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Biomedical subjects

K K Teo

Publications and source records attributed to K K Teo.

At least 37 records · Page 2Linked to original sources
PubMed1999

Primary stenting versus balloon angioplasty in occluded coronary arteries: the Total Occlusion Study of Canada (TOSCA).

BACKGROUND: Balloon angioplasty (PTCA) of occluded coronary arteries is limited by high rates of restenosis and reocclusion. Although stenting improves results in anatomically simple occlusions, its effect on patency and clinical outcome in a broadly selected population with occluded coronary arteries is unknown. METHODS AND RESULTS: Eighteen centers randomized 410 patients with nonacute native coronary occlusions to PTCA or primary stenting with the heparin-coated Palmaz-Schatz stent. The primary end point, failure of sustained patency, was determined at 6-month angiography. Repeat target-vessel revascularization, adverse cardiovascular events, and angiographic restenosis (>50% diameter stenosis) constituted secondary end points. Sixty percent of patients had occlusions of >6 weeks' duration, baseline flow was TIMI grade 0 in 64%, and median treated segment length was 30.5 mm. With 95.6% angiographic follow-up, primary stenting resulted in a 44% reduction in failed patency (10.9% versus 19.5%, P=0.024) and a 45% reduction in clinically driven target-vessel revascularization at 6 months (15.4% versus 8.4%, P=0.03). The incidence of adverse cardiovascular events was similar for both strategies (PTCA, 23.6%; stent, 23.3%; P=NS). Stenting resulted in a larger mean 6-month minimum lumen dimension (1.48 versus 1.23 mm, P<0.01) and a reduced binary restenosis rate (55% versus 70%, P<0.01). CONCLUSIONS: Primary stenting of broadly selected nonacute coronary occlusions is superior to PTCA alone, improving late patency and reducing restenosis and target-vessel revascularization.

Adolescent↗
PubMed1999

Insights into the contemporary epidemiology and outpatient management of congestive heart failure.

OBJECTIVES: To evaluate the epidemiology, prognosis, and patterns of practice in patients with chronic congestive heart failure (CHF) treated and followed at a specialized clinic. METHODS: Prospective cohort study of consecutive patients referred to and followed up in a specialized heart failure clinic between September 1989 and March 1996. RESULTS: Of the 628 patients referred, 566 were confirmed to have CHF. Mean duration of follow-up was 518 +/- 490 days (range 1 to 2192 days). Vital status was available for 99.3% of patients. Mean age at enrollment was 66 years, 68% were men, 67% had an ischemic cause of heart disease, and 78% had systolic dysfunction. Patients with preserved systolic function were older, more often female, had higher mean systolic blood pressures, and a lower prevalence of ischemic heart disease, ventricular arrhythmias, or impaired renal function when compared with those with systolic dysfunction (all P </=.001). Although there was a significant negative trend in survival with decreasing ejection fraction (P =. 03), the survival experience of those with CHF and preserved systolic function did not significantly differ from those with systolic failure (P =.25). Multiple logistic regression analysis showed increased mortality risk was associated with increasing age, New York Heart Association class IV, ischemic cause of disease, elevated serum creatinine level, use of diuretics, and systolic dysfunction, whereas use of beta-blockers was associated with reduced risk. CONCLUSIONS: Our data suggest that a specialized outpatient clinic can improve practice patterns in patients with CHF. The high mortality risk in CHF with preserved systolic function suggests the need to find efficacious (and effective) therapies for this condition.

Aged↗
PubMed1999

The treatment and prevention of coronary heart disease in Canada: do older patients receive efficacious therapies? The Clinical Quality Improvement Network (CQIN) Investigators.

OBJECTIVES: To review the evidence for clinical efficacy and cost-effectiveness of proven medications in the treatment and prevention of myocardial infarction (MI) in older patients; to summarize Canadian data on treatment patterns and clinical outcomes for younger and older patients with coronary heart disease; to explore the reasons for gaps between best care, based on the evidence of efficacy from trials, and usual care, based on the population effectiveness audits; and to explore potential approaches to closing the care gaps. DESIGN: Review of the recent clinical trial literature on the management of MI, highlighting results in older patients. Review of medication utilization and outcomes data from a series of large, consecutively enrolled patient cohorts with acute MI (N = 7070) in a variety of cardiac care settings (10 centers in five Canadian provinces, including university-based teaching hospitals, community hospitals, cardiologist and family physician out-patient clinics) from 1987 to 1996. RESULTS: There is no qualitative interaction of cardiac therapies: thrombolytics, beta-blockers, acetylsalicylic acid (ASA), and statins are efficacious in all clinically relevant patient subgroups, including older people. However, there are consistent gaps between usual care and best care, particularly among older patients (in whom there is also a concomitantly higher mortality risk). Repeated multivariate analyses confirm older age to be an independent contributor to increased risk. Use of efficacious medications is, in contrast, consistently associated with increased survival. Analysis of temporal trends suggests beneficial changes in practice patterns and outcomes are possible to achieve. However, "best care" has not been rapidly or completely achieved. Review of strategies to close these care gaps suggests that audit and feedback, critical pathways, and multifactorial interventions involving patients and other members of the healthcare team as well as physicians may be the most efficacious strategies for change. CONCLUSIONS: Despite equal or enhanced efficacy, there is consistently less prescription of proven drugs among older cardiac patients. These care patterns may contribute to their enhanced risk. The causes underlying these practice patterns are complex, and their population impact may be undervalued by clinicians and managers. Improvement of these patterns is difficult, but ultimately it would be beneficial for this presently disadvantaged, readily identified, high risk patient population.

Aged↗
PubMed1999

Contemporary utilization of digoxin in patients with atrial fibrillation. Clinical Quality Improvement Network Investigators.

OBJECTIVE: To define the contemporary practice patterns of digoxin utilization for the management of patients with atrial fibrillation (AF). METHODS: A retrospective medical records audit of 2490 patients with documented AF, from 12 Canadian hospitals and six outpatient clinics, during fiscal year 1993-1994, was conducted. RESULTS: There were 1158 women and 1332 men, with a mean age of 72 years; 956 patients were < 70 years of age and 1534 were > or = 70 years old. The majority of patients had nonvalvular AF (75% of those with a documented etiology). Paroxysmal AF (PAF) was documented in 800 patients, 936 had chronic AF, and 754 had new-onset AF. While the prescribing patterns were heterogeneous, the predominant strategy pursued in all subgroups appeared to be that of achieving rate control. Digoxin was the most commonly prescribed medication (79%) and was prescribed for the majority of patients in all subgroups, including patients with PAF (74%) and patients with a history of chronic AF who were currently in sinus rhythm (83%). Only 10% of the patients with PAF who were prescribed digoxin had congestive heart failure. Similarly, less than 25% of the patients with chronic AF who were prescribed digoxin after conversion to sinus rhythm had evidence of heart failure. CONCLUSIONS: In the absence of clinical trial evidence supporting either a strategy of antiarrhythmic therapy or rate control with anticoagulation, the appropriateness of the observed prescribing practices cannot be judged. However, digoxin is not the best rate-controlling agent for all patients and may be overused in certain subgroups of patients, such as those with PAF and those successfully converted to sinus rhythm.

Aged↗
PubMed1999

Use of nonprescription medications by patients with congestive heart failure.

OBJECTIVE: To define the utilization pattern of nonprescription therapies in patients with congestive heart failure (CHF) and to compare this pattern with that of an age- and gender-matched control group without any self-reported heart conditions. DESIGN: Survey questionnaire completed by participants at home. SETTING: Ambulatory CHF clinic in a tertiary care hospital. SUBJECTS: Patients attending the clinic between July 1995 and May 1996 who agreed to participate. Control subjects were age- and gender-matched participants identified and approached by participating patients. OUTCOME MEASURES: Nonprescription therapies used at least once weekly. RESULTS: Completed questionnaires were received from 180 (75%) of the 239 patients who agreed to participate and from 133 controls. Mean age of responding patients was 69 years (63% men). Controls were younger, with a mean age of 64 years (63% men). The most commonly used nonprescription medication categories for both patients and controls, with no significant intergroup differences, were vitamins and minerals (59% patients, 50% controls), pain relievers (48% and 43%, respectively), herbal or health food products (38% and 38%), antacids (26% and 28%), and laxatives (24% and 21%). Significantly fewer patients than controls used cough and cold products (9% vs. 17%; p < 0.05), specifically oral decongestants (0.6% vs. 5%; p < 0.01), and more patients than controls used nutritional supplements (17% vs. 4%; p < 0.01). CONCLUSIONS: Overall, use of nonprescription therapies by our CHF clinic patients is similar to that of an age- and gender-matched population without a self-reported heart condition. The differences in medication use observed between patients and controls included cough and cold products that might be harmful. This likely reflects appropriate caution with which CHF patients approach nonprescription therapies.

Aged↗
PubMed1999

Study of Cardiovascular Risk Intervention by Pharmacists (SCRIP): a randomized trial design of the effect of a community pharmacist intervention program on serum cholesterol risk.

OBJECTIVE: To determine the efficacy of a program of intervention by pharmacists on lipid risk management in patients at high risk for cardiovascular events. METHODS: Randomized, multicenter (44 sites in Alberta and Saskatchewan) study of community pharmacist intervention versus usual care in 1000 patients. Patients are those at high risk of vascular events (existing atherosclerotic vascular disease, or diabetes with > or = 1 other risk factor). After obtaining consent, the pharmacist calls the Project Office to randomize. Patients allocated to intervention receive a brochure and education about cardiovascular risk factors. Pharmacists also complete a physician contact form, which lists the patient's risk factors, medications, and any recommendations. A point-of-care cholesterol test is performed, the result is discussed with the patient, and it is entered on the contact form. If appropriate, the patient is asked to see his or her primary care physician for further assessment and/or treatment, and the form is faxed to the physician. Patients are followed up at two, four, eight, 12, and 16 weeks. During follow-up visits, pharmacists provide educational reinforcement and check for primary end point occurrence. Patients allocated to usual care receive the brochure only, with minimal follow-up. The primary end point is a composite of measurement of a complete lipid panel by the physician, or addition or modification of lipid-lowering drug therapy. Substudies will evaluate economics (third-party payer and pharmacy manager perspective), patient satisfaction, and quality of life. CONCLUSIONS: SCRIP (Study of Cardiovascular Risk Intervention by Pharmacists) is a unique ongoing trial that is evaluating a community pharmacist intervention designed to optimize cholesterol risk management in patients at high risk for cardiovascular events.

Aged↗
PubMed1999

Reliability and validity of measures of cardiac output during incremental to maximal aerobic exercise. Part I: Conventional techniques.

The assessment of cardiac function, particularly cardiac output (Q) during heavy exercise is essential for the evaluation of cardiovascular factors that might limit oxygen transport. A series of invasive and noninvasive techniques has been developed for the assessment and monitoring of Q during resting and submaximal exercise conditions. However, very few techniques have been found to give accurate and reliable determinations of Q during vigorous to maximum exercise. For exercise physiologists and sport cardiologists, maximal exercise data are of primary importance. The 'gold standard' measures of cardiac function are considered to be the direct Fick and dye-dilution methods. These have been widely shown to give accurate and reliable determinations of Q during resting and submaximal exercise conditions; however, their use during maximal exercise conditions is debatable due to the inherent risks involved with each and their increasing inaccuracy during the later stages of vigorous exercise. Thermodilution has also been considered to be a relatively good method for the determination of Q during rest and exercise conditions, but recent authors have questioned its use due to the nature of the measure and its inaccuracy during strenuous exercise. Various noninvasive measures of cardiac function have been developed to overcome the problems associated with the 'gold standard' measures. The first part of this article discusses conventional techniques used in exercise physiology settings. The majority of these provide accurate and reliable determinations of Q during rest and submaximal exercise. However, very few techniques are suitable for maximal exercise conditions. Perhaps only the foreign gas rebreathe using acetylene (C2H2) meets all the criteria of being noninvasive, simple to use, reliable over repeated measurements, accurate and useful during maximal exercise.

Animals↗
PubMed1999

Reliability and validity of measures of cardiac output during incremental to maximal aerobic exercise. Part II: Novel techniques and new advances.

For exercise physiologists and sport cardiologists, one of the greatest challenges is to develop a valid, reliable, noninvasive and affordable measure of cardiac output (Q). There are several techniques available to measure Q during exercise conditions. These procedures generally provide accurate and reliable determinations of Q during submaximal exercise, but may be limited during maximal exercise conditions. The most commonly used noninvasive measures are the acetylene (C2H2) and carbon dioxide (CO2) rebreathe methods as reviewed in part I of this article. Only the foreign gas rebreathe method, using C2H2, meets all of the criteria of being noninvasive, easy to use, reliable and valid for use during maximal exercise. New methodologies have recently been developed to measure Q during exercise conditions. Although not as popular as the C2H2 and CO2 rebreathe methods, these methods have increasingly gained favour in exercise physiology and sport cardiology settings. The majority of these measures (if performed meticulously), with the exception of impedance cardiography, provide reasonably accurate and reliable determinations of Q. However, the cost of usage and technological limitations during maximal exercise have prevented these techniques from replacing the conventional measures of Q during exercise conditions. Doppler echocardiography and the modified C2H2 methods hold promise for the assessment of Q during maximal exercise. With further advances in these technologies their use in exercise physiology and sport cardiology setting may become more common.

Breath Tests↗
PubMed1999

Cardiac rehabilitation: the forgotten intervention.

OBJECTIVE: To examine the influence of cardiac patients' demographic and health characteristics on physicians' cardiac rehabilitation (CR) referral practice and patients' attendance at such programs. DESIGN: A retrospective, systematic review of consecutive health records. SETTING: A tertiary care centre and the two associated CR programs in a Western Canadian city. PATIENTS: One thousand, three hundred and twenty-eight adult patients (21 years of age or older) discharged following acute myocardial infarction, percutaneous transluminal coronary angioplasty (PTCA) and/or coronary artery bypass graft surgery between September 1, 1996 and August 31, 1997. MAIN RESULTS: There were 1245 surviving patients. Evidence of attendance at a CR program was 28.4%, while auditable evidence of referral to a CR program was 23.9%. Stepwise logistic regression revealed that ability to speak English (OR 9.56) living in a city (OR 3.97) and current smoking (OR 1.51) were associated with an increased likelihood, whereas having a history of chronic obstructive pulmonary disease or asthma (OR 0.53), being 70 years of age or older (OR 0.42), having a current admission for PTCA (OR 0.32) and having a history of neurological or cognitive impairment (OR 0.26) were associated with a decreased likelihood of CR attendance. Sex, nature of coronary artery disease risk factors, incidence of postevent complications and pre-event cardiac status (including New York Heart Association status and number of previous events) were not associated with patients' CR attendance. CONCLUSIONS: This study suggests that there is an inconsistent and poorly documented approach to referral of patients to CR programs for reasons that remain unclear. These findings provide a foundation for development and testing of enhanced referral mechanisms and of innovative means to provide rehabilitation services to patients who are at risk for not being referred to or attending CR programs.

Adult↗
PubMed1998

Impact of managed waiting for coronary artery bypass graft surgery on patients' perceived quality of life.

BACKGROUND: Current demand for CABG surgery remains high, often exceeds available resources, and has led to the development of managed waiting lists. This study was designed to determine how being placed on a managed waiting list for > 6 weeks for CABG surgery affected patients' perceived quality of life in a Canadian center. METHODS AND RESULTS: Telephone interviews were carried out in the setting of a large urban hospital in northern Alberta. All participants were identified from 3 waiting lists of adult patients waiting for open heart surgery. A master list of patient statements was compiled to formulate the 47-item Waiting List Impact Questionnaire (WLIQ). A total of 102 patients completed the WLIQ by telephone interview. Patients (87.5%) indicated that their quality of life had deteriorated since being placed on the waiting list. None of the patients perceived an improvement in their quality of life. Frequency data for the WLIQ provided a broad, multidimensional perspective of the experience of waiting for CABG surgery and its impact on perceived quality of life. Negative impact was found in each of 5 main themes: employment and income, physical stress, social support, frustration, and quality of life. CONCLUSIONS: This study indicates that patients perceived a negative impact on their quality of life after being placed on a managed waiting list for CABG surgery. In the allocation of healthcare resources, attention should be paid to the impact of waiting on patients' physical well-being as well as on quality of life.

Adult↗
PubMed1998

Recent advances in the drug treatment of heart failure.

A number of important questions surrounding the treatment of systolic congestive heart failure have been answered by randomised clinical trials completed within the past 2 years. In particular, these studies have established that high-dose angiotensin-converting enzyme (ACE) inhibition is more beneficial than low dose therapy, and that angiotensin II receptor antagonists are an acceptable alternative in patients unable to tolerate ACE inhibitors. Digoxin has been shown to be the only inotropic agent not associated with increased mortality, while amiodarone exerts a modest survival benefit in arrhythmiaprone patients. Beta-blockers appear to be beneficial for selected patients although their precise role remains to be defined by ongoing studies.

Adrenergic beta-Antagonists↗
PubMed1998

An open design, multicentre, randomized trial of percutaneous transluminal coronary angioplasty versus stenting, with a heparin-coated stent, of totally occluded coronary arteries: rationale, trial design and baseline patient characteristics. Total Occlusion Study of Canada (TOSCA) Investigators.

BACKGROUND: Percutaneous transluminal coronary angioplasty (PTCA) of totally occluded coronary arteries is performed in a variety of clinical settings and for a variety of indications. Most commonly it is performed for relief of symptoms of myocardial ischemia. Studies have also suggested that PTCA of occluded arteries beyond the acute phase of myocardial infarction may improve left ventricular function even in the absence of objective evidence of ischemia. One of the major limitations of total occlusion PTCA is a high rate of reocclusion, reported to be as high as 40%. Recently, small studies have suggested that stenting may improve the long term outcome after PTCA of total coronary occlusions. OBJECTIVES: To determine in a prospective, randomized trial whether long term patency and clinical outcome following successful PTCA of a totally occluded coronary can be improved by the use of of a heparin-coated stent. PATIENTS AND METHODS: Subjects were randomly assigned to one of two strategies once the guide wire had crossed the occluded segment of the target artery: PTCA alone, or PTCA followed by insertion of Palmaz-Shatz heparin-coated stent(s). Randomization was stratified according to duration of the coronary occlusion: six weeks or less, and more than six weeks. The primary end-point is failure of sustained patency (Thrombolysis in Myocardial Infarction [TIMI] flow grade less than 3) at six months. Secondary end-points are change in minimal luminal diameter, target vessel revascularization at one year, cardiovascular events at one year, and change in global and regional left ventricular function. BASELINE CHARACTERISTICS: All 410 patients have been randomly assigned to the PTCA alone (n = 208) or PTCA plus stent (n = 202) group. Mean age was 58 +/- 11 years and 18% were female. Prior myocardial infarction had been documented in 67% of patients. The duration of occlusion was six weeks or less in 40% and more than six weeks in 60% of patients. In 64% of patients TIMI flow was grade 0 and in 36% it was grade 1. STUDY IMPLICATIONS: The trial will demonstrate whether the use of a heparin-bonded stent can improve long term patency and clinical outcome in patients undergoing clinically indicated PTCA of totally occluded coronary arteries. If a significant reduction in reocclusion and clinical events is demonstrated, the Total Occlusion Study of Canada (TOSCA) would offer a more effective long term revascularization strategy in future trials testing the open artery hypothesis.

Aged↗