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Biomedical subjects

David Massel

Publications and source records attributed to David Massel.

At least 19 recordsLinked to original sources
PubMed2005

Primary angioplasty in acute myocardial infarction: Hypothetical estimate of superiority over aspirin or untreated controls.

BACKGROUND: Primary percutaneous transluminal coronary angioplasty (PTCA) in the setting of ST-segment-elevation myocardial infarction has been compared with intravenous thrombolysis, but its effects versus no treatment are not known. Knowledge of the effects of PTCA in this setting is useful as a substantial minority of patients do not receive thrombolysis because of contraindications. METHODS: A hypothetical primary PTCA versus placebo/control odds ratio was computed using a recently described statistical technique that employed the logarithm of the odds ratios of the pooled results of meta-analyses of PTCA versus thrombolysis and thrombolysis versus placebo or controlled trials. RESULTS: Using data from 30 trials, the synthesized odds ratio for mortality for primary PTCA versus placebo/untreated controls is 0.56 (95% confidence interval [CI]: 0.46 to 0.68; P <0.00001), consistent with a 44% reduction. Primary PTCA and aspirin reduces mortality by 69% versus no aspirin (OR = 0.31; 95% CI: 0.21 to 0.45; P <0.00001). In a high-risk group of otherwise eligible patients with thrombolysis contraindications, the absolute benefit is estimated as 93 per 1000 treated (95% CI: 53 to 132 per 1000 treated). The risk of stroke is reduced with primary PTCA (OR = 0.46; 95% CI: 0.30 to 0.71; P = 0.0004). CONCLUSION: In this setting, primary PTCA would hypothetically reduce the short-term risk of death by 44%. Despite the use of aggressive antithrombotic regimens, the risk of stroke would also be reduced substantially with primary PTCA.

Acute Disease↗
PubMed2004

Composite confusion.

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Angioplasty, Balloon, Coronary↗
PubMed2004

Anticoagulation.

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Ambulatory Care Facilities↗
PubMed2004

External loop recorders: determinants of diagnostic yield in patients with syncope.

OBJECTIVES: The purpose of the current study was to determine the optimal duration of external loop recorder (ELR) monitoring in patients with presyncope or syncope and to identify factors that predict failure to activate the device effectively. DESIGN: A multivariate analysis was performed using data from the Comparison Of Loop Recorders Against Holter in Patients with Syncope (COLAPS) trial, a prospective study comparing diagnostic utility of ELRs and Holter monitors for assessment of syncope. METHODS: Patients with failure to effectively activate ELRs were compared to those who were successful. This analysis was performed separately for failure of test transmission and for failure to successfully record and transmit data from symptomatic episodes. Patient characteristics were compared among the groups to determine risk factors for device failure. RESULTS: Among 78 patients who received ELRs, a test transmission was successfully performed by 84.5% of patients. Twenty-one percent of diagnoses were made within 48 hours, 50% at 15 days, and 90% at 33 days. Patients performing a successful test transmission were more familiar with technology, with ability to use a bank automatic teller machine being a significant independent predictor. Patients with a successful test transmission were, in turn, significantly more likely to record and transmit data from symptomatic episodes. Patients living alone were much less likely to use the loop recorder effectively. The presence of factors that may influence motivation to reach a diagnosis (degree of worry/fear of symptoms and impact on daily life) were associated with successful use of the device in a univariate analysis. CONCLUSION: ELRs should be worn for at least 30 days to maximize their diagnostic yield. Patients who are unfamiliar with technology, live alone, or have low motivation to reach a diagnosis have a lower diagnostic yield from ELRs for assessment of syncope.

Electrocardiography, Ambulatory↗
PubMed2004

Predictors of intracranial hemorrhage with fibrinolytic therapy in unselected community patients: a report from the FASTRAK II project.

BACKGROUND: Patients at high risk for intracranial hemorrhage (ICH) are generally excluded from thrombolytic trials. Because the frequency and predictors of ICH reported from these studies may not be widely applicable, we sought to examine this matter further in unselected patients with acute myocardial infarction in the community. METHODS: FASTRAK II is a prospective ongoing registry of acute coronary syndromes involving 111 Canadian hospitals. Trained medical personnel recorded admission, treatment, and discharge data on patients admitted with acute coronary syndromes. RESULTS: From January 1, 1998, to December 31, 2000, 12,739 patients received fibrinolytic therapy for acute myocardial infarction. Of these, 146 patients (1.15%) sustained strokes and 82 patients (0.65%) had an ICH. Advanced age, female sex, history of cerebrovascular event, and systolic hypertension on arrival (systolic blood pressure >160 mm Hg) were identified with a multivariate logistic regression model to be important independent risks factors for ICH. Patients receiving streptokinase had a lower risk of ICH. Among the patients at high risk for ICH, the ICH rates remained low, ranging from 0.7% to 1.8%. CONCLUSION: ICH is an infrequent event after fibrinolytic therapy in ST-elevation MI; this low rate supports broad penetration of this therapy. Simple clinical characteristics are useful in predicting the risk of ICH and allow a clinician to individualize the risk-benefit assessment of this therapy.

Aged↗
PubMed2004

Model study of AREDS antioxidant supplementation of AMD compared to Visudyne: a dominant strategy?

OBJECTIVES: In Ontario, Canada, in a cohort of all people initially aged 50-54 years, modeling whether the Age-Related Eye Disease Study (AREDS) antioxidant supplementation for stage 3 and 4 AMD would decrease the costs of photodynamic treatment with Visudyne. PERSPECTIVE: Third party payer, the Ontario Health Insurance Plan. METHODS: Using reported risk reductions, prevalence data by age and sex from the Beaver Dam studies, and yearly costs: AREDS 182.50 Canadian dollars, potential savings were calculated as the difference or incremental cost between the estimated medical costs for the untreated cohort of 17,000 Canadian dollars for Visudyne treatment of individuals with neovascularization and the same cohort if stage 3 and 4 AMD patients were treated with antioxidants, decreasing progression to neovascularization. Different scenarios were explored for sensitivity analysis of direct cost savings. RESULTS: For the Ontario cohort of approximately 788,000 aged 51-55 years in 2001, for photodynamic therapy of the untreated cohort, modeled costs were 1.7 billion Canadian dollars. AREDS treatment costs would be 513 million Canadian dollars. AREDS would reduce photodynamic therapy costs, a net saving of 431 million Canadian dollars, a saving of 547 Canadian dollars per person in the total cohort, or 6,753 Canadian dollars per stage 3 and 4 patient treated. To explore the sensitivity of this model to AMD incidence rather than prevalence data, Framingham incidence data were incorporated in the model: net savings of 70.3 million Canadian dollars were modeled using Framingham incidence data. CONCLUSION: Under reasonable assumptions, if the case progresses to wet AMD (1) AREDS with Visudyne is less expensive than Visudyne alone in every five-year time period for the cohort that is age 50-54 right now until they become 75-79; thus, the lifetime cost is lower; (2) AREDS with Visudyne yields more QALYs than Visudyne alone in every five-year interval; (3) under all but the most extreme assumptions, the conclusions reached are robust. Even when AREDS costs a little more, it yields more QALYs at a reasonable cost per QALY. Thus, AREDS antioxidant supplementation appears to be a dominant strategy for macular degeneration. Applied to the whole Canadian population, the potential medical cost savings for Visudyne treatment of neovascular AMD are 5.6 billion Canadian dollars in direct costs. These values would be tenfold higher for the USA, because of the currency and population size differences.

Aged↗
PubMed2003

Instruments to measure acceptability of information and acquisition of knowledge in patients with heart failure.

BACKGROUND: Patients with heart failure suffer from poor health outcomes and require combinations of medications to treat their disease. Providing patients with knowledge through education is one mechanism to help them improve compliance with complicated treatment regimens. METHODS: We developed and tested two instruments. The first instrument, which we call the measure of educational material acceptability (EMA), was designed to help us differentiate between written educational materials according to patients' subjective responses. The second instrument, the knowledge acquisition questionnaire (KAQ), which measures knowledge gained, was designed to determine whether patients understand the rationale and mechanics of their heart failure management. We explored the measurement properties of both instruments. RESULTS: The internal consistency of the EMA was 0.79 (Cronbach's alpha). The internal consistency of the KAQ was 0.61 and its responsiveness, measured using change scores of knowledge before and after an educational intervention, was 0.75. CONCLUSIONS: We have developed instruments that measure acceptability and knowledge acquisition, and that clinicians and investigators involved in heart failure programs may find useful in developing educational material and measuring the impact of their interventions on patients' knowledge.

Aged↗
PubMed2003

Observer variability in ECG interpretation for thrombolysis eligibility: experience and context matter.

BACKGROUND: Despite the known benefit of thrombolysis it remains underutilized among eligible patients with acute myocardial infarction. We sought to determine whether potential errors in ECG interpretation might be a contributing factor and to what extent clinical history, a checklist outlining recognized inclusion criteria and a computerized interpretation would influence reliability and accuracy. METHODS: Seventy-five ECGs were interpreted on 8 separate occasions by 9 clinicians (3 cardiologists, 3 cardiology fellows, 3 medical residents) according to a 2 x 2 x 2 factorial design. RESULTS: The overall level of agreement among all raters was substantial with a kappa (kappa) of 70.4%. Intra-observer ECG reading reliability was stronger among cardiologists (CC) as compared with cardiology fellows (CF) and medical residents (MR). Similarly, inter-observer reliability was substantial to very good and a gradient was seen with greater reliability among CC, followed by CF, then MR ( P = 0.0013). CC recommended thrombolysis significantly more frequently ( p < 0.001) than either CF or MR. Trainees were biased by the presence of a computerized ECG interpretation resulting in a decision to recommend thrombolysis administration less often. CONCLUSION: The reliability of ECG interpretation for deciding to administer thrombolysis was substantial; there was a gradient from lowest to highest commensurate with training and experience. Errors in thrombolysis eligibility are influenced by clinical history and the presence of a computerized ECG interpretation among less experienced clinicians.

Consultants↗
PubMed2003

Diagnosing acute myocardial infarction in the setting of left bundle branch block: prevalence and observer variability from a large community study.

BACKGROUND: Despite the known benefit of thrombolysis it remains under-utilized among eligible patients with acute myocardial infarction (AMI) and left bundle branch block (LBBB). We sought to determine the test characteristics and observer reliability of well-known criteria for the diagnosis of AMI when LBBB is present on the electrocardiogram (ECG). METHODS: Four hundred and fourteen ECGs with LBBB from a large cohort of AMI patients (7.4% of the total) and 85 ECGs with LBBB not in the setting of acute coronary syndromes were interpreted for the presence of the Sgarbossa criteria. RESULTS: Agreement for the various Sgarbossa criteria ranged from only fair to moderate. The three-way comparison kappa values were significantly better for ST depression than for both discordant (P<0.001) and concordant (P=0.001) ST-segment elevation. Concordant ST-segment elevation [6.3%, 95% confidence interval (CI) 4.3-9.1%] and depression (3.1%, 95% CI 1.8-5.4%) were infrequently seen in the setting of AMI and rarely seen otherwise. Discordant ST-segment elevation was seen more frequently (19.0%, 95% CI 15.5-23.1%). Concordant ST elevation and ST depression in V1-V3 were highly specific, but insensitive, for the diagnosis of AMI. The presence of discordant ST elevation was neither sensitive nor specific. CONCLUSION: The low prevalence, poor sensitivity and marked observer variability make the Sgarbossa criteria for AMI in the setting of LBBB less than adequate. Although use of these criteria would be an advance over contemporary practice, it would still fall short among this high-risk subset.

Bundle-Branch Block↗
PubMed2002

Enoxaparin in acute coronary syndromes: evidence for superiority over placebo or untreated control.

BACKGROUND: Heparins, both standard unfractionated heparin (SUFH) and low-molecular weight heparin, play a prominent role in the treatment of acute coronary syndromes. Enoxaparin has been shown in 2 trials to be superior to heparin but has not been compared with placebo or untreated control. METHODS: A putative enoxaparin versus placebo/control odds ratio (OR) was computed with a recently described statistical technique with the logarithm of the ORs of the pooled results of both the enoxaparin-SUFH trials and SUFH-placebo or controlled trials. RESULTS: The combined heparin versus control results show a 33% reduction in the risk of death or acute myocardial infarction (AMI), with an OR of 0.67 (95% confidence interval [CI], 0.45 to 0.99). At up to 12 weeks (data from only 4 trials), the combined results show a 21% reduction (OR, 0.79; 95% CI, 0.54 to 1.15; P =.23). The 2 enoxaparin trials show a nonsignificant 20% reduction in the risk of death or AMI during treatment (OR, 0.80; 95% CI, 0.68 to 1.16; P =.24) and a significant reduction at 43 days (OR, 0.82; 95% CI, 0.69 to 0.97; P =.022). With these pooled data, the putative OR for enoxaparin versus placebo/untreated control during treatment is 0.53 (95% CI, 0.31 to 0.92; P =.023). The data are consistent with a 47% reduction in the risk of death or AMI. The difference persists on longer term follow-up period (OR, 0.65; 95% CI, 0.43 to 0.98; P =.04). The risk of bleeding is nonsignificantly increased (OR, 2.32; 95% CI, 0.8 to 7.85; P =.51). CONCLUSION: On the basis of this methodology, enoxaparin would appear to be more effective than placebo when added to aspirin in acute coronary syndromes. Moreover, the effect of enoxaparin is similar to the results of a metaanalysis of trials of other low-molecular weight heparins versus placebo/control.

Anticoagulants↗
PubMed2002

A prospective randomized trial of endoscopic versus conventional harvesting of the saphenous vein in coronary artery bypass surgery.

OBJECTIVES: Our objectives were (1) to determine whether minimally invasive endoscopic harvesting of the saphenous vein reduces morbidity due to postoperative wound infection and pain with improved cosmetic results and mobilization as compared with the conventional technique and (2) to compare the histologic properties of the saphenous veins harvested conventionally and endoscopically. METHODS: One hundred forty-four patients undergoing coronary artery bypass grafting were randomized to have vein harvesting performed by either the conventional (n = 72) or an endoscopic (n = 72) minimally invasive technique. RESULTS: Vein harvest time (open leg wound time) was significantly reduced in the endoscopic group (27.6 vs 64.4 minutes; P <.0001). The rate of leg wound infection was significantly reduced in the endoscopic group (4.3%) as compared with the conventional group (24.6%), a relative risk reduction of 83% (95% confidence interval: 36%-129%; P =.0006). The majority of infections (84.2%) occurred after hospital discharge. Postoperative leg pain, mobilization, and overall patient satisfaction were also significantly improved in the endoscopic group. Double blinded histologic assessment of harvested vein (n = 28) showed no evidence of any clinically important significant damage to the specimens in either group. CONCLUSIONS: In this prospective randomized trial, endoscopic harvesting of the saphenous vein significantly reduced postoperative leg wound complications, including infection, and improved patient satisfaction as compared with the conventional harvesting technique. There were no significant histologic differences between the conventional and endoscopically harvested saphenous veins.

Coronary Artery Bypass↗