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Biomedical subjects

P Bogaty

Publications and source records attributed to P Bogaty.

At least 19 recordsLinked to original sources
PubMed2001

Biological profiles in subjects with recurrent acute coronary events compared with subjects with long-standing stable angina.

BACKGROUND: At one end of the clinical spectrum of coronary artery disease (CAD) are subjects who have had repeated acute ischemic events, and at the other end are those with long-standing angina who have never been unstable. This study tests the hypothesis that a specific biological profile can distinguish these 2 extreme groups and predict acute coronary events. METHODS AND RESULTS: Blood levels of lipoprotein(a), homocysteine, tissue plasminogen activator, plasminogen activator inhibitor-1, C-reactive protein (CRP), fibrinogen, and von Willebrand factor were compared in 3 groups of 50 subjects each: (1) those with previous multiple acute coronary events, (2) age-matched subjects with >/=3 years of stable angina and no prior acute coronary events, and (3) matched controls without evidence of atherosclerotic disease and a normal coronary angiogram. All subjects were followed for 4.0 years. Lipoprotein(a), homocysteine, tissue plasminogen activator, and plasminogen activator inhibitor-1 were similar in both CAD groups and significantly higher than in the control group. However, compared with subjects with long-standing stable angina, those with previous multiple coronary events had higher values of CRP (5.7+/-5.4 versus 3.0+/-5.2 mg/L, P=0.012), fibrinogen (3.38+/-0.75 versus 2.92+/-0.64 g/L, P=0.001), and von Willebrand factor (1.60+/-0.55 versus 1.25+/-0.36 U/mL, P=0.0003). On follow-up, myocardial infarction and unstable angina occurred in 42% of the group with multiple events, 4% of the stable angina group (P<0.0001), and none of the control subjects. In the 100 patients with CAD, CRP was 4.9 mg/L in those with and 1.8 mg/L in those without new instability (P<0.0001). In a multivariate analysis, only CRP distinguished those with follow-up acute coronary events (adjusted odds ratio 5.9, 95% CI 2.0 to 17.9; P=0.002). A baseline CRP >3.5 mg/L had a relative risk of 7.6 (2.6 to 21.7, P=0.0002) for subsequent acute events. CONCLUSIONS: An inflammatory biological profile distinguished patients with previous multiple acute coronary events from those with long-standing stable angina and predicted acute coronary instability.

Angina Pectoris↗
PubMed2001

Aspirin, warfarin, or the combination for secondary prevention of coronary events in patients with acute coronary syndromes and prior coronary artery bypass surgery.

BACKGROUND: Patients with a non-ST-elevation acute coronary syndrome and prior CABG are at high risk of a recurrent ischemic event despite aspirin therapy. This trial investigated the potential benefit of secondary prevention with warfarin. METHODS AND RESULTS: In a double-blind randomized trial, 135 patients with unstable angina or non-ST-segment elevation myocardial infarction, with prior CABG, and who were poor candidates for a revascularization procedure received therapy with aspirin and placebo+warfarin, warfarin and placebo+aspirin, or aspirin and warfarin for 12 months. Warfarin was titrated to an international normalized ratio of 2.0 to 2.5. The primary end point (death or myocardial infarction or unstable angina requiring hospitalization 1 year after randomization) occurred in 14.6% of the patients in the warfarin-alone group, in 11.5% of patients in the aspirin-alone group, and in 11.3% of patients randomized to the combination therapy (P=0.76). Subgroup analyses by risk features provided no indications that warfarin alone or in combination with aspirin could be of benefit over aspirin alone. Bleeding was more frequent in the 2 groups of patients administered warfarin. CONCLUSIONS: Moderate-intensity oral anticoagulation alone or combined with low-dose aspirin does not appear to be superior to low-dose aspirin in the prevention of recurrent ischemic events in patients with non-ST-elevation acute coronary syndromes and previous CABG.

Aged↗
PubMed2001

Myocardial perfusion imaging findings and the role of adenosine in the warm-up angina phenomenon.

OBJECTIVES: This study examined the roles of myocardial perfusion and adenosine in warm-up angina. BACKGROUND: In warm-up angina, neither the role of an adenosine-mediated mechanism, as is found in experimental ischemic preconditioning, nor of increased myocardial perfusion is well defined. METHODS: In substudy A, a single-photon emission computed tomography (SPECT)-thallium-201 exercise test was performed by 12 subjects with ischemic heart disease on three occasions one week apart. The third test was preceded by a warm-up test. The extent of the thallium deficit and its intensity on the third test were compared with the baseline tests controlling for the heart rate-systolic blood pressure product (RPP) at thallium injection. In substudy B, 12 similar subjects did two successive exercise tests at two separate sessions and received the adenosine antagonist, aminophylline (intravenous 5 mg/kg bolus and 0.9 mg/kg/h infusion) at one session, and equivalent saline at the other session. Change in ischemic threshold (RPP at 1 mm ST segment depression) and in maximum ST depression adjusted for RPP were analyzed. RESULTS: In substudy A, despite a significant attenuation of electrocardiogram indexes of myocardial ischemia between the baseline and third (warmed-up) tests, the thallium extent deficits (20.8 +/- 15.1% and 16.8 +/- 12.4%) and intensity deficits (41.2 +/- 12.6% and 39.3 +/- 12.6%) did not differ significantly. In substudy B, the increase in ischemic threshold on re-exercise was unaffected by aminophylline. Adjusted maximum ST depression even decreased to a greater extent on re-exercise with aminophylline (by 51 +/- 21%) than with saline (by 32 +/- 19%) (p = 0.012). CONCLUSIONS: While warm-up angina is associated with a significant attenuation of exercise electrocardiogram indexes of ischemia, it is unaccompanied by significant changes in SPECT perfusion and does not appear to be mediated by an adenosine-dependent mechanism since it is not blocked by aminophylline. Thus, its mechanism, which appears distinct from experimental ischemic preconditioning, remains unidentified.

Adenosine↗
PubMed2001

Randomized trial of a noninvasive strategy to reduce hospital stay for patients with low-risk myocardial infarction.

OBJECTIVES: This study evaluated the feasibility, pertinence and psychosocial repercussions of a noninvasive reduced hospital stay strategy (three days) for low-risk patients with acute myocardial infarction using simple clinical criteria and predischarge 24-h ambulatory ST-segment ischemic monitoring. BACKGROUND: Previous studies evaluating shorter stays for uncomplicated myocardial infarction have been limited by retrospective or nonrandomized design and overdependence on invasive cardiac procedures. METHODS: One-hundred twenty consecutive patients admitted with an acute myocardial infarction fulfilling low-risk criteria were randomized 2:1 to a short hospital stay (80 patients) or standard stay (40 patients). Short-stay patients with no ischemia on ST-segment monitoring were discharged on day 3, returning for exercise testing a week later. All analyses were on an intention-to-treat basis. RESULTS: Forty-one percent of all screened patients with acute myocardial infarction would have been medically eligible for the short-stay strategy. Seventeen patients (21%) were not discharged early because of ischemia on ST-monitoring or angina. Median initial hospital stay was halved from 6.9 days in the standard stay to 3.5 days in the short-stay group. At six months, median total days hospitalized were 7.5 in the standard stay and 3.6 in the short-stay group (p < 0.0001). Adverse events and readmissions were low and not significantly different, and there were 25% fewer invasive cardiac procedures in the short-stay group. Psychosocial outcomes, risk factor changes and exercise test results were similar in the two groups. CONCLUSIONS: This reduced hospital stay strategy for low-risk patients with acute myocardial infarction is feasible and worthwhile, resulting in a substantial and sustained reduction in days hospitalized. It is without unfavorable psychosocial consequences, appears safe and does not increase the number of invasive cardiac procedures.

Adult↗
PubMed2001

Elevated C-reactive protein: another component of the atherothrombotic profile of abdominal obesity.

Recent studies have suggested that elevated plasma C-reactive protein (CRP) levels are associated with the features of insulin resistance syndrome. In the present study, we have examined the contribution of body composition measured by hydrostatic weighing and of abdominal adipose tissue (AT) accumulation assessed by computed tomography to the variation in plasma CRP levels associated with atherogenic dyslipidemia of the insulin resistance syndrome in a sample of 159 men, aged 22 to 63 years, covering a wide range of adiposity (body mass index values from 21 to 41 kg/m(2)). Plasma CRP levels showed positive and significant correlations with body fat mass (r=0.41, P<0.0001), waist girth (r=0.37, P<0.0001), and visceral AT accumulation measured by computed tomography at L4 to L5 (r=0.28, P<0.0003). Although CRP levels were associated with plasma insulin levels measured in the fasting state and after a 75-g oral glucose load, no significant correlations were found with plasma lipoprotein levels. Finally, comparison of body fatness, of abdominal fat accumulation, and of the features of the insulin resistance syndrome across quintiles of CRP revealed major differences in body fatness and in indices of abdominal AT accumulation between the lowest and the highest CRP quintiles, whereas no significant differences were found for variables of the plasma lipoprotein-lipid profile. These results suggest that obesity and abdominal AT accumulation are the critical correlates of elevated plasma CRP levels found in men with atherogenic dyslipidemia of the insulin resistance syndrome.

Abdomen↗
PubMed2001

Diastolic dysfunction in normotensive men with well-controlled type 2 diabetes: importance of maneuvers in echocardiographic screening for preclinical diabetic cardiomyopathy.

OBJECTIVE: Because a pseudonormal pattern of ventricular filling has never been considered in studies that reported a prevalence of left ventricular diastolic dysfunction (LVDD) between 20 and 40%, our aim was to more completely evaluate the prevalence of LVDD in subjects with diabetes. RESEARCH DESIGN AND METHODS: We studied 46 men with type 2 diabetes who were aged 38-67 years; without evidence of diabetic complications, hypertension, coronary artery disease, congestive heart failure, or thyroid or overt renal disease; and with a maximal treadmill exercise test showing no ischemia. LVDD was evaluated by Doppler echocardiography, which included the use of the Valsalva maneuver and pulmonary venous recordings to unmask a pseudonormal pattern of left ventricular filling. RESULTS: LVDD was found in 28 subjects (60%), of whom 13 (28%) had a pseudonormal pattern of ventricular filling and 15 (32%) had impaired relaxation. Systolic function was normal in all subjects, and there was no correlation between LVDD and indexes of metabolic control. CONCLUSIONS: LVDD is much more common than previously reported in subjects with well-controlled type 2 diabetes who are free of clinically detectable heart disease. The high prevalence of this phenomenon in this high-risk population suggests that screening for LVDD in type 2 diabetes should include procedures such as the Valsalva maneuver and pulmonary venous recordings to unmask a pseudonormal pattern of ventricular filling.

Adult↗
PubMed2001

The endocarditis that was not: an unusual case of heparin-induced thrombocytopenia with unusual complications.

The complications of heparin-induced thrombocytopenia have been well described previously. However, evidence of the possibility that heparin-induced thrombocytopenia can trigger a thyroid storm has never been published before. A catastrophic evolution of a man referred with a high endocarditis suspicion previously treated with heparin, who successively developed arterial thrombosis and thyroid storm, is described.

Adult↗
PubMed2000

Impact of left ventricular diastolic dysfunction on maximal treadmill performance in normotensive subjects with well-controlled type 2 diabetes mellitus.

Patients with type 2 diabetes often have impaired exercise capacity compared with nondiabetic subjects. Left ventricular (LV) diastolic dysfunction has been shown to limit exercise performance in nondiabetic subjects. Men with well-controlled type 2 diabetes were divided into 2 groups: normal LV diastolic function (group 1, n = 9) or LV diastolic dysfunction (group 2, n = 10) based on standard echocardiographic criteria using pulmonary veins and transmitral flow recordings. They were matched for age and had no evidence of systemic hypertension, macroalbuminuria, coronary artery disease, congestive heart failure, clinical diabetic complications, and thyroid disease. Good metabolic control was demonstrated by glycated hemoglobin levels of 6.7+/-1.6% and 6.6+/-2.5% (means +/- SD) in patients with LV diastolic dysfunction and in controls, respectively. Each subject performed a symptom-limited modified Bruce protocol treadmill exercise test. Maximal treadmill performance was higher in subjects with normal diastolic function compared with subjects with LV diastolic dysfunction when expressed in time (803+/-29 vs. 662+/-44 seconds, respectively, p<0.02) or in METs (11.4+/-1.2 vs. 9.5+/-1.9 METs, respectively, p<0.02). Moreover, there was a correlation between E/A ratio and exercise duration (r = 0.64, p = 0.004) or E/A ratio and METs (r = 0.658, p = 0.003). There were no significant differences in maximal heart rate, maximal systolic and diastolic blood pressure, or maximal rate-pressure product attained during the exercise test. In conclusion, this study demonstrated that LV diastolic dysfunction influences maximal treadmill performance and could explain lower maximal performance observed in patients with type 2 diabetes.

Blood Flow Velocity↗
PubMed2000

Platelet GPIIb/IIIa receptor blockade reduces infarct size in a canine model of ischemia-reperfusion.

OBJECTIVES: We studied the effects of N-acetyl-cys-asn-(5,5-dimethyl-4-thiazolidine-carbonyl)-4-amino-methyl-phe-gly-asp-cys, monoacetate (MK-0852) (platelet GPIIb/IIIa receptor blocker) on peak reactive hyperemia, distribution of blood flow, regional contractile function and infarct size in a canine model of acute ischemia-reperfusion injury. BACKGROUND: Platelet activation and formation of platelet microaggregates in coronary vessels could contribute to ischemia-induced myocyte injury. Inhibition of platelet aggregation could reduce ischemia-reperfusion injury. METHODS: Three groups of dogs (n = 10/group) were studied; group 1--heparin (HEP) (100 U/kg/h intravenously), group 2--MK-0852 (300 microg/kg intravenous bolus followed by 3 microg/kg/min for 3 h) and group 3--MK-0852 plus HEP. Infarct size after 60 min regional ischemia and 3 h reperfusion was evaluated by tetrazolium staining and normalized to risk area (Monastral blue dye). RESULTS: Infarct size in HEP-treated controls was 32.4+/-2.8%; in MK-0852 without or with HEP groups, infarct size was 17.4+/-1.9% (p = 0.001) and 23.4+/-3.0% (p = 0.04), respectively. Cardiac hemodynamics and rate-pressure product were comparable between groups. Multivariate analysis using collateral blood flow as the independent variable confirmed the cytoprotective actions of MK-0852. Postischemic peak reactive hyperemia in the infarct-related artery was depressed in all groups; during reperfusion, transmural distribution of myocardial blood flow returned to near control levels, but severe regional hypokinesia persisted. CONCLUSIONS: Diminished infarct size with MK-0852 treatment suggests an additional mechanism of benefit for GPIIb/IIIa blockers beyond stabilization of a "culprit" acute coronary lesion. This cytoprotective effect was unrelated to preservation of coronary vasoreactivity (assessed by reactive hyperemia), restoration of blood flow across the myocardium or acute improvement in contractility.

Animals↗
PubMed1998

Attenuation of myocardial ischemia with repeated exercise in subjects with chronic stable angina: relation to myocardial contractility, intensity of exercise and the adenosine triphosphate-sensitive potassium channel.

OBJECTIVES: This study characterized the attenuation of myocardial ischemia observed with re-exercise to determine whether: 1) a differing exercise intensity modifies this attenuation; 2) it could be explained by contractile down-regulation or stunning; 3) it is mediated by activation of ATP-sensitive potassium channels (K+-ATP). BACKGROUND: Subjects with ischemic heart disease (IHD) frequently note less angina with re-exercise after a brief rest. Potential mechanisms of this 'warm-up' phenomenon have been little explored. METHODS: IHD subjects with a positive exercise test were studied. Groups I and II (12 subjects each) underwent 2 successive Naughton protocol exercise echocardiography tests (with 1 min instead of 2 min stages for Group II). Group D (10 subjects) had type II diabetes, were on > or =10 mg daily of the K+-ATP blocker, glibenclamide, and underwent the group I exercise protocol. The ischemic threshold or rate-pressure product at 1 mm ST segment depression, ST depression corresponding to the peak rate-pressure product of the first exercise (maximum ST depression equivalent), and left ventricular wall motion indexes before and immediately after each exercise were analyzed. RESULTS: Exercise-induced myocardial ischemia with re-exercise was similarly attenuated in groups I, II, and D. The ischemic threshold was raised by nearly 20% with re-exercise (p=0.001, p=0.02, and p=0.02, respectively) and the maximum ST depression equivalent was nearly halved on re-exercise (p=0.005, p=0.006, and p=0.001, respectively). Exercise-induced wall motion dysfunction was attenuated with re-exercise. In group I, wall motion returned to the initial baseline score prior to exercise 2, whereas in the more intense protocol of group II, wall motion dysfunction persisted prior to exercise 2. CONCLUSIONS: Thus, the attenuation of myocardial ischemia observed with re-exercise appears to be independent of the intensity of the exercise protocol and is not explained by down-regulation of myocardial contractility induced by the initial ischemic stimulus. Since results were similar in diabetic subjects on robust doses of glibenclamide, this phenomenon does not appear to be mediated by K+-ATP activation.

Adenosine Triphosphate↗
PubMed1998

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.

Aged↗
PubMed1998

Atherogenic, hemostatic, and other potential risk markers in subjects with previous isolated myocardial infarction compared with long-standing uncomplicated stable angina.

BACKGROUND: Several atherogenic, hemostatic, inflammatory, and genetic parameters and markers have been implicated as risk factors in coronary artery disease, although whether they are risk factors for acute as opposed to chronic coronary disease is unclear. METHODS AND RESULTS: Fifty subjects with an isolated myocardial infarction >3 months previously were compared with 50 subjects with a minimum 3-year history of stable angina, documented coronary artery disease, normal electrocardiogram and normal ventricular wall motion, and no episode suggesting infarction or unstable angina. Biologic variables analyzed included apolipoprotein B (apo B), lipoprotein (a), C-reactive protein (CRP), fibrinogen, factor VII, tissue plasminogen activator (TPA) and inhibitor (PAI-1), thrombin-antithrombin (TAT), fragment 1+2 (F1+2), von Willebrand factor (vWF), activated protein C resistance, homocyst(e)ine, anticardiolipin antibodies, blood group, and the angiotensin-converting enzyme insertion/deletion (I/D) and angiotensin II receptor gene polymorphisms. There were no significant differences between the 2 groups for any of the variables studied, although fibrinogen and F 1+2 tended to be slightly higher in the angina group (P = .09 for each). These significant correlations were present: age with fibrinogen, homocyst(e)ine, and vWF; factor VII with apo B, homocyst(e)ine, and TPA; apo B with TPA and CRP; CRP with fibrinogen, TPA, PAI-1, and factor VII; fibrinogen with vWF. CONCLUSIONS: Examination of atherogenic, hemostatic, inflammation, and genetic variables in the clinically quiescent state permitted no distinction between subjects with a previous isolated myocardial infarction in contrast to those with long-standing uncomplicated stable angina, favoring the notion that acute coronary events occur at random on a varying background of atherosclerosis. The multiple correlations found among these variables also underscore their complex interaction in the atherosclerotic process.

Adult↗
PubMed1997

A reappraisal of exercise electrocardiographic indexes of the severity of ischemic heart disease: angiographic and scintigraphic correlates.

OBJECTIVES: We explored how the exercise electrocardiographic (ECG) indexes generally presumed to signify severe ischemic heart disease (IHD) correlate with coronary angiographic and scintigraphic myocardial perfusion findings. BACKGROUND: In exercise testing, it is generally assumed that the early onset of ST segment depression and its occurrence at a low rate-pressure product (ischemic threshold); the amount of maximal ST segment depression; and a horizontal or downsloping ST segment and its prolonged recovery after exercise signify more severe IHD. However, the relation of these indexes to coronary angiographic and exercise myocardial perfusion findings in patients with IHD is unclear. METHODS: We prospectively carried out a symptom-limited 12-lead Bruce protocol thallium-201 single-photon emission computed tomographic (SPECT) exercise test in 66 consecutive subjects with stable angina, > or = 70% stenosis of at least one coronary artery, normal rest ECG and left ventricular wall motion and a prior positive exercise ECG. The above ECG indexes, vessel disease (VD), a VD score and the quantitative thallium-SPECT measures of the extent, maximal deficit and redistribution gradient of the perfusion abnormality were characterized. RESULTS: Maximal ST segment depression could not differentiate the number of diseased vessels; was not related to VD score, maximal thallium deficit or redistribution gradient; but was related to the extent of perfusion abnormality (r = 0.29, 95% confidence interval [CI] 0.08 to 0.52, p = 0.02). Time of onset of ST segment depression correlated inversely only with VD (r = -0.22, 95% CI -0.44 to -0.05, p < 0.05), whereas the ischemic threshold had low inverse correlation only with VD score (r = -0.25, 95% CI -0.47 to -0.01, p < 0.05) and the redistribution gradient (r = -0.33, 95% CI -0.53 to -0.10, p < 0.01). A horizontal or downsloping compared with an upsloping ST segment did not demonstrate more severe angiographic and scintigraphic disease. Recovery time did not correlate with angiographic and scintigraphic findings, and correlations between angiographic and scintigraphic findings were also low or absent. CONCLUSIONS: In this homogeneous study group, the exercise ECG indexes did not necessarily signify more severe IHD by angiographic and scintigraphic criteria. Lack of concordance between the exercise ECG, angiography and myocardial scintigraphy suggests that these diagnostic modalities examine different facets of myocardial ischemia, underscoring the need for caution in the interpretation of their results.

Aged↗
PubMed1996

Unstable angina--report from a Canadian expert roundtable.

Unstable angina is generally considered to encompass a spectrum of symptomatic manifestations of ischemic heart disease, intermediate between stable angina and acute myocardial infarction. Approximately 75,000 Canadians are hospitalized yearly with unstable angina. The pathophysiology of unstable angina is still imperfectly understood, but is related to the same pathophysiological factors underlying myocardial infarction and sudden cardiac death. In March 1995 a group of Canadian cardiologists met to review the current understanding of unstable angina and to define a Canadian approach to this common problem. Important issues and questions regarding the diagnosis and management of unstable angina were defined. The objective was to outline approaches to the management of unstable angina that would be appropriate in Canada. Topics discussed included definition, incidence, clinical presentations, pathophysiology, initial diagnostic and risk stratification approaches, acute medical management, role of invasive interventions and long term management.

Angina, Unstable↗