Outpatient cardiology: follow-up after myocardial infarction

BACKGROUND: If an observer first learns to recognize an object in a specific orientation, a significant increase in processing time usually occurs when the object is subsequently seen in a different orientation; this phenomenon is called the "misorientation effect." The present study examines how quickly and how accurately human observers discriminate between airport maps that are viewed in orientations other than those in which they were initially learned. METHOD: Participants were trained to discriminate between two navigation maps that were seen in only one orientation; they subsequently were tested with maps and aerial photographs of the same airports that were presented in various orientations. RESULTS AND CONCLUSIONS: There were three principal findings: a) discriminative responses to maps of airports were most rapid when the maps were seen in the same orientation as that in which they were initially learned; b) a significant reduction in reaction time (RT) occurred with repeated presentations of the misoriented stimuli; and c) information learned from navigation maps was not sufficient for all observers to recognize aerial photographs of the same airports.     

Coronary angioplasty, a privileged method of myocardial revascularization of the elderly

Coronary angioplasty is a myocardial revascularisation technique of choice in the elderly, avoiding the need for general anesthesia as well as the complications of thoracotomy and extracorporeal circulation. Used in a continuous series of 62 patients, it provided a 79% primary success rate in this situation, where reaching the coronary artery and penetrating the stenosis may be difficult. Femoral complications (hematoma, false aneurysm) are commoner in this age group, but appear to be beneficially influenced by the replacement of heparin by ticlopidine peri-operatively. With 24 months follow-up, the proportion of patients free of any major cardiac event and NYHA classes I and II is 66%, actuarial survival rate without infarction is 76%. These results would tend to restrict the indications for bypass after the age of 75 to cases of stenosis of the left main coronary artery, failure of angioplasty or multi-vessel atheroma with a "culprit lesion" inaccessible to dilatation.     

Coronary intervention in myocardial infarction

The ability to achieve rapid and sustained reperfusion in cases of acute MI with an interventional approach constitutes a true revolution in the practice of cardiology. This article discusses those interventions.     

Improvement in long-term prognosis of elderly patients with acute myocardial infarction after the introduction of intravenous thrombolytic therapy

Survival rate from a "thrombolytic" period of 351 patients above 66 years of age with acute myocardial infarction (AMI) was compared with that of 289 patients from a "prethrombolytic" period. The two groups were comparable regarding sex, age, previous AMI, cerebrovascular events, morbidity and mortality during admission. Survival rates after four years were 45.0% in the "thrombolytic" group and 38.4% in the "prethrombolytic" group (p = 0.047, log rank test). Using the Cox proportional hazard analysis, thrombolytic therapy was shown to be an independent prognostic predictor in "the thrombolytic population" with a relative risk of death from day 30 to end of follow-up of 0.4 (95% confidence interval 0.2-0.8). No interaction was found between age and thrombolysis. Although only one-fifth of the patients with AMI were eligible for thrombolysis, this treatment may have contributed to the improved long-term survival.     

Coronary arterial hyperreactivity and mesenteric arterial hyporeactivity after myocardial infarction in the rat

After myocardial infarction, several neurohumoral systems become activated to maintain systemic perfusion pressure. We evaluated whether this leads to alterations of wall structure and contractile reactivity in the thoracic aorta, coronary septal artery, and mesenteric resistance arteries. In male Wistar rats, myocardial infarction (MI) was induced by permanent ligation of the left coronary artery. At 5 weeks after MI or sham operation, vessel segments were isolated, chemically sympathectomized, and mounted in a myograph for recording of isometric force development. Contractile reactivity to high potassium, norepinephrine, phenylephrine, serotonin, and Arg-vasopressin was determined. At the end of the experiments, vessels were fixed for morphometric analysis (cross-sectional area, media thickness, radius, and wall-to-lumen ratio). At 5 weeks after myocardial infarction, no alterations of contractile reactivity or wall structure were observed in the thoracic aorta of MI rats. In mesenteric resistance arteries, a nonselective reduction of maximal active wall tension and of active wall stress in response to vasoconstrictors was observed, whereas vessel wall structure and sensitivity to stimuli were not modified. On the other hand, coronary septal arteries displayed hyperreactivity to all strong contractile stimuli. These observations demonstrate a heterogeneity of arterial reactivity changes at 5 weeks after MI in the rat: (a) no alterations in thoracic aorta, (b) hyporeactivity of mesenteric resistance arteries despite maintenance of media mass, and (c) hyperreactivity of coronary vessels obtained from the hypertrophic remnant myocardium. This could result from the complex regional hemodynamic and neurohumoral changes associated with heart failure and may contribute to the further deterioration of cardiovascular function in this setting.     

Improved long-term prognosis after myocardial infarction 1984-1991

AIMS: We set out to examine whether long term prognosis in terms of 2-year mortality after myocardial infarction has improved after the introduction of intravenous beta-blockers, nitroglycerin infusion, aspirin and thrombolytics, in an unselected population of patients hospitalized with a myocardial infarction. METHODS AND RESULTS: We investigated retrospectively 3791 acute myocardial infarctions in 3187 G?teborg women and men (1039 women and 2148 men), who were consecutively admitted to the coronary care unit at the Ostra hospital during 1984-1991. Throughout this period, data were entered continuously into the coronary care unit database. Mortality data were collected through the Swedish cause-specific mortality register. The primary end-point was mortality within 2 years after the onset of the index infarction. Two-year mortality decreased from 36% in 1984 to 25% in 1991. In a Cox regression model (including myocardial infarctions up to 1993) year of hospitalization, age, diabetes mellitus, sex, prior myocardial infarction and indeterminable infarct location all had a significant impact on survival after myocardial infarct. Thrombolytic therapy and hypertension had no prognostic significance. CONCLUSION: Against a background of radical changes in the treatment of acute myocardial infarction during 1984-1991 we have seen decreasing in-hospital mortality as well as a substantial decrease in 2-year mortality.     

Treatment of myocardial ischemia and myocardial infarction in the elderly

The diagnosis of coronary artery disease in the elderly is problematic because older patients often present atypical symptoms or are asymptomatic. Once coronary disease is diagnosed, the proper course of treatment is not always clear, since few studies have focused on patients older than 65 years. Moreover, older patients often have medical conditions that may aggravate coexisting cardiovascular problems or interfere with conventional pharmacotherapy. For these reasons many physicians who treat cardiovascular problems aggressively in younger patients are reluctant to do so in older individuals. There is considerable evidence, however, that older patients could benefit as much or more from aggressive therapy because of their greater risk of mortality from myocardial ischemia and infarction.     

Poor long-term survival after acute myocardial infarction among patients on long-term dialysis

BACKGROUND: Cardiovascular disease is common in patients on long-term dialysis, and it accounts for 44 percent of overall mortality in this group. We undertook a study to assess long-term survival after acute myocardial infarction among patients in the United States who were receiving long-term dialysis. METHODS: Patients on dialysis who were hospitalized during the period from 1977 to 1995 for a first myocardial infarction after the initiation of renal-replacement therapy were retrospectively identified from the U.S. Renal Data System data base. Overall mortality and mortality from cardiac causes (including all in-hospital deaths) were estimated by the life-table method. The effect of independent predictors on survival was examined in a Cox regression model with adjustment for existing illnesses. RESULTS: The overall mortality (+/-SE) after acute myocardial infarction among 34,189 patients on long-term dialysis was 59.3+/-0.3 percent at one year, 73.0+/-0.3 percent at two years, and 89.9+/-0.2 percent at five years. The mortality from cardiac causes was 40.8+/-0.3 percent at one year, 51.8+/-0.3 percent at two years, and 70.2+/-0.4 percent at five years. Patients who were older or had diabetes had higher mortality than patients without these characteristics. Adverse outcomes occurred even in patients who had acute myocardial infarction in 1990 through 1995. Also, the mortality rate after myocardial infarction was considerably higher for patients on long-term dialysis than for renal-transplant recipients. CONCLUSIONS: Patients on dialysis who have acute myocardial infarction have high mortality from cardiac causes and poor long-term survival.     

Myocardial revascularization with one and two mammary arteries: clinical results and long-term follow-up

The manufacturing process for albumin in Australia is based primarily on ion-exchange chromatography. The capacity of ion-exchange matrices to remove non-enveloped viruses (canine parvovirus and poliovirus type 1) was assessed using a scaled-down chromatographic process which was shown to yield product meeting purity criteria set for the manufacturing process. Poliovirus type 1 and canine parvovirus were added at one tenth the volume of desalted and delipidated Supernatant II + III produced by traditional Cohn Fractionation from human plasma before the material was applied to DEAE and CM ion-exchangers connected in series. Samples were taken at equilibration, wash, elution and regeneration steps and the log clearance and reduction of the viruses calculated. The mean clearance and reduction factors for viral load of poliovirus type 1 were 5.3 logs and 3.2 logs, respectively and 1.8 logs and 1.8 logs for canine parvovirus.     

Coronary recanalization by elective angioplasty prevents ventricular dilation after anterior myocardial infarction

OBJECTIVES: In a prospective study we evaluated whether late recanalization of the left anterior descending coronary artery (LAD) affects ventricular volume and function after anterior myocardial infarction. BACKGROUND: Persistent coronary occlusion after anterior myocardial infarction leads to ventricular dilation and heart failure. METHODS: We studied 73 consecutive patients with acute anterior myocardial infarction as a first cardiac event; all had an isolated lesion or occlusion of the proximal LAD. Six patients died before hospital discharge. The 67 survivors were classified into two groups: group I (patent LAD and good distal flow, n = 40) and group II (LAD occlusion or subocclusion, n = 27). The 20 patients in group I who had significant residual stenosis and all patients in group II underwent elective percutaneous transluminal coronary angioplasty (PTCA) within 18 days of myocardial infarction. The procedure was successful in 17 patients in group I (group IB) and in 16 patients in group II (group IIA): in the remaining 11 patients of group II, patency could not be reestablished (group IIB). Left ventricular volumes, ejection fraction and a dysfunction score were measured by echocardiography on admission, before PTCA, at discharge and after 3 and 6 months. RESULTS: Although cumulative ST segment elevation was similar in groups I and II, ejection fraction and dysfunction score were significantly worse in group II. However, ventricular function and volumes progressively improved in group IIA, whereas group IIB exhibited progressive deterioration of function (dysfunction score [mean +/- SD] increased from 21 +/- 6 to 25 +/- 8, p < 0.05; ejection fraction decreased from 43 +/- 10% to 37 +/- 11%, p < 0.05); and end-systolic volume increased from 34 +/- 10 to 72 +/- 28 ml/m2, p < 0.05). Patients in group IIB also had worse effort tolerance, higher heart rate at rest, lower blood pressure and significantly greater prevalence of chronic heart failure. CONCLUSIONS: Delayed PTCA of an occluded LAD can frequently restore vessel patency. Success appears to be associated with better ventricular function and a lack of chronic dilation. Large randomized studies are warranted to evaluate the effect of delayed PTCA on late mortality.     

Temporal changes in the care and outcomes of elderly patients with acute myocardial infarction, 1987 through 1990

OBJECTIVE: To investigate changes between 1987 and 1990 in the care and outcomes associated with acute myocardial infarction (AMI) in elderly patients. DESIGN: Retrospective cohort study using a longitudinal database created from Medicare administrative files. PATIENTS: Cohorts comprising a total of 856,847 AMI patients insured by Medicare between 1987 and 1990. MAIN OUTCOME MEASURES: Annual rates of mortality at 30 days and 1 year following AMI, and the use of coronary angiography, coronary artery bypass graft surgery, and percutaneous transluminal coronary angioplasty during the first 90 days after a new AMI. RESULTS: Between 1987 and 1990, mortality rates decreased 10% overall from 26% to 23% at 30 days (P < .001) and from 40% to 36% at 1 year following AMI (P < .001). Declines in mortality and adjusted risks of 1-year mortality were similar in men and women and in blacks and whites, but mortality declines were more evident in those younger than 85 years. Meanwhile, the proportion of elderly AMI patients having angiography within the first 90 days after their index admission increased from 24% to 33% (P < .001); proportions increased for both genders and all races. The proportion of patients undergoing revascularization procedures increased from 13% to 21%; while rates of bypass surgery increased from 8% to 11%, rates of angioplasty doubled from 5% to 10% (all P < .001). CONCLUSIONS: Between 1987 and 1990, survival of elderly patients following AMI improved significantly. While changes in patient treatment may be responsible, the increased use of thrombolytic therapy appears to be only a partial explanation. Also, while the use of coronary angiography and revascularization procedures increased dramatically, the degree to which it caused the improvement in survival could not be determined.     

Improvement in exercise performance after unsuccessful myocardial revascularization

Two types of mechanosensitive units were found in the parenchyma of the rat mammary gland (SA and RA). Most of SA units had a spontaneous activity 1-3/sec. and responded to an abrupt displacement with a decline in the activity for 5-10 sec. RA had no such a response. The relation between average firing rate and displacement velocity at a constant displacement amplitude was linear for both SA and RA. RA however had the velocity threshold higher than SA. The number and frequency of SA afferent impulses decreased at a repeated stimulation. Electron microscopy revealed that free nerve endings correspond to SA and RA.     

Acute myocardial infarction: prognosis after recovery

A prognostic index for 2-year survival after recovery from acute myocardial infarction was constructed from variables obtained during its course. One hundred ten of 143 patients survived 2 years, and 27 of 33 patients died of cardiac-related causes. Univariate analysis showed that 12 variables were significantly different between the surviving and nonsurviving groups. Discriminant analysis indicated five variables with meaningful predictive value to be included in a prognostic index: admission systolic blood pressure; highest blood urea nitrogen level in the cardiac care unit: atrial arrhythmias in the cardiac care unit; angina pectoris for more than 3 months or a previous myocardial infarction; and more than one ventricular ectopic beat per hour recorded on a dynamic electrocardiogram during the 17th to 24th hospital day. The prognostic index emphasizes the importance of extensive myocardial impairment and provides a means for identifying patients at risk of early mortality.     

Transmyocardial laser revascularization fails to prevent left ventricular functional deterioration and aneurysm formation after acute myocardial infarction in sheep

OBJECTIVE: Transmyocardial laser revascularization is an investigational technique for revascularizing ischemic myocardium in patients with inoperable coronary arterial disease. This study tests the hypothesis that laser revascularization prevents left ventricular functional deterioration and aneurysm formation after acute anteroapical myocardial infarction. METHODS: An ultrasonic ascending aortic flow probe and snares around the distal left anterior descending and second diagonal coronary arteries were placed in 26 Dorsett hybrid sheep. Ten to 14 days later, snared arteries were occluded to produce an anteroapical infarction of 23% of left ventricular mass. Before infarction 14 animals had 34 +/- 4 transmyocardial perforations in the area of the anticipated infarction made with a carbon dioxide laser. Twelve animals served as controls. Hemodynamic measurements and transdiaphragmatic quantitative echocardiograms were obtained before, immediately after, and 2, 5, and 8 weeks after infarction. Eighteen sheep completed the protocol. RESULTS: All animals had large anteroapical left ventricular aneurysms with massive ventricular enlargement. Immediately after infarction the anterior wall became thinner and dyskinetic in all sheep. At 8 weeks aneurysmal size and shape were indistinguishable between groups. Two days after infarction, laser holes were filled with fibrin. At 5 and 8 weeks the infarct consisted of dense collagen, fibroblasts, scattered calcifications, myocyte fragments, neutrophils, macrophages, and no laser holes. There were no significant differences at any time between groups for cardiac pressures or output, ventricular volumes, ejection fraction, stroke work, and the stroke work-left ventricular end-diastolic pressure index. CONCLUSION: Transmyocardial laser perforations do not revascularize acute myocardial infarction in sheep.     

Atenolol use and clinical outcomes after thrombolysis for acute myocardial infarction: the GUSTO-I experience. Global Utilization of Streptokinase and TPA (alteplase) for Occluded Coronary Arteries

OBJECTIVES: We assessed the use and effects of acute intravenous and later oral atenolol treatment in a prospectively planned post hoc analysis of the GUSTO-I dataset. BACKGROUND: Early intravenous beta blockade is generally recommended after myocardial infarction, especially for patients with tachycardia and/or hypertension and those without heart failure. METHODS: Besides one of four thrombolytic strategies, patients without hypotension, bradycardia or signs of heart failure were to receive atenolol 5 mg intravenously as soon as possible, another 5 mg intravenously 10 min later and 50 to 100 mg orally daily during hospitalization. We compared the 30-day mortality of patients given no atenolol (n=10,073), any atenolol (n=30,771), any intravenous atenolol (n=18,200), only oral atenolol (n=12,545) and both intravenous and oral drug (n=16,406), after controlling for baseline differences and for early deaths (before oral atenolol could be given). RESULTS: Patients given any atenolol had a lower baseline risk than those not given atenolol. Adjusted 30-day mortality was significantly lower in atenolol-treated patients, but patients treated with intravenous and oral atenolol treatment vs. oral treatment alone were more likely to die (odds ratio, 1.3; 95% confidence interval, 1.0 to 1.5; p=0.02). Subgroups had similar rates of stroke, intracranial hemorrhage and reinfarction, but intravenous atenolol use was associated with more heart failure, shock, recurrent ischemia and pacemaker use than oral atenolol use. CONCLUSIONS: Although atenolol appears to improve outcomes after thrombolysis for myocardial infarction, early intravenous atenolol seems of limited value. The best approach for most patients may be to begin oral atenolol once stable.     

Coronary thrombosis during acute myocardial infarction: Roberts was right!

Pathologic studies have varied with clinical belief regarding the role of acute thrombotic occlusion as the inciting event during myocardial infarction. Aspiration thrombectomy, by employing a new catheter, has been performed during myocardial infarction and confirms the pathologic findings that intracoronary thrombus is absent in a substantial number of patients with acute myocardial infarction.