Differences in left ventricular function between anterior and inferior myocardial infarction of equivalent enzymatic size

The reasons for the poorer prognosis of anterior versus inferior myocardial infarction of equivalent enzymatic size remain uncertain. We investigated whether there are differences in left ventricular function between patients with anterior and inferior infarctions of equivalent enzymatic size to account for their differing outcomes. Clinical, serum enzyme, and electrocardiographic data were prospectively recorded in a consecutive series of patients less than 70 years of age with their first myocardial infarction. At 29 +/- 6 days following infarction, ejection fraction and left ventricular wall motion were assessed by gated heart scintigraphy and functional capacity by treadmill exercise testing in 19 patients with anterior and in 23 patients with inferior myocardial infarction. Peak creatine kinase and QRS scores were used to estimate total infarct size and left ventricular infarct size respectively. The anterior infarcts were of similar size to the inferior infarcts as determined by peak creatine kinase (1444 [mean] +/- 1161 [SD] U/L versus 1484 [mean] +/- 1182 [SD] U/L, respectively, P = 0.91) and peak aspartate transaminases (174 +/- 112 U/L versus 164 +/- 102 U/L, P = 0.78). The anterior myocardial infarct group had a greater percentage of the left ventricle infarcted on QRS scoring than the inferior infarct group (25.9 +/- 14.4% versus 11.1 +/- 6.0% respectively, P = 0.0004), lower global left ventricular ejection fraction (45.8 +/- 16% versus 54.6 +/- 9.2%, P = 0.04) and greater left ventricular regional wall abnormality. A significant negative correlation existed between left ventricular ejection fraction and peak creatine kinase for both groups, but was more marked with anterior infarction (r = -0.78, P less than 0.01) compared with inferior infarction (r = -0.49, P less than 0.05). Exercise-induced ST segment elevation was more frequent in the anterior than the inferior infarct group (59% versus 18%, P less than 0.02). However, both infarct locations had similar exercise tolerance, exercise-induced angina and ST segment depression. Despite equivalence of infarct size of the two infarct locations on enzyme testing, anterior infarction was associated with greater abnormality of left ventricular function with lower resting global left ventricular ejection fraction; greater resting left ventricular regional wall abnormality and greater exercise-induced ST segment elevation. These differences probably contribute to the poorer prognosis of patients with anterior infarction compared to those with inferior infarction of equivalent enzymatic size, given the previously well-documented prognostic importance of left ventricular function.     

Right ventricular infarction with shock but without significant left ventricular infarction: a new clinical syndrome

Right ventricular infarction has been described as concurrent with infarction involving the inferior (posterior) aspect of the left ventricular free wall and adjacent interventricular septum. Patients with right ventricular infarction typically show the ECG changes of inferior infarction in leads II, III, and aVF. This report describes two patients with right ventricular infarction but without changes in the QRS complex of the ECG, indicating an inferior infarct of the left ventricle. An autopsy-proven infarct of the right ventricular free wall with neither QRS nor other clinical evidence of left ventricular involvement was responsible for cardiogenic shock and death in one patient. This observation led to a review of a computerized data bank containing records of patients who had undergone cardiac catheterization to determine if there were other patients with clinical criteria suggesting right ventricular infarction without QRS changes of left ventricular infarction. One of the 167 patients with a history of a myocardial infarction also met the following clinical criteria: (1) transiently elevated total creatine kinase and creatine kinase myocardial band; (2) diffuse ST segment elevation without QRS changes indicative of left ventricular infarction on the ECG; (3) normal left ventricular function; (4) hemodynamic evidence of right ventricular dysfunction; and (5) cardiogenic shock.     

Influence of left ventricular function on signal averaged late potentials in patients with coronary artery disease with and without ventricular tachycardia

Left ventricular dysfunction has been suggested as a cause of late potentials on the signal averaged ECG of patients with coronary artery disease. We compared the averaged surface ECG with angiographic findings in 57 patients with coronary artery disease and left ventricular dysfunction. Sixteen patients had sustained ventricular tachycardia and 41 had no documented arrhythmia. These two patient groups were comparable with respect to age, mean ejection fraction, and wall motion score. Late potentials, defined as voltage less than 25 microV in the last 40 msec of the filtered QRS complex, were found in 10 of 16 patients with ventricular tachycardia and in 6 of 41 patients without arrhythmia (p less than 0.005). However, late potentials were independent of ejection fraction, wall motion score, or presence of dyskinesis in both groups. There was no correlation between the total filtered QRS duration and ejection fraction or wall motion score in either patient group. In patients with coronary artery disease, late potentials are associated with ventricular tachycardia but are independent of global or regional left ventricular function. This finding has important implications for studies of the prognostic value of late potentials following myocardial infarction.     

Prolongation of the averaged QRS complex. A simple prognostic factor in patients with post-infarction bundle branch block and a history of syncope

Patients with a history of myocardial infarction and complete bundle branch block with syncopal episodes have a high risk of sudden death: the identification of the cause of the syncope is therefore essential. The aim of the study was to assess the diagnostic value of non-invasive techniques used in the investigations of syncope: 24 hour Holter recording, high amplification ECG and measurement of left ventricular ejection fraction. The results of these investigations were compared with those of complete electrophysiological investigation evaluating atrioventricular conduction and the inducibility of tachycardia. The patient population was 134 patients, 83 with right bundle branch block and 51 with left bundle branch block. Ninety one patients had inducible sustained ventricular tachycardia and 24 had atrioventricular conduction defects: of these, 14 also had ventricular tachycardia. During follow-up, there were 12 sudden deaths and 13 deaths from cardiac failure. Uni- and multivariate analysis showed induction of ventricular tachycardia to be a significant risk factor for global mortality and sudden death but prolongation of the averaged QRS complex (> 165 msec) was also an independent risk factor of global cardiac mortality. The authors conclude that simple prolongation of the averaged QRS duration > 160 ms in patients with right bundle branch block and > 170 ms in patients with left bundle branch block after myocardial infarction and syncope is a significant poor prognostic factor. However, this sign is not predictive of sudden death.     

Global and regional right ventricular function after acute myocardial infarction: dependence upon site of left ventricular infarction

The relation of global and regional right and left ventricular function during the acute phase after a first myocardial infarction was assessed by first pass radionuclide angiography in 20 patients (10 after anterior and 10 after inferior myocardial infarction). The right ventricular ejection fraction did not differ significantly between the groups, but left ventricular ejection fraction was significantly depressed after anterior myocardial infarction. There was evidence of right ventricular dilatation and impaired transit in the group with inferior infarction. Five patients with anterior infarction and six with inferior infarction had abnormal right ventricular ejection fractions. Right ventricular wall motion abnormalities affected the septal wall in the group with anterior infarction and the free wall in the group with inferior infarction. The relation between right and left ventricular ejection fractions was markedly different in the two groups. In the group with anterior infarction there was a significant linear relation between right and left ventricular ejection fraction, whereas in the group with inferior infarction there was not. Thus right ventricular dysfunction commonly occurs after both anterior and inferior myocardial infarction. Right and left ventricular impairment are related after anterior myocardial infarction, but are independent after inferior myocardial infarction. Finally, the different effects of anterior and inferior myocardial infarction on right ventricular function may be explained by differences in septal and free wall involvement.     

Usefulness of QRS prolongation in predicting risk of inducible monomorphic ventricular tachycardia in patients referred for electrophysiologic studies

QRS prolongation on surface electrocardiography has been identified as a marker for increased cardiac mortality. A potential mechanism for increased mortality is ventricular tachycardia (VT). This study aimed to evaluate the relation between bundle branch block and sustained monomorphic VT inducibility in patients referred for electrophysiologic studies. We analyzed a cohort of 777 patients (age 63 +/- 18 years, 67% men, left ventricular [LV] ejection fraction [EF] 45% +/- 16, prior myocardial infarction 41%) referred for electrophysiologic studies between 1994 and 2001 who underwent programmed stimulation for VT. Forty-five percent of patients were referred for syncope or a history of VT and/or ventricular fibrillation. Thirty-one percent of patients had prolonged QRS duration (> or =120 ms). Patients with prolonged QRS duration were older, had lower LVEFs, and were more likely to have a history of myocardial infarction. Prolonged QRS was a significant predictor of sustained monomorphic VT inducibility (p <0.0001). On multivariate analysis correcting for age, sex, LVEF, history of myocardial infarction, medications, and QRS conduction delay proved to be independently associated with sustained monomorphic VT inducibility (relative risk 3.290, 95% confidence interval 2.185 to 4.953 for prolonged vs normal QRS duration). Thus, a prolonged QRS duration on surface electrocardiography is a strong, independent predictor of inducible sustained monomorphic VT. Conduction delay may be an important risk factor, providing a substrate for the development of reentrant monomorphic VT, and furthermore suggests a potential mechanism for the increased mortality observed in patients with prolonged QRS.     

Regional left ventricular function in acute myocardial infarction: Evaluation with quantitative radionuclide ventriculography

Regional and global left ventricular performance was noninvasively assessed with quantitative gated equilibrium radionuclide ventriculography in 43 patients an average of 40 hours after the onset of a first acute transmural myocardial infarction. In all 16 patients with anterior infarction, regional ejection fraction, a quantitative measure of regional left ventricular performance, was uniformly depressed in the infarcted zone. In patients with inferior infarction the abnormalities of regional performance were less severe. Fourteen of 20 patients (70 percent) with inferior infarction had depressed performance in the infarcted zone. Function in noninfarcted zones was abnormal in only 6 of the 20 patients (30 percent) with inferior infarction, but it was abnormal in 11 of the 16 patients (69 percent) with anterior infarction, particularly in those with severe pump failure. As a consequence, global left ventricular ejection fraction was significantly lower in patients with anterior than in those with inferior infarction (mean ± standard error of the mean 31 ± 3 percent versus 51 ± 3 percent, p < 0.005). Prognosis and clinical functional class were related to performance not only in infarcted zones, but also in noninfarcted zones as assessed with electrocardiography.It is concluded that depressed function in apparently noninfarcted left ventricular zones contributes significantly to left ventricular dysfunction after acute myocardial infarction, particularly in patients with anterior infarction.     

Global and regional right ventricular function after acute myocardial infarction: dependence upon site of left ventricular infarction.

The relation of global and regional right and left ventricular function during the acute phase after a first myocardial infarction was assessed by first pass radionuclide angiography in 20 patients (10 after anterior and 10 after inferior myocardial infarction). The right ventricular ejection fraction did not differ significantly between the groups, but left ventricular ejection fraction was significantly depressed after anterior myocardial infarction. There was evidence of right ventricular dilatation and impaired transit in the group with inferior infarction. Five patients with anterior infarction and six with inferior infarction had abnormal right ventricular ejection fractions. Right ventricular wall motion abnormalities affected the septal wall in the group with anterior infarction and the free wall in the group with inferior infarction. The relation between right and left ventricular ejection fractions was markedly different in the two groups. In the group with anterior infarction there was a significant linear relation between right and left ventricular ejection fraction, whereas in the group with inferior infarction there was not. Thus right ventricular dysfunction commonly occurs after both anterior and inferior myocardial infarction. Right and left ventricular impairment are related after anterior myocardial infarction, but are independent after inferior myocardial infarction. Finally, the different effects of anterior and inferior myocardial infarction on right ventricular function may be explained by differences in septal and free wall involvement.     

Bradycardia and hypotension following reperfusion with streptokinase (Bezold-Jarisch reflex): a sign of coronary thrombolysis and myocardial salvage

Acute myocardial infarction, particularly of the inferior wall, is frequently associated with bradycardia and hypotension. This study reports the occurrence of transient bradycardia hypotension (TBH) (Bezold-Jarisch reflex) following thrombolytic therapy with intravenous streptokinase. Of the 52 patients, 42 had successful reperfusion, and 12 of the latter developed reflex TBH. The Bezold-Jarisch reflex occurred in 10 of 24 patients with inferior wall acute myocardial infarction and in 2 of 28 patients with anterior wall infarction (p less than 0.05). The reflex was associated with significantly more non-Q wave infarctions (p less than 0.05) and also with reduction of left ventricular damage, as evidenced by a lower QRS score (4 +/- 3.8 vs 8.9 +/- 5.6, p less than 0.01) and a higher ejection fraction (61 +/- 13% vs 49 +/- 16%, p less than 0.05). Patients with inferior wall acute myocardial infarction were divided into those with TBH (10 patients) and those without TBH (14 patients). TBH was associated with a significantly higher infarct-related regional ejection fraction (60 +/- 19% vs 35 +/- 18%, p less than 0.05). The results of this study confirm previous findings that reperfusion of the inferoposterior myocardium is capable of stimulating reflex TBH. Furthermore, TBH is associated with patency of infarct-related coronary arteries and myocardial salvage.     

Radionuclide assessment of regional left ventricular function in acute myocardial infarction

To determine changes in global and regional left ventricular function following acute myocardial function, 17 patients underwent radionuclide angiography at 3 and 10 days post infarction. Five patients had nontransmural myocardial infarction and 12 had transmural infarction (six anterior and six inferior). There were no previous infarctions in 16 (94%) patients. Regional ejection fractions were calculated by dividing the left ventricle into four quadrants using the geometric center of the left ventricle on the end-diastolic frame as a reference point. At 3 days post infarction, 8 of 17 (47%) patients had an abnormality of global left ventricular ejection fraction (LVEF), whereas 16 of 17 (94%) patients had abnormalities of one or more regional ejection fractions (p less than 0.01). Between 3 and 10 days, global LVEF did not change (51% to 49%, p = NS). However, there were significant changes in 23 of 68 (34%) regional LVEFs. These changes did not relate to type, ECG location, creatine kinase (CK) size of infarction, or initial global LVEF. These data suggest that regional LVEF is a sensitive technique for identifying segmental dysfunction associated with myocardial infarction. In addition, significant changes occur in regional LV function during acute myocardial infarction despite stable serial global LV performance.     

Extension of necrosis and left ventricular function in recent myocardial infarct. Correlation between a QRS scoring system and various echocardiographic indexes

The purpose of this study was to evaluate the extension of myocardial necrosis and the impairment of left ventricular function in patients with recent myocardial infarction by means of the standard 12-lead ECG. Then, we tried to correlate the QRS scoring system proposed by Wagner and coll. with some indexes obtained from a M-Mode and Two-Dimensional echocardiographic examination (echo-score, number of compromised areas, E-septum separation and left ventricular ejection fraction) in a group of 105 pts. (mean age 61.54 +/- 9.66 SD years). Patients were divided into three groups: 47 with anterior infarction, 45 with inferior infarction and 13 with anterior and inferior infarction. A statistically significant correlation was found between the QRS scoring system and (a) the infarct size (r between ECG-score and echo-score = 0.40, p less than 0.001; r between ECG-score and compromised areas = 0.47, p less than 0.001) and (b) left ventricular ejection fraction (r = -0.48, p less than 0.001), measured echocardiographically, particularly in pts. with anterior infarction. No correlation was found with the E-septum separation. In conclusion, the correlation between QRS scoring system and echo indexes appeared statistically significant, even if minimally applicable to single cases.     

Factors determining the occurrence of late potentials on the signal-averaged electrocardiogram after a first myocardial infarction: a multivariate analysis

To determine the natural history of late potentials on the signal-averaged electrocardiogram (ECG), multivariate analysis was performed in 167 patients (138 men, 29 women) with a first anterior or inferior acute myocardial infarction. Seventy-four patients received thrombolytic therapy; the remaining 93 patients were treated conventionally. All patients underwent coronary angiography, left ventricular ejection fraction determination and signal-averaged ECG recording. Eight variables thought to be correlated with the presence of late potentials were studied; that is, age, infarct location, number of diseased coronary vessels, left ventricular ejection fraction, infarct-related coronary artery patency, treatment received, delay between admission and signal-averaged recording and delay between admission and coronary angiography. Statistical analysis showed that two independent factors (coronary artery occlusion and impaired left ventricular ejection fraction) were highly correlated with the incidence of late potentials. The occurrence of late potentials was multiplied by 5 in case of an occluded infarct-related vessel and by 1.75 each time the left ventricular ejection fraction value decreased by 0.10. This study suggests that coronary artery patency is the most important factor that decrease the rate of late potentials after a first acute myocardial infarction and it occurs independently of infarct location and left ventricular function.     

Vectorcardiographic, electrocardiographic, and angiographic correlations in apparently isolated inferior wall myocardial infarction.

Twenty-six patients with ECG evidence of localized inferior myocardial infarction and poor ejection fraction (less than 50 per cent) were compared with 26 patients with similar ECG's, but with normal ejection fraction (over 50 per cent). The poor ejection fraction group had significantly more frequent and more severe disease in left anterior descending artery and a higher incidence of triple coronary obstruction than the normal ejection fraction group. The poor ejection fraction group had a significantly greater incidence of ventricular asynergy in the anterior and apical segments of left ventricle. Vectorcardiography was available in 35 of the 52 patients studied and frequently supplied diagnostic information not available in the scalar ECG's. Of 18 patients with scalar ECG patterns of isols, vectorcardiography identified five cases with anterior infarction, three with left ventricular hypertrophy, and one with left anterior hemiblock. Vectorcardiography is a valuable supplementary tool in the clinical assessment of patients with apparently isolated inferior infarction. When extensive coronary and poor ventricular function exist, VCG clues may be expected in about half the patients.     

Clinical, hemodynamic and angiographic aspects of inferior and anterior myocardial infarctions in patients with angina pectoris

Clinical, hemodynamic and angiographic findings were reviewed in 82 patients with isolated inferior, 55 patients with isolated anterior and 27 with combined inferior and anterior myocardial infarction and were compared with findings in 100 patients without electrocardiographic evidence of a prior transmural myocardial infarction. All of the 264 patients were referred and evaluated because of angina pectoris and found, on selective coronary angiography, to have coronary artery disease. There was no significant difference in the ages of the patients in each group studied. A history of heart failure, audible gallops and cardiomegaly were more prevalent in the two groups with anterior infarction (isolated and combined with inferior infarction) than in the other two groups. The mean left ventricular hemodynamic measurements (end-diastolic pressure, end-diastolic volume and ejection fraction) in the groups of patients with a normal QRS or an isolated inferior myocardial infarction were not significantly different from those of patients with a normal left ventricle. Patients with isolated anterior myocardia infarction had abnormal end-diastolic pressure (68 percent), end-diastolic volume (51 percent) and ejection fraction (67 percent). Similarly, the group with multiple infarctions had abnormal hemodynamic measurements, with 81 percent having an abnormal ejection fraction. For the entire group of patients studied, an abnormal end-diastolic volume was always associated with an abnormal ejection fraction. Cardiomegaly on X-ray film was associated with an abnormal end-diastolic volume and ejection fraction. An abnormal contractile pattern (asynergy) was noted in 42 percent of the patients with a normal QRS; inferior asynergy was observed in 88 percent with inferior infarction, and anterior or apical asynergy, or both, was found in 90 percent with anterior infarction. All the patients with multiple infarctions had asynergy. The right coronary artery was significantly involved in 90 percent of the patients with inferior infarction, while all the patients with anterio infarction had significant disease of the left anterior descending artery. More than 80 percent of the patients with an infarction pattern on electrocardiogram had double or triple vessel disease, as compared with 68 percent of the patients with a normal QRS pattern. This study represents a select group of patients referred because of angina pectoris and cannot be extended to the asymptomatic patient with coronary artery disease. The observations made on these patients indicate that an anterior infarction (isolated or combined with inferior) in patients referred because of angina pectoris is accompanied by significant impairment of left ventricular function, whereas an inferior infarction (isolated), although accompanied by asynergy, is usually associated with normal hemodynamics. The electrocardiogram is not sensitive enough to predict reliably in the individual patient the extent and severity of the coronary artery disease.     

Assessment of right ventricular function in acute inferior myocardial infarction using 133-xenon imaging

The detection of right ventricular dysfunction in acute inferior myocardial infarction is important because of its potentially serious consequences which may be remediable with the appropriate therapeutic manoeuvres. A technique has been developed to assess right ventricular function using 133-xenon. This technique was applied to 26 patients who had sustained an acute inferior myocardial infarction. Right ventricular ejection fractions ranged from 7-54%, mean 30 +/- 11%, which was significantly lower than values obtained from normal volunteers (n = 21), mean 43 +/- 5%, and patients with arteriographically proven coronary artery disease without previous myocardial infarction (n = 12), mean 39 +/- 9%, P less than 0.001, and P less than 0.001, respectively. In the patients with acute inferior myocardial infarction 18 patients (69%) had evidence of right ventricular dysfunction (right ventricular ejection fraction less than 35%). 13/26 patients (50%) had clinical evidence of right ventricular dysfunction with a mean right ventricular ejection fraction 26 +/- 11% (range 7-54%) which was significantly lower than the patients without evidence of right ventricular dysfunction, mean 35 +/- 9% (range 16-49%), P less than 0.001. The clinical signs had a sensitivity of 72% (13/18), a specificity of 87.5% (7/8) and a predictive accuracy of 76% (20/26) when compared to the imaging data. In conclusion: (1) gated 133-xenon imaging provides a method for assessing right ventricular function in the setting of acute myocardial infarction; (2) a wide spectrum of right ventricular dysfunction occurs following inferior myocardial infarction which may not manifest itself clinically.     

Temporal changes in body surface peak R isochrone maps and left ventricular function in patients with myocardial infarction

Body surface peak R isochrone mapping and radionuclide ventriculography were performed twice in 22 patients with myocardial infarction. Eighty-seven unipolar electrocardiograms distributed over the anterior chest and the back were recorded simultaneously. For each lead, the time from the onset of QRS to the peak of the R wave was measured. From this data for 87 leads an isochrone map was constructed. The lead points where R waves were not observed were designated the no R-wave area (No-R area), which was postulated to correspond to the unexcited regional myocardium. Other abnormal findings, i.e., delay of peak R time near the No-R area (peri-No-R area delay), crowding of isochrone lines, and an island-like zone of delayed peak R times were postulated to indicate slow conduction in the partially excited regional myocardium. In three patients, abnormal patterns in the peak R isochrone maps during the acute phase (within a month from the onset of myocardial infarction) improved in the chronic phase with a significant increase in left ventricular ejection fraction. In two patients, the No-R area decreased after the left ventricular aneurysmectomy. In other patients, abnormal patterns of the isochrone maps and the ejection fraction remained unchanged during the chronic phase of myocardial infarction. We conclude that the comparison of peak R isochrone map patterns between the acute and chronic phase may be useful in evaluating the balance of reversible and irreversible regional damage in myocardial infarction.     

Selection of patients for programmed ventricular stimulation: a clinical decision-making model based on multivariate analysis of clinical variables.

OBJECTIVE. This study was conducted to assess the utility of clinical variables in predicting the inducibility of sustained ventricular arrhythmias in a heterogeneous group of patients undergoing programmed ventricular stimulation. METHODS. Variables were considered in a simulated chronologic order to determine the incremental information added by the signal-averaged electrocardiogram (ECG) and left ventricular ejection fraction. All patients undergoing baseline programmed ventricular stimulation for induction of ventricular tachyarrhythmia during a 30-month period were included in the study. Fourteen historical, ECG, signal-averaged ECG and left ventricular wall motion variables were evaluated for their ability in predicting inducibility of a sustained ventricular arrhythmia, a "positive" event, at programmed ventricular stimulation. RESULTS. On univariate analysis of the clinical variables, comparison between patients with positive or negative results showed significant differences in 10 of the 14 clinical variables: major cardiac diagnosis, history of ventricular tachycardia, myocardial infarction by history or ECG, all five signal-averaged ECG variables, left ventricular ejection fraction and presence of left ventricular aneurysm. On multivariate analysis, five independent variables were determined to be important: history of ventricular tachycardia, historical or ECG evidence of myocardial infarction, history of loss of consciousness, filtered QRS duration on the signal-averaged ECG and left ventricular ejection fraction. However, with sequential multivariate analysis, a model based only on historical and conventional ECG data was found to do as well as a model that included signal-averaged ECG and left ventricular ejection fraction data. CONCLUSIONS. Routinely available noninvasive historical, ECG, signal-averaged ECG and left ventricular wall motion variables can be used to accurately predict the outcome of programmed ventricular stimulation. The majority of the predictive power was obtained with the routine model, using only historical and ECG data. The signal-averaged ECG and left ventricular wall motion analysis added no significant incremental information.     

Echocardiographic determinants of left ventricular ejection fraction after acute myocardial infarction

OBJECTIVE: This study was performed to determine if factors other than the size of regional dysfunction influence the global left ventricular ejection fraction after acute myocardial infarction. BACKGROUND: Left ventricular ejection fraction is an important prognostic variable after acute myocardial infarction. Although infarct size is known to affect the subsequent global left ventricular ejection fraction, it remains unclear whether other factors such as site or severity of the wall motion abnormality influence the ejection fraction after acute myocardial infarction. METHODS: Sixty-nine consecutive patients (mean age 61 +/- 14 years, 46 [67%] male) who did not receive thrombolytic therapy or undergo early revascularization were studied by echocardiography 1 week after Q-wave myocardial infarction. The absolute size of the region of abnormal wall motion (AWM) and the percentage of the endocardium involved (%AWM) were quantitated along with the wall motion score. A severity index was then derived as the mean wall motion score within the region of AWM. Site of myocardial infarction was classified as either anterior or inferior from the endocardial map. Left ventricular ejection fraction was measured by Simpson's method with 2 apical views. RESULTS: Twenty-nine (42%) patients had anterior and 40 had inferior myocardial infarction. The mean left ventricular ejection fraction was significantly lower in anterior than in inferior myocardial infarction (44.8% +/- 11.5% vs 53% +/- 8.6%; P =. 001). The mean %AWM was greater in anterior than in inferior myocardial infarction (32.1 +/- 15.5 vs 22.4 +/- 14.1; P =.01). The mean wall motion score was greater in anterior than in inferior myocardial infarction (9.8 +/- 6.4 vs 6.4 +/- 4.4; P =.01). The mean severity index did not differ by site. Multiple regression analysis demonstrated that, in descending order of importance, %AWM, extent of apical involvement, and site of myocardial infarction were independent determinants of global left ventricular ejection fraction. CONCLUSIONS: For myocardial infarctions of similar size, left ventricular ejection fraction is lower when apical involvement is extensive and the site of infarction is anterior. This site-dependent difference may be related to characteristics specific to the apex.     

Comparison of the influence of acute transmural and nontransmural myocardial infarction on ventricular function

In order to assess the relative impact on left and right ventricular function of nontransmural and transmural acute myocardial infarction (AMI), we performed radionuclide ventriculography in 86 patients (54 men and 32 women) within 16 hours after a first infarct. Nontransmural infarction was present in 19 patients (11 anterior and 8 inferior). Transmural infarction was found in 67 patients (30 anterior and 37 inferior). Left ventricular ejection fractions were higher (0.57 +/- .014 vs 0.46 +/- 0.14, p less than 0.005) and left ventricular end-systolic volume lower (29 +/- 11 vs 42 +/- 20 ml/m2, p = 0.013) in patients with nontransmural infarction compared to those with transmural infarction. Right ventricular ejection fraction also may have been different in the two groups (0.63 +/- 0.15 vs 0.55 +/- 0.13, p = 0.057). In patients with inferior infarction, left and right ventricular ejection fractions were similar in patients with nontransmural and transmural infarction (0.60 +/- 0.09 vs 0.55 +/- 0.10, p = 0.119 and 0.58 +/- 0.14 vs 0.51 +/- 12, p = 0.226). On the other hand, patients with anterior transmural infarction had lower left ventricular ejection fractions (0.36 +/- 0.12 vs 0.54 +/- 0.17, p = 0.003) but similar right ventricular ejection fractions (0.60 +/- 0.13 vs 0.66 +/- 0.14, p = 0.14) compared to those with nontransmural anterior infarction. In 29 additional patients with a history of previous infarction, no differences in any of the parameters studied were found between those with transmural and those with nontransmural infarcts.(ABSTRACT TRUNCATED AT 250 WORDS)     

Difference in the residual left ventricular pump function between anterior and inferior myocardial infarctions.

To evaluate the left ventricular regional ejection fraction (EF) of noninfarcted area in relation to the left ventricular end-diastolic volume (EDV) in patients with recent myocardial infarction (MI), 75 patients with Q-wave MI (anterior: 51 patients; inferior; 24 patients) were studied. The regional EF of noninfarcted area was obtained by radionuclide angiocardiography 4 weeks after the onset of MI and was used to estimate the left ventricular regional function of the noninfarcted area. Peak creatine kinase and QRS scores were not significantly different between anterior and inferior MI in each left ventricular EDV (EDV < or = 100, 101-139 and > or = 140 ml). Global EF and regional EF of noninfarcted area in anterior MI with left ventricular EDV > or = 140 ml was significantly lower than in those with EDV < or = 139 ml (p < 0.01), whereas there were no significant differences in global EF and regional EF of noninfarcted area in the three groups of left ventricular EDV in inferior MI. Thus, the effect of left ventricular EDV on regional EF of noninfarcted area and on the total cardiac performance was more important in anterior than in inferior MI, because a similar degree of left ventricular dilatation resulted in more severe derangements after anterior MI.