Site and sequelae of myocardial infarction

Novel strategies for the detection of systolic and diastolic heart failure

The incidence and prevalence of dyspnea increases with age. Frequently, for the general practitioner with his limited diagnostic facilities, it is impossible to separate dyspnea from cardiac causes and non-cardiac causes. Without cardiac imaging it is also impossible to separate systolic dysfunction from diastolic dysfunction. After a thorough physical examination, initial screening of systolic and diastolic heart failure can be done by measurement of plasma NT-pro BNP or plasma BNP. Additionally a Chest X-Ray or ECG can be performed. To improve diagnostic performance an open access echocardiographic service can be initiated. Recent studies showed, that open access echocardiography can easily detect systolic and diastolic dysfunction in the community and can separate cardiac from non-cardiac dyspnea.

MR study of the effect of infarct size and location on left ventricular functional and microstructural alterations in porcine models

PURPOSE

To investigate the effect of infarct size and location on left ventricular (LV) functional and microstructural alterations in well-established porcine models.

MATERIALS AND METHODS

Myocardium infarction was induced in mini-pigs at apical septum (Group 1, n = 6) or basal lateral wall (Group 2, n = 6) by permanent occlusion of the left anterior descending or left circumflex coronary artery, respectively. In vivo cardiac magnetic resonance (CMR) was performed 4 and 13 weeks later. Hearts were then excised and examined by ex vivo diffusion tensor imaging (DTI) for myocardium structural changes in infarct, adjacent and remote regions.

RESULTS

LV ejection fractions correlated negatively with infarct sizes. Between week 4 and 13, Group 1 exhibited more changes in end-systolic volume, LV mass, and ejection fraction, although it showed a smaller infarct volume percentage. Ex vivo results revealed the decreased water diffusion fractional anisotropy and increased diffusivities in infarct region in correlation with infarct size, but with no significant difference between the two groups. However, LV myocardial double-helical fiber architecture was found to alter in Group 1, shifting more towards left-handed direction as compared to controls.

CONCLUSION

Postinfarct LV functional and structural remodeling is affected by both infarct size and location.

Myocardial revascularization in patients with ischemic cardiomyopathy: functional observations

OBJECTIVE

A prospective angiographic study was undertaken to investigate, with an objective analysis, the global and regional wall response to myocardial revascularization.

METHODS

Thirty-one patients (30 men and 1 woman, mean age, 61 years) with a left ventricular ejection fraction of less than 0.30 were admitted to our institution between 1992 and 1995 for two- or three-vessel coronary artery disease requiring myocardial revascularization. All patients underwent isolated coronary artery bypass grafting and were studied 3 months later with angiography. Preoperative and postoperative wall motion were analyzed using special software that computed a segmental left ventricular ejection fraction, generating a segmental score. Computerized analysis allowed us to distinguish patients with diffuse hypokinesis and a symmetric contraction pattern from patients with akinesis involving at least two segments and an asymmetric contraction pattern.

RESULTS

There were no operative deaths and no patient required intraaortic balloon counterpulsation. One patient had postoperative enzymatic evidence of myocardial infarction. Postoperative angiography showed a graft patency rate of 84%. Global analysis showed a small but significant rise in the left ventricular ejection fraction (0.25 +/- 0.51 to 0.31 +/- 0.70, p < 0.001) and a fall in the left ventricular end-diastolic pressure (23.7 +/- 10 to 16.5 +/- 9 mm Hg, p < 0.01). Mean scores always have been lower after the operation than before it, with the best results obtained for the apex and the worst for the anterobasal segment. The group with a symmetric contraction pattern showed a trend toward a better hemodynamic response than the group with an asymmetric contraction pattern. Regression analysis revealed two important predictors of segmental functional improvement: (1) the absence of an echocardiographic scar, and (2) the presence of a collateral circulation.

CONCLUSIONS

Coronary artery bypass grafting produced a small but substantial improvement in patients with ischemic cardiomyopathy. The greater benefit occurred in patients with a symmetric contraction pattern. The absence of an echocardiographic scar and the presence of a collateral circulation predicted segmental functional improvement.

[Clinical prediction of the early prognosis in acute myocardial infarct]

Several clinical factors can influence the pathophysiology, clinical course and prognosis of acute myocardial by different means. Some of them may be easily detected through the history, physical examination or ECG in an early phase. The knowledge of these factors may help the therapeutic decision making of patients with myocardial infarction. The influence for the main clinical factors (age, sex, risk factors, cardiologic antecedents and evolutive findings) on the short-term prognosis of acute myocardial infarction is reviewed. An analysis of the likely mechanisms of the influence of these factors on infarct prognosis is also performed.

Lack of ventricular remodeling in non-Q-wave myocardial infarction

We prospectively examined 45 patients with serial echocardiography to measure left ventricular end-diastolic volume index within 1 week and at 6 weeks after infarction. Left ventricular volume increased in patients with Q-wave infarction but not in those with non-Q or in control patients without recent infarction. Peak creatine phosphokinase levels were greater in Q-wave infarction compared with those in non-Q-wave infarction. There was a strong correlation between the change in the left ventricular end-diastolic index and the peak creatine phosphokinase level. After correcting for infarct size, there was still a difference between the two groups. Our data indicate that ventricular remodeling does not occur in non-Q-wave as opposed to Q-wave infarcts, and this may be related both to the limited amount of myocardial necrosis and to the nontransmural extent of the necrosis.

Determinants of 6-month mortality in survivors of myocardial infarction after thrombolysis. Results of the GISSI-2 data base. The Ad hoc Working Group of the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico (GISSI)-2 Data Base

BACKGROUND

Current knowledge of risk assessment in survivors of myocardial infarction is largely based on data gathered before the advent of thrombolysis. It must be determined whether and to what extent available information and proposed criteria of prognostication are applicable in the thrombolytic era.

METHODS AND RESULTS

We reassessed risk prediction in the 10,219 survivors of myocardial infarction with follow-up data available (ie, 98% of the total) who had been enrolled in the GISSI-2 trial, relying on a set of prespecified variables. The 3.5% 6-month all-cause mortality rate of these patients compared with the higher value of 4.6% found in the corresponding GISSI-1 cohort, originally allocated to streptokinase therapy, indicates a 24% reduction in postdischarge 6-month mortality. On multivariate analysis (Cox model), the following variables were predictors of 6-month all-cause mortality: ineligibility for exercise test for both cardiac (relative risk [RR], 3.30; 95% confidence interval [CI], 2.36-4.62) and noncardiac reasons (RR, 3.28; 95% CI, 2.23-4.72), early left ventricular failure (RR, 2.41; 95% CI, 1.87-3.09), echocardiographic evidence of recovery phase left ventricular dysfunction (RR, 2.30; 95% CI, 1.78-2.98), advanced (more than 70 years) age (RR, 1.81; 95% CI, 1.43-2.30), electrical instability (ie, frequent and/or complex ventricular arrhythmias) (RR, 1.70; 95% CI, 1.32-2.19), late left ventricular failure (RR, 1.54; 95% CI, 1.17-2.03), previous myocardial infarction (RR, 1.47; 95% CI, 1.14-1.89), and a history of treated hypertension (RR, 1.32; 95% CI, 1.05-1.65). Early post-myocardial infarction angina, a positive exercise test, female sex, history of angina, history of insulin-dependent diabetes, and anterior site of myocardial infarction were not risk predictors. On further multivariate analysis, performed on 8315 patients with the echocardiographic indicator of left ventricular dysfunction available, only previous myocardial infarction was not retained as an independent risk predictor.

CONCLUSIONS

A decline in 6-month mortality of myocardial infarction survivors, seen within 6 hours of symptom onset, has been observed in recent years. Ineligibility for exercise test, early left ventricular failure, and recovery-phase left ventricular dysfunction are the most powerful (RR, > 2) predictors of 6-month mortality among patients recovering from myocardial infarction after thrombolysis. Qualitative variables reflecting residual myocardial ischemia do not appear to be risk predictors. The lack of an independent adverse influence of early post-myocardial infarction angina on 6-month survival represents a major difference between this study and those of the prethrombolytic era.

Acute myocardial infarction with ventricular septal rupture

The interventricular septum is one of the three main sites at which the myocardium can rupture. The features of the interventricular septal rupture that occurred in a 72-year-old woman are characteristic of interventricular septal ruptures in general: (1) they occur most commonly in elderly women; (2) the most common site is the mid-portion of an acute, transmural anteroseptal apical infarct; (3) they are also most common during the patient's first heart attack; (4) the clinical diagnosis of acute myocardial infarct is confirmed by both ECG and by serum enzyme levels; (5) the usual time of the rupture is 3-10 days after the onset of the infarction (it occurred after 3 days in our patient); (6) a new cardiac murmur usually is heard and the patient frequently goes into shock; (7) the diagnosis can be confirmed by a step-up in pO2 levels from right atrium to right ventricle; (8) the usual cause is severe old coronary atherosclerosis with a recent thrombotic occlusion as the final precipitating event.

Acute effects of delayed reperfusion on myocardial infarct shape and left ventricular volume: a potential mechanism of additional benefits from thrombolytic therapy

The purpose of this study was to characterize the effects of late reperfusion on myocardial infarct shape and to quantitate associated changes in left ventricular volume. Reperfusion was delayed until there was no salvage of ischemic myocardium. Dogs underwent 6.5 h of left anterior descending coronary artery occlusion (n = 5) or 5.5 h of occlusion and 1 h of reperfusion (n = 5). Infarct shape was measured with pairs of ultrasonic crystals implanted circumferentially in the mid myocardium. Infarct stiffness was determined from end-diastolic pressure-segment length curves produced by aortic clamping. Left ventricular volume was measured with three pairs of endocardial ultrasonic crystals and the effect of infarct shape change on left ventricular volume was determined. Infarct size, expressed as a percent of the area at risk, was similar in reperfused (97 +/- 1%) and nonreperfused (98 +/- 1%) hearts. After coronary artery occlusion, infarct segments became akinetic and functional dilation, measured as end-diastolic ultrasonic crystal separation, increased to a similar extent in reperfused (24 +/- 7%) and nonreperfused (19 +/- 3%) hearts. In 13 additional dogs that underwent reperfusion and instrumentation with endocardial ultrasonic crystals for volume measurement, left ventricular volume increased 42 +/- 6% over the preocclusion level (p less than 0.001). Within minutes of reperfusion, the infarct stiffened, infarct dilation decreased to 1 +/- 4% over the baseline preocclusion level (p less than 0.05 vs. prereperfusion) and left ventricular volume decreased to 16 +/- 11% over the baseline level (p less than 0.01 vs. postocclusion). Thus, coronary artery reperfusion reverses initial infarct dilation. Changes in infarct dilation occur immediately after reperfusion and are accompanied by infarct stiffening and a decrease in left ventricular volume. Reperfusion can affect infarct shape and stiffness at a point in time when myocardial salvage is no longer possible.

Transesophageal echocardiographic assessment of systolic and diastolic dysfunction during percutaneous transluminal coronary angioplasty

Left ventricular short-axis cross-sections at the level of the papillary muscles and transmitral flow were obtained with transesophageal echocardiography during percutaneous transluminal coronary angioplasty (PTCA) in 15 patients who had received anesthesia and who all demonstrated new areas of or more severe wall motion abnormality 10.2 +/- 4.3 seconds after initiation of balloon inflation. Both systolic (percentage area reduction and ejection fraction of the ischemic segment) and diastolic (early to atrial peak flow ratio and time velocity integral) function parameters and end-systolic wall stress changed significantly during PTCA. These changes were most profound during PTCA of the left anterior descending artery than they were during PTCA of the right coronary artery. Systolic and diastolic dysfunction are therefore invariably linked during transient ischemia, and PTCA of the left anterior descending artery consistently produced more profound dysfunction.

Beneficial effect of residual flow to the infarct region on left ventricular volume changes after acute myocardial infarction

To determine the relationship between alterations in left ventricular (LV) volumes and residual flow to the infarct region after myocardial infarction (MI), 57 patients with a first acute transmural MI underwent two-dimensional echocardiography within 48 hours of infarction and after 1 month. A reduction in ST segment elevation by greater than or equal to 35% of the peak value of ST segment elevation within the initial 6 hours was used as an indirect indicator for early reperfusion of the infarct-related artery (IRA). IRA patency and collateral circulation were assessed by coronary arteriography performed at 1 month. LV volumes increased in patients with a persistent ST segment elevation within the initial 6 hours of infarction and in those with a totally occluded IRA without collaterals. However, LV volumes were unchanged in patients with early reperfusion and in those who had subtotally occluded IRA or who had collateral circulation. LV dilation (greater than or equal to 20% increase in end-diastolic volume) occurred less often when early reperfusion and angiographically patent IRA or collateral supply to the infarct zone were present. This prospective study indicates that residual flow to the infarct region may exert a beneficial effect on LV volume changes after acute MI.

Coronary reserve is depressed in postmyocardial infarction reactive cardiac hypertrophy

After a myocardial infarction (MI), the remaining myocardium undergoes a compensatory reactive hypertrophy. Although coronary perfusion to the surviving myocardium can be an important determinant of cardiac function in this setting, there are no available data regarding myocardial blood flow in reactive hypertrophy. Accordingly, we measured coronary blood flow and reserve using radioactive microspheres in rats 4 weeks after induction of an MI by ligation of the left coronary artery. Maximal coronary dilation was induced by Carbochrome, a potent coronary vasodilator, infused at a rate of 0.45 mg/kg/min up to a total dose of 12 mg/kg. Sham-operated rats served as controls. All animals in the infarct group had a large MI affecting 30-51% (average, 41%) of the left ventricle. Left ventricular end-diastolic pressure was significantly elevated (30 +/- 6.5 vs. 8.0 +/- 2.5 mm Hg in sham-operated rats, p less than 0.01) and baseline hemodynamic indexes of cardiac performance were significantly (p less than 0.01) reduced in this group. Myocyte cross-sectional area measurements were used as an index to quantify the degree of reactive hypertrophy and indicated that the infarcted animals had, on average, a 30% hypertrophic response of the surviving left ventricular myocardium. In the infarcted animals, both coronary flow and vasodilator reserve in the surviving myocardium were depressed. Maximal coronary blood flow in the remaining myocardium was significantly lower than that measured in the sham-operated animals (839 and 1,479 ml/min/100 g, respectively; p less than 0.001). Similarly, minimal coronary resistance was significantly higher in the MI group as compared with the sham group (0.12 vs. 0.07 mm Hg/ml/min/100 g, respectively; p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Medical and surgical management of early Q wave myocardial infarction. II. Effects on mortality and global and regional left ventricular function at 10 or more years of follow-up

To determine the long-term effect of surgical reperfusion on survival and left ventricular function of patients with anterior and inferior Q wave myocardial infarction, 387 patients were followed up for greater than or equal to 10 years after early Q wave infarction. In the anterior infarction group, 102 received conventional therapy and 101 underwent surgical reperfusion. The overall hospital mortality rate in the medically and surgically treated patients was different (16.7% [17 of 102] versus 6.9% [7 of 101], p less than 0.05). The cumulative 13 year actuarial mortality rate widened between the anterior medical and surgical groups (54% versus 31%, p = 0.0003) by the adjusted Cox proportional hazards model. The hospital mortality rate with early reperfusion (that is, less than or equal to 6 h of symptom onset) was 2% (1 of 51), whereas the mortality rate with late reperfusion was 12% (6 of 50). The 13 year actuarial cumulative mortality rate was significantly lower in both the early and late reperfusion groups (30% and 33%, respectively) than in the conventional therapy group (54%, p = 0.0006). The mortality rate in patients receiving surgery after surviving initial medical therapy was 50% (15 of 30). In the survivors of anterior Q wave myocardial infarction, improved global ejection fraction was seen in the patients undergoing early (54 +/- 13%) and late (50 +/- 10%) surgery relative to those receiving conventional therapy (43 +/- 11%, p less than 0.05). Only the early reperfusion group had better regional function of the anterior wall than that of the conventional therapy group. Thus, ventricular function correlated with improved long-term survival. In the patients with inferior Q wave myocardial infarction, the overall hospital mortality rate in the medical and surgical groups was not different (6.1% [6 of 98] versus 4.6% [6 of 86], p = NS). Likewise, the 13 year actuarial cumulative mortality rate was not different between the medical and surgical groups overall (32% versus 30%, p = 0.29) by the adjusted Cox proportional hazards model. The hospital mortality rate in the early reperfusion group was lower than that in the late reperfusion group (2.0% [1 of 49] versus 8.1% [3 of 37], p = NS). The 13 year actuarial cumulative mortality rate was lower in the early surgical group compared with that in the medical group (19% versus 32%, p = 0.04). The late surgical group had a similar 13 year actuarial cumulative mortality rate to that of the medical group (47% versus 32%, respectively, p = 0.47).(ABSTRACT TRUNCATED AT 400 WORDS)

Prognostic significance of the extent of myocardial injury in acute myocardial infarction treated by streptokinase (the GISSI trial)

To evaluate the different contributions of infarct site and infarct extent in determining the in-hospital outcome and efficacy of thrombolytic therapy, 8,731 patients with a first Q-wave acute myocardial infarction (AMI) enrolled in the GISSI trial were studied. On the basis of the standard 12-lead electrocardiogram, the sample was classified in 2 ways: classic electrocardiographic site pattern (anterior, inferior, lateral and multiple location), and number of standard electrocardiographic leads with ischemic ST elevation (small, modest, large and extensive infarct in 2 to 9 leads). In-hospital mortality was evaluated according to infarct site, infarct extent and fibrinolytic treatment. The mortality rate was differently distributed in the various infarct sites. Streptokinase significantly reduced mortality only in anterior (13.8 vs 18.7%) and multiple site infarcts (8.1 vs 12.5%). According to the infarct extent observed, there is a progressive increase in the mortality rate--from 6.5% in small infarcts to 9.6% in modest, 14.3% in large and 21.7% in extensive. No significant benefit was obtained by streptokinase in small infarcts; in contrast, a significant decrease in mortality was achieved in modest (7.7 vs 11.4%), large (12.8 vs 16.6%) and extensive infarcts (19.5 vs 23.9%). Thus, the extent of myocardial injury seems to be more relevant than the site in determining in-hospital mortality and efficacy of thrombolytic therapy.

Importance of collateral circulation for prevention of left ventricular aneurysm formation in acute myocardial infarction

The effect of preexistent coronary collateral perfusion on the prevention of left ventricular aneurysm formation was examined in 47 patients undergoing an intracoronary thrombolysis within 6 hours after the onset of a first acute anterior myocardial infarction. Left ventricular aneurysm formation and wall motion were analyzed with cineventriculography. A left ventricular aneurysm was determined as well-defined demarcation of the infarcted segment from normally contracting myocardium. In 25 patients with successful thrombolysis (group A), a left ventricular aneurysm was observed in one patient (4%) during the chronic stage of infarction. In 10 patients who had a significant collateral circulation to the infarct-related coronary artery and unsuccessful reperfusion (group B), the left ventricular aneurysm was observed in only one patient (10%). In the remaining 12 patients with unsuccessful recanalization in the absence of a significant collateral perfusion (group C), there was a higher incidence (seven of 12, 58%) of left ventricular aneurysm formation than in groups A and B (p less than 0.05). In group A, both the global ejection fraction and regional wall motion in the infarct areas improved significantly (p less than 0.05) between the acute and chronic stages of infarction. By contrast, in groups B and C, these indexes on the ventricular function did not change significantly during the convalescent period. Thus, although the collateral perfusion existing at the onset of acute myocardial infarction may not improve ventricular function, it exerts a beneficial effect on the prevention of left ventricular aneurysm formation.

Increased afterload aggravates infarct expansion after acute myocardial infarction

After acute transmural myocardial infarction, the heart may undergo major remodeling characterized by thinning and dilation of the infarct zone and overall enlargement of the heart. The effect of increased left ventricular pressure on infarct expansion and the extent to which it alters postinfarction remodeling were studied in a rat model. Rats with either aortic banding or a sham operation and a survival period of 3 weeks were further randomized to sham thoracotomy or left coronary ligation. Surviving rats were killed 7 days later and the hearts were fixed in diastole for morphologic analysis. Hearts with aortic banding had a mean peak to peak gradient of 20.7 +/- 4.9 mm Hg across the aortic band at death and a significantly thicker heart than that of the comparison group without an aortic band. Infarct size, as a percent of total left ventricular mass, at the time of death was less in the group with aortic banding, yet infarct expansion was more marked. However, when original infarct size was estimated taking into account the effects of aortic banding, scar formation, infarct expansion and infarct-induced hypertrophy, it was found to be similar in both infarct groups (45.50 +/- 4.2 versus 47.90 +/- 3.1%). Infarct expansion, as measured by cavity dilation and infarct thinning, occurred in both infarct groups but was greater in the group with aortic banding.(ABSTRACT TRUNCATED AT 250 WORDS)

Prognostic significance of location and type of myocardial infarction: independent adverse outcome associated with anterior location

To determine the relative prognostic significance of location (anterior or inferior) and type (Q wave or non-Q wave) of infarction, the hospital course and follow-up outcome (mean duration 30.8 months) of 471 patients with a first infarction were analyzed. Analyses were performed grouping the patients according to infarct location (anterior, n = 253; inferior, n = 218), infarct type (Q wave, n = 323; non-Q wave, n = 148), and both location and type (inferior non-Q wave, n = 85; inferior Q wave, n = 133; anterior non-Q wave, n = 63; and anterior Q wave, n = 190). Patients with anterior infarction had a substantially worse in-hospital and follow-up clinical course compared with those with inferior infarction, evidenced by a larger infarct size (21.2 versus 14.9 g Eq/m2 creatine kinase, MB fraction [MB CK], p less than 0.001), lower admission left ventricular ejection fraction (38.1 versus 55.3%, p less than 0.001) and higher incidence of heart failure (40.7 versus 14.7%, p less than 0.001), serious ventricular ectopic activity (70.2 versus 58.9%, p less than 0.05), in-hospital death (11.9 versus 2.8%, p less than 0.001) and total cumulative cardiac mortality (27 versus 11%, p less than 0.001). Patients with Q wave infarction similarly experienced a worse in-hospital course compared with patients with non-Q wave infarction, evidenced by a larger infarct size (20.7 versus 12.7 MB CK g Eq/m2, p less than 0.001), lower admission left ventricular ejection fraction (43.7 versus 50.6%, p less than 0.001), and a higher incidence of heart failure (31.9 versus 21.6%, p less than 0.05) and in-hospital death (9.3 versus 4.1% p less than 0.05). However, there was no increased rate of reinfarction or mortality in hospital survivors with non-Q wave infarction compared with those with Q wave infarction, and total cardiac mortality was similar (16 versus 21%, p = NS). To evaluate the role of infarct location and type independent of infarct size, patients were grouped according to quartile of infarct size, and outcome was reanalyzed within each group. Patients with anterior infarction demonstrated a lower left ventricular ejection fraction on admission and after 10 days than did patients with inferior infarction, even after adjustment for infarct size, as well as a higher incidence of congestive heart failure and cumulative cardiac mortality.(ABSTRACT TRUNCATED AT 400 WORDS)

Is localization of acute myocardial infarction time related?

A total of 1744 patients admitted to the ICCU with acute myocardial infarction (AMI) were studied in 1462 consecutive days (1982-1986). The aim of the study was to check whether the localization of the AMI was time related. Anterior (anterolateral) (AW) (n = 834) versus inferior-posterior (inferolateral) (IPW) (n = 823) AMI were compared: a third group with isolated lateral wall (LW) AMI (n = 87) was included in the study. Significant differences between monthly AMI localizations were registered, but no rhythmicity (monthly, seasonal) was found. A small absolute prevalence of AW localizations was found in all four seasons, but monthly differences made those differences not statistically significant. Some significant correlation (p less than 0.01) was found between AW AMI domination and daily geomagnetic activity (GMA level I-IV). Only on days with low (quiet) levels of GMA were there more IPW AMIs. Adverse relationship was seen with LW AMI, relatively benign in AMI, was adversely correlated with GMA level (p less than 0.01). Differences in AW/IPW and left/right coronary artery autonomic receptors distribution and flow regulation and/or changes in cardiovascular homeostasis/coagulation, aggregation, viscosity, microcirculation, and so on connected with AMI expansion may be involved in these differences of AMI localization.

Myocardial infarct expansion, infarct extension, and reinfarction: pathophysiologic concepts

Infarct expansion and infarct extension are events early in the course of myocardial infarction with serious short- and long-term consequences. Infarct expansion, disproportionate thinning, and dilatation of the infarct segment probably begin within hours of acute infarction and usually reach peak extent within seven to 14 days. Clinical data suggest that infarct expansion occurs in approximately 35% to 45% of anterior transmural myocardial infarctions and to a lesser extent in infarctions at other sites. Although expansion usually develops in large infarcts, the extent of transmural necrosis rather than absolute infarct size predicts its occurrence. Expansion has an adverse effect on infarct structure and function for several reasons. Functional infarct size is increased because of infarct segment lengthening, and expansion results in over-all ventricular dilatation. Thus, patients with expansion of an infarct have poorer exercise tolerance, more congestive heart failure symptoms, and greater early and late mortality than those without expansion. Infarct rupture and late aneurysm formation are two additional structural consequences of infarct expansion. Experimental and clinical data suggest that the incidence and severity of expansion can be modified by interventions. Increased ventricular loading conditions and steroidal and nonsteroidal antiinflammatory agents make expansion more severe. Reperfusion of the infarct segment and pharmacologic interventions that decrease ventricular afterload lessen the severity of expansion. Previous myocardial infarction and preexisting ventricular hypertrophy may also limit the development of infarct expansion. Infarct extension is defined clinically as early in-hospital reinfarction after a myocardial infarction. The pathologic finding of infarct extension is necrotic and healing myocardium of several different recent ages within the same vascular territory. Although this pathologic criterion usually cannot be verified, studies employing invasive and noninvasive assessment of patients with early reinfarction provide evidence that the new myocardial injury is usually in the same vascular risk region as the original infarction. A variety of different criteria have been applied in the clinical diagnosis of infarct extension, and this has resulted in a large range of estimated frequencies from under 10% to as high as 86%. High estimates are found in studies using one or two nonspecific criteria such as ST segment shift or reelevation of total CK. The lowest rates have been found when combinations of criteria are used.(ABSTRACT TRUNCATED AT 400 WORDS)

Prognostic implications of regional hyperkinesia and remote asynergy of noninfarcted myocardium

To determine the clinical significance of regional hyperkinesia and remote asynergy of noninfarcted areas in patients with a first acute myocardial infarction (AMI), 2-dimensional echocardiography was performed in 113 consecutive patients within 12 hours after admission to the coronary care unit. In 98 patients (87%) all segments of the left ventricular wall were recorded. Infarct-associated asynergy was anterior in 63 and inferior in 35 patients. Regional hyperkinesia was present in 66 patients (67%)--44 of 63 with anterior (69%) and 22 of 35 with inferior (63%) infarcts--and was more frequently seen in patients with 1- and 2-vessel coronary artery disease (CAD) than in patients with 3-vessel CAD (87 and 72% vs 25%, p less than 0.001). In contrast to enzymatic infarct size, absence of regional hyperkinesia was significantly associated with a higher left ventricular wall motion score (p less than 0.01). Twenty patients died within 30 days after onset of AMI; in 15 (75%) regional hyperkinesia was absent. Absence of regional hyperkinesia, especially in anterior infarcts, was associated with a high mortality rate (13 of 19 patients [68%]). Remote asynergy, i.e., not adjacent to the infarct area and supposed to be related to another vascular region, was present in 17 of 98 patients (17%)--11 of 63 with anterior (17%) and 6 of 35 with inferior (17%) infarcts. Remote asynergy was present only in patients with multivessel CAD and was significantly related to a higher wall motion score (p less than 0.001), but not to enzymatic infarct size.(ABSTRACT TRUNCATED AT 250 WORDS)

Two-dimensional echocardiography during percutaneous transluminal coronary angioplasty

In order to study myocardial and clinical events during transient coronary occlusion in humans, two-dimensional echocardiography was continuously performed in 15 patients undergoing 49 balloon inflations during percutaneous transluminal coronary angioplasty (PTCA). Transient segmental asynergy developed in all patients 8 +/- 3 seconds after balloon inflation and returned to baseline 19 +/- 8 seconds after balloon deflation. Segmental dyskinesis was seen in only 8 of 11 patients undergoing PTCA of the left anterior descending artery (LAD). A wall motion score, based on degree of asynergy of 13 segments of the left ventricle, was significantly higher during LAD than during right coronary artery inflation (7.9 +/- 1.3 vs 4.0 +/- 1.4, p less than 0.01). Left ventricular size index increased significantly during balloon inflation, from 179 +/- 9 to 196 +/- 10 mm (p less than 0.01). Four patients developed transient ST segment changes in the extremity leads of the ECG and five patients had angina pectoris. The very first sign of ischemia in three patients, who developed all of these symptoms together, was consistently asynergy, followed by ECG changes, and last, angina pectoris. Thus during PTCA, transient asynergy and left ventricular dilatation develop, which are often clinically silent.

Prognostic significance of electrocardiographic site of infarction after correction for enzymatic size of infarction

To assess whether the site of myocardial infarction is an independent prognostic indicator, the outcome of patients with anterior myocardial infarction was compared with that of patients with inferior infarction. A consecutive series of patients who had suffered their first myocardial infarction was analyzed (398 with anterior and 391 with inferior infarction). Patients with anterior myocardial infarction had a higher 1 year mortality than those with inferior infarction (18.3% vs 10.5%, p = .002). When patients were matched for infarct size determined by peak creatine kinase (CK) level expressed as a multiple of the upper limit of normal, those with anterior myocardial infarction tended to have a higher 1 year mortality than those with inferior infarction for all subgroups of peak CK. Early mortality (day 1 to 28 after myocardial infarction) was greater in the anterior than in the inferior myocardial infarction group (10% vs 6.4%, p = .03); this was most significant when peak CK was greater than four times normal (12.4% vs 7.0%, p = .04). Late mortality was also higher in the anterior (8.4% vs 4.1%, p = .04) than the inferior infarction group and this was most significant when peak CK was less than two times normal (15.2% vs 0%, p = .02) or greater than eight times normal (10.6% vs 4.1%, p = .04). Multivariate analysis with proportional-hazards regression confirmed the prognostic significance of location of infarction independent of peak CK level. Thus, infarct location was found to be a predictor of prognosis that is independent of infarct size based on peak CK levels.

Incidence, timing and prognostic value of left ventricular aneurysm formation after myocardial infarction: a prospective, serial echocardiographic study of 158 patients

Serial 2-dimensional echocardiography was performed prospectively in 158 consecutive patients with first acute myocardial infarction (AMI) to determine the incidence of left ventricular (LV) aneurysm formation and the time course required for, and the clinical significance of, onset of LV aneurysm formation. Studies were performed throughout the first 5 days and after 3 months and 1 year. LV aneurysm was defined as an abnormal bulge in the LV contour during both systole and diastole. Eighty-four patients had anterior, 68 posterior and 6 anteroposterior AMI defined echocardiographically. During the study period, LV aneurysm was found in 35 of 158 patients (22%): in anterior AMI in 27, in posterior AMI in 6 and in anteroposterior AMI in 2. No new aneurysm developed after 3 months. Early aneurysm formation, during the first 5 days after AMI, was seen in 15 patients with anterior infarction. Twelve of these 15 (80%) died within 1 year (10 within 3 months), in contrast to 5 (25%) of the remaining 20 patients with LV aneurysm (p less than 0.05). Dyskinesia of the anterior wall in the acute stage usually resulted in aneurysm formation. Thus, LV aneurysm formation is seen in 22% of mostly anterior AMI and occurs within 3 months after AMI. Early aneurysm formation is associated with a high 3-month (67%) and 1-year (80%) mortality rate.

Significance of infarct site and methylprednisolone on survival following acute myocardial infarction

Eight hundred and forty-nine patients with confirmed myocardial infarction were enrolled in a double-blind, placebo-controlled clinical trial of the efficacy of methylprednisolone sodium succinate (MPSS, Solu-Medrol Sterile Powder, The Upjohn Company) for reduction of morbidity and mortality following an acute myocardial infarction complicated by left ventricular failure. Two study groups were prospectively defined based on time from onset of chest pain to administration of investigational therapy. Study Group 1 received investigational therapy before 6 hours had elapsed while Study Group 2 was treated 6 to 12 hours from the onset of chest pain. Both study groups were randomized to receive either a 30 mg/kg i.v. dose of MPSS (3 g maximum) or a matching placebo at the time of study admission, to be followed by an identical dose three hours later. Definitive electrocardiograms were available for 814 patients at admission. The mortality rates at 28 days and 6 months for the anterior transmural and nontransmural infarctions did not differ significantly with regard to time to treatment or investigational therapy. For the inferior/posterior transmural infarctions, however, there was a 92% relative reduction in mortality at 28 days in the MPSS treatment arm of Study Group 2 (1/83 [1.2%] for patients given MPSS versus 15/97 [15.5%] for those given placebo; p less than 0.001). This significant difference persisted at the 6 month follow-up evaluation (3/82 [3.6%] for patients on MPSS versus 17/96 [16.6%] for those on placebo, P less than 0.01). Site-specific efficacy has been reported for the anterior infarction groups of the major beta-blocker trials.(ABSTRACT TRUNCATED AT 250 WORDS)

Survival after hospital discharge in matched populations with inferior or anterior myocardial infarction

Prognostic differences between patients with anterior or inferior myocardial infarction are often related to such variables as previous infarction or the size of the myocardial infarct. We examined the determinants of mortality in 997 hospital survivors of acute Q wave infarction (anterior in 449, inferior in 548) who, although not preselected, were well matched with respect to age, sex and prior infarction or congestive heart failure. Additionally, there was no significant difference in peak serum creatine kinase (CK) between the groups with anterior and inferior infarction (1,459 +/- 1,004 versus 1,357 +/- 1,036). Among the patients with anterior infarction who died during the 1 year follow-up period, 56% died in the first 60 days after hospital discharge compared with 18% of those without inferior infarction (p less than 0.01). Survival curves then became nearly identical at 3 months, and remained so until 1 year when the total mortality rate was 10% for the anterior and 7% for the inferior infarction group (p = NS). Variables associated with heart failure during the hospital phase were more prevalent in anterior infarction, but rales above the scapulae during the hospital stay (p less than 0.0001) and ventricular gallop at the time of discharge (p less than 0.0001) were the top two predictors of 1 year mortality by both univariate and multivariate analysis in inferior infarction. Age (p less than 0.0001) and peripheral edema (p less than 0.0001) were the strongest predictors of mortality in anterior infarction. Previous infarction, although just as common in the group with anterior infarction, was present at 1 year in 48% of nonsurvivors of the group with inferior infarction compared with only 19% of survivors (p less than 0.0001).(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term follow-up of left ventricular thrombus after acute myocardial infarction. A two-dimensional echocardiographic study in 96 patients

To determine the incidence, natural history, and relation to anticoagulant therapy of left ventricular thrombus (LVT) following acute myocardial infarction (MI), we performed two-dimensional echocardiography in 96 consecutive patients with isolated MI during the acute episode and after four and 12 months. Only patients with anterior MI received oral anticoagulant therapy on admission and throughout the study period. The LVT was identified in 21/65 patients with anterior and in 1/31 patients with inferior MI. The large majority of LVT cases were seen for the first time during the acute phase of MI. LVT was associated with a significantly higher peak value of CK-MB (118 +/- 24 vs 76 +/- 35, p less than 0.001) and Killip class (2.5 +/- 0.8 vs. 1.5 +/- 0.7, p less than 0.002). Patients with anterior MI and LVT more frequently had segmental dyskinesia during acute MI than patients without LVT (86 percent vs 18 percent, p less than 0.001). In four patients LVT resolved during the study period. Discontinuation of anticoagulant therapy in four patients with an aneurysm led to LVT formation in three. Two patients suffered a clinically recognized embolic event; one never had LVT demonstrated by echocardiography. Thus, LVT usually develops in the early days following large anterior MI, complicated by pump failure and segmental dyskinesia, even when patients receive oral anticoagulant therapy. Surprisingly, the incidence of embolic events was low (1/22) in our LVT patients.

Ischemic cardiomyopathy

The term "ischemic cardiomyopathy" was used initially to describe a clinical syndrome that was indistinguishable from primary congestive cardiomyopathy but due to severe, diffuse coronary artery disease. The term has been expanded to include the larger category of myocardial disease secondary to coronary artery disease. Using this expanded definition, we have discussed the varied clinical presentations of congestive ischemic cardiomyopathy and restrictive ischemic cardiomyopathy (stiff heart syndrome and right ventricular infarction), and how the effects of ischemia on left ventricular systolic and diastolic performance may cause these varied presentations. The prognosis of any ischemic cardiomyopathy is related primarily to the degree of ventricular dysfunction and the extent of coronary artery disease. Therapy is aimed at preventing or ameliorating myocardial ischemia and halting the progression of, or even reversing, the deterioration in myocardial function.

Detection of active left ventricular thrombosis during acute myocardial infarction using indium-111 platelet scintigraphy

Platelet scintigraphy with radioactive indium-111 may be used both to identify and to reflect the activity of thrombin in vivo in man. Forty-one patients with acute myocardial infarction were studied for active left ventricular thrombosis by platelet scintigraphy and followed until in-hospital death, discharge, or same-admission cardiac surgery for evidence of systemic embolization. A total of 4.7 +/- 2.4 X 10(9) platelets (mean +/- 1 SD) labelled with 381 mu Ci +/- 51 mu Ci of indium-111 was injected intravenously at 91 +/- 88 hours following the onset of chest pain. Patients were imaged in multiple views on the day of and three to four days after injection of the platelet suspension. Group 1 (n = 29) had transmural myocardial infarctions, of which 21 were anterior (peak total level of creatine phosphokinase [CPK], 2,272 +/- 2,026 IU; mean +/- 1 SD) and eight were inferior (CPK level, 1,673 +/- 589 IU). Group 2 (n = 12) had subendocardial myocardial infarctions (CPK level 799 +/- 751 IU). Those with subendocardial and transmural inferior myocardial infarctions had neither left ventricular thrombosis nor emboli. Ten (48 percent) of 21 with anterior transmural myocardial infarctions had left ventricular thrombosis by platelet scintigraphy. Three with and one without such thrombosis by scintigraphy had acute neurologic episodes. In the group with anterior myocardial infarctions, seven of ten patients with and four of 11 without left ventricular thrombosis received heparin subcutaneously (chi 2 = 1.22 [Yates correction]; p greater than 0.30). We conclude that platelet scintigraphy may be used to monitor antiplatelet and anticoagulant therapy in patients with anterior transmural myocardial infarctions who are at risk for left ventricular thrombosis and systemic embolization.

Myocardial infarction in patients with previous coronary artery bypass surgery

An increasing proportion of patients hospitalized with myocardial infarction have previously undergone coronary artery bypass surgery. To define this subgroup, 77 patients with acute infarction occurring 2 or more months (mean 52.8) after bypass surgery were compared with 77 control patients with infarction. Baseline characteristics of the groups were similar except that post-bypass patients were more often men (p = 0.02) and more likely to have had a previous infarction (37 versus 21, p = 0.008). Infarct size was smaller in the post-bypass group as assessed by peak creatine kinase (CK), peak CK-MB, maximal number of electrocardiographic leads with ST elevation, maximal summed ST elevation and QRS score measured 7 to 10 days after admission (p less than 0.001 for each variable). Five control patients but none of the post-bypass patients died in the hospital (p = 0.06). Serious complications (death, acute heart failure, ventricular fibrillation, second or third degree atrioventricular block) occurred in 24 control patients but in only 5 post-bypass patients (p less than 0.001). Angiography was performed after infarction in 45 of the 77 post-bypass patients. Occlusion of both a native coronary artery and its graft was found in 24 of the 45; these patients had had higher peak CK levels (p = 0.008) than the other 21 patients who had angiography. The probable causes of infarction in these 21 were disease progression in nonbypassed arteries or graft occlusion with arterial stenosis, or vice versa, and disease progression distal to a patent graft.(ABSTRACT TRUNCATED AT 250 WORDS)

Salvaging ischemic myocardium after myocardial infarction

Today's sophisticated diagnostic techniques make it possible to determine, virtually at the bedside, the site and size of an infarct and its effect on the patient's hemodynamic status. Thus, it is now possible to identify the patient who will benefit from aggressive therapy and to spare those who do not need or will not be helped by such treatment. Three phases of management are discussed.

Effect of infarct location on the in-hospital prognosis of patients with first transmural myocardial infarction

We studied the in-hospital prognosis of 1105 patients who had their first transmural myocardial infarction; 611 patients (55.3%) had anterior myocardial infarction (AMI) and 494 (44.7%) had inferior myocardial infarction (IMI). Patients with IMI had a significantly lower in-hospital mortality rate (9.1% vs 15.6%, p = 0.0014) and significantly lower prevalences of congestive heart failure (39.4% vs 47.6%, p = 0.0066), cardiogenic shock ( 8.7% vs 12.6%, p = 0.0384) and conduction defects (left anterior hemiblock, right bundle branch block and intraventricular conduction defect). The patients with AMI had significantly higher peak enzyme levels, and a greater percentage of them (40.1% vs 25.9%) had SGOT greater than 240 IU/l, whereas more patients with IMI (34.6% vs 27.8%) had SGOT less than 120 IU/l (p = 0.0001). When the parallel subgroups were compared according to the peak SGOT levels (less than 120, 120-240, and greater than 240 IU/l, the differences in the mortality and morbidity between the two infarct locations diminished. However, patients with AMI still had a less favorable outcome. Logistic regression analysis demonstrated that both the peak enzyme level and the infarct location had an independent influence on the in-hospital prognosis of patients with first transmural infarction.

Pathogenesis of left ventricular aneurysms: an experimental study in the rat model

Left ventricular aneurysms, convex protrusions at sites of transmural scar, are clinically recognized late after myocardial infarction because of their hemodynamic or arrhythmic complications. Whether aneurysms develop from dilation of freshly infarcted myocardium early after myocardial infarction or from late dilation of scar is not known. To investigate this question, the time course of changes in shape of the left ventricle early and late after myocardial infarction was studied. One hundred forty-one myocardial infarcts were produced in rats by coronary ligation, and the animals were killed at time periods of up to 6 weeks. True aneurysms developed as early as 2 weeks and only in rats with a transmural infarct. The percent of rats that manifested "aneurysmal shape changes" (defined as a protrusion of the full thickness of the left ventricular wall) increased from day 1 to day 5, but did not change significantly thereafter. The extent of left ventricular dilation in hearts with early aneurysmal shape changes did not progress significantly up to day 42. Accordingly, in the rat, regional aneurysmal shape alterations are due not to late dilation of scare tissue, but rather to "expansion" of freshly necrotic myocardium within the first 5 days of infarction. Thus, early changes in shape appear to determine late aneurysm formation.

Comparison of Indium-111 platelet scintigraphy and two-dimensional echocardiography in the diagnosis of left ventricular thrombi

In a study comparing indium-111 platelet scintigraphy and two-dimensional echocardiography as methods of identifying left ventricular thrombi, the results obtained with both techniques were verified at surgery or autopsy in 53 patients--34 with left ventricular aneurysms, and 19 with mitral-valve disease. Left ventricular thrombi were found at surgery or autopsy in 14 of the patients with aneurysms and in none of those with mitral-valve disease. Thirteen of 53 echocardiograms (25 per cent) were technically inadequate and excluded from the analysis. In the group with aneurysms, the sensitivity of scintigraphy in detecting thrombi was 71 per cent, and that of echocardiography was 77 per cent. The specificity of scintigraphy was 100 per cent, and that of echocardiography was 93 per cent. We conclude that indium-111 platelet scintigraphy and two-dimensional echocardiography have useful and complementary roles in the detection of left ventricular thrombi. Both these noninvasive techniques can be used to monitor therapy.