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Biomedical subjects

M G Bourassa

Publications and source records attributed to M G Bourassa.

At least 19 recordsLinked to original sources
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

Strategy of complete revascularization in patients with multivessel coronary artery disease (a report from the 1985-1986 NHLBI PTCA Registry).

Percutaneous transluminal coronary angioplasty (PTCA) is increasingly performed in patients with multivessel coronary artery disease (CAD) despite reports showing relatively low rates of complete revascularization and poorer long-term prognosis for patients with significant residual narrowings. Reasons for incomplete revascularization were assessed in 618 patients with multivessel CAD in the 1985-1986 National Heart, Lung, and Blood Institute (NHLBI) PTCA Registry. The PTCA operator was asked to describe the treatment plan and outcome for each of the 1,942 significant lesions (greater than or equal to 50% luminal diameter stenosis) in the Registry patients. Although all significant narrowings were considered amenable to balloon angioplasty in 77% of patients, complete correction was intended only for 34% of them. It was attempted in 28% and successful in 19%. Only 63% of total occlusions were considered amenable to PTCA and only 54% of those attempted were successfully dilated. PTCA was intended for 38% with 50 to 69% stenoses versus 80% with 70 to 89% stenoses and for greater than 85% with narrowings greater than or equal to 90%. Dilatation in narrowings of the left circumflex and left anterior descending artery systems was intended less frequently than in lesions of the right coronary artery. Finally, there was wide variability in operator strategy among the different Registry sites.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1992

Prognostic importance of quantitative analysis of coronary cineangiograms.

Many studies have shown the prognostic value of angiographic data, but few have examined quantitative parameters of wall motion and shape or coronary stenosis severity. To determine whether these parameters have prognostic importance, baseline angiograms of 283 patients with up to 11.2 years (mean 8.3) of follow-up were quantitated. Event-free survival curves were constructed using log-rank testing. These indexes were also considered in 2 predictive models (Cox regression models): 1 with ("clinical") and 1 without ("quantitative") subjective angiographic analysis and clinical information. Regional shape (anterior and inferior walls) and motion (anterior wall only) indexes were predictive of event-free survival when considered singly. But these parameters were not of independent prognostic importance in the regression models. The most important independent parameters in the quantitative model for predicting overall cardiac mortality or an initial lethal cardiac event were the ejection fraction and the percent diameter narrowing of each major coronary artery. Myocardial infarction was predicted by the percent diameter stenosis of the left main and left anterior descending arteries but not the ejection fraction. In the clinical model, the factors of overriding prognostic importance were the ejection fraction and the subjective determination of the number of vessels involved with "significant" stenoses. Quantitative coronary arteriography still contributed independent prognostic value. Thus, quantification of the ejection fraction and severity of coronary lesions were of independent, prognostic importance, whereas indexes of regional function and shape were not.

Adult↗
PubMed1992

Cilazapril and early atherosclerotic changes after balloon injury of porcine carotid arteries.

BACKGROUND: Cilazapril, a converting enzyme inhibitor, has been shown to significantly decrease the extent of intimal smooth muscle cell proliferation after arterial injury in a normotensive rat model. METHODS AND RESULTS: To assess the influence of cilazapril on myofibrotic changes after balloon injury, control (n = 7) or cilazapril-treated (n = 9) (20 mg/kg b.i.d.) normal 3-month-old pigs underwent dilatation angioplasty of the right, and deendothelialization of the left common carotid artery. Carotid arteries isolated at 4 weeks were examined morphometrically with a computerized digitizer after in situ glutaraldehyde fixation. Both in the deendothelialized and dilated arteries, the surface area in square millimeters of the neointima and media were similar in the treated and control animals; therefore, the ratio of neointima to media was again not different. The neointimal changes included a combination of proliferative changes as well as organization of mural thrombus and were equally well distributed in the two groups of animals. At the time that the animals were killed, blood pressure (38.2 +/- 2.1 versus 56.8 +/- 4.8 mm Hg, p = 0.003) and plasma angiotensin converting enzyme activity (5.6 +/- 4.1 versus 182.3 +/- 70.4, p = 0.02) were lower in treated than in control pigs, but aortic media thrombogenicity (as assessed in an ex vivo perfusion flow chamber) and serum lipids were not different between groups. CONCLUSIONS: In pigs, cilazapril did not alter the development of myofibrotic changes after mild or severe balloon injury despite plasma angiotensin converting enzyme activity inhibition.

Angioplasty, Balloon↗
PubMed1991

Clinical, physiologic, anatomic and procedural factors predictive of restenosis after percutaneous transluminal coronary angioplasty.

In a recent prospective double-blind placebo-controlled trial, a combination of aspirin and dipyridamole was not associated with a reduction in the rate of restenosis within the 1st 6 months after coronary angioplasty. The purpose of this study was to determine whether clinical, anatomic or procedural factors were predictive of the observed restenosis rates in that prospective trial. A total of 247 patients and 280 segments underwent follow-up angiography and quantitative coronary angiographic analysis between 4 and 7 months after coronary angioplasty. Two baseline clinical characteristics--angina class and duration of angina in months--were related to the rate of restenosis by univariate analysis. Patient-related stepwise logistic regression analysis identified severity of angina as the only clinical predictor of restenosis. Three univariate baseline anatomic characteristics--percent diameter stenosis before angioplasty, stenosis greater than 10 mm in length and calcific stenosis--and two early postangioplasty characteristics--residual percent diameter stenosis and residual mean pressure gradient--were predictive of restenosis. Of these, only two--length of stenosis and residual percent diameter stenosis--were independently related to restenosis by multivariate analysis and only the former is identifiable before the procedure. It is concluded that in prospective studies in contrast to retrospective studies, few clinical and anatomic factors appear to be predictive of restenosis after coronary angioplasty.

Angioplasty, Balloon, Coronary↗
PubMed1990

Computerized determination of lactate threshold during three modes of exercise.

The lactate threshold (LT) and corresponding exercise levels (rate-pressure product, workload, and exercise duration) have been proposed as objective quantitative parameters of functional capacity and cardiovascular status. The purpose of the present study was to compare three modes of exercise and to evaluate the influence of the body position, using a rapid lactate analyser and computerized determination of the LT. Eight healthy male subjects were studied. No significant difference was found between the LT measured during treadmill (1.55 +/- 0.22 mmol/l), upright bicycle (1.61 +/- 0.17 mmol/l), and supine bicycle (1.41 +/- 0.05 mmol/l) exercises. However, while exercise levels corresponding to the lactate threshold were similar in running and upright bicycling, the supine bicycle was associated with lower exercise duration and workload corresponding to the LT.

Adult↗
PubMed1990

Prevention of acute complications after percutaneous transluminal coronary angioplasty.

The prevention of major complications occurring during or early after percutaneous transluminal coronary angioplasty was evaluated in 376 patients in a randomized, double-blind, placebo-controlled multicenter trial. Starting 24 hours before angioplasty, 187 patients received an aspirin-dipyridamole combination and 189 were given placebo. There were no periprocedural deaths. Periprocedural non-fatal myocardial infarction was diagnosed in 34 patients (9.0%). Q wave myocardial infarction occurred in 16 patients: 3 (1.6%) in the aspirin-dipyridamole group and 13 (6.9%) in the placebo group (p = 0.0113). Non-Q wave myocardial infarction occurred in 18 patients: 6 (3.2%) in the active drug group and 12 (6.3%) in the placebo group (p = 0.1538). Emergency myocardial revascularization was performed in 9 patients in each treatment arm. Q wave myocardial infarction occurred following revascularization in 5 patients (55.5%) in the placebo group and in only 2 (22.2%, p = 0.1670) in the aspirin-dipyridamole group. Thus the incidence of periprocedural Q and non-Q wave myocardial infarction is high in patients not on antiplatelet therapy (13.2%) and is markedly lower in those on the aspirin-dipyridamole combination (4.8%, p = 0.0044). Short-term antiplatelet therapy before and after angioplasty can be recommended for patients who do not have contraindications to this medication.

Acute Disease↗
PubMed1990

The role of antiplatelet agents in modifying the extent of restenosis following percutaneous transluminal coronary angioplasty.

We previously reported that a combination of aspirin and dipyridamole given before, during, and for 6 months following percutaneous transluminal coronary angioplasty (PTCA) did not reduce the incidence of restenosis. In that trial, a total of 272 successfully dilated segments in 243 patients reached final quantitative angiography and of these, 86 segments (31.6%) had restenosed (46 of 130 segments in the group of patients given placebo and 40 of 142 segments in the aspirin-dipyridamole group). A secondary analysis of these 86 segments revealed that at follow-up angiography the severity of restenosis was greater in the 46 segments in the placebo group than in the 40 segments in the active treatment group (mean minimal luminal diameter at the stenosis = 0.76 +/- 0.52 and 1.03 +/- 0.45 mm, respectively, p = 0.01). The frequency of total or subtotal occlusions was higher in the placebo group (17.4%) than in the active treatment group (5.0%), but this observation did not reach statistical significance (p = 0.07). Although long-term treatment with aspirin and dipyridamole after successful PTCA does not reduce the incidence of recurrence, this secondary analysis suggests that it is associated with a decreased likelihood of severe restenosis.

Adult↗
PubMed1990

Incidence and consequences of periprocedural occlusion. The 1985-1986 National Heart, Lung, and Blood Institute Percutaneous Transluminal Coronary Angioplasty Registry.

Of 1,801 patients in the 1985-1986 Percutaneous Transluminal Coronary Angioplasty (PTCA) Registry, 122 (6.8%) had periprocedural occlusion (4.9% in the catheterization laboratory, 1.9% outside the laboratory). Baseline patient factors independently associated with increased occlusion rates included triple-vessel disease, high risk status for surgery, and acute coronary insufficiency. Lesion characteristics showing significant positive association included severe stenosis before PTCA, diffuse or multiple discrete morphology, thrombus, and collateral flow from the lesion. Intimal tear and dissection were also very strongly associated with occlusion. Sixty patients (49%) had a transient occlusion that was reopened with PTCA, 43 (35%) were not redilated and managed with bypass surgery, and 19 (16%) were not redilated and managed medically. In-hospital mortality was 5% in each of these treatment groups, compared with 1% in occlusion-free patients. In-hospital infarction rates ranged from 27% in patients with transient occlusion to 56% in the patients managed with surgery, compared with 2% in patients without occlusion. During 2 years of follow-up, somewhat increased mortality continued in patients with occlusion, whereas follow-up infarction rates were comparable for all patients regardless of occlusion. Patients with an occlusion that was reopened or managed medically had increased rates of surgery during follow-up. Rates of repeat PTCA were comparable (about 23% by 2 years) in patients with transient occlusion and those without occlusion. Occlusion remains a serious complication of angioplasty and is associated most strongly with major events and surgical procedures that occur during the in-hospital period.

Aged↗
PubMed1990

Ten-year follow-up of survival and myocardial infarction in the randomized Coronary Artery Surgery Study.

The Coronary Artery Surgery Study (CASS) randomized 780 patients to an initial strategy of coronary surgery or medical therapy. Of medically randomized patients, 6% had surgery within 6 months and a total of 40% had surgery by 10 years. At 10 years, there was no difference in cumulative survival (medical, 79% vs. surgical, 82%; NS) and no difference in percentage free of death and nonfatal myocardial infarction (medical, 69% vs. surgical, 66%; NS). Patients with an ejection fraction of less than 0.50 exhibited a better survival with initial surgery treatment (medical, 61% vs. surgical, 79%; p = 0.01). Conversely, patients with an ejection fraction greater than or equal to 0.50 exhibited a higher proportion free of death and myocardial infarction with initial medical therapy (medical, 75% vs. surgical, 68%; p = 0.04) although long-term survival remained unaffected (medical, 84% vs. surgical, 83%; p = 0.75). There were no significant differences either in survival and freedom from nonfatal myocardial infarction, whether stratified on presence of heart failure, age, hypertension, or number of vessels diseased. Thus, 10-year follow-up results confirm earlier reports from CASS that patients with left ventricular dysfunction exhibit long-term benefit from an initial strategy of surgical treatment. Patients with mild stable angina and normal left ventricular function randomized to initial medical treatment (with an option for later surgery if symptoms progress) have survival equivalent to those patients randomized to initial surgery.

Coronary Artery Bypass↗
PubMed1989

Long-term follow-up of coronary angioplasty: the 1977-1981 National Heart, Lung, and Blood Institute registry.

Between September 1977 and September 1981, 1587 consecutive patients underwent a first coronary angioplasty (PTCA) at 16 clinical centres. After excluding patients with prior coronary bypass surgery (CABG) and left main or minimal vessel disease, 1390 were available for in-hospital and long-term follow-up. Mean duration of follow-up was 5.9 years (range 0-9.0 years). PTCA was successful (all attempted lesions reduced greater than or equal to 20%) in 882 patients (63.4%) and, overall, 624 patients (44.9%) had complete (COREV) and 766 (55.1%) incomplete (INCOREV) revascularization or a failed PtCA. In-hospital events included death in 0.7%, myocardial infarction (MI) in 5.0% and CABG in 24.0% of patients. Patients with COREV had significantly lower rates of these events than the INCOREV group. At 6 years, mortality in all registry patients was 6.5% and MI rate 15.0%; CABG was performed after the initial hospitalization in 15.5% of patients and repeat PTCA in 19.1%. All events, except repeated PTCA, were less frequent in the COREV than the INCOREV group. Among patients with a successful first PTCA, cumulative 6-year mortality was 5.8% and incidence of MI 10.8%; 16.9% underwent CABG and 24.7% repeat PTCA during follow-up. CABG was slightly more frequent in INCOREV than COREV patients with successful PTCA, but all other events were similar in the two groups, suggesting that INCOREV 'by intent' has a good prognosis. In patients with INCOREV, mortality and incidence of MI were higher during follow-up for patients with multivessel rather than single vessel disease. However, the incidence of CABG and repeat PTCA was similar in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗