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Biomedical subjects

S Yusuf

Publications and source records attributed to S Yusuf.

At least 199 records · Page 11Linked to original sources
PubMed1993

Cardiac mechanics during development of heart failure. SOLVD Investigators.

BACKGROUND: The changes in myocardial performance responsible for the progression from a stage of asymptomatic left ventricular dysfunction toward overt congestive heart failure are still poorly understood. Accordingly, using invasive methods, we examined the differences in baseline left ventricular function between a subgroup of patients enrolled in the treatment arm (presence of congestive heart failure) and in the prevention arm (asymptomatic patients) of the Studies of Left Ventricular Dysfunction. METHODS AND RESULTS: High-fidelity left ventricular pressures and frame-by-frame angiographic volumes were simultaneously obtained under baseline conditions in 65 patients with left ventricular ejection fraction < or = 35%. Sixteen patients had New York Heart Association congestive heart failure (class II or III), whereas the remaining 49 patients had no clinical signs of heart failure and did not receive therapy for this syndrome. A second set of data was obtained an average of 12.4 months later in 42 patients. The group with heart failure had significantly greater end-diastolic and end-systolic volumes than the asymptomatic group (both p < 0.001), but the stroke index at rest was similar in both groups. Accordingly, ejection fraction was significantly lower in the heart failure group (19.6 +/- 7.0% versus 26.3 +/- 7.2%; p < 0.02). Left ventricular end-diastolic pressure was greater and peak +dP/dt was lower in heart failure patients, but the difference did not reach statistical significance after Bonferroni correction for multiple comparisons. Moreover, the individual end-systolic stress/end-systolic volume data of the heart failure patients fell within the 95% confidence interval of the relation observed in the patients without heart failure both at baseline and after 1 year of follow-up irrespective of their changes in functional status. It was also noted that during follow-up, the changes in end-diastolic and end-systolic volumes correlated linearly, as if both dimensions always shifted in parallel, whereas alterations in contractility primarily influence end-systolic volume. CONCLUSIONS: These observations are compatible with the hypothesis that a depression in the mechanical performance of the viable myocardial areas is not the major determinant for the progression from asymptomatic to symptomatic left ventricular dysfunction. Abnormalities in left ventricular diastolic distensibility, on the other hand, might underlie the progressive ventricular dilation and create a vicious cycle through the afterload mismatch.

Adult↗
PubMed1992

Effect of enalapril on myocardial infarction and unstable angina in patients with low ejection fractions.

An association between raised renin levels and myocardial infarction has been reported. We studied the effects of enalapril, an angiotensin-converting enzyme (ACE) inhibitor, on the development of myocardial infarction and unstable angina in 6797 patients with ejection fractions < or = 0.35 enrolled into the two Studies of Left Ventricular Dysfunction (SOLVD) trials. Patients were randomly assigned to placebo (n = 3401) or enalapril (n = 3396) at doses of 2.5-20 mg per day in two concurrent double-blind trials with the same protocol. Patients with heart failure entered the treatment trial (n = 2569) and those without heart failure entered the prevention trial (n = 4228). Follow-up averaged 40 months. In each trial there were significant reductions in the number of patients developing myocardial infarction (treatment trial: 158 placebo vs 127 enalapril, p < 0.02; prevention trial: 204 vs 161 p < 0.01) or unstable angina (240 vs 187 p < 0.001; 355 vs 312, p < 0.05). Combined, there were 362 placebo group patients with myocardial infarction compared with 288 in the enalapril group (risk reduction 23%, 95% CI 11-34%; p < 0.001). 595 placebo group patients developed unstable angina compared with 499 in the enalapril group (risk reduction 20%, 95% CI 9-29%, p < 0.001). There was also a reduction in cardiac deaths (711 placebo, 615 enalapril; p < 0.003), so that the reduction in the combined endpoint of deaths, myocardial infarction, and unstable angina was highly significant (20% risk reduction, 95% CI 14-26%; p < 0.0001). Enalapril treatment significantly reduced myocardial infarction, unstable angina, and cardiac mortality in patients with low ejection fractions.

Angina, Unstable↗
PubMed1992

Effect of enalapril on mortality and the development of heart failure in asymptomatic patients with reduced left ventricular ejection fractions.

BACKGROUND: It is not known whether the treatment of patients with asymptomatic left ventricular dysfunction reduces mortality and morbidity. We studied the effect of an angiotensin-converting--enzyme inhibitor, enalapril, on total mortality and mortality from cardiovascular causes, the development of heart failure, and hospitalization for heart failure among patients with ejection fractions of 0.35 or less who were not receiving drug treatment for heart failure. METHODS: Patients were randomly assigned to receive either placebo (n = 2117) or enalapril (n = 2111) at doses of 2.5 to 20 mg per day in a double-blind trial. Follow-up averaged 37.4 months. RESULTS: There were 334 deaths in the placebo group, as compared with 313 in the enalapril group (reduction in risk, 8 percent by the log-rank test; 95 percent confidence interval, -8 percent [an increase of 8 percent] to 21 percent; P = 0.30). The reduction in mortality from cardiovascular causes was larger but was not statistically significant (298 deaths in the placebo group vs. 265 in the enalapril group; risk reduction, 12 percent; 95 percent confidence interval, -3 to 26 percent; P = 0.12). When we combined patients in whom heart failure developed and those who died, the total number of deaths and cases of heart failure was lower in the enalapril group than in the placebo group (630 vs. 818; risk reduction, 29 percent; 95 percent confidence interval, 21 to 36 percent; P less than 0.001). In addition, fewer patients given enalapril died or were hospitalized for heart failure (434 in the enalapril group; vs. 518 in the placebo group; risk reduction, 20 percent; 95 percent confidence interval, 9 to 30 percent; P less than 0.001). CONCLUSIONS: The angiotensin-converting--enzyme inhibitor enalapril significantly reduced the incidence of heart failure and the rate of related hospitalizations, as compared with the rates in the group given placebo, among patients with asymptomatic left ventricular dysfunction. There was also a trend toward fewer deaths due to cardiovascular causes among the patients who received enalapril.

Blood Pressure↗
PubMed1992

Studies of Left Ventricular Dysfunction (SOLVD) Registry: rationale, design, methods and description of baseline characteristics.

The Studies of Left Ventricular Dysfunction (SOLVD) comprises 2 double-blind, randomized clinical trials to test improved survival by angiotensin-converting enzyme inhibitor in patients with left ventricular dysfunction, with or without congestive heart failure. Patients entering the trials may be a highly selected subset of the population of such patients; those with the worst and best prognosis are likely to be excluded. To obtain the clinical history of a broader group, a registry of 6,273 patients included a relatively unselected cohort of patients with heart failure or left ventricular dysfunction, or both, from SOLVD hospitals. Registry data were obtained from hospital records. Because data collection from medical records may lead to incomplete data and more investigations in "sicker" patients, 898 randomly chosen subjects from different disease strata were seen in clinic where neurohumoral measures, echocardiograms, x-rays and electrocardiograms were obtained, and a 6-minute walking test was performed. The design and methodologic features, and the baseline characteristics of the participants in this 2-tiered registry are described, and its use in complementing the results and interpretation of the SOLVD trials is discussed.

Adult↗
PubMed1992

Need for a large randomized trial to evaluate the effects of digitalis on morbidity and mortality in congestive heart failure.

Despite major advances in the prevention and treatment of cardiovascular diseases, the incidence and prevalence of congestive heart failure (CHF) have been increasing in recent years. As the average age of the population increases, the prevalence of CHF is expected to continue to increase. The number of deaths in which CHF was considered the underlying or contributing cause increased from 51,000 in 1955 to 274,000 by 1988 in the United States. Even accounting for population growth and an increase in the number of elderly, this represents a 2-fold increase. Additionally, CHF was responsible for about 643,000 hospitalizations in 1988. Digitalis is one of the drugs most commonly prescribed for CHF and has been used for greater than 200 years. In 1990, digoxin was one of the most commonly prescribed drugs in the United States, accounting for greater than 21 million prescriptions. There has been little decline in the drug's use over the last 5 years, indicating that newer treatments for CHF have not replaced the widespread use of digitalis. Despite these findings, considerable controversy surrounds the appropriateness of its role and value in treating CHF patients who are in sinus rhythm. A number of recent, uncontrolled studies have arrived at apparently contradictory conclusions concerning the effects of digitalis on mortality in postmyocardial infarction and heart failure patients. A large, double-blind, randomized, controlled clinical trial to evaluate the effects of digitalis on mortality, morbidity and quality of life is being sponsored by the National Heart, Lung, and Blood Institute in conjunction with the Department of Veterans Affairs Cooperative Studies Program.(ABSTRACT TRUNCATED AT 250 WORDS)

Digitalis Glycosides↗
PubMed1992

The effect of treatment on survival in congestive heart failure.

Congestive heart failure (CHF) is a disorder characterized by a variety of clinical, biochemical, electrophysiological, and hemodynamic abnormalities. During the past two decades, numerous drugs have been employed in the treatment of this complex syndrome, and many agents have been shown to improve symptoms and ventricular function in patients with CHF. Because CHF is associated with a high risk of death, treatment should be directed not only toward the relief of symptoms, but also toward a reduction in mortality. Many variables have been shown to be related to survival; taken individually, however, each is limited in its utility in predicting prognosis. In recent years, large-scale studies with large sample sizes have directly assessed the effects of treatment on mortality in CHF. Results from these trials indicate that vasodilators and angiotensin-converting enzyme (ACE) inhibitors may improve mortality in patients with symptoms of heart failure. Additional trials are now in progress to evaluate the effect of treatment on patients with asymptomatic left ventricular dysfunction.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1992

Preserved left ventricular function during supine exercise in patients after orthotopic cardiac transplantation.

Cardiac denervation may affect cardiovascular responses during exercise in patients after orthotopic cardiac transplantation. In 17 such patients, haemodynamic responses and left ventricular function were examined by radionuclide ventriculography during and after supine exercise, at an average of 17.1 +/- 2.6 months after surgery. Data were also obtained during 'volume loading' brought about by leg elevation before exercise. Results were compared with those of six normal controls. At rest, heart rate was significantly faster among transplant patients than among controls (P less than 0.0003). No significant inter-group differences in changes in cardiovascular parameters were found between the two groups during leg elevation. During exercise, heart rate in transplant patients rose at a significantly slower rate than controls (P = 0.0001), but similar increases in ejection fraction, stroke volume and cardiac output were observed among transplant patients and controls. Decline in heart rate (P = 0.0001), ejection fraction (P = 0.0007) and cardiac output (P = 0.0001) was significantly slower in transplant patients during recovery. Although there were differences in rates of increases in heart rate between transplant patients and controls during supine exercise, there were no inter-group differences in increases in cardiac output and ejection fraction and changes in haemodynamic responses and left ventricular volumes.

Adult↗
PubMed1991

Effects of intravenous magnesium in suspected acute myocardial infarction: overview of randomised trials.

OBJECTIVE: To investigate the effect of intravenous magnesium on mortality in suspected acute myocardial infarction. DESIGN: Systematic overview of all available randomised trials in which patients were allocated to receive either intravenous magnesium or otherwise similar treatment without magnesium. SETTING: Coronary care units of several hospitals. PATIENTS: 1301 patients in seven randomised trials. MAIN OUTCOME MEASURE: Short term mortality. RESULTS: Considering the seven trials collectively there were 25 (3.8%) deaths among 657 patients allocated to receive magnesium and 53 (8.2%) deaths among 644 patients allocated control, generally during hospital follow up. This represents a 55% reduction in the odds of death (p less than 0.001) with 95% confidence intervals ranging from about one third to about two thirds. 70 of 648 patients allocated magnesium compared with 109 of 641 controls had serious ventricular arrhythmias, suggesting that magnesium reduces the incidence, though the definition varied among trials. Other adverse effects were rare in the limited number of patients for whom this data were available. CONCLUSION: Despite the limited number of patients randomised this overview suggests that intravenous magnesium therapy may reduce mortality in patients with acute myocardial infarction. Further large scale trials to confirm (or refute) these findings are desirable.

Hospitalization↗
PubMed1991

Analysis and interpretation of treatment effects in subgroups of patients in randomized clinical trials.

A key principle for interpretation of subgroup results is that quantitative interactions (differences in degree) are much more likely than qualitative interactions (differences in kind). Quantitative interactions are likely to be truly present whether or not they are apparent, whereas apparent qualitative interactions should generally be disbelieved as they have usually not been replicated consistently. Therefore, the overall trial result is usually a better guide to the direction of effect in subgroups than the apparent effect observed within a subgroup. Failure to specify prior hypotheses, to account for multiple comparisons, or to correct P values increases the chance of finding spurious subgroup effects. Conversely, inadequate sample size, classification of patients into the wrong subgroup, and low power of tests of interaction make finding true subgroup effects difficult. We recommend examining the architecture of the entire set of subgroups within a trial, analyzing similar subgroups across independent trials, and interpreting the evidence in the context of known biologic mechanisms and patient prognosis.

Cardiovascular Diseases↗
PubMed1991

Exposing patients with chronic, stable, exertional angina to placebo periods in drug trials.

Because the safety of withholding standard therapy and enrolling patients with stable angina in placebo-controlled trials is not known, we identified all events leading to dropout from trials of 12 antianginal drugs submitted in support of new drug applications to the US Food and Drug Administration. Persons who dropped out of the trials were classified as cause due to adverse cardiovascular events or other causes without knowledge of drug assignment. There were 3161 subjects who entered any randomized, double-blind phase of placebo-controlled protocols; 197 (6.2%) withdrew because of cardiovascular events. There was no difference in risk of adverse events between drug and placebo groups. A prospectively defined subgroup analysis showed that groups who received calcium antagonists were at an increased risk of dropout compared with placebo groups (P = .04), primarily because of a disproportionate number of adverse events in studies of one drug. In conclusion, there were few adverse experiences associated with short-term placebo use. Withholding active treatment does not increase the risk of serious cardiac events.

Adrenergic beta-Antagonists↗