Dennis J. Esterbrooks

Comparison of adenosine and exercise thallium-201 single-photon emission computed tomography (SPECT) myocardial perfusion imaging

Pharmacologic stress with dipyridamole has provided useful diagnostic, as well as prognostic, information in patients undergoing thallium-201 myocardial perfusion imaging. With its ultrashort half-life and a potent and consistent vasodilator effect, adenosine may be the coronary vasodilator of choice with myocardial perfusion imaging. Fifty-one healthy subjects and 93 patients with suspected coronary artery disease constituted the study group. In this multicenter study the comparative safety and diagnostic efficacy of single-photon emission computed tomography (SPECT) thallium imaging during adenosine-induced coronary hyperemia was compared with exercise treadmill stress. There was a mean increase in heart rate of 37% and a mean decrease in diastolic blood pressure of 5% during the adenosine infusion of 140 micrograms/kg per min for 6 min. Adenosine infusion was well tolerated in 95% of the subjects. Side effects requiring intervention occurred in seven subjects (5%). None of the subjects experienced a life-threatening complication. The sensitivity, specificity and predictive accuracy for detection of coronary artery disease with use of quantitative analysis was 83%, 87% and 84% for adenosine SPECT and 82%, 80% and 81% for exercise SPECT studies, respectively. Most false negative results with adenosine, as well as exercise SPECT studies, occurred in patients with single-vessel disease. The first-order concordance (no defect vs. defect) and second-order concordance (no defect vs. irreversible vs. reversible defect) was 89% and 78% between the two studies, respectively. Thus, the results of adenosine SPECT imaging are highly concordant with exercise SPECT thallium imaging. Adenosine SPECT thallium imaging provides a safe and highly accurate imaging mode for the detection of coronary artery disease.

Early exercise training in patients older than age 65 years compared with that in younger patients after acute myocardial infarction or coronary artery bypass grafting

To evaluate potential benefits that elderly cardiac patients might gain from early exercise programs, 361 such patients were studied: group I--60 patients aged 44 years or younger; group II--114 patients aged 45 to 54 years; group III--111 patients aged 55 to 64 years; and group IV--76 elderly patients aged 65 years or older. All patients participated in a 12-week exercise program within 6 weeks of acute myocardial infarction or coronary artery bypass grafting. All patients performed symptom-limited exercise tests before and after completion of the exercise program. Between tests, elderly patients manifested significant differences in body weight (76.9 to 75.2 kg), percent body fat (22.3 to 20.8 kg), heart rate at rest (77 to 68 beats/min), maximal heart rate (126 to 138 beats/min), maximal METs (5.3 to 8.1), submaximal average double product (17,305 to 14,071), and submaximal average rating of perceived exertion (12 to 10 [p less than 0.05]). Magnitudes of change were similar among groups, although the elderly patient group had a significantly lower absolute physical work capacity at testing after training than the other 3 groups (p less than 0.05). In the 25 elderly patients who received beta-blocking drugs, METs increased from 5.1 to 7.8 (p less than 0.05). In the remaining 51 elderly patients not receiving beta-blocking drugs, METs increased from 5.4 to 8.2 (p less than 0.05). The magnitude of increase in patients who received beta-blocking drugs was not significantly different from that in patients not receiving beta-blocking drugs.(ABSTRACT TRUNCATED AT 250 WORDS)

Outcomes After Carotid Artery Stenting and Endarterectomy in the Medicare Population

Background and Purpose— Carotid artery stenting (CAS) is an alternative to carotid endarterectomy (CEA) for stroke prevention. The value of this therapy relative to CEA remains uncertain. Methods— In 10 958 Medicare patients aged 66 years or older between 2004 and 2006, we analyzed in-hospital, 1-year stroke, myocardial infarction, and death rate outcomes and the effects of potential confounding variables. Results— CAS patients (87% were asymptomatic) had a higher baseline risk profile, including having a higher percentage of coronary and peripheral arterial disease, heart failure, and renal failure. In-hospital stroke rate (1.9% CAS versus 1.4% CEA; P=0.14) and mortality (CAS 0.9% versus 0.6% CEA; P=0.20) were similar. By 1 year, CAS patients had similar stroke rates (5.3% CAS versus 4.1% CEA; P=0.12) but higher all-cause mortality rates (9.9% CAS versus 6.1% CEA; P<0.001). Using Cox multivariable models, there was a similar stroke risk (hazard ratio, 1.28; 95% CI, 0.90–1.79) but CAS patients had a significantly higher mortality (HR, 1.32; 95% CI, 1.02–1.71). Sensitivity analyses suggested that unmeasured confounders could be responsible for the mortality difference. In multivariable analysis, stroke risk was highest in the patients symptomatic at the time of revascularization. Conclusions— CAS patients had a similar stroke risk but an increased mortality rate at 1 year compared with CEA patients, possibly related to the higher baseline risk profile in the CAS patient group.

Delayed Defibrillator Lead Perforation: An Increasing Phenomenon

Delayed intracardiac lead perforation has been defined as migration and perforation after one month of implantation. It is a rare complication; pathophysiology and optimal management are currently unclear. Recognition of these cases becomes important with increasing use of these devices. We describe such a case of delayed lead perforation.

Efficacy and tolerance of high-dose intravenous amiodarone for recurrent, refractory ventricular tachycardia

High-dose intravenous amiodarone was given to 35 patients with recurrent life-threatening ventricular tachycardia (VT) refractory to conventional antiarrhythmic agents. Intravenous amiodarone was given as a 5 mg/kg dose over 30 minutes followed by 20 to 30 mg/kg/day as a constant infusion for 5 days. Twenty-two (63%) patients responded to intravenous amiodarone. All 22 responders received oral amiodarone. Thirteen (59%) continue to receive oral amiodarone after an average follow-up of 19 months, 4 (18%) had sudden cardiac death on oral amiodarone, 2 (9%) died while receiving amiodarone, secondary to left ventricular failure, and 3 (14%) discontinued amiodarone because of side effects. Of the 13 (37%) nonresponders, 10 died in the hospital while receiving intravenous amiodarone, secondary to lethal arrhythmia. Three nonresponders were discharged from the hospital; 2 with automatic cardioverter/defibrillators and 1 receiving a combination of antiarrhythmic agents. Serious adverse events occurred in 13 (37%) patients during intravenous amiodarone therapy. These included hypotension in 8 patients, symptomatic bradycardia in 4 patients and sinus arrest with bradycardia and hypotension in 1 patient. Minor side effects occurred in 23 (66%) patients. In conclusion, high dose intravenous amiodarone is effective in most patients with recurrent, sustained VT but is associated with an unacceptably high incidence of serious adverse events. The optimal dose and duration of intravenous amiodarone for patients with recurrent, refractory sustained VT remain unknown.

Improving Death Certificate Completion: A Trial of Two Training Interventions

The death certificate is an important medical document that impacts mortality statistics and health care policy. Resident physician accuracy in completing death certificates is poor. We assessed the impact of two educational interventions on the quality of death certificate completion by resident physicians. Two-hundred and nineteen internal medicine residents were asked to complete a cause of death statement using a sample case of in-hospital death. Participants were randomized into one of two educational interventions: either an interactive workshop (group I) or provided with printed instruction material (group II). A total of 200 residents completed the study, with 100 in each group. At baseline, competency in death certificate completion was poor. Only 19% of residents achieved an optimal test score. Sixty percent erroneously identified a cardiac cause of death. The death certificate score improved significantly in both group I (14±6 vs 24±5, p<0.001) and group II (14±5 vs 19±5, p<0.001) postintervention from baseline. Group I had a higher degree of improvement than group II (24±5 vs 19±5, p<0.001). Resident physicians’ skills in death certificate completion can be improved with an educational intervention. An interactive workshop is a more effective intervention than a printed handout.

Clinical and echocardiographic characteristics of patients with mitral anular calcification. Comparison with age- and sex-matched control subjects.

The clinical and echocardiographic features of 104 patients (53 women and 51 men) with mitral anular calcification (MAC) were compared with those of 121 age- and sex-matched control subjects (62 women and 59 men) without MAC. The incidence of coronary artery disease, rheumatic heart disease, systemic hypertension, and diabetes mellitus was similar in both groups. Patients with MAC had a greater incidence of cardiomegaly (p less than 0.001), cardiac conduction defects (p less than 0.001), and aortic outflow tract murmurs (p less than 0.005) than did control patients. Patients with MAC and without aortic root calcification had a higher incidence (p less than 0.001) of conduction defects than did patients with aortic root calcification without MAC. Control patients with and without aortic root calcification had a similar incidence of conduction defects. A higher incidence of atrioventricular block (p less than 0.025) and bundle branch block or left anterior hemiblock or intraventricular conduction defect (p less than 0.05) was present in anterior MAC than in posterior MAC. In conclusion, patients with MAC have a higher incidence of cardiomegaly, cardiac conduction defects, and aortic outflow tract murmurs than a control group.

Diagnostic and prognostic significance of exercise-induced premature ventricular complexes in men and women: A four year follow-up

Two hundred eighty patients (197 men and 83 women) with normal rest electrocardiograms and no history of prior myocardial infarction were referred for evaluation of chest pain. It was found that exercise-induced premature ventricular complexes had a lower sensitivity, specificity, positive predictive value and negative predictive value in predicting significant coronary artery disease than exercise-induced ST segment depression greater than or equal to 1 mm. The incidence of exercise-induced premature ventricular complexes was not significantly different in patients with no significant coronary artery disease, single vessel disease or multivessel disease. The site of origin of exercise-induced premature ventricular complexes was not helpful in predicting the presence or severity of coronary artery disease. At a mean follow-up period of 47.1 months, exercise-induced premature ventricular complexes did not predict coronary events (cardiac death or nonfatal myocardial infarction) in men or women.

Effectiveness of Thrombolytic Therapy in Acute Embolic Stroke due to Infective Endocarditis

Objective. To identify the role of thrombolytic therapy in acute embolic stroke due to infective endocarditis. Design. Case report. Setting. University hospital. Patient. A 70-year-old male presented with acute onset aphasia and hemiparesis due to infective endocarditis. His head computerized tomographic scan revealed left parietal sulcal effacement. He was given intravenous tissue plasminogen activator with significant resolution of the neurologic deficits without complications. Main Outcome Measures. Physical examination, National Institute of Health Stroke Scale, radiologic examination results. Conclusions. Thrombolytic therapy in selected cases of stroke due to infective endocarditis manifesting as major neurologic deficits can be considered as an option after careful consideration of risks and benefits. The basis for such favorable response rests in the presence of fibrin as a major constituent of the vegetation. The risk of precipitating hemorrhage with thrombolytic therapy especially with large infarcts and mycotic aneurysms should be weighed against the benefits of averting a major neurologic deficit.

Tocainide kinetics in congestive heart failure.

Our subjects were 20 patients with life‐threatening or symptomatic ventricular arrhythmias refractory to standard oral antiarrhythmic drugs but responsive to intravenous lidocaine. After evaluation of arrhythmias and treatment with intravenous lidocaine, oral tocainide dosage regimens were based on age, weight, and clinical status. During initial tocainide treatment, six plasma tocainide concentrations were recorded within a single dosing interval in 17 of 20 patients, by which standard kinetic parameters were calculated. Eventual trough steady‐state tocainide plasma concentrations were predicted from the derived patient‐specific kinetic parameters. Mean daily tocainide dose was 1800 mg (1200 to 2400). Mean daily tocainide doses (milligram per kilogram) did not differ significantly among responders and nonresponders or among patients with or without congestive heart failure. Mean peak and trough plasma concentrations 48 hr after initiation of therapy were 9.8 and 7.5 mcg/ml. Tocainide plasma concentrations did not correlate with responders and nonresponders or identify patients who were developing adverse reactions to tocainide. There were no significant differences in any of the calculated kinetic parameters as a function of response to tocainide or the presence of congestive heart failure, but there was a trend toward smaller volumes of distribution and higher average plasma concentrations at steady state in patients with congestive heart failure. There were no significant kinetic differences among patients with and without congestive heart failure, but a trend toward higher plasma concentrations in patients with congestive heart failure and the small number of patients suggests that further data collection is necessary before dosage recommendations can be made.