Comparison of adenosine and exercise thallium-201 single-photon emission computed tomography (SPECT) myocardial perfusion imaging. The GE SPECT Multicenter Adenosine Study Group.

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.

Clinical significance of exercise-induced bundle branch block.

To evaluate the diagnostic significance and long-term follow-up data of patients with exercise-induced bundle branch block (BBB), 10,176 consecutive patients' exercise test data were reviewed and 50 patients found to have exercise-induced BBB. Clinical, exercise test and arteriographic data were analyzed along with follow-up data during a mean of 43 months. Of the 50 patients, 37 had exercise-induced left BBB and 13 had exercise-induced right BBB. Significant coronary artery disease (CAD) was diagnosed in 26 of 37 patients (70%) with exercise-induced left BBB and in all 13 patients (100%) with exercise-induced right BBB. In patients who underwent coronary arteriography, data demonstrated a high prevalence of proximal left anterior descending disease (17 of 20, 85%). Follow-up data revealed that exercise-induced BBB was associated with a 36% (18 of 50) incidence of coronary events, including 16 patients who underwent coronary artery bypass grafting and 2 hospitalized for congestive heart failure. Results indicated that exercise-induced BBB was infrequent and occurred primarily in association with CAD, had a high prevalence of proximal left anterior CAD, infrequently had similar onset and offset heart rates, was reproducible and associated with a greater incidence of coronary artery bypass grafting than had been previously reported, although the incidence of cardiac events was similar to those investigations.

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)

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.

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.

Diagnostic and prognostic value of Holter-detected ST-segment deviation in unselected patients with chest pain referred for coronary angiography: a long-term follow-up analysis.

OBJECTIVE: To evaluate the diagnostic and prognostic significance of ST-segment deviation detected by ambulatory Holter monitoring in unselected chest pain patients referred for coronary angiography. METHODS: Two hundred seventy-seven patients (71% were men) who underwent coronary angiography for evaluation of chest pain were studied with 24-h ambulatory Holter monitoring within 72 h of angiography. A lumen diameter reduction of > or = 50% was considered coronary artery disease. The ST-segment deviation was defined as > or = 1-mm deviation from the baseline lasting > or = 1 min separated by a minimum of 1 min. The patients were followed up for 65 +/- 21 months (mean +/- SD) for occurrences of death, myocardial infarction, hospitalization for unstable angina, and need for revascularization. RESULTS: Of the 277 patients, 223 (80%) had coronary artery disease. The prevalence of coronary artery disease was not significantly different in patients with (43 of 48 patients; 90%) and without (180 of 229 patients; 79%) Holter-detected ST-segment deviation. The diagnostic accuracy of Holter-detected ST-segment deviation in predicting the presence of coronary artery disease was poor (33%), with a sensitivity of 19% and a specificity of 91%. The presence of Holter-detected ST-segment deviation was not predictive of future cardiac events or death. CONCLUSION: The ST-segment changes detected on ambulatory Holter monitoring are of limited value in identifying coronary artery disease and predicting the future adverse cardiac events or death in unselected patients with chest pain.

The comparative safety and diagnostic accuracy of adenosine myocardial perfusion imaging in women versus men.

STUDY OBJECTIVE: To determine if the diagnostic accuracy and safety of intravenous adenosine myocardial perfusion imaging is significantly different in men compared with women. DESIGN: Prospective, comparative, open-label clinical trial. SETTING: Nuclear medicine laboratory in a university-affiliated hospital. PATIENTS: Consecutive patients who were referred for evaluation of known or suspected coronary artery disease. Patients were judged not to be able to exercise adequately. INTERVENTIONS: Coronary angiography was conducted within 6 weeks of an adenosine thallium-201 myocardial perfusion imaging study. MEASUREMENTS AND MAIN RESULTS: Diagnostic accuracy is shown in the table. [table: see text] Overall, side effects from adenosine were not different between men and women. The frequencies of ST depression and chest pain were significantly greater in women than men, although their etiologies are unknown. The frequency of severe side effects such as heart block and hypotension was not different between men and women. CONCLUSIONS: The diagnostic accuracy and safety of adenosine thallium-201 myocardial perfusion imaging are generally similar in women and men.

Safety of different dosages of intravenous adenosine used in conjunction with diagnostic myocardial imaging techniques.

STUDY OBJECTIVE: To determine the safety of three different dosage regimens of intravenous adenosine. DESIGN: Open-label, observational safety evaluation. SETTING: University hospital-based department of nuclear medicine. PATIENTS: Cohort of 854 patients referred for myocardial perfusion imaging to evaluate their coronary artery disease and who were judged unable to perform physical exercise. INTERVENTIONS: Subjects underwent myocardial perfusion imaging in conjunction with one of three intravenous dosage regimens: 1 = fixed dosage 140 micrograms/kg/minute for 6 minutes; 2 = dosage titration to a maximum of 140 micrograms/kg/minute; and 3 = dosage titration to a maximum of 200 micrograms/kg/minute. In regimens 2 and 3, maximum tolerated dosages were continued for a minimum of 3 minutes prior to radioisotope injection. MEASUREMENTS AND MAIN RESULTS: Adenosine-induced hemodynamic, electrocardiographic, and biochemical changes were measured. Adverse effects of the different adenosine dosages were compared. Noncardiac side effects such as flushing, dyspnea, neck tightness, and lightheadedness occurred at a significantly higher rate during regimens 2 and 3 than regimen 1. Chest pain and first- and second-degree atrioventricular block were also more frequent during regimens 2 and 3. However, the frequency of other side effects such as complete heart block, hypotension, and ST segment depression did not differ among the regimens. High-dose adenosine was associated with a significant increase in serum uric acid, a significant decrease in blood glucose, and a significant increase in serum triglyceride levels. Mean changes in hemodynamics and electrocardiographic intervals were also not different among the groups except for a greater increase in PR interval in regimens 2 and 3 than regimen 1. Discontinuation of adenosine was infrequent (< 1%) and did not differ among the regimens. CONCLUSIONS: Adenosine-assisted myocardial perfusion imaging procedures are relatively safe for evaluating coronary artery disease. Despite 82% of patients reporting at least one side effect, only 10 (< 1%) had to discontinue adenosine. No patient suffered any residual sequelae from the adverse effects. The fixed-dose regimen is associated with fewer subjective side effects and is better tolerated than titration regimens. Appropriate safety precautions should nonetheless be taken during adenosine infusions.

After myocardial infarction. How to determine future risk and what to do then.

Management of the postinfarction patient should be directed toward identifying and treating individuals at risk of future coronary morbidity or mortality. The history, physical examination, resting ECG, and chest film, supplemented with ambulatory electrocardiographic monitoring, noninvasive assessment of left ventricular function, graded exercise testing, and sometimes angiography allow stratification of patients into high- and low-risk subgroups. A program of exercise training, risk factor modification, and prophylactic therapy with beta blockers would be warranted in most patients. Use of antiarrhythmic agents may alter prognosis in certain subgroups. Evidence is currently insufficient to warrant routine use of anticoagulant or antiplatelet agents in the postinfarction patient.

Guidelines for exercise therapy of the elderly after myocardial infarction.

We have previously demonstrated that elderly male cardiac patients benefit from participation in early exercise programmes through enhancement of functional capacity and improved psychological responses to exertion. Based on our experience, we present guidelines for early exercise therapy in elderly cardiac patients. It appears that no special considerations need be made to reduce risk beyond those precautions already present in a standard programme for younger patients. In general, it is recommended that exercise therapy in the elderly utilize 70-85% of maximal heart rate, 3 days per week for 40 min per session. Specific modifications include: decreasing intensity of work on certain modalities due to limitations of specific muscle groups, increasing frequency of exercise sessions for persons with particularly low functional capacity, and emphasizing flexibility exercises which should also be included in the regular exercise therapy sessions. Our experience has indicated that elderly cardiac patients have little problem with adherence and safety in the exercise programme and that standard methods of exercise prescription can be utilized with only minor modifications.

Crossover comparison of cibenzoline and quinidine in ambulatory patients with chronic ventricular arrhythmias.

This study was designed to compare the efficacy and safety of cibenzoline and quinidine in ambulatory patients with ventricular arrhythmias. Following washout of previous antiarrhythmic treatment, a 48-h ambulatory electrocardiographic (ECG) recording was obtained. Twenty-seven patients were screened, of whom 20 met the entry criteria of greater than or equal to 30 ventricular premature beats (VPBs)/h. Cibenzoline was started at 130 mg every 12 h and was increased to 160 mg every 12 h if necessary. Quinidine was started at 300 mg every 6 h and was increased to 400 mg every 6 h if necessary. Treatment was assessed by 24-h ambulatory ECG recording. Efficacy was defined as greater than 75% reduction in single VPBs, greater than 90% reduction in paired VPBs, and total abolition of ventricular tachycardia events. A 7-day washout with repeat 24-h ambulatory ECG recording to document return of ventricular arrhythmias was required prior to crossover. Efficacy was documented in 9 of 20 (45%) patients receiving cibenzoline and in 9 of 20 (45%) patients receiving quinidine. Response to cibenzoline 130 mg every 12 h was documented in 8 of 20 (40%) patients and in 1 of 11 (9%) patients receiving cibenzoline 160 mg every 12 h. Response to quinidine 300 mg every 6 h was documented in 8 of 20 (40%) patients and in 2 of 6 (33%) patients receiving 400 mg every 6 h. Dose-limiting side effects occurred in 1 of 20 (5%) patients receiving cibenzoline and in 7 of 20 (35%) patients receiving quinidine. Cibenzoline and quinidine are equal in efficacy, but cibenzoline is significantly better tolerated.

Ventricular fibrillation complicating pacemaker insertion in acute myocardial infarction.

Temporary transvenous pacing catheters were placed in 101 patients with acute myocardial infarction (MI) for the management of bradyarrhythmias or conduction disturbances. Fourteen (14%) patients (group A) developed ventricular fibrillation (VF) at the time of pacing catheter manipulation in the right ventricle. Compared to the remaining 87 (86%) patients (group B), the patients in group A were younger (56.1 vs 65.8 yrs, P = 0.007). Thirteen (92.8%) of 14 patients in group A had inferior MI compared to 58 (66.6%) of 87 patients in group B (P = 0.04). All but one patient in group A had pacemaker insertion within 24 h of the onset of symptoms of MI compared to 55 (63%) of 87 in group B (P = 0.02). In 12 of the 14 patients in group A, following defibrillation and intravenous bolus administration of lidocaine, the pacing catheter was positioned in the right ventricle without further episodes of VF. It is concluded that 1) in patients with acute MI temporary transvenous pacemaker insertion may be complicated by VF; 2) VF is most likely to occur in younger patients with inferior MI infarction when the pacing catheter is inserted within 24 h of the onset of symptoms of infarction; and 3) administration of an intravenous bolus of lidocaine may be effective in preventing the induction of VF by catheter manipulation.

The value of early out-patient cardiac exercise programmes for the elderly in comparison with other selected age groups.

To evaluate potential benefits that elderly cardiac patients might gain from early exercise programs, 361 cardiac patients were studied. Seventy-six patients were older than 65 years (elderly). All patients participated in a 12 week exercise program within six weeks of myocardial infarction or cardiac surgery. All patients performed symptom limited exercise tests prior to and after completion of the exercise program. Comparison of pre- and post-training data revealed that elderly patients had significant decrease in body weight, percent body fat, resting heart rate, submaximal average double product, and submaximal average rating of perceived exertion, P less than 0.05. Maximal achieved heart rate and mets significantly increased, P less than 0.05. Comparison of magnitude of changes seen in the elderly with those of younger patients failed to reveal significant differences, P greater than 0.05. These results suggest that the benefits of early exercise program seen in younger patients may also be expected in elderly patients.

Thallium-201 myocardial imaging in patients with coronary artery disease: comparison of intravenous adenosine and oral dipyridamole.

OBJECTIVE: To compare thallium-201 (201Tl) myocardial perfusion imaging following intravenous adenosine and oral dipyridamole. DESIGN: Open-label, randomized, comparison. SETTING: Outpatient, university-affiliated clinic. PATIENTS: Fifteen patients with angiographically documented coronary artery disease. INTERVENTIONS: Planar 201Tl myocardial perfusion imaging following both intravenous adenosine 140 micrograms/kg/min for six minutes and oral dipyridamole suspension 300 mg. MAIN OUTCOME MEASURES: A comparison between adenosine and dipyridamole was made in the following areas: concordance in interpretation of 201Tl scintigrams, cardiac and noncardiac 201Tl uptake and clearance, hemodynamic and electrocardiographic changes, and adverse effects. RESULTS: The scintigraphic studies showed perfusion defects in 13 patients (87 percent) after dipyridamole and in 15 patients (100 percent) after adenosine. 201Tl uptake and clearance were quantitated in nine myocardial segments and in four extracardiac segments in each patient. 201Tl uptake was not significantly different between adenosine and dipyridamole studies in most cardiac regions. Extracardiac 201Tl uptake was significantly less in the liver and splanchnic regions following adenosine compared with dipyridamole. 201Tl clearance was not significantly different following adenosine and dipyridamole except in the anterolateral region in the anterior view. Hemodynamic changes following administration of intravenous adenosine and oral dipyridamole were not significantly different. Adverse effects were more common with adenosine than with dipyridamole. Adverse effects with adenosine were transient; however, adverse effects with dipyridamole were prolonged and required reversal with aminophylline in 2 patients. No patients required termination of the adenosine infusion or administration of aminophylline. CONCLUSIONS: These preliminary data suggest that adenosine 201Tl imaging may be a useful alternative to dipyridamole 201Tl imaging. Although adenosine produces more frequent adverse effects, they are generally better tolerated than those associated with dipyridamole.

Myocardial uptake and clearance of T1-201 in healthy subjects: comparison of adenosine-induced hyperemia and exercise stress.

Pharmacologic stress testing with dipyridamole is useful in patients undergoing thallium-201 myocardial perfusion scintigraphy who cannot adequately exercise. Because dipyridamole increases coronary blood flow by reducing the metabolism of adenosine, the authors compared the uptake and clearance of T1-201 following exercise stress testing (EST) and resting intravenous infusion of adenosine (AI) in crossover fashion in 20 healthy men. No perfusion defects or areas of redistribution were noted in any of the scans. Mean absolute myocardial T1-201 uptake was 1.3 times greater with AI than with EST. Mean absolute extracardiac uptake was 2.0 times greater with AI. Mean T1-201 myocardial clearance was virtually the same in all AI and EST views. During AI, 70% of the subjects experienced subjective side effects, mean arterial blood pressure decreased by 15%, and heart rate increased by 48%. The effects of adenosine on T1-201 kinetics in the myocardium are similar to those of EST. Adenosine may be useful as a pharmacologic stress agent in patients undergoing T1-201 myocardial perfusion scintigraphy.