The role of reperfusion therapy in paced patients with acute myocardial infarction.

BACKGROUND/OBJECTIVE: Our purpose was to evaluate the effectiveness of reperfusion therapy among elderly paced patients with acute myocardial infarction (MI). Current guidelines make no recommendation for the use of reperfusion therapy among patients who have a paced rhythm during MI. METHODS: We evaluated 1954 Medicare beneficiaries 65 years and older treated for acute MI between 1994 and 1996 who had a paced rhythm for use of reperfusion therapy. Use of reperfusion therapy was evaluated for associations with outcomes by logistic regression and Cox proportional hazards models incorporating propensity score analysis. RESULTS: Reperfusion therapy was used in 171 (8.8%) patients; 70 were treated with primary PTCA and 101 with thrombolytic therapy. Patients who received reperfusion therapy had 30-day mortality rates similar to those who did not receive reperfusion (26.3% vs 25.7%, P =.87). Multivariate adjustment for mortality risk factors and treatment propensity indicated no survival benefit associated with reperfusion therapy at 30 days (relative risk [RR] 1.07, 95% confidence interval [CI] 0.77-1.43) or long-term follow-up (hazard ratio [HR] 0.86, 95% CI 0.68-1.10). Mortality risks varied by type of reperfusion therapy. Patients treated with primary percutaneous transluminal coronary angioplasty were at comparable risk of mortality at 30 days (RR 0.73, 95% CI 0.40-1.23) but at lower risk at long-term follow-up (HR 0.60, 95% CI 0.40-0.88). Mortality risks were unchanged among patients treated with thrombolytics at 30 days (RR 1.32, 95% CI 0.92-1.79) and long-term follow-up (HR 1.08, 95% CI 0.82-1.43). CONCLUSION: We find suggestive evidence that primary percutaneous transluminal coronary angioplasty provides a long-term survival benefit in the treatment of elderly patients with acute MI who have a paced rhythm.

Treatment of patients with myocardial infarction who present with a paced rhythm.

BACKGROUND: A paced rhythm can mask the electrocardiographic features of an acute myocardial infarction, complicating timely recognition and treatment. OBJECTIVE: To evaluate characteristics, treatment, and outcomes among patients presenting with paced rhythms during myocardial infarction. DESIGN: Retrospective cohort study. SETTING: U.S. acute care hospitals. PATIENTS: 102 249 Medicare beneficiaries at least 65 years of age who were treated for acute myocardial infarction between 1994 and 1996. MEASUREMENTS: Provision of three treatments for acute myocardial infarction (emergent reperfusion, aspirin, and beta-blockers), death at 30 days, and long-term follow-up. RESULTS: 1954 patients (1.9%) presented with paced rhythms during myocardial infarction. These patients were older; were predominantly male; and had higher rates of congestive heart failure, diabetes, and previous infarction. They were significantly less likely to receive emergent reperfusion (relative risk [RR], 0.27 [95% CI, 0.22 to 0.33]), aspirin (RR at admission, 0.91 [CI, 0.88 to 0.94]; RR at discharge, 0.87 [CI, 0.83 to 0.92]), and beta-blockers at admission (RR, 0.89 [CI, 0.82 to 0.96]). In addition, there was a trend toward decreased use of beta-blockers at discharge (RR, 0.91 [CI, 0.76 to 1.06]). Crude mortality rates were higher among patients with paced rhythms than among those without at 30 days (25.8% vs. 21.3%; P = 0.001) and at 1 year (47.1% vs. 36.1%; P = 0.001). Among patients with paced rhythms, risk for death at 30 days decreased after adjustment for illness severity and decreased use of therapy (RR, 1.03 [CI, 0.93 to 1.14]). Patients with paced rhythms remained at additional risk for long-term mortality (hazard ratio, 1.12 [CI, 1.06 to 1.18]). CONCLUSIONS: Patients with paced rhythms were less likely than those without to receive treatment for acute myocardial infarction and had poorer short- and long-term outcomes. However, this mortality risk diminished after adjustment for treatment. This suggests that improved recognition and treatment of myocardial infarction may improve outcomes, particularly in the short term.

Effect of diabetes mellitus and insulin use on survival after acute myocardial infarction in the elderly (the Cooperative Cardiovascular Project).

Using data from a retrospective cohort study of Medicare beneficiaries hospitalized with an acute myocardial infarction (AMI), we evaluated the role of diabetes mellitus on 30-day and 1-year mortality. We classified subjects as nondiabetics, diabetics controlled with diet alone, diabetics receiving an oral hypoglycemic agent, and diabetics on insulin at time of admission. We compared baseline admission characteristics of subgroups using chi-square and Wilcoxon rank-sum tests and evaluated the effect of each diabetic state using sequential logistic models. We identified 80,832 nondiabetic patients, 9,862 diet-controlled diabetic patients, 14,664 diabetics receiving an oral hypoglycemic agent, and 12,241 diabetic patients on insulin therapy. Although mean age was similar among the groups, prevalence of hypertension, prior AMI, prior congestive heart failure, and prior revascularization were higher among diabetic patients, particularly those taking insulin. Diabetic patients, particularly those taking insulin, were less likely to receive aspirin and beta blockers and to undergo coronary revascularization. Diabetic patients had higher 30-day and 1-year mortality than nondiabetic patients. After adjustment for demographics, clinical and hospital characteristics, and treatment strategies, insulin-treated diabetics had the highest risk of mortality, followed by diabetics receiving oral hypoglycemic agents, followed by diet-controlled diabetics. Thus, diabetes is highly prevalent among elderly patients with an AMI. Mortality rates for these patients, particularly insulin-using diabetics, are higher than among their nondiabetic counterparts. Preventive and therapeutic strategies must be developed to ensure improved short- and long-term outcomes for elderly patients with diabetes and AMI.

Acute myocardial infarction complicated by heart block in the elderly: prevalence and outcomes.

BACKGROUND: Although second- and third-degree heart block (HB) are common conduction disorders associated with acute myocardial infarction (MI), patient characteristics and HBs association with outcomes, particularly among the elderly, remain poorly defined. METHODS: We evaluated 106,780 Medicare beneficiaries aged 65 years and older treated for acute MI between January 1994 and February 1996 for development of HB. HB and non-HB patients were compared by univariate analysis, and the influence of HB on outcomes was evaluated by unadjusted and multiple logistic regression. RESULTS: HB was documented in 5048 (4.7%) patients; 1646 presented with HB and 3402 developed HB during hospitalization. HB was more common among patients with inferior infarctions than anterior infarctions (7.3% vs 3.0%, P =.001), particularly the cohort of patients with inferior MI treated with reperfusion therapy (8.3%). HB patients had higher rates of in-hospital mortality (29.6% vs. 17.5% vs. non-HB patients, P =.001). After adjustment for demographic and clinical factors, HB remained an independent predictor of in-hospital mortality (relative risk [RR] 1.41, 95% confidence interval [CI] 1. 34-1.48), but HB had no prognostic significance at 1 year among hospital survivors (RR 0.94, 95% CI 0.88-1.01). Mortality risks varied on the basis of MI location. Both anterior MI (RR 1.46, 95% CI 1.30-1.63) and inferior MI (RR 1.52, 95% CI 1.39-1.66) patients with HB had increased risks of in-hospital mortality. There was a trend toward increased mortality among patients with anterior MI (RR 1.15, 95% CI 0.99-1.32) at 1 year, whereas those with inferior MI were at lower risk (RR 0.83, 95% CI 0.75-0.98). CONCLUSIONS: HB is a common complication of acute MI in elderly patients, particularly among patients with inferior MIs who received reperfusion therapy. HB is independently associated with short-term but not long-term mortality.

Time to presentation with acute myocardial infarction in the elderly: associations with race, sex, and socioeconomic characteristics.

BACKGROUND: Although prompt treatment is a cornerstone of the management of acute myocardial infarction (AMI), prior studies have shown that one fourth of AMI patients arrive at the hospital >6 hours after symptom onset. It would be valuable to identify individuals at highest risk for late arrival, but predisposing factors have yet to be fully characterized. METHODS AND RESULTS: Data from the Cooperative Cardiovascular Project, involving Medicare beneficiaries aged >65 years hospitalized between January 1994 and February 1996 with confirmed AMI, were used to identify patients who presented "late" (>/=6 hours after symptom onset). Patient characteristics were tested for associations with late presentation by use of backward stepwise logistic regression. Among 102 339 subjects, 29.4% arrived late. Significant predictors of late arrival (odds ratio, 95% CI) included diabetes (1.11, 1.07 to 1.14) and a history of angina (1.32, 1.28 to 1.35), whereas prior MI (0.82, 0.79 to 0.85), prior angioplasty (0.80, 0.75 to 0.85), prior bypass surgery (0.93, 0.89 to 0.98), and cardiac arrest (0.52, 0.46 to 0. 58) predicted early presentation. Additionally, initial evaluation at an outpatient clinic (2.63, 2.51 to 2.75) and daytime presentation (1.67, 1.59 to 1.72) predicted late arrival. Finally, female sex, black race, and poverty, which were evaluated with an 8-level race-sex-socioeconomic status interaction term, were also risk factors for delay. CONCLUSIONS: Delayed hospital presentation is a common problem among Medicare beneficiaries with AMI. Factors associated with delay include not only clinical and logistical issues but also race, sex, and socioeconomic characteristics. Education efforts designed to hasten AMI treatment should be directed at individuals with risk factors for late arrival.

Race, sex, poverty, and the medical treatment of acute myocardial infarction in the elderly.

BACKGROUND: Race, sex, and poverty are associated with the use of diagnostic cardiac catheterization and coronary revascularization during treatment of acute myocardial infarction (AMI). However, the association of sociodemographic characteristics with the use of less costly, more readily available medical therapies remains poorly characterized. METHODS AND RESULTS: We evaluated 169 079 Medicare beneficiaries >/=65 years of age treated for AMI between January 1994 and February 1996 to determine the association of patient race, sex, and poverty with the use of medical therapy. Multivariable regression models were constructed to evaluate the unadjusted and adjusted influence of sociodemographic characteristics on the use of 2 admission (aspirin, reperfusion) and 2 discharge therapies (aspirin, beta-blockers) indicated during the treatment of AMI. Therapy use varied by patient race, sex, and poverty status. Black patients were less likely to undergo reperfusion (RR 0.84, 95% CI 0. 78, 0.91) or receive aspirin on admission (RR 0.97, 95% CI 0.96, 0. 99) and beta-blockers (RR 0.94, 95% CI 0.88, 1.00) at discharge. Female patients were less likely to receive aspirin on admission (RR 0.98, 95% CI 0.97, 0.99) and discharge (RR 0.98, 95% CI 0.96, 0.99). Poor patients were less likely to receive aspirin (RR 0.97, 95% CI 0. 96, 0.98) or reperfusion (RR 0.97, 95% CI 0.93, 1.00) on admission and aspirin (RR 0.98, 95% CI 0.96, 1.00), or beta-blockers (RR 0.95, 95% CI 0.91, 0.99) on discharge. CONCLUSIONS: Medical therapies are currently underused in the treatment of black, female, and poor patients with AMI.

Lack of benefit for intravenous thrombolysis in patients with myocardial infarction who are older than 75 years.

BACKGROUND: The benefit of intravenous thrombolytic therapy in elderly patients with myocardial infarction is uncertain. There are no randomized trials of thrombolytic efficacy or observational studies of clinical effectiveness that focus specifically on the elderly. METHODS AND RESULTS: To determine whether thrombolytic therapy for elderly patients is associated with a survival advantage in a large observational database, we conducted a retrospective cohort study of 7864 Medicare fee-for-service patients aged 65 to 86 years with the primary discharge diagnosis of acute myocardial infarction who were admitted with clinical and ECG indications for thrombolytic therapy and no absolute contraindications. The study included all US acute care nongovernment hospitals without on-site angioplasty capability. Using proportional-hazards methods, we found that in a comprehensive multivariate model, there was a significant interaction (P<0.001) between age and the effect of thrombolytic therapy on 30-day mortality rates. For patients 65 to 75 years old, thrombolytic therapy was associated with a survival benefit, consistent with randomized trials. Among patients aged 76 to 86 years, thrombolytic therapy was associated with a survival disadvantage, with a 30-day mortality hazard ratio of 1.38 (95% CI 1. 12 to 1.71, P=0.003). For these patients, there was no benefit from thrombolytic therapy in any clinical subgroup. CONCLUSIONS: In nationwide clinical practice, thrombolytic therapy for patients >75 years old is unlikely to confer survival benefit and may have a significant survival disadvantage. Reperfusion research that is focused on elderly patients is urgently needed.

Acute myocardial infarction complicated by atrial fibrillation in the elderly: prevalence and outcomes.

BACKGROUND: Although atrial fibrillation (AF) is a common complication of acute myocardial infarction (MI), patient characteristics and association with outcomes remain poorly defined in the elderly. METHODS AND RESULTS: We evaluated 106 780 Medicare beneficiaries > or =65 years of age from the Cooperative Cardiovascular Project treated for acute MI between January 1994 and February 1996 to determine the prevalence and prognostic significance of AF complicating acute MI in elderly patients. Patients were categorized on the basis of the presence of AF, and those with AF were further subdivided by time of AF (present on arrival versus developing during hospitalization). AF and non-AF patients were compared by univariate analysis, and logistic regression modeling was used to identify clinical predictors of AF. The influence of AF on outcomes was evaluated by unadjusted Kaplan-Meier survival curves and logistic regression models. AF was documented in 23 565 patients (22. 1%): 11 510 presented with AF and 12,055 developed AF during hospitalization. AF patients were older, had more advanced heart failure, and were more likely to have had a prior MI and undergone coronary revascularization. AF patients had poorer outcomes, including higher in-hospital (25.3% versus 16.0%), 30-day (29.3% versus 19.1%), and 1-year (48.3% versus 32.7%) mortality. AF remained an independent predictor of in-hospital (odds ratio [OR], 1. 21), 30-day (OR, 1.20), and 1-year (OR, 1.34) mortality after multivariate adjustment. Patients developing AF during hospitalization had a worse prognosis than patients who presented with AF. CONCLUSIONS: AF is a common complication of acute MI in elderly patients and independently influences mortality, particularly when it develops during hospitalization.

The association between hospital volume and survival after acute myocardial infarction in elderly patients.

BACKGROUND: Patients with chest pain thought to be due to acute coronary ischemia are typically taken by ambulance to the nearest hospital. The potential benefit of field triage directly to a hospital that treats a large number of patients with myocardial infarction is unknown. METHODS: We conducted a retrospective cohort study of the relation between the number of Medicare patients with myocardial infarction that each hospital in the study treated (hospital volume) and long-term survival among 98,898 Medicare patients 65 years of age or older. We used proportional-hazards methods to adjust for clinical, demographic, and health-system-related variables, including the availability of invasive procedures, the specialty of the attending physician, and the area of residence of the patient (rural, urban, or metropolitan). RESULTS: The patients in the quartile admitted to hospitals with the lowest volume were 17 percent more likely to die within 30 days after admission than patients in the quartile admitted to hospitals with the highest volume (hazard ratio, 1.17; 95 percent confidence interval, 1.09 to 1.26; P<0.001), which resulted in 2.3 more deaths per 100 patients. The crude mortality rate at one year was 29.8 percent among the patients admitted to the lowest-volume hospitals, as compared with 27.0 percent among those admitted to the highest-volume hospitals. There was a continuous inverse dose-response relation between hospital volume and the risk of death. In an analysis of subgroups defined according to age, history of cardiac disease, Killip class of infarction, presence or absence of contraindications to thrombolytic therapy, and time from the onset of symptoms, survival at high-volume hospitals was consistently better than at low-volume hospitals. The availability of technology for angioplasty and bypass surgery was not independently associated with overall mortality. CONCLUSIONS: Patients with acute myocardial infarction who are admitted directly to hospitals that have more experience treating myocardial infarction, as reflected by their case volume, are more likely to survive than are patients admitted to low-volume hospitals.

Resource use and quality of care for Medicare patients with acute myocardial infarction in Maryland and the District of Columbia: analysis of data from the Cooperative Cardiovascular Project.

This study sought to evaluate the quality of care rendered to Medicare beneficiaries with acute myocardial infarction by establishing the use patterns of well-proven therapies in this population. We analyzed the quality of care rendered to 4300 Medicare beneficiaries seen at Maryland and District of Columbia hospitals with retrospectively confirmed acute myocardial infarction by evaluating the use of proven therapies. The proportion of patients ideal for therapies ranged from 10% for reperfusion to 100% for smoking cessation counseling. For ideal patients the following therapies were implemented: aspirin (87%), reperfusion therapy (64%), beta-blockers on discharge (60%), and smoking cessation counseling (41%). A substantial proportion of Medicare patients with acute myocardial infarction has one or more relative or absolute contraindications to standard regimens and therefore are not ideal therapeutic candidates. In the group of ideal patients, those with no therapeutic contraindications, a significant proportion do not receive these treatments.

Artificial neural networks: current status in cardiovascular medicine.

Artificial neural networks are a form of artificial computer intelligence that have been the subject of renewed research interest in the last 10 years. Although they have been used extensively for problems in engineering, they have only recently been applied to medical problems, particularly in the fields of radiology, urology, laboratory medicine and cardiology. An artificial neural network is a distributed network of computing elements that is modeled after a biologic neural system and may be implemented as a computer software program. It is capable of identifying relations in input data that are not easily apparent with current common analytic techniques. The functioning artificial neural network's knowledge is built on learning and experience from previous input data. On the basis of this prior knowledge, the artificial neural network can predict relations found in newly presented data sets. In cardiology, artificial neural networks have been successfully applied to problems in the diagnosis and treatment of coronary artery disease and myocardial infarction, in electrocardiographic interpretation and detection of arrhythmias and in image analysis in cardiac radiography and sonography. This report focuses on the current status of artificial neural network technology in cardiovascular medical research.

Primary amyloid heart disease presenting as hypertrophic obstructive cardiomyopathy.

This report describes the unusual presentation of a patient with primary cardiac amyloidosis. Initial clinical symptoms and hemodynamic studies, including Technetium-99m-pyrophosphate scintigraphy, suggested hypertrophic obstructive cardiomyopathy, but endomyocardial biopsy revealed diffuse amyloid infiltration. Only two other cases of left ventricular outflow tract obstruction due to cardiac amyloidosis have been reported. The false-negative technetium-99m-pyrophosphate scintigram in this patient argues for the use of endomyocardial biopsy to aid in the diagnosis of left ventricular hypertrophy.

Right ventricular visualization by thallium 201 myocardial scintigraphy in chronic obstructive pulmonary disease.

The right ventricle is not normally displayed by studies with thallium 201 in patients at rest, but it can be shown by thallium 201 myocardial scintigraphy with pressure or volume overload of the right ventricle and with right ventricular hypertrophy. We sought to determine the frequency of right ventricular demonstration by thallium 201 in 20 patients at rest, who had chronic obstructive pulmonary disease of varying severity studied at baseline. The ventricle was viewed in 11 of 20 patients (55%); these patients had significantly lower values for forced expiratory volume in one second (FEV1) and PO2. Eight patients had catheterization of the right side of the heart; mean pulmonary artery pressure and pulmonary vascular resistance were significantly higher in patients with right ventricular visualization. We conclude that thallium 201 scintigraphy frequently shows the right ventricle in patients with chronic obstructive pulmonary disease and that such visualization correlates with the severity of the ventilatory defect and with pulmonary hypertension.

Intracardiac electrophysiologic studies in the medical evaluation of aviators.

Ten aviators with cardiac symptoms or electrocardiographic abnormalities underwent electrophysiologic testing. Four patients were studied because of symptoms including palpitations, nearsyncope, and sudden cardiac death. Six patients were studied because of electrocardiographic abnormalities including AV block, right bundle branch block, sinus bradycardia, ventricular tachycardia, and questionable Wolff-Parkinson-White syndrome. Three patients with bradycardia and/or AV block were found to have increased vagal tone. A fourth patient had nearsyncope and intra-Hisian block. Of four patients evaluated for palpitations and/or tachycardias; one had nonsustained ventricular tachycardia; one had easily inducible ventricular tachycardia and fibrillation; one had a normal study, and one had coronary artery disease with an unanticipated prolonged HV interval. The diagnosis of congenital right bundle branch block and Wolff-Parkinson-White syndrome were confirmed in the final two patents. Performance of electrophysiologic testing provided objective data to allow appropriate therapeutic and administrative decisions in these aviators.

Pulmonary vascular response during Raynaud's phenomenon in progressive systemic sclerosis.

Progressive systemic sclerosis and Raynaud's phenomenon are associated with a distinctly vascular form of pulmonary involvement and pulmonary hypertension. To investigate a possible underlying vasospastic predisposition in these patients, the pulmonary vascular response to Raynaud's phenomenon induced by cold-water hand immersion was examined in nine patients. Four patients had pulmonary fibrosis and four patients had the CREST syndrome; no patient had pre-existing pulmonary hypertension. During Raynaud's phenomenon, there was no significant rise in mean pulmonary artery pressure (15 +/- 3 versus 15 +/- 2 mm Hg, p = NS) or pulmonary vascular resistance (112 +/- 38 versus 118 +/- 50 dynes X second X cm-5, p = NS) over baseline, despite a significant rise in mean aortic pressure (104 +/- 14 versus 92 +/- 11 mm Hg, p less than 0.01) and systemic vascular resistance (1,700 +/- 450 versus 1,500 +/- 470 dynes X second X cm-5, p less than 0.01). It is concluded that pulmonary vasospasm with transient pulmonary hypertension does not occur in patients with progressive systemic sclerosis and Raynaud's phenomenon during episodes of Raynaud's phenomenon. Abnormal pulmonary vasospasm in these patients in response to other stimuli, however, is not excluded.

Percutaneous balloon valvuloplasty of the pulmonary valve: role of right to left shunting through a patent foramen ovale.

Percutaneous balloon valvuloplasty was performed on a patient with pulmonary stenosis. Right to left shunting through a patent foramen ovale during balloon inflation was documented by contrast two-dimensional echocardiography. Right and left ventricular pressures recorded during balloon inflation showed a decrease in left ventricular end-diastolic pressure and equilibration with right ventricular end-diastolic pressure. Systemic hypotension was minimal during balloon inflation, possibly due to persistent filling of the left ventricle via the patent foramen ovale. Persistent right ventricular systolic hypertension immediately after valvuloplasty may have been due to infundibular narrowing and resolved on restudy 2 weeks later.

Amiodarone-digoxin interaction. Clinical and experimental observations.

Twenty-two patients were given amiodarone for refractory cardiac arrhythmias, and pre- and post-amiodarone serum digoxin levels were studied. The interval between pre- and post-amiodarone serum digoxin levels ranged from five days to nine months (mean interval, seven weeks). The mean (+/- SD) pre-amiodarone serum digoxin level was 1.0 +/- 0.4 ng/ml, and the post-amiodarone serum digoxin level was 1.9 +/- 0.8 ng/ml (p less than .001). To develop an animal model for study of the digoxin-amiodarone interaction, 18 pigs were given digoxin for a four-week period. Half of the animals were given amiodarone as well as digoxin for the last two weeks of the study. At the end of the initial two-week period, there was no difference in serum digoxin levels between the two groups. At the end of the second two-week period, the serum digoxin level in the group receiving digoxin alone was 0.6 +/- 0.2 ng/ml, and the serum digoxin level in the group receiving the digoxin and amiodarone was 1.2 +/- 0.6 ng/ml (p less than .01). These data confirm the presence of an amiodarone-digoxin interaction in man and show that the pig is an appropriate model for study of this clinical phenomenon in the animal laboratory.