in the community.

METHODS

We conducted a case-control study within a cohort of Quebec residents who had received a revascularization procedure from 1995 to 2004. Cohort members were followed up from the date of their first procedure until the earliest of: (1) study outcome, (2) date of death or (3) end of health care coverage. Cases were defined as those with the first diagnosis of a UGB. For each case, 20 controls were selected and matched to the cases by index date, age and cohort entry. Adjusted odds ratios for current use of bisphosphonates, NSAIDs and co-therapy of both drugs were computed.

RESULTS

Within the initial cohort, 3253 incident cases of UGBs and corresponding 65 060 matched controls were identified. The adjusted odds ratio (OR) for UGB by current users of bisphosphonates was 1.01 (95% CI, 0.72-1.43). Current NSAID use was associated with an increased risk of UGB OR = 1.75; 95% CI, 1.53-1.99. The OR for use of bisphosphonates and NSAIDs was elevated OR = 2.00; 95% CI, 1.12-3.57. This risk was still elevated for users of bisphosphonates and COX-2 inhibitors [OR = 2.38 (95% CI, 1.26-4.50)].

CONCLUSION

We found no evidence of an increase in the risk of UGB among current users of bisphosphonates. The risk of combined NSAID and bisphosphonate therapy was increased, but this risk was not higher than the risk for NSAID users alone.

Treating the right patient at the right time: access to heart failure care

Heart failure affects over 500,000 Canadians, and 50,000 new patients are diagnosed each year. The mortality remains staggering, with a five-year age-adjusted rate of 45%. Disease management programs for heart failure patients have been associated with improved outcomes, the use of evidence-based therapies, improved quality of care, and reduced costs, mortality and hospitalizations. Currently, national benchmarks and targets for access to care for cardiovascular procedures or office consultations do not exist. The present paper summarizes the currently available data, particularly focusing on the risk of adverse events as a function of waiting time, as well as on the identification of gaps in existing data on heart failure. Using best evidence and expert consensus, the present article also focuses on timely access to care for acute and chronic heart failure, including timely access to heart failure disease management programs and physician care (heart failure specialists, cardiologists, internists and general practitioners).

The coronary risk of cyclo-oxygenase-2 inhibitors in patients with a previous myocardial infarction

BACKGROUND

Cyclo-oxygenase-2 selective inhibitors have been associated with cardiovascular side effects, but previous studies have generally excluded people with previous myocardial infarction, thereby limiting our knowledge of their cardiotoxicity in this population.

OBJECTIVES

To determine whether a history of myocardial infarction modified the risk of acute myocardial infarction associated with the use of various non-steroidal anti-inflammatory drugs (NSAIDs).

METHODS

A population-based cohort of 122 079 elderly people with and without previous myocardial infarction newly treated with an NSAID between 1 January 1999 and 30 June 2002 were identified using the computerised health databases of Québec, Canada. A nested-case-control approach was used for the analysis, with controls matched by cohort entry and age. Current users of NSAIDs, those whose last prescription overlapped with the index date, were compared with those who were not exposed to NSAIDs in the year preceding the event. Rate ratios of acute myocardial infarction were estimated using conditional logistic regression and adjusted for potential confounders.

RESULTS

Users of rofecoxib, both with and without previous myocardial infarction, were at increased risk of myocardial infarction, with a trend for greater risk among those with a previous event (rate ratio (RR) 1.59, 95% confidence interval (CI) 1.15 to 2.18 v RR 1.23, 95% CI 1.05 to 1.45; p = 0.14 for interaction). By contrast, celecoxib was only associated with an increased risk in people with previous myocardial infarction (RR 1.40, 95% CI 1.06 to 1.84 v RR 1.03, 95% CI 0.88 to 1.20; p = 0.04 for interaction). The available power was insufficient to reliably assess risks among patients with previous myocardial infarction treated with other NSAIDs, dose-response relationships or interaction with aspirin.

CONCLUSIONS

Although only rofecoxib use was associated with an increased risk of myocardial infarction in those without a previous event, both rofecoxib and celecoxib were associated with an excess risk of acute myocardial infarction for current users with a history of myocardial infarction. A large randomised trial is required to more completely and reliably assess the cardiovascular safety of celecoxib and traditional NSAIDs in this population of high-risk patients.

ACE-inhibitor use and the long-term risk of renal failure in diabetes

The incidence of end-stage renal disease (ESRD) owing to diabetes has continued to increase despite the extensive use of angiotensin-converting enzyme (ACE) inhibitors to prevent diabetic nephropathy, primarily from evidence of short-term effectiveness. We assessed the long-term effect of ACE inhibitors on the risk of ESRD. We formed a population-based cohort of all diabetic patients treated with antihypertensive drugs in the Province of Saskatchewan, Canada, between 1982 and 1986. The patients were followed up to the end of 1997 to identify cases of end-stage renal failure. A nested case-control analysis was used with the controls matched to each case on age, diabetes type, and duration of follow-up. The cohort comprised 6102 subjects, of which the 102 cases who developed end-stage renal failure were matched to 4129 controls. Relative to thiazide diuretic use, the adjusted rate ratio of end-stage renal failure associated with the use of ACE inhibitors was 2.5 (95% confidence interval 1.3-4.7), whereas it was 0.8 (95% confidence interval 0.5-1.4) for beta-blockers and 0.7 (95% confidence interval 0.4-1.3) for calcium antagonists. The rate ratio of end-stage renal failure with the use of ACE inhibitors was 0.8 (95% confidence interval 0.3-2.5) during the first 3 years of follow-up, but increased to 4.2 (95% confidence interval 2.0-9.0) after 3 years. ACE-inhibitor use does not appear to decrease the long-term risk of end-stage renal failure in diabetes. Our data suggest instead that ACE inhibitors might actually increase this risk, which may possibly contribute to the continued increasing incidence of ESRD owing to diabetes.

General commentary on access to cardiovascular care in Canada: universal access, but when? Treating the right patient at the right time

In 2004, the Canadian Cardiovascular Society formed an Access to Care Working Group with a mandate to use the best science and information available to establish reasonable triage categories and safe wait times for common cardiovascular services and procedures through a series of commentaries. The present commentary is the first in the series and lays out issues regarding timely access to care that are common to all cardiovascular services and procedures. The commentary briefly describes the 'right' to timely access, wait lists as a health care system management tool, and the role of the physician as patient advocate and gatekeeper. It also provides advice to funders, administrators and providers who must monitor and manage wait times to improve access to cardiovascular care in Canada and restore the confidence of Canadians in their publicly funded health care system.

Treating the right patient at the right time: access to care in non-ST segment elevation acute coronary syndromes

In 2004, the Canadian Cardiovascular Society formed an Access to Care Working Group with a mandate to use the best science and information available to establish reasonable triage categories and safe wait times for common cardiovascular services and procedures through a series of commentaries. The present commentary discusses the rationale for access benchmarks for urgent cardiac catheterization and revascularization, including hospital transfer in the setting of non-ST elevation acute coronary syndromes. The literature on standards of care, wait times, wait list management and clinical trials was reviewed. A survey of all cardiac catheterization directors in Canada was performed to develop an inventory of current practices in identifying and triaging patients. The Working Group recommended the following medically acceptable wait times for access to diagnostic catheterization and revascularization in patients presenting with acute coronary syndromes: for diagnostic catheterization and percutaneous coronary intervention, the target should be 24 h to 48 h for high-risk, three to five days for intermediate-risk and five to seven days for low-risk patients; for coronary artery bypass graft surgery, the target should be three to five days for high-risk, two to three weeks for intermediate-risk and six weeks for low-risk patients. All stakeholders must affirm the appropriateness of these standards and work continuously to achieve them. However, some questions remain around what are the best clinical risk markers to delineate the triage categories and the utility of clinical risk scores to assist clinicians in triaging patients for invasive therapies.

Canadian Cardiovascular Society commentary on implantable cardioverter defibrillators in Canada: waiting times and access to care issues

The Canadian Cardiovascular Society is the national professional society for cardiovascular specialists and researchers in Canada. In the spring of 2004, the Canadian Cardiovascular Society Council formed an Access to Care Working Group in an effort to use the best science and information to establish reasonable triage categories and safe wait times for access to common cardiovascular services and procedures. The Working Group has elected to publish a series of commentaries to initiate a structured national discussion on this very important issue. Access to treatment with implantable cardioverter defibrillators is the subject of the present commentary. The prevalence pool of potentially eligible patients is discussed, along with access barriers, regional disparities and waiting times. A maximum recommended waiting time is proposed and the framework for a solution-oriented approach is presented.

Beta-blockers in congestive heart failure. A Bayesian meta-analysis

PURPOSE

Congestive heart failure is an important cause of patient morbidity and mortality. Although several randomized clinical trials have compared beta-blockers with placebo for treatment of congestive heart failure, a meta-analysis quantifying the effect on mortality and morbidity has not been performed recently.

DATA SOURCES

The MEDLINE, Cochrane, and Web of Science electronic databases were searched from 1966 to July 2000. References were also identified from bibliographies of pertinent articles.

STUDY SELECTION

All randomized clinical trials of beta-blockers versus placebo in chronic stable congestive heart failure were included.

DATA EXTRACTION

A specified protocol was followed to extract data on patient characteristics, beta-blocker used, overall mortality, hospitalizations for congestive heart failure, and study quality.

DATA SYNTHESIS

A hierarchical random-effects model was used to synthesize the results. A total of 22 trials involving 10 135 patients were identified. There were 624 deaths among 4862 patients randomly assigned to placebo and 444 deaths among 5273 patients assigned to beta-blocker therapy. In these groups, 754 and 540 patients, respectively, required hospitalization for congestive heart failure. The probability that beta-blocker therapy reduced total mortality and hospitalizations for congestive heart failure was almost 100%. The best estimates of these advantages are 3.8 lives saved and 4 fewer hospitalizations per 100 patients treated in the first year after therapy. The probability that these benefits are clinically significant (>2 lives saved or >2 fewer hospitalizations per 100 patients treated) is 99%. Both selective and nonselective agents produced these salutary effects. The results are robust to any reasonable publication bias.

CONCLUSIONS

beta-Blocker therapy is associated with clinically meaningful reductions in mortality and morbidity in patients with stable congestive heart failure and should be routinely offered to all patients similar to those included in trials.

Medical decision making in the choice of a thrombolytic agent for acute myocardial infarction. Quebec Acute Coronary Care Working Group

Little is known about how physicians make decisions when the evidence is incomplete or controversial. While thrombolysis improves survival following acute myocardial infarction (AMI), conflicting evidence exists as to any specific agent's superiority, particularly if cost-effectiveness is considered. Using a Bayesian hierarchical model, the authors examined the patient, physician, and hospital characteristics that are related to the decision-making process concerning the choice of thrombolytic agent in a prospective registry of 1,165 AMI patients receiving thrombolysis. Tissue plasminogen activator (t-PA) was administered to 432 patients (31.8%) and streptokinase (SK) to the remainder. The presence of an anterior infarction, a previous myocardial infarction, low blood pressure, a cardiologist decision maker, younger age, and receiving treatment within six hours after the start of symptoms were independent predictors of receiving t-PA. The levels of importance that physicians accorded to these patient characteristics differed according to their practicing institutions. Generally, they followed evidence-based medicine and reasonably targeted high-risk patients to receive the more expensive t-PA. However, they also preferentially treated younger patients, where only a small absolute advantage appears to exist.

Use of abciximab (c7E3 Fab, ReoPro) as an adjunct to balloon angioplasty

OBJECTIVE

To estimate the magnitude of the clinical benefits that may result from use of abciximab at the time of angioplasty and the cost of achieving them.

DATA SOURCES

Four published randomized control trials.

DATA SYNTHESIS

Meta-analysis of outcomes at six months.

RESULTS

Use of abciximab in comparable high risk populations, in the manner described in these trials, is estimated to have the following effects: It does nto influence mortality within the first six months. It reduces the rate of myocardial infarction (MI) by 3.3/100 treatments with a 95% CI of 1.6 to 5.2. It may reduce the need for revascularization (angioplasty or coronary artery bypass graft) by 2.1/100 treatments (95% CI -1.0 to 5.0). It does not cause any significant increase in major hemorrhagic events. There is no evidence that it influences restenosis rates. The net cost per MI prevented would be approximately $44,000, ranging from approximately $29,000 to $71,000 on sensitivity analysis. The net cost per adverse event prevented (MI plus revascularization procedure) would be approximately $27,000 (sensitivity analysis $16,000 to $57,000). Use of abciximab for all of the approximately 17,487 angioplasties carried out in Canada each year may prevent 395 myocardial infarcts and 186 revascularization procedures, at an overall cost of approximately $29 million and a cost effectiveness of approximately $50,000 per adverse event prevented. (This assumes the same proportional reduction in events as in these four studies, and that 35% of procedures are high risk).

SIGNIFICANCE

Possible eventual prolongation of life due to fewer periprocedural MIs with abciximab use cannot be quantified. Thus, these estimates of cost effectiveness cannot be used to compare this intervention directly with others in terms of dollars per life year saved. The field is evolving rapidly and these conclusions may soon have to be modified. Increasing use of stents will probably slightly reduce, but not abolish, the health benefits of abciximab use. These estimates are based on only four trials. However, until more trials are completed they provide the best available evidence on which to base policy decisions.

The delay to thrombolysis: an analysis of hospital and patient characteristics. Quebec Acute Coronary Care Working Group

OBJECTIVE

To describe the various components of the delay to thrombolytic treatment for patients with acute myocardial infarction (MI) and to identify the hospital and patient characteristics related to these delays.

DESIGN

Cohort analysis from a hospital registry of patients receiving thrombolytic treatment.

SETTING

Forty acute care hospitals in Quebec.

SUBJECTS

All 1357 patients who received thrombolysis between January 1995 and May 1996.

MAIN OUTCOME MEASURES

Time from onset of symptoms to arrival at hospital and the various components of the in-hospital delay.

RESULTS

The median delay before presentation to hospital was 98 (interquartile range [IR] 56 to 180) minutes and was longer for women (p < 0.001), patients over 65 years of age (p < 0.001) and patients with diabetes mellitus (p < 0.01). The median time from arrival at hospital to thrombolysis was 59 (IR 41 to 89) minutes, the medical decision-making component taking a median of 12 (IR 4 to 27) minutes. Women (p < 0.005), older patients (p < 0.001) and patients with a past history of MI (p < 0.001) had increased in-hospital delays to thrombolysis. Delays were longer in community hospitals (p < 0.05) and low-volume centres (p < 0.01) and when a cardiologist made the decision to administer thrombolysis (p < 0.001). Multivariate analysis showed that increased age (odds ratio 1.5, 95% confidence interval 1.3 to 1.7, p < 0.001) and having the medical decision made by a cardiologist (odds ratio 1.8, 95% confidence interval 1.6 to 2.0, p < 0.001) were independently associated with an increased risk of being in the upper median of in-hospital delays.

CONCLUSIONS

Despite certain improvements, there remain substantial delays between symptom onset and the administration of thrombolysis for patients with acute MI. A large part of the delay is due to the hesitation of patients (particularly women, older patients and patients with diabetes) to seek medical attention. Although the median time for medical decision-making appears reasonable, care must be taken to ensure that all patient groups receive timely evaluation and therapy. The delay associated with having the treatment decision made by a cardiologist probably represents a marker for more difficult, complex cases. Methods should be developed to permit specialty consultation, if needed, while minimizing treatment delays. Community and low-volume hospitals may require special attention.

Public policy and coronary stenting: a different perspective

Coronary stenting is an innovative technology, which, in nonexperimental trials, has improved patient outcomes following threatened or abrupt closure. Randomized trials have shown a decrease in the restenosis rate and an accompanying decrease in repeat angioplasty in very specific patient groups. Stenting is becoming widespread in a variety of clinical situations where few controlled clinical trials have been performed. Further research is required to ascertain fully the safety, efficacy and cost effectiveness of coronary stenting in routine practice before public policy can be formulated sensibly.

The epidemiology of acute myocardial infarction and ischemic heart disease in Canada: data from 1976 to 1991

OBJECTIVE

To present national trends in mortality rates for myocardial infarction and cardiovascular disease.

DESIGN

Observational study using mortality statistics and hospital separation data from Statistics Canada for the period 1976 to 1991.

RESULTS

Despite ageing of the population, there has been a substantial decrease in the number of deaths attributed to ischemic heart disease, from 51,000 in 1976 to 44,000 in 1991, with most of the decrease due to fewer deaths from myocardial infarction. Although age-adjusted death rates remain higher for men, the observed mortality decline has been more pronounced in men than in women. Age-adjusted separation rates have also decreased, suggesting a decrease in the incidence of myocardial infarction, particularly in the 45 to 64 year age group. The duration of hospital stay has shortened dramatically.

CONCLUSIONS

From 1976 to 1991, mortality rates for ischemic heart disease in Canada decreased sharply, suggesting that advancements observed in clinical trials are being translated to the population level. The decrease appears to be due to both preventive measures and improved hospital care, but further studies are necessary to define better the relative contribution of each factor. The extent of this progress over the past 15 years is similar to the American experience.

The long term prognosis in patients following thrombolysis for acute myocardial infarction: a view from a community hospital

Thrombolysis in patients with acute myocardial infarction has been established to improve hospital survival. Less information is available about the long term evolution of unselected patients seen in community hospitals. Consequently, consecutive patients treated with thrombolysis for acute myocardial infarction and surviving until hospital discharge (n = 129) were followed for an average of 22 months. Mortality, recurrent ischemic events, coronary angiography and re-vascularizations were recorded for all patients. Two-year total and cardiovascular survival rates of 95 and 98% respectively were obtained with a conservative approach to early re-vascularization (n = 17, 13%). A history of prior myocardial infarction and early recurrent myocardial ischemia were significant predictors of increased cardiac events, while thallium stress testing provided no incremental value. Angiography and re-vascularizations were more frequently performed in younger patients (under 65 years old), anterior vs. inferior infarction and those with early residual ischemia. Women received less aggressive investigation and therapy then men and this may represent a gender bias, unmeasured residual confounding or the play of chance in a small sample size. Further studies are needed to confirm or refute these findings.

Placing trials in context using Bayesian analysis. GUSTO revisited by Reverend Bayes

Standard statistical analyses of randomized clinical trials fail to provide a direct assessment of which treatment is superior or the probability of a clinically meaningful difference. A Bayesian analysis permits the calculation of the probability that a treatment is superior based on the observed data and prior beliefs. The subjectivity of prior beliefs in the Bayesian approach is not a liability, but rather explicitly allows different opinions to be formally expressed and evaluated. The usefulness of this approach is demonstrated using the results of the recent GUSTO study of various thrombolytic strategies in acute myocardial infarction. This analysis suggests that the clinical superiority of tissue-type plasminogen activator over streptokinase remains uncertain.

Long-term prognosis of patients presenting to the emergency room with decompensated congestive heart failure

OBJECTIVES

This observational study was done to describe the long term prognosis of patients presenting to an emergency room with decompensated heart failure and to determine the factors that influence their survival.

DESIGN

The routine clinical and laboratory characteristics of consecutive patients presenting to an emergency room with decompensated heart failure were documented and the patients followed for an average of 44 months (range 41 to 47).

SETTING

One teaching hospital and one community-based hospital in Montreal, Quebec.

PATIENTS

A prospective cohort of 153 consecutive patients presenting to the emergency room with decompensated heart failure.

OUTCOME MEASURES

Total mortality was the main outcome. Survival status was validated by the government health insurance board.

RESULTS

Survival was poor, with 61% dying within the 47-month follow-up. Univariate analysis revealed the following variables to be associated with decreased survival; low sodium (P < 0.001), decreased renal function (P < 0.001), prior hospitalization for decompensated heart failure (P < 0.001), intraventricular conduction defect (P < 0.002), failure despite prior use of angiotensin-converting enzyme (ACE) inhibitors (P < 0.005) and increased cardiac dimensions as determined by increased left ventricular end systolic diameter (P < 0.04). The multivariate analysis using the Cox proportional hazards model showed a prior admission for heart failure (relative risk [RR] 1.9 [P = 0.005], 95% confidence interval [CI] 1.2 to 2.9), hyponatremia (RR 2.1 [P = 0.005], 95% CI 1.2 to 3.5), presence of an intraventricular conduction delay (RR 1.9 [P = 0.003], 95% CI 1.2 to 2.9), and the cumulative required dose of intravenous furosemide (RR 1.7 [P = 0.03], 95% CI 1.1 to 2.8) to be associated with increased mortality. Patients with hyponatremia despite the use of ACE inhibitors were at greatest risk (RR 11.5 [P < 0.001], 95% CI 5.3 to 24.9).

CONCLUSIONS

This prospective observational study confirms that the long term prognosis of patients needing hospitalization for congestive heart failure remains poor. Readily available acute-phase clinical variables may assist in predicting prognosis.

The hospital course and short term prognosis of patients presenting to the emergency room with decompensated congestive heart failure

OBJECTIVES

This observational study was done to describe the characteristics, hospital course and short term prognosis of patients presenting to an emergency room with decompensated heart failure and to determine the parameters influencing the length of their hospital stay.

DESIGN

The routine clinical and laboratory characteristics of consecutive patients presenting to an emergency room with decompensated heart failure were documented and the patients followed for six months.

SETTING

One teaching hospital and one community-based hospital in Montreal, Quebec.

PATIENTS

A prospective cohort of 153 consecutive patients presenting to the emergency room with decompensated heart failure. Follow-up was by clinic visit and telephone survey at one, three and six months. Follow-up was 100%.

MEASURES OF OUTCOME

Length of hospital stay, in-hospital mortality, readmissions and after hospital discharge deaths were measured.

RESULTS

The average length of hospital stay was 6.2 days with a skewed distribution ranging from one to 56 days. A multivariate analysis showed that the length of hospital stay was associated with increasing left atrial size (P < 0.05), an ischemic etiology of the heart failure (P < 0.03) and a slow response to diuretic therapy (P < 0.001). This mathematical model accounted for only a small amount of hospital stay variability (R2 = 0.22). Six month mortality and morbidity of these patients was high, with 23% dying and 30% readmitted for heart failure, but was independent of the duration of the initial hospitalization.

CONCLUSIONS

This prospective study confirms that the hospital course for congestive heart failure is shortening. The six month prognosis of patients presenting to an emergency room for decompensated heart failure is poor and appears independent of the length of hospital stay.

Epidemiology of congestive heart failure: Canadian data from 1970 to 1989

OBJECTIVE

To assess mortality rates from congestive heart failure in Canada from 1970 to 1989.

DESIGN

Observational, retrospective design using national population and mortality data.

MAIN RESULTS

There is a definite age gradient for deaths from congestive heart failure which, combined with a general ageing of the Canadian population, has lead to an increase in the absolute number of deaths. However, Standardized Mortality Ratios, which account for shifting population distributions, have shown steadily decreasing values for both men and women since 1980.

CONCLUSIONS

Recent improvements in cardiology care demonstrated in controlled clinical trials appear also to be present in epidemiological studies.

Risk stratification in patients with non Q wave myocardial infarction: a role for thallium exercise testing

The ability of maximal exercise thallium testing to stratify patients after non Q wave myocardial infarction was prospectively examined in 20 patients. Patients were enrolled in the study if there was no evidence of residual ischemia nor congestive heart failure during initial hospitalization. The thallium exercise test showed four patients to be at high risk, three of whom had successful revascularization. The remaining 16 patients were considered to be at low risk. There were no re-admissions for unstable angina, no myocardial infarctions and no deaths in the follow-up period (average 15 months). Thus patients with no evidence of early ischemia, no signs of left ventricular failure and a negative maximum thallium exercise test are at low risk following non Q wave myocardial infarction.

Adhesion of platelets to artificial surfaces: effect of red cells

Adhesion of platelets to several polymer- and protein-coated glass surfaces has been studied in vitro. The apparatus consists of a cylindrical probe rotating in a test tube containing the platelet medium and allows close control of fluid shear and mass transport. Suspensions of washed pig platelets constitute the basic platelet medium, and can be modified by adding back red cells and plasma proteins. Adhesion is measured via 51Cr-labeling of platelets. In the absence of red cells, identical low levels of adhesion were seen on all surfaces and saturation was reached within 2 min. In the presence of red cells, adhesion was greater. Saturation on all surfaces except fibrinogen and collagen again occurred within 2 min. The adhesion levels on polymer surfaces and glass were indistinguishable, while those on albumin were lower and those on fibrinogen were higher. Collagen was the most reactive surface. It did not equilibrate within 15 min., and kinetic data indicated a platelet diffusivity strongly dependent on hematocrit. These effects were attributed to rotational and translational motion of the red cells causing increased diffusion and surface-platelet collision energy.