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Biomedical subjects

M G Bourassa

Publications and source records attributed to M G Bourassa.

At least 37 records · Page 2Linked to original sources
PubMed1998

Prevention of restenosis after angioplasty in small coronary arteries with probucol.

BACKGROUND: Restenosis remains the major limitation of coronary angioplasty. Coronary stents have reduced the incidence of restenosis in selected patients with relatively large vessels. No strategies to date have demonstrated a beneficial effect in vessels < 3.0 mm in diameter. We have shown in the MultiVitamins and Probucol (MVP) Trial that probucol, a potent antioxidant, reduces restenosis after balloon angioplasty. The purpose of this study was to determine whether the benefit of probucol therapy is maintained in the subgroup of patients with smaller coronary vessels. METHODS AND RESULTS: We studied a subgroup of 189 patients included in the MVP trial who underwent successful balloon angioplasty of at least one coronary segment with a reference diameter < 3.0 mm. One month before angioplasty, patients were randomly assigned to one of four treatments: placebo, probucol (500 mg), multivitamins (beta-carotene 30000 IU, vitamin C 500 mg, and vitamin E 700 IU), or probucol plus multivitamins twice daily. The treatment was maintained until follow-up angiography was performed at 6 months. The mean reference diameter of this study population was 2.49+/-0.34 mm. Lumen loss was 0.12+/-0.34 mm for probucol, 0.25+/-0.43 mm for the combined treatment, 0.35+/-0.56 mm for vitamins, and 0.38+/-0.51 mm for placebo (P=.005 for probucol). Restenosis rates per segment were 20.0% for probucol, 28.6% for the combined treatment, 45.1% for vitamins, and 37.3% for placebo (P=.006 for probucol). CONCLUSIONS: Probucol reduces lumen loss and restenosis rate after balloon angioplasty in small coronary arteries.

Aged↗
PubMed1998

Clinical and detailed angiographic findings in patients with ambulatory electrocardiographic ischemia without critical coronary narrowing: results from the Asymptomatic Cardiac Ischemia Pilot (ACIP) Study.

BACKGROUND: Patients with ambulatory electrocardiographic (AECG) ST-segment depression and critical coronary narrowing are known to be at increased risk for adverse outcome, but little is known about patients with AECG ST-segment depression without critical coronary narrowing. HYPOTHESIS: The objectives of this study were to characterize the coronary angiographic pathology in patients with AECG ST-segment depression but without critical (< 50% diameter stenosis) coronary narrowing and to compare demographic and clinical findings in these patients with those enrolled in the Asymptomatic Cardiac Ischemia Pilot Study with AECG ST-segment depression and critical (> or = 50% diameter stenosis) coronary narrowing. METHODS: Coronary angiograms from patients with AECG ST-segment depression were reviewed in a central laboratory and quantitative measurement of percent stenosis was performed. Clinical and angiographic comparisons were made between patients with and without critical coronary narrowing. RESULTS: Patients without critical coronary narrowing (n = 64) were younger (p = 0.02), less likely to be male (p < 0.001) or to have risk factors for coronary atherosclerosis or a history of myocardial infarction (p < 0.001), and had fewer ischemic episodes per 24 h on the screening AECG (p = 0.02) than patients with critical coronary narrowing (n = 441). Of patients without critical narrowing, one half had angiographic evidence for coronary artery disease (> or = 20% stenosis) and 60% had an ejection fraction > 70%. CONCLUSIONS: Patients with AECG ST-segment depression without critical coronary narrowing are heterogeneous, with half having measurable coronary artery disease. Demographically and clinically, they appear to be different than patients with AECG ST-segment depression with critical coronary narrowing.

Coronary Angiography↗
PubMed1998

Biocompatibility aspects of new stent technology.

Stent implantation represents a major step forward since the introduction of coronary angioplasty. As indications continue to expand, better understanding of the early and late biocompatibility issues appears critical. Persisting challenges to the use of intracoronary stents include the prevention of early thrombus formation and late neointima development. Different metals and designs have been evaluated in animal models and subsequently in patients. Polymer coatings have been proposed to improve the biocompatibility of metallic stents or to serve as matrix for drug delivery and they are currently undergoing clinical studies. The promises of a biodegradable stent have not yet been fulfilled although encouraging results have recently been reported. Continuous low dose-rate brachytherapy combining the scaffolding effect of the stent with localized radiation therapy has witnessed the development and early clinical testing of radioactive stents. The combined efforts of basic scientists and clinicians will undoubtedly contribute to the improvement of stent biocompatibility in the future.

Angioplasty, Balloon, Coronary↗
PubMed1998

Long-term outcome of patients with incomplete vs complete revascularization after multivessel PTCA. A report from the NHLBI PTCA Registry.

BACKGROUND: Incomplete revascularization is frequently the goal as well as the final outcome in patients with multivessel coronary disease undergoing PTCA. However, the long-term impact of incomplete revascularization is not known and this common PTCA strategy deserves further scrutiny. METHODS AND RESULTS: Complete revascularization was achieved in 132 of 757 patients with multivessel disease in the 1985-86 NHLBI PTCA Registry. Compared to patients in whom complete revascularization was achieved, patients with incomplete revascularization were older (P < 0.05), more likely to be females (P < 0.05) and to have recent myocardial infarction (P < 0.05), unstable angina (P < 0.001), and urgent or emergent PTCA (P < 0.001). Early death, Q wave myocardial infarction and CABG rates were higher in patients with incomplete than in those with complete revascularization [significantly different (P < 0.05) only for emergency and elective CABG]. At 9 years, nearly twice as many patients with incomplete revascularization experienced recurrent angina (19% vs 10% for patients with complete revascularization, P < 0.05). Patients with complete revascularization were more likely to undergo repeat PTCA than those with incomplete revascularization (40% vs 30%, P < 0.05). Patients with incomplete revascularization were more likely to undergo CABG than patients with complete revascularization (32% vs 14%, P < 0.001; adjusted risk 2.56, 95% CI 1.60, 4.10). Among patients with incomplete revascularization, those in whom PTCA was intended but not attempted had the highest early event rates and late CABG rates. Finally, the adjusted risk of dying, having a Q wave myocardial infarction, recurrent angina or repeat PTCA was not different at 9-year follow-up among patients with and without complete revascularization. CONCLUSIONS: Complete revascularization achieved by PTCA reduces late occurrence of CABG, but not adjusted rates of death, Q wave myocardial infarction, recurrent angina, and repeat PTCA in patients with multivessel coronary disease. These data tend to support the PTCA strategy of incomplete revascularization in patients with multivessel disease when complete revascularization is not feasible or not planned before the procedure.

Adult↗
PubMed1998

[Use of ionizing radiation to prevent restenosis in interventional cardiology].

Recently, the use of ionizing radiations has received much interest as a new treatment tool to reduce restenosis after angioplasty or stent implantation. There are two main approaches for delivering endovascular radiation: one is based on gamma or beta sources with very high activities to deliver locally through a catheter the dose in a limited period of time. The other approach is based on a stent rendered radioactive for long exposure and continuous low-dose rate treatment. External radiation is also contemplated but indications seem more oriented towards the peripheral vascular system. After a brief introduction to fundamentals of radiobiology, radiation physics and radioprotection, we review the experimental data which have led to large ongoing multicenter trials. The results of these trials involving more than 2000 patients will be available in the next few years and will allow to better define the risk/benefit ratio of this potentially new indication for radiotherapy.

Angioplasty, Balloon, Coronary↗
PubMed1997

Prognostic significance of myocardial ischemia detected by ambulatory electrocardiography, exercise treadmill testing, and electrocardiogram at rest to predict cardiac events by one year (the Asymptomatic Cardiac Ischemia Pilot [ACIP] study)

Myocardial ischemia identified by ambulatory electrocardiography (AECG), exercising treadmill testing, (ETT), or 12-lead electrocardiogram at rest is associated with an adverse prognosis, but the effect of improving these ischemic manifestations by treatment on outcome is unknown. The Asymptomatic Cardiac Ischemia Pilot (ACIP) study was a National Heart, Lung, and Blood Institute funded study to determine the feasibility of conducting a large-scale prognosis study and to assess the effect of 3 treatment strategies (angina-guided strategy, AECG ischemia-guided strategy, and revascularization strategy) in reducing the manifestations of ischemia as indicated by AECG and ETT. The study cohort for this database study consisted of 496 randomized patients who performed the AECG, ETT, and 12-lead electrocardiogram at rest at both the qualifying and week 12 visits. The effect of modifying ischemia by treatment on the incidence of cardiac events (death, myocardial infarction, coronary revascularization procedure, or hospitalization for an ischemic event) at 1 year was examined. In the 2 medical treatment groups (n = 328) there was an association between the number of ambulatory electrocardiographic ischemic episodes at the qualifying visit and combined cardiac events at 1 year (p = 0.003). In the AECG ischemia-guided patients there was a trend associating greater reduction in the number of ambulatory electrocardiographic ischemia episodes with a reduced incidence of combined cardiac events (r = -0.15, p = 0.06). In the revascularization strategy patients this association was absent. In the medical treatment patients the exercise duration on the baseline ETT was inversely associated with an adverse prognosis (p = 0.02). The medical treatment strategies only slightly improved the exercise time and the exercise duration remained of prognostic significance. In the revascularization group strategy patients this association was absent. Thus, myocardial ischemia detected by AECG and an abnormal ETT are each independently associated with an adverse cardiac outcome in patients subsequently treated medically.

Electrocardiography↗
PubMed1997

Documentation of decline in morbidity in women undergoing coronary angioplasty (a report from the 1993-94 NHLBI Percutaneous Transluminal Coronary Angioplasty Registry). National Heart, Lung, and Blood Institute.

To determine whether there has been an improvement in the relatively unfavorable outcome of percutaneous transluminal coronary angioplasty (PTCA) in women, the 1993 to 1994 National Heart, Lung, and Blood Institute Percutaneous Transluminal Coronary Angioplasty Registry collected data from 12 clinical centers that participated in the earlier registries. We compared 274 consecutive women in 1993 to 1994 with 545 consecutive women in 1985 to 1986 undergoing PTCA. Women in the 1993 to 1994 registry were older (64.3 vs 61.0 years, p <0.001) with more diabetes mellitus (34.3% vs 19.9%, p <0.001), congestive heart failure (13.7% vs 8.6%, p <0.05), and comorbid disease (19.5% vs 9.3%, p <0.001). Left ventricular function and multivessel coronary artery disease were similar between groups. Angiographic success (90.9% vs 85.1%, p <0.05) and clinical success (89.4% vs 79.4%, p <0.001) were higher in women undergoing PTCA in 1993 to 1994 than in 1985 to 1986. Whereas there was no difference in in-hospital mortality (1.5% vs 2.6%), the incidence of nonfatal myocardial infarction (1.8% vs 4.6%, p <0.05), emergency coronary artery bypass graft surgery (1.8% vs 4.6%, p <0.05), and the combined end points of death, myocardial infarction, and emergency coronary artery bypass grafting (4.4% vs 9.7%, p <0.01) were lower in women in 1993 to 1994 than in women in 1985 to 1986, respectively. Multivariate analysis revealed an odds ratio of 0.36 (95% confidence interval 0.18 to 0.72) for major complications and of 2.34 (95% confidence interval, 1.49 to 3.69) for clinical success in the 1993 to 1994 versus 1985 to 1986 registry. Therefore, despite a higher risk profile, women undergoing PTCA in 1993 to 1994 have a higher clinical success and lower major complication rate than women treated with PTCA in 1985 to 1986.

Aged↗
PubMed1997

Myocardial infarction and cardiac mortality in the Bypass Angioplasty Revascularization Investigation (BARI) randomized trial.

BACKGROUND: Cardiac mortality and myocardial infarction (MI) rates are used to evaluate the efficacy of coronary artery bypass grafting (CABG) and percutaneous transluminal coronary angioplasty (PTCA). We compared 5-year cardiac mortality and MI rates in 1829 patients with multivessel disease randomized to CABG or PTCA. METHODS AND RESULTS: The 5-year cardiac mortality rate was 8.0% in patients assigned to PTCA compared with 4.9% in those assigned to CABG (relative risk [RR] of 1.55 with a 95% confidence interval [CI] of 1.07 to 2.23; P=.022). In a subgroup of 1476 nondiabetic patients, there were no significant differences between treatment groups in cardiac mortality either overall (4.6% versus 4.2%; RR= 1.04, 95% CI, 0.65 to 1.66; P=.908) or in subgroups based on symptoms, left ventricular function, number of diseased vessels, or stenotic proximal left anterior descending artery. The two treatment groups had similar event rates for the combined end point of cardiac death or MI. The RR for cardiac mortality in 264 patients who sustained an MI compared with those who did not was 5.9 (P<.001). MIs were more common after CABG during index hospitalization (P=.004), but in the PTCA group, they were more common after discharge (P<.001). CONCLUSIONS: The Bypass Angioplasty Revascularization Investigation (BARI) trial indicates 5-year cardiac mortality in patients with multivessel disease was significantly greater after initial treatment with PTCA than with CABG. The difference was manifest in diabetic patients on drug therapy. There were no significant differences overall for the composite end point of cardiac mortality or MI between treatment groups or for cardiac mortality in nondiabetic patients regardless of symptoms, left ventricular function, number of diseased vessels, or stenotic proximal left anterior descending artery.

Angioplasty, Balloon, Coronary↗
PubMed1997

Randomised trial of home-based psychosocial nursing intervention for patients recovering from myocardial infarction.

BACKGROUND: Increases in life stress have been linked to poor prognosis, after myocardial infarction (MI). Previous research suggested that a programme of monthly screening for psychological distress, combined with supportive and educational home nursing interventions for distressed patients, may improve post-MI survival among men. Our study assessed this approach for both men and women. We aimed to find out whether the programme would reduce 1-year cardiac mortality for women and men. METHODS: We carried out a randomised, controlled trial of 1376 post-MI patients (903 men, 473 women) assigned to the intervention programme (n = 692) or usual care (n = 684) for 1 year. All patients completed a baseline interview that included assessment of depression and anxiety. Survivors were also interviewed at 1 year. FINDINGS: The programme had no overall survival impact. Preplanned analyses showed higher cardiac (9.4 vs 5.0%, p = 0.064) and all-cause mortality (10.3 vs 5.4%, p = 0.051) among women in the intervention group. There was no evidence of either benefit or harm among men (cardiac mortality 2.4 vs 2.5%, p = 0.94; all-cause mortality 3.1 vs 3.1%, p = 0.93). The programme's impact on depression and anxiety among survivors was small. INTERPRETATION: Our results do not warrant the routine implementation of programmes that involve psychological-distress screening and home nursing intervention for patients recovering from MI. The poorer overall outcome for women, and the possible harmful impact of the intervention on women, underline the need for further research and the inclusion of adequate numbers of women in future post-MI trials.

Aged↗
PubMed1997

The role of cardiac troponin T and other new biochemical markers in evaluation and risk stratification of patients with acute chest pain syndromes.

BACKGROUND AND HYPOTHESIS: Increased serum creatinine kinase (CK) and CK-MB enzyme levels have been used for years to detect myocardial infarction (MI). However, serum myoglobin and CK-MB mass or protein levels may indicate MI earlier; cardiac troponin T is the most specific marker of myocardial injury and it can detect even minor myocardial necrosis. The diagnostic and prognostic utility of the traditional and new markers of cardiac injury in the emergency evaluation of patients with acute chest pain syndromes were therefore compared. METHODS: One hundred and fifteen consecutive patients with an acute coronary syndrome, and 64 controls recruited during the same period, were examined. The time elapsed from onset of symptoms to blood collection was recorded. Cardiac markers were measured in specimens collected upon arrival (0 h), and 2 and 5-9 h, and later in cases of longer observation. The major cardiac events occurring up to 40 months after the index examination were recorded. RESULTS: cTnT levels provided unique information: they were the most specific indicators of myocardial damage and identified unstable angina patients at high risk of future major events. Up to 6 h after the onset of chest pain, the new markers were elevated more frequently than the traditional ones and permitted earlier MI recognition. The worst prognosis (nonfatal myocardial infarction or death) was noted in subjects with chest pain at rest within 48 h before the index examination and elevated cTnT levels. CONCLUSIONS: The new markers, particularly cardiac troponin T, offer considerable advantages and they should be more widely used in the diagnosis and risk stratification of acute coronary syndromes.

Adult↗
PubMed1996

Asymptomatic Cardiac Ischemia Pilot (ACIP) Study. Relationship between exercise-induced and ambulatory ischemia in patients with stable coronary disease.

BACKGROUND: We investigated whether the presence and frequency of asymptomatic ischemic episodes recorded during ambulatory ECG (AECG) monitoring could be predicted on the basis of clinical characteristics or exercise treadmill test (ETT) performance in patients with stable coronary disease and whether the estimate of ischemia severity was similar between the AECG and ETT. METHODS AND RESULTS: Patients screened for the Asymptomatic Cardiac Ischemia Pilot (ACIP) study were selected for the current analysis if data were available from 48-hour AECG monitoring as well as from an ETT during which the patient developed > or = 1-mm ST-segment depression. Exercise ECG data were available for 143 of the 910 patients without ischemic episodes and for 659 of the 910 patients with ischemic episodes during AECG monitoring. Angina was more frequent among patients with ambulatory ischemic episodes than among patients without such ischemia (P < .001). Patients with AECG ischemia had a consistently more marked ischemic response on the ETT than patients without AECG ischemia; patients likely to have AECG ischemia could be predicted on the basis of ETT performance characteristics. However, the correlation coefficients between the severity of ischemia estimated by ETT and by AECG were small. CONCLUSIONS: There are significant relations between ischemia detected by AECG monitoring and by ETT, but the relations are limited, indicating that the two tests are not redundant to characterize coronary patients. A larger study investigating the prognostic significance of the ischemia identified by each modality, with follow-up for clinical events, will be necessary to determine the most appropriate methods to evaluate patients with stable coronary disease.

Coronary Disease↗
PubMed1996

The reuse of single-use balloon angioplasty catheters: is it now legitimate?

A recent nonrandomized study comparing the experience of 2 Canadian centers, 1 reusing balloon angioplasty catheters and the other using only new catheters, concluded that the reuse of angioplasty catheters was associated with higher rates of in-hospital complications and procedural drawbacks. However, after subsequent adjustment for differences in baseline characteristics of the patients in the 2 centers, the rates of in-hospital events was found to be similar in both centers.

Angioplasty, Balloon, Coronary↗
PubMed1996

Diabetics with coronary disease have a prevalence of asymptomatic ischemia during exercise treadmill testing and ambulatory ischemia monitoring similar to that of nondiabetic patients. An ACIP database study. ACIP Investigators. Asymptomatic Cardiac Ischemia Pilot Investigators.

BACKGROUND: There are conflicting data as to whether diabetics have a higher prevalence of asymptomatic ST-segment depression during exercise treadmill testing (ETT) and ambulatory ECG (AECG) monitoring. This study was conducted to determine whether diabetic patients with coronary disease enrolled in the Asymptomatic Cardiac Ischemia Pilot (ACIP) have more episodes of asymptomatic ischemia during ETT and 48-hour AECG monitoring than nondiabetic patients and to compare differences in angiographic variables and the magnitude of ischemia as measured by standard ETT and AECG criteria. METHODS AND RESULTS: Angiographic variables and the prevalence and magnitude of ischemia during the qualifying ETT and 48-hour AECG were compared by the presence and absence of diabetes mellitus in 558 randomized ACIP patients. Seventy-seven patients had a history of diabetes and were taking oral hypoglycemics or insulin (diabetic group); 481 patients did not meet these criteria (nondiabetic group). Multivessel disease (87% versus 74%, P = .01) was more frequent in the diabetic group. The percentages of patients without angina during the ETT were similar in the diabetic and nondiabetic groups (36% and 39%, respectively). Time to onset of > or = 1-mm ST-segment depression and time to onset of angina were similar in both groups. The percentages of patients with only asymptomatic ST-segment depression during the 48-hour AECG were similar in the diabetic and nondiabetic groups (94% versus 88%, respectively). However, total ischemic time per 24 hours (15.0 +/- 21.4 versus 23.6 +/- 31.1 minutes, P = .02), ischemic time per episode (6.3 +/- 4.6 versus 9.0 +/- 8.7 minutes, P < .01), and the maximum depth of ST-segment depression tended to be less in the diabetic group. CONCLUSIONS: Patients enrolled in ACIP were selected on the basis of an abnormal ETT and 48-hour AECG and ability to undergo coronary revascularization. When patients with diabetes mellitus were compared with those without diabetes, there was a similar prevalence of asymptomatic ischemia during ETT and 48-hour AECG monitoring. Despite more extensive and diffuse coronary disease, diabetic ACIP patients tended to have less measurable ischemia during the 48-hour AECG.

Aged↗
PubMed1996

Angiographic correlates of lesion relevance and suitability for percutaneous transluminal coronary angioplasty and coronary artery bypass grafting in the Bypass Angioplasty Revascularization Investigation study (BARI).

The Bypass Angioplasty Revascularization Investigation (BARI) randomized 1,829 patients to percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass grafting (CABG). Clinical site angiographers categorized lesions of > or = 50% diameter stenosis (n = 4,977) as clinically significant (86.4%) or nonsignificant (13.6%), and as favorable or nonfavorable for PTCA or CABG. More lesions were considered favorable for revascularization by CABG than by PTCA (91.5% vs 78.4%; p <0.001), particularly in the subgroup of 99% to 100% lesions (77.6% for CABG vs 21.9% for PTCA, p <0.001). Lesion features, characterized by the BARI core laboratory, were correlated with clinical site angiographers' assessment of clinical importance and suitability for PTCA or CABG. By multivariate analysis, positive predictors of clinical importance for 50% to 95% stenoses were greater stenosis severity, more jeopardized myocardium, larger reference diameter, and proximal vessel location. For 99% to 100% occlusions, predictors were shorter duration of occlusion and more jeopardized myocardium. PTCA suitability for 50% to 95% stenoses was inversely related to lesion length, ostial location, location on a bend, difficult access, and age, and was directly associated with greater Thrombolysis in Myocardial Infarction (TIMI) trial flow rate and more jeopardized myocardium. Predictors of PTCA suitability for 99% to 100% lesions were a lower American College of Cardiology/American Heart Association class and higher TIMI grade. Predictors for 50% to 95% stenoses were more jeopardized myocardium, larger reference diameter, and more proximal vessel location, and for 99% to 100% occlusions, more jeopardized myocardium and shorter duration of occlusion. Suitability for PTCA depended on lesion potency (<99%) and multiple morphologic characteristics that contrasted with the few angiographic features that adversely affect CABG suitability.

Angioplasty, Balloon, Coronary↗
PubMed1995

A meta-analysis of randomized trials comparing coronary artery bypass grafting with percutaneous transluminal coronary angioplasty in multivessel coronary artery disease.

We performed a meta-analysis of randomized trials that compared percutaneous transluminal coronary angioplasty (PTCA) with coronary artery bypass graft (CABG) surgery in patients with multivessel coronary artery disease. The outcomes of death, combined death, and nonfatal myocardial infarction (MI), repeat revascularization, and freedom from angina were analyzed. The overall risk of death and nonfatal MI was not different over a follow-up of 1 to 3 years (CABG:PTCA odds ratio [OR] 1.03, 95% confidence interval 0.81 to 1.32, p = 0.81). Patients randomized to CABG tended to have a higher risk of death or MI in the early, periprocedural period (OR 1.33, p = 0.091), but a lower risk in subsequent follow-up (OR 0.74, p = 0.093). CABG patients were much less likely to undergo another revascularization procedure (p < 0.00001), and were more likely to be angina free (OR 1.57, p < 0.00001). Thus, CABG and PTCA patients have similar overall risks of death and nonfatal MI at 1 to 3 years of follow-up, but relative risk differences in mortality of up to 25% cannot be excluded. CABG patients have significantly less angina and less repeat revascularization than PTCA patients.

Angioplasty, Balloon, Coronary↗