Immediate exercise testing of low risk patients with known coronary artery disease presenting to the emergency department with chest pain.

OBJECTIVES: The purpose of this study was to demonstrate the safety and utility of immediate exercise treadmill testing (IETT) of low risk patients presenting to the emergency department with known coronary artery disease (CAD). BACKGROUND: More than 70% of the two million patients admitted to U.S. hospitals annually for suspected acute myocardial infarction (AMI) are found not to have had a cardiac event. We have previously demonstrated the safety and efficacy of IETT of selected low risk patients without known CAD presenting to the emergency department with chest pain. This study extends this approach to selected patients with a history of CAD. METHODS: One hundred patients evaluated by the chest pain emergency room to rule out AMI underwent IETT using a modified Bruce protocol upon admission to the hospital (median time <1 h). RESULTS: Twenty-three patients (23%) had positive exercise electrocardiograms (ExECGs); an uncomplicated non-Q wave AMI was diagnosed in two patients. Thirty-eight patients (38%) had negative ExECGs and 39 patients (39%) had nondiagnostic ExECGs. Of these 100 patients, 64 were discharged immediately after IETT, 19 were discharged in less than 24 h after negative serial cardiac enzymes and stable electrocardiograms and 17 were discharged after further evaluation and treatment. There were no complications from exercise testing and no late deaths or AMI during six-month follow-up. CONCLUSIONS: Immediate exercise treadmill testing of low risk patients with chest pain and known CAD is effective in further stratifying this group into patients who can be safely discharged and those who require hospital admission.

Conversion efficacy and safety of intravenous ibutilide compared with intravenous procainamide in patients with atrial flutter or fibrillation.

OBJECTIVES: This multicenter study compared the efficacy and safety of ibutilide versus procainamide for conversion of recent-onset atrial flutter or fibrillation. BACKGROUND: Ibutilide fumarate is an intravenous (IV) class III antiarrhythmic agent that has been shown to be significantly more effective than placebo in the pharmacologic conversion of atrial flutter and fibrillation to sinus rhythm. Procainamide is commonly used for conversion of recent-onset atrial fibrillation to normal sinus rhythm. METHODS: One hundred twenty-seven patients (age range 22 to 92 years) with atrial flutter or fibrillation of 3 h to 90 days' (mean 21 days) duration were randomized to receive either two 10-min IV infusions of 1 mg of ibutilide fumarate, separated by a 10-min infusion of 5% dextrose in sterile water, or three successive 10-min IV infusions of 400 mg of procainamide hydrochloride. RESULTS: Of the 127 patients, 120 were evaluated for efficacy: 35 (58.3%) of 60 in the ibutilide group compared with 11 (18.3%) of 60 in the procainamide group had successful termination within 1.5 h of treatment (p < 0.0001). Seven patients were found to have violated the protocol and were not included in the final evaluation. In the patients with atrial flutter, ibutilide had a significantly higher success rate than procainamide (76% [13 of 17] vs. 14% [3 of 22], p=0.001). Similarly, in the atrial fibrillation group, ibutilide had a significantly higher success rate than procainamide (51% [22 of 43] vs. 21% [8 of 38], p=0.005). One patient who received ibutilide, which was found to be a protocol violation, had sustained polymorphic ventricular tachycardia requiring direct current cardioversion. Seven patients who received procainamide became hypotensive. CONCLUSIONS: This study establishes the superior efficacy of ibutilide over procainamide when administered to patients to convert either atrial fibrillation or atrial flutter to sinus rhythm. Hypotension was the major adverse effect seen with procainamide. A low incidence of serious proarrhythmia was seen with the administration of ibutilide occurring at the end of infusion.

Evaluation of the patient with 'rule out myocardial infarction'.

Evaluation in the emergency department of the patient with chest pain remains a common problem. Large numbers of patients are admitted to the hospital because of diagnostic uncertainty. Strategies dealing with this population include risk stratification by clinical presentation, serial cardiac enzyme assays to exclude myocardial infarction, and detection of myocardial ischemia with nuclear scintigraphy or echocardiography. Each of these strategies is rational with specific benefits and weaknesses. Bypassing these steps and performing immediate exercise testing is the newest approach that appears to be safe, timely, and cost-effective.

Systolic blood pressure at rest, not the degree of beta blockade, predicts the result of follow-up tilt-table testing for vasovagal syncope.

Tilt-table testing after therapy with beta blockade is frequently used to predict clinical success. This study found that heart rate and blood pressure reductions after beta-blocker therapy did not predict the results of the follow-up tilt-table test, but low blood pressure at rest before the initial test predicts failure of this therapy.

Utility and safety of immediate exercise testing of low-risk patients admitted to the hospital for suspected acute myocardial infarction.

More than 2 million patients are admitted to U.S. hospitals annually for clinical suspicion of acute myocardial infarction (AMI), and > 70% are found not to have had a cardiac event. This study evaluates the safety and efficacy of immediate exercise testing for patients admitted to the hospital for suspected AMI. Ninety-three nonconsecutive low-risk patients admitted to the hospital from the emergency department to rule out AMI underwent exercise treadmill testing using a modified Bruce protocol immediately on admission to the hospital (median time < 1 hour). Twelve patients had positive exercise electrocardiograms, 6 of whom had significant coronary narrowing by angiography. An uncomplicated non-Q-wave AMI was diagnosed in 1 patient. Fifty-nine patients had negative and 22 patients had nondiagnostic exercise electrocardiograms. Of these 81 patients, 44 were discharged immediately after exercise testing, 17 were discharged within 24 hours, and 20 were discharged after 24 hours of observation. There were no complications from exercise testing. There were 2 late noncardiac deaths and 1 late AMI. Thus, immediate exercise testing of low-risk patients with chest pain who are at sufficient risk to be designated for hospital admission is effective in further stratifying this group into those who can be safely discharged immediately and those who require hospitalization.

Intravenous diltiazem for the treatment of patients with atrial fibrillation or flutter and moderate to severe congestive heart failure.

The objective of this multicenter, randomized, double-blind, placebo-controlled study was to determine the safety and efficacy of intravenous diltiazem in the treatment of 37 patients with rapid (ventricular rate, mean +/- SD 142 +/- 17 beats/min) atrial fibrillation or flutter and moderate to severe congestive heart failure (ejection fraction, mean +/- SD 36 +/- 14%; New York Heart Association class III [23 patients], class IV [14 patients]). During the double-blind portion of the study, patients received either intravenous diltiazem, 0.25 mg/kg over 2 minutes, or placebo followed 15 minutes later by diltiazem or placebo, 0.35 mg/kg over 2 minutes, if the first dose was tolerated but ineffective. Placebo nonresponders were given open-label intravenous diltiazem in a similar fashion as in the double-blind portion of the study. In the double-blind part of the study, 21 (18 with 0.25 mg/kg, 3 with an additional 0.35 mg/kg) of the 22 patients (95%) responded to diltiazem, and 0 of 15 patients (0%) responded to placebo (p < 0.001). All 15 patients (13 with 0.25 mg/kg and 2 with an additional 0.35 mg/kg) who received placebo during the double-blind period had a therapeutic response to diltiazem during open-label therapy. Overall, 36 of 37 patients (97%) had a therapeutic response to intravenous diltiazem. Heart rate response to diltiazem after the 2-minute bolus infusions consisted of a > or = 20% decrease in heart rate from baseline in 36 patients; in addition, 17 patients also had heart rates decreased to < 100 beats/min, whereas no patient had conversion to sinus rhythm.(ABSTRACT TRUNCATED AT 250 WORDS)

Protective metabolic effects of propranolol during total myocardial ischemia.

Clinical trials have shown an increase in survival in patients treated with beta blockers after infarction. In addition, the majority of patients undergoing myocardial revascularization are also treated preoperatively with beta blockers. It is commonly thought that beta blockers exert their protective effect primarily by decreasing heart rate and subsequent myocardial work. The present study was designed to determine whether beta blockade has any primary protective metabolic effects on globally ischemic myocardium. Thirty-four anesthetized dogs underwent total myocardial ischemia at 37 degrees C. High-energy nucleotide and lactate levels in left ventricular tissue samples were determined at control and at 15 minute intervals as well as at the onset of ischemic contracture in 24 dogs. Seventeen dogs were treated with propranolol before ischemia. The time to ischemic contracture in control dogs was 63.3 +/- 1.4 minutes compared with 75.9 +/- 2.2 minutes in the propranolol-treated group (p less than 0.01). In addition to significantly delaying the onset of ischemic contracture, propranolol also decreased the rate of anaerobic glycolysis during ischemia. Ischemic contracture occurred in the control group with an average adenosine triphosphate level of 1.26 +/- 0.08 mumol compared to 0.91 +/- 0.08 mumol/gm wet weight for the beta blocked group (p less than 0.0025). These are the first data suggesting that the protective effects of beta blockade may be related to a beneficial effect on ischemic myocardial metabolism allowing myocardium to survive with lower levels of adenosine triphosphate.

Central retinal artery occlusion during cardiac catheterization.

A massive embolus of the central retinal artery occurred during cardiac catheterization and selective coronary angiography. Anterior chamber paracentesis and coughing resulted in restoration of retinal blood flow and vision within two hours. In two other cases retinal arteriolar embolization was observed in patients who had minimal or no ocular symptoms after cardiac catheterization.

Acute myocardial infarction associated with dobutamine stress echocardiography.

Acute myocardial infarction as a complication of dobutamine stress echocardiography (DSE) is described in two patients during or shortly after undergoing the procedure. Both clinical events resulted in characteristic elevations in cardiac enzymes and the development of new electrocardiographic Q waves in the inferior leads. Subsequent coronary angiography was performed in both cases; one patient required two-vessel coronary artery bypass grafting to his first obtuse marginal and posterior descending arteries, and the other underwent successful angioplasty of an occluded proximal right coronary artery. Only two cases of DSE-associated myocardial infarction have been reported previously in the literature.

Evaluation of low-risk patients with chest pain in the emergency department: value and limitations of recent methods.

More than 2 million patients are hospitalized annually in this country because of chest pain suggestive of myocardial ischemia. However, a coronary event is demonstrated in <20% of this population. It has been further shown that among patients presenting with acute chest pain, a very low-risk group, with <5% probability of a coronary event, can be identified by the initial clinical assessment. Recognition of this group could prevent many unnecessary hospital admissions, affording more appropriate patient care and improved cost-effectiveness. To enhance identification and management of low-risk patients with chest pain, several diagnostic approaches are currently being investigated to determine their value in the early detection of myocardial ischemia to select those requiring admission. In addition to the initial history, these strategies include physical examination and electrocardiogram, new serum markers, early noninvasive cardiac imaging by echocardiography or myocardial scintigraphy, new electrocardiographic methods, and early exercise testing. Most of these methods have shown promise for stratifying patients presenting with chest pain into high-risk and low-risk groups, thereby extending the initial clinical assessment in the critical decision of patient admission or discharge from the emergency department with early follow-up. This review presents the current status of these techniques with emphasis on our experience with immediate treadmill testing of selected patients in the emergency department. These methods are still in the developmental phase and their long-term utility will be determined by their safety, accuracy, cost, and specific institutional expertise.

Management of cardiac complications in neuromuscular disease.

Cardiovascular complications are common and varied in neuromuscular diseases. Knowledge of the complications specific to each disease is essential for appropriate screening for cardiovascular disease. Appropriate treatment of complications varies between neuromuscular diseases and draws primarily on experience from patients without neuromuscular disease. This article details the known cardiovascular complications and treatments for some of the major neuromuscular diseases.