Negative T waves shortly after ST-elevation acute myocardial infarction are a powerful marker for improved survival rate.

BACKGROUND: Recent studies have reported that negative T waves in the setting of acute coronary events are associated with Thrombolysis In Myocardial Infarction flow grade 3 in the infarct-related artery and with improved parameters of ventricular function rather than with ischemia. METHODS: Patients enrolled in the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO-I) angiographic substudy (ie, patients with acute infarction randomly assigned to one of 4 thrombolytic regimens who then underwent coronary angiography) were included in this study if they survived at least 24 hours and had no confounding electrocardiographic factors (n = 1505). RESULTS: More patients had negative T waves develop (NT group, n = 938 [62%]) than not (PT group, n = 567 [38%]). Peak creatine kinase MB, time to thrombolysis, and randomization to accelerated alteplase were no different between the groups. Thirty days after admission, 12 patients in the NT group had died versus 25 patients in the PT group (1.3% vs. 4.4%; P <.001; odds ratio for negative T waves 0.28; 95% confidence interval 0.14-0.56). The difference persisted when only patients who survived at least 3 days were analyzed. After adjusting for relevant covariates (including presence of new Q waves in the follow-up electrocardiogram), negative T waves were an independent predictor for survival (P =. 007; odds ratio for negative T waves 0.38; 95% confidence interval 0. 18-0.78). Patients in the NT group were 35% more likely to have achieved patency of the infarct-related artery, although this difference was not statistically significant. CONCLUSIONS: Negative T waves shortly after acute myocardial infarction treated with thrombolysis were markers for improved 30-day survival rate. This finding merits prospective testing.

Acute myocardial infarction and complete bundle branch block at hospital admission: clinical characteristics and outcome in the thrombolytic era. GUSTO-I Investigators. Global Utilization of Streptokinase and t-PA [tissue-type plasminogen activator] for Occluded Coronary Arteries.

OBJECTIVES: We sought to assess the outcome of patients with acute myocardial infarction (MI) and bundle branch block in the thrombolytic era. BACKGROUND: Studies of patients with acute MI and bundle branch block have reported high mortality rates and poor overall prognosis. METHODS: The North American population with acute MI and bundle branch block enrolled in the Global Utilization of Streptokinase and t-PA [tissue-type plasminogen activator] for Occluded Coronary Arteries (GUSTO-I) trial was matched by age and Killip class with an equal number of GUSTO-I patients without conduction defects. RESULTS: Of all 26,003 North American patients in GUSTO-I, 420 (1.6%) had left (n = 131) or right (n = 289) bundle branch block. These patients had higher 30-day mortality rates than matched control subjects (18% vs. 11%, p = 0.003, odds ratio [OR] 1.8) and were more likely to experience cardiogenic shock (19% vs. 11%, p = 0.008, OR 1.78) or atrioventricular block/asystole (30% vs. 19%, p < 0.012, OR 1.57) and to require ventricular pacing (18% vs. 11%, p = 0.006, OR 1.73). Bundle branch block also carried an independent 53% higher risk for 30-day mortality. Thirty-day mortality rates for patients with complete, partial and no reversion of the bundle branch block were 8%, 12% and 20%, respectively (two-tailed chi-square test for trend 5.61, p = 0.02, OR 0.34 for complete reversion, OR 0.55 for partial reversion). CONCLUSIONS: Bundle branch block at hospital admission in patients with acute MI predicts in-hospital complications and poor short-term survival.

The incidence of scintigraphically viable and nonviable tissue by rubidium-82 and fluorine-18-fluorodeoxyglucose positron emission tomographic imaging in patients with prior infarction and left ventricular dysfunction.

BACKGROUND: Although reversible perfusion defects, perfusion-metabolism mismatch and match patterns are important for differentiating viable from nonviable myocardium, the frequency of these scintigraphic patterns has not been reported. The study objective was to establish the incidence of these scintigraphic patterns to estimate the clinical need for metabolic positron emission tomography for evaluating tissue viability in patients with prior myocardial infarction (MI). METHODS AND RESULTS: 82Rb perfusion images were interpreted to identify reversible or irreversible defects, followed by determination of their 18F-fluorodeoxyglucose (18F-FDG) uptake pattern. In 155 patients with prior MI, analysis of 613 abnormal segments showed reversible perfusion defects in 13%. The 87% irreversible defects, 18% showed perfusion-metabolism mismatch, whereas 69% showed the match pattern. Reversible perfusion defects and perfusion-metabolism mismatches were noted in 20% (31/155) and 29% (45/155) of patients, respectively, whereas the match pattern was noted in 51% (79/155) of patients. CONCLUSION: Irreversible perfusion defects were common in our patients with prior MI, and distinction between viable and nonviable tissue was not possible by perfusion imaging alone. The identification of hibernating myocardium was possible only with the additional 18F-FDG imaging in about one third of patients. This indicates a significant clinical demand for 18F-FDG imaging that identifies patients who will benefit from revascularization.

Electrocardiographic diagnosis of evolving acute myocardial infarction in the presence of left bundle-branch block. GUSTO-1 (Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries) Investigators.

BACKGROUND: The presence of left bundle-branch block on the electrocardiogram may conceal the changes of acute myocardial infarction, which can delay both its recognition and treatment. We tested electrocardiographic criteria for the diagnosis of acute infarction in the presence of left bundle-branch block. METHODS: The base-line electrocardiograms of patients enrolled in the GUSTO-1 (Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries) trial who had left bundle-branch block and acute myocardial infarction confirmed by enzyme studies were blindly compared with the electrocardiograms of control patients who had chronic coronary artery disease and left bundle-branch block. The electrocardiographic criteria for the diagnosis of infarction were then tested in an independent sample of patients presenting with acute chest pain and left bundle-branch block. RESULTS: Of 26,003 North American patients, 131 (0.5 percent) with acute myocardial infarction had left bundle-branch block. The three electrocardiographic criteria with independent value in the diagnosis of acute infarction in these patients were an ST-segment elevation of 1 mm or more that was concordant with (in the same direction as) the QRS complex; ST-segment depression of 1 mm or more in lead V1, V2, or V3; and ST-segment elevation of 5 mm or more that was disconcordant with (in the opposite direction from) the QRS complex. We used these three criteria in a multivariate model to develop a scoring system (0 to 10), which allowed a highly specific diagnosis of acute myocardial infarction to be made. CONCLUSIONS: We developed and validated a clinical prediction rule based on a set of electrocardiographic criteria for the diagnosis of acute myocardial infarction in patients with chest pain and left bundle-branch block. The use of these criteria, which are based on simple ST-segment changes, may help identify patients with acute myocardial infarction, who can then receive appropriate treatment.

Hibernating myocardium versus scar: severity of irreversible decreased myocardial perfusion in prediction of tissue viability.

PURPOSE: To determine whether quantitation of the relative severity of decreased perfusion in irreversible defects on myocardial perfusion images enables differentiation of viable hibernating myocardium from scar. MATERIALS AND METHODS: In 145 patients with previous myocardial infarction, 1,252 regions with irreversible defects proved by means of rubidium-82 rest-stress imaging were analyzed for relative severity (percentage decrease in perfusion). Myocardial tissue viability was determined by means of positron emission tomography with fluorine-18 fluorodeoxyglucose (FDG). RESULTS: The relative decreases in Rb-82 uptake in the 1,252 regions were categorized into nine levels of severity (30% to > or = 70%) in 381 regions of hibernating myocardium and 871 regions of scar. The values of relative decreased perfusion in the irreversible defects alone did not enable differentiation of hibernating myocardium and scar (P = .61). CONCLUSION: The results show no relationship between the relative severity of irreversible perfusion defects and the ability to distinguish between hibernating myocardium and scar.

Temporal electrical heterogeneity for detecting coronary artery disease: results in a heterogeneous cardiac population.

BACKGROUND: A new 22-lead electrocardiographic test has been advocated as a screening tool for coronary artery disease and has been shown to have accuracy similar to stress electrocardiography in specific patient populations. OBJECTIVE: To determine the accuracy of this test for detecting coronary artery disease in patients undergoing coronary angiography for a variety of cardiac conditions. METHODS: We prospectively determined the temporal electrical heterogeneity (TEH) index at rest in 70 patients who had no angina or Q waves on the resting 12-lead electrocardiogram before they underwent coronary angiography. RESULTS: Twenty-six of the 70 patients had significant coronary artery disease, defined as 70% stenosis or greater in at least one major epicardial coronary artery. A TEH index of 80 or more had a sensitivity of 58%, a specificity of 75%, and a positive predictive value of 58%. The group with significant coronary disease had a mean TEH index of 77.2, and the group without coronary disease had a mean index of 65.5 (P = .02), despite similar clinical characteristics and indications for angiography. CONCLUSION: The TEH index shows promise as a screening tool for coronary artery disease in a heterogeneous cardiac population. However, larger studies are needed before it can be endorsed for widespread clinical use.

Signal-averaged ECG parameters in cardiac normals using Frank lead system and Fourier transform filter and gender specific differences: a multicenter study.

There is only limited data on normal reference values for signal-averaged electrocardiograms (SAECGs) using Frank leads and fast Fourier transform filter (FFT). Furthermore, the influence of gender on reference values and their relation to body characteristics was only the subject of a few studies on small series of normals. One hundred eighty-five cardiac normals (85 women and 100 men) were examined in this multicenter study. The obtained SAECG values (mean +/- standard deviation) are as follows: filtered QRS duration (FQRSD) = 108.6 +/- 7.5 msec; low amplitude signal duration < 40 microV (LASD) = 30.4 +/- 8.4 msec; and root mean square voltage in the terminal 40 msec (RMSV) = 43.5 +/- 20.6 microV. Between men and women, significant differences were found in FQRSD (111.7 +/- 6.5 vs 105.0 +/- 7.0 msec, P < 0.001) and in RMSV (38.6 +/- 17.4 vs 49.4 +/- 22.7 microV, P < 0.001). No difference was observed for LASD. After normalizing the three SAECG parameters for body characteristics, FQRSD normalized for height was the only variable where gender differences were eliminated. For FQRSD and LASD the 90th percentile and for RMSV the 10th percentile are proposed as cut-off values. Only for the 90th percentile of FQRSD a clear difference between men and women was observed. The following gender specific normal values for SAECG, at 40-Hz high pass filtering, using Frank leads and an FFT filter are proposed: for males, FQRSD < 122 msec; for females, FQRSD < 115 msec; for both genders, LASD < 41 msec and RMSV > 20 microV.

Development and benefits of a pharmacy technician career ladder.

The development and benefits of a career ladder for pharmacy technicians are described. A career ladder for technicians was implemented at a 575-bed community hospital in 1989 to provide incentives for technicians to improve their skills and take on additional responsibilities. The ladder consisted of four steps, each requiring additional years of experience, proficiency at specific skills, and involvement in specific departmental activities (e.g., maintaining floor-stock medications, preparing i.v. admixtures, and implementing new policies and procedures). Pay increases were given with each move up the ladder. At the start of the program, eight technicians were placed at level 2 and the remaining 16 were placed at level 1. Three years after the ladder was implemented, annual technician turnover had decreased from 33% to 15%. Employee surveys suggested increased job satisfaction among the technicians. Reassignment of tasks to technicians (e.g., maintaining narcotic distribution and coordinating daily purchasing activities) increased scheduling flexibility and helped provide an additional eight hours per week for pharmacist involvement in patient care activities. A pharmacy technician career ladder was associated with lower technician turnover, expansion of technicians' job responsibilities, and an increase in pharmacists' time for clinical activity.

Coronary artery disease in women: a risk-factor analysis.

BACKGROUND: Risk factor modification is important in preventing coronary artery disease; however, risk factors for coronary artery disease have been studied mostly in men, not women. OBJECTIVE: To examine risk factors for coronary artery disease in women. METHODS: We retrospectively reviewed the records of all adult women who underwent their first-ever cardiac catheterization at our institution in 1983. Risk factors in women with angiographic evidence of coronary atherosclerosis were compared with risk factors in women without angiographic evidence of coronary artery disease. RESULTS: Risk factors identified included age, diabetes mellitus, hypertension for more than 5 years, hyperlipidemia, smoking, and familial coronary artery disease. CONCLUSIONS: Risk factors for coronary artery disease in women are similar to those of men.

Establishment of signal-averaged electrocardiographic criteria with Frank XYZ leads and spectral filter used alone and in combination with ejection fraction to predict inducible ventricular tachycardia in coronary artery disease.

Signal-averaged electrocardiographic criteria are reported for corrected Frank XYZ leads and a spectral filter. The new criteria were used alone and in combination with ejection fraction to predict inducibility of ventricular tachycardia (VT) at electrophysiologic testing. Signal-averaged electrocardiographic criteria were developed in 87 control subjects and validated in 182 patients (aged 63 +/- 10 years) with coronary artery disease and QRS duration less than 118 ms. Patients underwent electrophysiologic testing in which up to 3 extra-stimuli were used during 2 paced drives from 2 right ventricular sites. A positive finding was monomorphic VT lasting 30 seconds or needing intervention. An ejection fraction less than 40% was considered abnormal. Signal-averaged electrocardiographic variables that best characterized control subjects and separated patients with and without inducible VT were filtered QRS duration less than 120 ms, low-amplitude signal duration less than 38 ms and root-mean-square voltage greater than 20 muv. With these criteria, signal-averaged electrocardiographic and ejection fraction sensitivities were 87 and 45%, respectively, and specificities were 65 and 77%, respectively. Combining signal-averaged electrocardiography with ejection fraction improved the predictive accuracy. In conclusion, diagnostic criteria for signal-averaged electrocardiography with use of Frank XYZ leads and a spectral filter produced results similar to those reported for use of bipolar XYZ leads and a Butterworth filter. Signal-averaged electrocardiography was a better predictor of VT than was ejection fraction.

Identification of recurrent ischemia after coronary artery bypass surgery: a comparison of positron emission tomography and single photon emission computed tomography.

Current techniques for the detection of recurrent coronary stenoses following bypass grafting have shown disappointing diagnostic accuracy. This study used the same dipyridamole-handgrip stress to compare the accuracy of rubidium-82 positron emission tomography and thallium-201 single photon emission computed tomography, in 50 consecutive post-bypass patients undergoing coronary arteriography at a mean interval of 6.5 years after surgery. Significant stenoses in native coronary vessels (greater than 50% diameter) or grafts (greater than 70% diameter) were defined by quantitative angiography. Forty-six patients had recurrent or residual stenoses, 43 (93%) had a perfusion defect identified by positron emission tomography, and 35 (76%) were identified by single photon emission computed tomography (P = 0.04). Fourteen of the 17 patients (82%) without previous Q-wave myocardial infarction were identified by positron emission tomography; 10 of the 17 (59%) were detected by single photon emission computed tomography (P = NS). Stress-induced perfusion defects were demonstrated by positron emission tomography in 19 patients; of this group, thallium imaging identified reversible defects in 11, showed no perfusion defect in 1, and portrayed a persistent defect in 7 patients. Significant graft disease was present in 33 patients; perfusion defects were identified by positron emission tomography in 30 (91%), and by single photon emission computed tomography in 24 (73%, P = NS). Four patients were fully revascularized, without significant recurrent coronary disease; normal perfusion was present in 3 (75%) by positron emission tomography, and 4 (100%) by single photon emission computed tomography.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of left ventricular mass on the diagnostic accuracy of myocardial perfusion imaging using positron emission tomography with dipyridamole stress.

This study assesses the influence of left ventricular hypertrophy (LVH) on the accuracy of myocardial perfusion imaging using pharmacologic coronary vasodilation. Seventy-five patients without previous infarction, and with known coronary anatomy, were studied by echocardiography and PET. LVH (defined by mass greater than 131 g/m2 in males or greater than 100 g/m2 in females) was identified in 25 patients; this group did not differ significantly from the remainder in terms of clinical or angiographic parameters. Twenty patients with hypertrophy had significant coronary artery stenoses, which were identified correctly by PET in 11 (55%), in contrast to 29 of 34 patients (85%, p = 0.03) with coronary disease but normal LV mass. Normal perfusion images were obtained in three of five patients (60%) with hypertrophy but no coronary disease; in contrast, 14 of 16 patients without either coronary disease or hypertrophy (88%, p = ns) had normal scans. The accuracy of PET was 14/25 (56%) in those with hypertrophy, and 43/50 (86%, p = 0.01) in patients with normal LV mass. In this group, the presence of hypertrophy was associated with reduction in the diagnostic accuracy of PET using dipyridamole stress. These findings may account for the phenomenon of "dipyridamole nonresponsiveness" in some patients.

Signal-averaged electrocardiography for detection of ventricular tachycardia using fast Fourier transform filtering on a standard ECG cart.

Signal-averaged electrocardiography has been advocated as a technique to predict the occurrence of ventricular tachycardia, especially in patients with ischemic heart disease. We studied a heterogeneous population of 77 patients referred for electrophysiologic testing using a recently developed fast Fourier transform filtering system available as part of a standard electrocardiography cart. The sensitivity, specificity, and positive predictive accuracy of this system were consistent with those previously determined using bidirectional Butterworth filters or finite impulse response filtering techniques. This new filtering approach in generation of signal-averaged ECG data for detection of ventricular tachycardia has promise but will require use in larger groups to establish its true clinical value.

Myocardial perfusion imaging with positron emission tomography and single photon emission computed tomography: frequency and causes of disparate results.

The purpose of this study was to compare rubidium-82 PET with thallium-201 SPECT imaging in 150 patients. Both techniques followed a single dipyridamole-handgrip stress, and images were displayed using the same 3-dimensional format and quantitative colour scale. Coronary arteriography was employed to assign the correct diagnosis in situations of disparity. Results of PET and SPECT were at least partially concordant in 110 patients (73%), although 22 had more than one defect. A reversible perfusion defect was identified in 60 patients, but the scans were concordant in only 20 (33%). These disparities were chiefly due to false-negative SPECT imaging (22 patients, 55%), and probable delayed thallium redistribution (13 patients, 33%). No patients had ischaemia correctly identified by SPECT in the presence of normal PET imaging. Persistent defects were identified in 91 patients, some of whom also had reversible defects, and the results were consistent in 54 (59%). Other than the delayed thallium redistribution group, the major categories causing disparities were false-positive (6 patients, 16%), and false negative SPECT (8 patients, 22%), attributable to attenuation and scatter. PET appears able to identify smaller, less ischaemic areas subtended by milder coronary stenoses. The availability of a true resting scan with Rb-PET enhances the discrimination between ischaemia and infarction. Attenuation correction, and the high energy photons of positron annihilation, yield more accurate evaluation of inferior wall defects and greater specificity in the presence of soft tissue attenuation.

Cardiac rhythm and conduction disturbances in patients undergoing mitral valve surgery.

The occurrence and course of supraventricular rhythm and atrioventricular conduction disturbances were retrospectively compared in 206 patients with isolated mitral valve disease undergoing either valve replacement or ring annuloplasty (mitral repair) between January 1, 1985 and December 31, 1986. The replacement and repair groups were the same size and had approximately equal numbers of patients in sinus rhythm and atrial fibrillation preoperatively. The type of mitral valve operation did not affect the short-term outcome in terms of cardiac rhythm. For both groups, the incidence of patients crossing from sinus rhythm to atrial fibrillation and vice versa on the pre-discharge electrocardiography was equal, and both groups had a low incidence of clinically significant atrioventricular block.

Diagnostic accuracy of the resting electrocardiogram in detection and estimation of left atrial enlargement: an echocardiographic correlation in 551 patients.

The identification of LA enlargement may have important clinical implications. Previous correlations of ECG P wave morphologies associated with LA enlargement and echocardiography have been limited by the use of small numbers of patients and by the employment of M-mode echocardiography without the benefit of two-dimensional guidance. The purpose of this study was to further examine the sensitivity and specificity of various P wave morphologies (P wave greater than or equal to 110 msec, notched P greater than or equal to 40 msec, and PTFV1 greater than or equal to 40 msec.mm) for the diagnosis of LA enlargement and to determine if these waveforms may be predictive of LA size. ECGs and surface echocardiograms obtained within 1 week of each other were evaluated in 551 patients (140 normal and 411 study subjects). The various P wave morphologies were found to be poorly sensitive (30% to 60%) but very specific (90%) for LA enlargement. Combinations of P wave morphologies did not improve sensitivity or specificity. ECG features did give an estimate of the degree of LA enlargement. When PTFV1 is greater than or equal to 40 msec.mm, 95% of patients had LA size greater than or equal to 40 mm; and when this parameter was greater than or equal to 60 msec.mm, 75% had LA size greater than or equal to 60 mm. These criteria for LA enlargement on the ECG are specific and predictive of the degree of LA enlargement measured by echocardiography.

A prospective comparison of rubidium-82 PET and thallium-201 SPECT myocardial perfusion imaging utilizing a single dipyridamole stress in the diagnosis of coronary artery disease.

The purpose of the present study is to prospectively compare myocardial perfusion imaging with rubidium-82 (82Rb) by positron emission tomography (PET) with thallium-201 (201Tl) imaging by single-photon emission tomography (SPECT) by recording both studies with a single dipyridamole handgrip stress, and reading both sets of images with the same display technique. In a series of 202 patients with previous coronary arteriography, the sensitivity, specificity, and accuracy of 82Rb PET were 93%, 78%, and 90% and for 201Tl SPECT 76%, 80%, and 77%, respectively. When 70 patients with previous therapeutic interventions were excluded, the remaining 132 patients showed a sensitivity, specificity, and accuracy of 95%, 82% and 92% for 82Rb PET and 79%, 76%, and 78% for 201Tl SPECT. The improved contrast resolution of PET resulted in markedly superior images and a more confident identification of defects.

Electrocardiographic criteria for anterior myocardial infarction.

In a two-stage review, electrocardiographic patterns associated with anterior infarction were determined in 135 patients whose diagnoses were established by contrast ventriculography. The five most common findings were tested in 1,324 consecutive patients to assess sensitivity, specificity, and predictive accuracies for anterior myocardial infarction. The criteria were shown to have high positive predictive accuracy and specificity levels, and confirmed the value of the standard 12-lead electrocardiogram for detecting anterior myocardial injury.

Incidence and prognostic significance of intraventricular conduction abnormalities after coronary bypass surgery.

To determine the incidence and prognostic significance of new postoperative conduction disturbances, 2,000 consecutive patients who underwent primary elective coronary bypass surgery were evaluated. One hundred eleven (5.5%) of the 2,000 patients developed a new intraventricular conduction defect that persisted to hospital discharge. Right bundle branch block occurred in 86 (85%), left bundle branch block in 5 (4%) and nonspecific intraventricular conduction defect in 9 (11%). One hundred of these 111 patients were successfully matched with others in the study population who had maintained normal intraventricular conduction during the operative period. Patients were matched on the basis of age, gender, absence of preoperative conduction disturbances, left ventricular function and bypass grafts to the same vessels. Follow-up of the two groups for a period of 1 to 76 months (mean 60 months) failed to show any difference in survival or cardiac events such as myocardial infarction, repeat coronary bypass surgery, coronary angioplasty and permanent pacemaker implantation. The appearance of right or left bundle branch block or a nonspecific intraventricular conduction defect after coronary bypass surgery does not appear to have an unfavorable impact on the long-term prognosis of these patients.

Dipyridamole thallium imaging may not be a reliable screening test for coronary artery disease in patients undergoing vascular surgery.

Dipyridamole thallium imaging has been proposed for cardiac risk stratification in patients undergoing peripheral vascular surgery. The purpose of this study was to define the benefit of this investigation in routine preoperative evaluation of these patients. The outcome of 86 patients undergoing vascular surgery procedures was examined in light of preoperative clinical assessment and dipyridamole SPECT thallium imaging (DST). Fifty-one patients (59%) were considered at high risk on clinical grounds, and 22 patients (26%) had perfusion defects. Ten patients suffered a perioperative coronary event, including unstable angina, myocardial infarction, or cardiac death. Seven of the patients with such events were among the 51 clinically high-risk subjects (14%). Three perioperative events occurred in the group of 19 patients with positive DST images who underwent surgery (16%), but the DST test failed to identify 7 patients who suffered coronary events. The frequency of abnormal thallium imaging was similar to the prevalence of angiographically significant coronary disease reported previously at this center, but considerably less than the rate of abnormal thallium imaging in past studies of vascular surgery patients. The application of the test to a low to moderate risk population is probably responsible for its lower predictive accuracy for coronary events. DST is not an ideal routine noninvasive technique for risk stratification in patients undergoing vascular surgery.