Donald S. Beanlands

Beta-blocker therapy in the cardiac arrhythmia suppression trial

Abstract The Cardiac Arrhythmia Suppression Trial (CAST) showed antiarrhythmic drug suppression of asymptomatic or mildly symptomatic ventricular arrhythmias in survivors of myocardial infarction to be harmful. This study retrospectively searched the CAST results for evidence of mortality and morbidity reduction in patients receiving optional β-blocker therapy. All enrolled (n = 2,611) and suppressed main study (n = 1,735) CAST patients with an ejection fraction of ≤40% were examined using univariate analysis, Kaplan-Meier curves, and a Cox proportional-hazards multivariate analysis with respect to optional β-blocker therapy prescribed at baseline. CAST patients receiving β-blocker therapy had significantly enhanced survival at 30 days, and at 1 and 2 years of follow-up against all-cause and arrhythmic death or nonfatal cardiac arrest. Multivariate analysis showed β-blocker therapy to be independently associated with a one-third reduction in arrhythmic death or cardiac arrest (p = 0.036). In CAST patients with a history of congestive heart failure, β-blocker therapy was independently associated with longer time to occurrence of new or worsened congestive heart failure (p = 0.015). This study supports the secondary preventive benefit of β-blocker therapy in high-risk post-myocardial infarction patients, and calls attention to the possible preventive benefit of β-blocker therapy against proarrhythmic events experienced in the CAST.

Effects of late percutaneous transluminal coronary angioplasty of an occluded infarct-related coronary artery on left ventricular function in patients with a recent (<6 weeks) Q-wave acute myocardial infarction (total occlusion post-myocardial infarction intervention study [TOMIIS]—A pilot study)

The effect of late percutaneous transluminal coronary angioplasty (PTCA) of an occluded infarct-related artery on left ventricular ejection fraction was studied in patients with a recent, first Q-wave myocardial infarction in a prospective, randomized study. Forty-four patients (31 men and 13 women, mean age 58 +/- 12 years) with an occluded infarct-related coronary artery were randomized to PTCA (n = 25) or no PTCA (n = 19). Patients received acetylsalicylic acid, a beta blocker and an angiotensin-converting enzyme inhibitor unless contraindicated. Left ventricular ejection fraction was determined at baseline and 4 months. Coronary angiography was repeated at 4 months. Baseline ejection fraction measured 20 +/- 12 days after myocardial infarction was 45 +/- 12% in both groups. PTCA was performed 21 +/- 13 days after the event. The primary PTCA success rate was 72%. One patient in each group died before angiographic follow-up, which was completed in 37 of the remaining 42 patients (88%; 21 with and 16 without PTCA). At 4 months, the infarct-related artery was patent in 43% of PTCA patients and in 19% of no PTCA patients (p = NS). Reocclusion occurred in 40% of patients after successful PTCA. Secondary analyses showed that the change in left ventricular ejection fraction was significantly greater in patients with a patent infarct-related artery (+9.4 +/- 6.2%) than in those with an occluded artery (+1.6 +/- 8.8%; p = 0.0096). Baseline ejection fraction also independently predicted improvement in left ventricular ejection fraction (p = 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of Clinical and Treadmill Variables for the Prediction of Outcome After Myocardial Infarction

To assess the relative prognostic merits of 15 clinical and 10 predischarge exercise test variables, 226 patients who had sustained an acute myocardial infarction were studied. A submaximal treadmill test was performed on 205 patients to a mean work load of 5.7 +/- 2.9 METS. Testing was performed an average of 11.7 (range 6 to 33) days after myocardial infarction. During the first year of observation, major cardiac events were noted in 33 patients (16%), unstable angina in 7 (3.4%), recurrent myocardial infarction in 14 (6.8%) and death in 12 patients (5.9%). Cardiac mortality correlated with mean peak serum creatine kinase (CK) (p less than 0.05), history of previous myocardial infarction (p less than 0.01) and ST segment depression at rest (p less than 0.01). The only exercise variable that correlated with cardiac mortality was poor exercise endurance (p less than 0.05). Multivariate risk stratification of clinical and treadmill variables from these 205 patients using linear discriminant analysis produced a function that correctly classified 95% of those who were event-free and 80% of those who died. The first four discriminant variables that contributed independent information for the prediction of cardiac mortality were: 1) ST segment depression at rest; 2) CK greater than 1,280 IU/liter; 3) exercise duration less than 3 minutes; and 4) a history of previous myocardial infarction. ST segment depression on the predischarge treadmill test did not predict any event, nor did it improve the predictive accuracy of the clinical variables. It is concluded that a history of previous myocardial infarction and ST segment depression on the rest electrocardiogram indicate a poor prognosis after acute myocardial infarction. Poor endurance is the only exercise variable that suggests a future cardiac event. Prognosis after acute myocardial infarction is more accurately predicted by these clinical data than by variables derived from the predischarge treadmill test.

The time course and characterization of myocardial hemorrhage after coronary reperfusion in the anesthetized dog.

We quantitated hemorrhage associated with reperfusion after varying periods of myocardial ischemia and examined the flow characteristics that accompany reperfusion hemorrhage. Anesthetized dogs were reperfused after 2, 6 or 24 hours of circumflex occlusion. A control group underwent coronary occlusion without reperfusion. Radioactive microspheres were injected before and 5 minutes and 24 hours after reperfusion. The papillary muscles were analyzed for hemoglobin content, flow during myocardial ischemia and flow early and 24 hours after reperfusion. Myocardial creatine kinase activity was assayed to determine the severity of myocardial necrosis in the papillary muscles. Hemorrhage into the posterior papillary muscle was dependent upon the duration of coronary artery occlusion. Posterior papillary hemoglobin averaged 14 mglg in the 2-hour group, 28 mg/g in the 6-hour group and 36 mg/g in the group reperfused 24 hours after occlusion, compared with 8.7 mg/g in the control group.Myocardial hemorrhage was associated with severe depression in myocardial CK and marked depression in flow to the ischemic area (i.e., collateral flow) during the occlusion. Early reflow averaged 112 ml/min/100 g in the 2-hour group, 61 ml/min/100 g in the 6-hour group and only 5.8 ml/min/lO0 g in the 24- hour group. Therefore, myocardial hemorrhage induced by reperfusion of the acutel ischemic myocardium is associated with severe ischemia during occlusion and severe myocardial necrosis, but does not depend upon the magnitude of early reflow. Myocardial hemorrhage may occur even though initial reflow values are markedly decreased.

Assessment of reused catheters.

Demands for health care cost containment have prompted the assessment of recycling medical devices, including catheters. The investigation of catheter reuse for effectiveness and safety began at the University of Ottawa Heart Institute in early 1994. This report provides the preliminary results from this ongoing assessment on the feasibility of catheter reuse. Burst tests were conducted to detect changes in catheter mechanical integrity. Scanning electron microscopy (SEM) was performed to assess surface changes and protein deposition after use and the subsequent cleaning process. Results of burst testing showed no significant difference in burst patterns or burst pressures between single use and unused catheters. Surface differences were observed between used and unused catheters. SEM studies detected physical changes such as scratches, gouges, cuts, and deposits on the used catheters. Unused balloon surfaces appeared to be clean and uniform compared to used ones. Residue and cracking were identified on other used devices. In conclusion, the methods used can assess various effects of recycling. A blind study of large samples of used catheters is planned to establish statistically the level and variance of structural damage to catheters during typical use.

Fluorine-18–Labeled Deoxyglucose Positron Emission Tomography in the Diagnosis and Management of Aortitis With Pulmonary Artery Involvement

A 58-year-old woman presented with a complex history of constitutional symptoms, heart block requiring pacemaker, and subsequent heart failure. Initial echocardiograms reported some periaortic thickening but no definite vegetations. The patient had received antibiotic therapy before initial presentation. She had multiple negative serial blood cultures and was treated for culture-negative endocarditis. Over the ensuing months, however, her condition progressively worsened. At the time of her presentation to our facility, she had persistent elevations of her C-reactive protein (CRP; 66 mg/dL), an accelerated erythrocyte sedimentation rate (ESR; 60 mm/h), and a P-antineutrophil cytoplasmic antibody (ANCA) immunofluorescence assay that was positive. She had negative serology for bartonella, coxiella, and brucella, as well as nonreactive syphilis and human immunodeficiency virus …