Inferior After Acute Myocardial Infarction Research Articles

Recovery of Left Ventricular Twist and Left Ventricular Untwist Rate in Patients with ST-segment Elevation Acute Myocardial Infarction

Background: Left ventricular (LV) functional recovery and morphological remodeling after acute myocardial infarction (AMI) followed by reperfusion remain incompletely understood. The aim of the study was to describe the recovery of LV twist (LVT) and LV untwist rate (LVUR) upon revascularization after AMI using two-dimensional (2D) speckle tracking. Methods: We evaluated 88 subjects: 22 normal volunteers (mean age 31 ± 5 years), and 66 patients with AMI (mean age 65 ± 12 years), of which 40 had an inferior AMI and 26 an anterior one. All AMI patients had ST-segment elevation. Echocardiography was performed in all subjects. Patients were scanned within 36 h (baseline) after revascularization (percutaneous coronary intervention) and after 4 months (4 mFU). Apical and basal short-axis images were acquired (frame rate 67 ± 5 frames/s) and analyzed offline to extract the rotation (rate) curves. From these, maximal systolic LVT and peak LVUR were derived. Finally, the infarct size (IS) was estimated based on magnetic resonance imaging delayed enhancement and expressed as a percentage of the total LV volume. Results: At 36 h, LVT and LVUR were significantly reduced in both AMI groups when compared to normals. At 4 mFU, both AMI groups showed recovery in ejection fraction (EF) and reduction in IS (7.24 ± 10.07 vs. 20.13 ± 13.9, P < 0.0001 for inferior AMI and 13.13 ± 10.3 vs. 24.40 ± 15, P < 0.0001 for anterior AMI). LVT and LVUR increased significantly but remained below normal levels. Correlation of LVT and LVUR with IS was significant, but weak (r = 0.34 and r = 0.34, respectively). In addition, a fair correlation of LVT with EF (r = 0.64) and a weak correlation of LVUR with end-diastolic volume (r = 0.43) were found. Conclusion: LVT and LVUR are reduced in AMI patients early after reperfusion and recover incompletely upon follow-up. Interestingly, recovery of LVT characteristics as measured with this 2D speckle tracking-based method showed to be independent of infarct location or extent. LVT and LVUR might be good parameters to monitor the recovery of global LV function after treatment.

Usefulness of Speckle-Tracking Imaging for Right Ventricular Assessment after Acute Myocardial Infarction: A Magnetic Resonance Imaging/Echocardiographic Comparison within the Relation between Aldosterone and Cardiac Remodeling after Myocardial Infarction Study

Right ventricular (RV) dysfunction after acute myocardial infarction (AMI) is frequent and associated with poor prognosis. The complex anatomy of the right ventricle makes its echocardiographic assessment challenging. Quantification of RV deformation by speckle-tracking echocardiography is a widely available and reproducible technique that readily provides an integrated analysis of all segments of the right ventricle. The aim of this study was to investigate the accuracy of conventional echocardiographic parameters and speckle-tracking echocardiographic strain parameters in assessing RV function after AMI, in comparison with cardiac magnetic resonance imaging (CMR). A total of 135 patients admitted for AMI (73 anterior, 62 inferior) were prospectively studied. Right ventricular function was assessed by echocardiography and CMR within 2 to 4days of hospital admission. Right ventricular dysfunction was defined as CMR RV ejection fraction<50%. Right ventricular global peak longitudinal systolic strain (GLPSS) was calculated by averaging the strain values of the septal, lateral, and inferior walls. Right ventricular dysfunction was documented in 20 patients. Right ventricular GLPSS was the best echographic correlate of CMR RV ejection fraction (r=-0.459, P<.0001) and possessed good diagnostic value for RV dysfunction (area under the receiver operating characteristic curve [AUROC], 0.724; 95% CI, 0.590-0.857), which was comparable with that of RV fractional area change (AUROC, 0.756; 95% CI, 0.647-0.866). In patients with inferior myocardial infarctions, the AUROCs for RV GLPSS (0.822) and inferolateral strain (0.877) were greater than that observed for RV fractional area change (0.760) Other conventional echocardiographic parameters performed poorly (all AUROCs<0.700). After AMI, RV GLPSS is the best correlate of CMR RV ejection fraction. In patients with inferior AMIs, RV GLPSS displays even higher diagnostic value than conventional echocardiographic parameters.

Clinical and Echocardiographic Predictors of Cardiorenal Syndrome Type I in Patients with Acute Ischemic Right Ventricular Dysfunction

Background: In current cardiology practice, the importance of acute cardiorenal syndrome (CRS) in determining the outcome of patients with acute coronary syndrome (ACS) is well recognized. Certain groups of ACS patients are at higher risk of developing CRS. Data on the association between right ventricular (RV) functions and CRS after acute myocardial infarction (AMI) are scarce. The purpose of the current study was to evaluate the relation between RV function and the development of CRS in patients presenting with inferior wall AMI and RV involvement. Patients and Methods: Patients with inferior wall AMI with RV involvement underwent echocardiography at admission to assess RV function. RV functions were quantified according to RV fractional area change (RVFAC), tricuspid annular plane systolic excursion (TAPSE), and RV outflow tract fractional shortening (RVOTFS). The patients were followed up until discharge from hospital. All patients who developed CRS were included in group I, all patients who did not develop CRS were included in group II (controls). Multivariate analysis was carried out to determine the significance of the echocardiographic and clinical parameters in predicting the development of CRS in these patients. Results: In our study, a history of diabetes mellitus, cardiogenic shock at admission, and RVFAC and TAPSE could significantly predict the development of CRS in patients presenting with inferior wall AMI and RV involvement. Conclusions: RV functions provide strong prognostic information regarding the development of CRS in patients of inferior wall AMI with RV involvement.

Electrocardiographic findings in cardiogenic shock, risk prediction, and the effects of emergency revascularization: Results from the SHOCK trial

Objectives To evaluate electrocardiographic (ECG) parameters as predictors of 1-year mortality in patients developing cardiogenic shock after acute myocardial infarction (AMI), and to document associations between these ECG parameters and the survival benefit of emergency revascularization versus initial medical stabilization. Background Emergency revascularization reduces the risk of mortality in patients developing cardiogenic shock after AMI. The prognostic value of ECG parameters in such patients is unclear, and it is uncertain whether emergency revascularization reduces the mortality risk denoted by ECG parameters. Methods In a prospective substudy of 198 SHOCK (SHould we emergently revascularize Occluded Coronaries for cardiogenic shocK) trial patients, ECGs recorded within 12 hours of shock were interpreted by personnel blinded to the patients' treatment assignment and outcome. Results The baseline heart rate was higher in non-survivors than in survivors (106 ± 20 versus 95 ± 24 beats/minute, P = .001). There was a significant association between the QRS duration and 1-year mortality in medically stabilized patients (115 ± 28 ms in non-survivors versus 99 ± 23 ms in survivors, P = .012), but not in emergently revascularized patients (110 ± 31 versus 116 ± 27 ms respectively, P = .343). The interaction between the QRS duration, mortality and treatment assignment was significant ( P = .009). Among patients with inferior AMI, a greater sum of ST depression was associated with higher 1-year mortality in medically stabilized patients ( P = .029), but not in emergently revascularized patients ( P = .613, treatment interaction P = .025). On multivariate analysis, the independent mortality predictors were increasing age, elevated pulmonary capillary wedge pressure, heart rate, sum of ST depression in medically stabilized patients, and interaction ( P = .016) between a prolonged QRS duration and treatment assignment. The adjusted hazard ratio for 1-year mortality per 20 ms increase in the QRS duration was 1.19 (95% CI 0.98–1.46) in medically stabilized patients and 0.81 (95% CI 0.63–1.03) in emergently revascularized patients. Conclusion ECG parameters identified patients with cardiogenic shock who were at high risk. Emergency revascularization eliminated the incremental mortality risk associated with cardiogenic shock in patients with a prolonged QRS duration, or inferior AMI accompanied by precordial ST depression. Prospective assessments of the magnitude of the treatment effect based on ECG parameters are required.

Heart Rate Variability and Plasma Catecholamine Levels Early After Acute Myocardial Infarction

BackgroundAn imbalance between sympathetic and parasympathetic tone has been shown to contribute to the genesis of malignant arrhythmias after acute myocardial infarction (AMI). To assess a relationship between the magnitude of sympathoadrenal activation and the balance of autonomic input to the heart early after AMI, plasma catecholamine levels and spectral analysis of short‐term heart rate variability (HRV) were evaluated on day 2 and 5 after hospital admission under standardized conditions.MethodsThirty‐two patients with AMI (27 men, 5 women, mean age 58 ± 10 years) were studied, 13 with anterior and 19 with inferior AMI. Mean left ventricular ejection fraction (LVEF), assessed by two‐dimensional echocardiography, was 48%± 10%. Thirty‐minute ECG recordings were performed in recumbent position, between 9–11 A.M., and edited data were used for analysis of HRV in frequency domain. The control group consisted of 9 patients (6 men, 3 women, mean age 49 ± 10 years) without a history of cardiovascular or systemic disease, who had normal findings on physical examination of the cardiovascular system, and normal 12‐lead ECG. All control subjects were admitted to the hospital for eye or dermatological surgery and underwent the same study procedures according to the identical time schedule.ResultsPlasma catecholine levels decreased significantly from day 2 to 5 of AMI, however, compared to control subjects, the only significant difference suggesting early sympathoadrenal activation in AMI patients was elevated plasma norepinephrine on day 2 (1.73 ± 1.6 vs 0.81 ± 0.7, P &lt; 0.049). Among spectral components of HRV, a trend toward decrease from day 2 to 5 was found for both high frequency (HF) (123.8 ± 184.8 vs 66.7 ± 80.1 ms2, P &lt; 0.03) and low frequency (LF) (293 ± 423.3 vs 164.3 ± 235.4 ms2, P &lt; 0.14) components, although statistically significant only for HF components. However, the ratio between LF and HF components remained unchanged (3.4 ± 2.6 vs 3.6 ± 2.7). Significantly lower values of both LF and HF components, total power, and mean NN interval together with a tendency for a higher LF/HF ratio on day 2 were found in patients with anterior AMI as compared to those with inferior AMI or control subjects. This difference already disappeared on day 5 due to a decrease in both components of HRV in patients with inferior localization of the infarct. Patients with depressed LVEF presented with significantly lower HF components (both in absolute and relative units) while no difference was observed in the mean heart rate or in relative LF components. No significant correlations were found between LF or HF components or their ratio and either measure of sympathoadrenal activity (epinephrine, or norepinephrine and dopamine).ConclusionThe findings of increased plasma norepinephrine levels early after AMI confirm initial sympathoadrenal activation, which was probably related to the presence of myocardial ischemia and/or necrosis per se, independently on the site of myocardial infarction and the degree of impairment of LVEF. The observed changes in spectral measures of short‐term HRV assessed at supine rest under standardized conditions appear to reflect the extent of impairment of cardiac autonomic regulation rather than the magnitude of sympathoadrenal activation. Significant depression of HF

Usefulness of ST-segment depression in non-infarct-related electrocardiographic leads in predicting prognosis after thrombolytic therapy for acute myocardial infarction

This study investigated both the in-hospital and long-term prognostic significance of ST-segment depression in non-infarct-related leads in patients who received thrombolytic therapy after acute myocardial infarction (AMI). We evaluated 221 consecutive patients who were admitted with their first AMI and underwent thrombolysis. Patients were followed for an average of 31 months and were classified into 3 groups: group 1 included 51 patients with persistent ST-segment depression, group 2 had 97 patients with transient ST-segment depression, and group 3 consisted of 73 patients without ST-segment depression (absent). Group 1 had significantly worse long-term survival during follow up by Kaplan-Meier analysis (55%) versus group 2 (81%) and group 3 (94%) (p = 0.0004) and higher event rates. This prognostic significance seemed to be maintained in both the anterior and inferior wall AMI groups. Multivariate analysis, using the Cox model, showed that Killip class, in-hospital left ventricular ejection fraction, and the persistence of ST-segment depression on the predischarge electrocardiogram (group 1) were independent predictors of survival. ST-segment depression in non-infarct-related leads on the predischarge electrocardiogram is an independent risk factor for worse long-term survival after anterior as well as inferior AMI treated with thrombolytic therapy.

Serial assessment of left ventricular chamber stiffness after acute myocardial infarction

Left ventricular (LV) systolic function after acute myocardial infarction (AMI) has been the subject of detailed studies during the last decade, but diastolic phenomena during and after AMI are less well understood. Recently, it has been shown that early filling deceleration time accurately predicted LV chamber stiffness in an experimental model. To assess changes of LV stiffness after AMI, we studied 116 consecutive patients with 2-dimensional and Doppler echocardiographic examinations 1, 2, 3, 7, 21, and 42 days after AMI. Coronary angiography was performed in 101 patients. For the entire study group, deceleration time decreased nonsignificantly on day 2 and subsequently increased on days 3 (p = 0.001) and 7 (p = 0.036), returning toward initial values afterward. Deceleration time was shorter in large (peak creatine kinase level > 1,000 U/L) versus small infarcts (p = 0.0008) and in patients with anterior versus inferior AMI (p = 0.02); there was no difference between patients with good and poor (⩽45%) ejection fraction. These data indicate that increased LV stiffness can be detected 24 to 48 hours after AMI, but returns to normal within several days. Chamber stiffness is higher in large and anterior infarcts, but appears to be independent of LV systolic function.

945-118 Validation of a Simple Exercise-Test Based Method for Early Identification of Multivessel Coronary Disease After Acute Myocardial Infarction

The presence of multivessel coronary disease (MVD) is a powerful determinant of prognosis after acute myocardial infarction (AMI). The use of early exercise testing (ExT) in the detection of MVD has produced conflicting results in part due to the use of submaximal protocols and the selective use of angiography. We routinely perform coronary angiography after AMI irrespective of the results of ExT. In this setting, we studied the use of multivariate analysis of clinical and exercise parameters derived from maximal ExT, to detect the presence of MVD in consecutive patients after AMI. Of 240 patients with AMI (October 1992-May 1994), 117 had both early (8 ± 2 days) maximal ExT and coronary angiography (13 ± 8 days) after uncomplicated AMI. No complications occurred related to ExT. Using a discriminant analysis, a statistical model was established in the first 72 patients (learning group) and validated in the next 45 patients (testing group). Baseline variables were comparable in terms of age (56 yrs vs 59 yrs), Q-wave AMI (83% vs 76%), inferior AMI (65% vs 69%), use of thrombolytic therapy (64% vs 60%) and MVD (44% vs 36%). Of 9 clinical and 15 exercise variables which were incorporated in the discriminant analysis, the number of METs achieved (p &lt; 0.0005), maximal ST segment depression in V5 (p &lt; 0.0051 and maximal exercise heart rate were the only variables significantly associated with the presence of MVD in the learning group. The discriminant function, using these 3 variables, correctly classified 75% of patients with MVD in the learning group and 79% of patients in the testing group, whereas the use of maximal ST depression alone, the most conventional index, correctly classified only 60% of patients in the testing group (p &lt; 0.005). Thus, maximal ExT can be safely performed early after uncomplicated AMI. The accuracy of early ExT in the detection of MVD can be improved using a discriminant analysis that incorporates 3 easily derived exercise variables which were prospectively validated.

A difference between front-loaded streptokinase and standard-dose recombinant tissue-type plasminogen activator in preserving left ventricular function after acute myocardial infarction (the Central Illinois Thrombolytic Therapy Study)

A blinded, randomized trial compared the effects of front-loaded streptokinase with those of the conventional dose of intravenous recombinant tissue-type plasminogen activator (rt-PA) on left ventricular (LV) function after acute myocardial infarction (AMI). Thrombolytic therapy was administered in the emergency departments of 30 community hospitals in central Illinois, and subsequent studies were performed at 1 tertiary referral center. Patients aged ⪯75 years with a first AMI who could be treated within 4 hours of the onset of chest pain were randomly assigned to receive either streptokinase (375,000 111 bolus, followed by 1,125,000 IU over 1 hour) or rt-PA (10 mg bolus, followed by 50 mg in the first hour, and 20 mg/hour for the next 2 hours). All patients were treated with aspirin (325 mg) and intravenous heparin. Patients were transferred for angiography within 24 hours. During the 30-month study, 253 patients were treated with intravenous thrombolytic therapy 2.4 ± 1.0 hour after the onset of AMI. In patients with anterior wall AMI (n = 90), global LV ejection fraction measured by angiography within 24 hours was 45 ± 12% with rt-PA, and 39 ± 13% with streptokinase (p < 0.03). Convalescent radionuclide angiography documented a persistent beneficial effect of rt-PA on LV regional wall contractility, but not global ejection fraction. There were no differences between rt-PA and streptokinase in preserving global or regional LV function in patients with inferior wall AMI.

Usefulness of ejection fraction response to exercise one month after acute myocardial infarction in predicting coronary anatomy and prognosis

The prognostic value of left ventricular (LV) ejection fraction (EF) measured during maximal exercise testing early after acute myocardial infarction (AMI) was assessed in 75 patients, aged 65 years or younger, a mean of 36 days after AMI. At follow-up for a mean 12 months (range 6 to 26), medical complications developed in 15 patients: cardiac death in 5, ventricular fibrillation in 1, reinfarction in 2, unstable angina in 5, and severe cardiac failure in 2. Seven other patients underwent coronary artery bypass grafting for severe angina. When LVEF less than 50% at rest was compared with LVEF of 50% or more, the 2-year life-table survival free of complications was 54 ± 21% compared with 84 ± 19% (p < 0.05). When exercise LVEF less than 50% was compared with LVEF of 50% or more, the 2-year survival rate free of medical complication was 42 ± 32% compared with 83 ± 20% (p < 0.05). LVEF change from rest to exercise was not related to prognosis. Patients with combined medical and surgical events tended to have lower rest and exercise LVEFs, but changes in LVEF during exercise were again unrelated to prognosis. Sixty-five patients underwent coronary arteriography. After inferior AMI the mean LVEF was lower in those with multivessel than in those with 1-vessel coronary artery disease at rest (47 ± 13% vs 59 ± 7%, p < 0.005) and during exercise (47 ± 13% vs 59 ± 9%, p < 0.005); however, the change in LVEF during exercise was not related to coronary anatomy. After anterior AMI, neither the rest LVEF, exercise LVEF nor change in LVEF during exercise was related to the extent of coronary artery disease.

An angiographic and functional comparison of patients with silent and symptomatic treadmill ischemia early after myocardial infarction

Sixty consecutive patients were studied who had positive responses to Naughton exercise treadmill testing (at least 1.5 mm of ST-segment shift in at least 2 leads or thallium reperfusion abnormalities) with or without symptoms of angina 11 ± 1 days after acute myocardial infarction (AMI). All patients had undergone coronary angiography 24 ± 4 days after infarction. Thirty-eight patients (63%) had no treadmill angina (silent ischemia, group I) and 22 patients had typical treadmill angina (symptomatic ischemia, group II). Use of β-blocking drugs, calcium antagonists and nitrates at the time of exercise testing did not differ in the 2 groups. All 9 patients with diabetes mellitus were in the asymptomatic group (p <0.40) and group I had a greater proportion of inferior wall AMI (30 of 38) than group II (11 of 22, p = 0.02). Total exercise treadmill test duration (group 1422 ± 31 seconds, group II 400 ± 46 seconds) and rate-pressure product were not different in the 2 groups. The number of patients unable to exercise 5 minutes (12 in group I and 7 in group II), the number with diffuse electrocardiographic changes (9 in group I and 7 in group II), and the number with inadequate blood pressure response (8 in group I and 4 in group II) were also similar. At coronary arteriography the mean number of arteries with at least 70% diameter stenosis was 2.0 ± 0.2 in group I and 2.2 ± 0.2 In group II (difference not significant). No significant difference was noted in the number of patients with multivessel coronary artery disease (74% in group I and 73% in group II). The infarct-related artery was totally occluded in 66% patients in group I and 55% patients in group II (difference not significant). Thus, asymptomatic ischemia occurs frequently in patients who undergo early post-AMI exercise treadmill testing and the exercise performance and angiographic characteristics of these patients are similar to those in patients with symptomatic treadmill ischemia.

Effect of ventricular fibrillation complicating acute myocardial infarction on long-term prognosis: Importance of the site of infarction

Identification of high-risk subgroups of patients after acute myocardial infarction (AMI) is essential for evaluation of targeted preventive strategies. A case-control study was performed in 250 post-AMI patients to examine whether an episode of ventricular fibrillation (VF) during the in-hospital period modifies the long-term prognosis for patients with either an anterior or an inferior AMI. After identification of 70 patients with an anterior AMI and 55 patients with an inferior AMI, all complicated by VF and discharged alive, we selected 125 additional patients who had an AMI not complicated by VF (control subjects). To minimize the potential sources of differences in outcome, cases and controls were matched for the following variables: sex (all men), age (same ± 2 years), coronary care unit (same), epoch of AMI (same ± 3 months), and site of AMI (same). Left ventricular dysfunction and prior AMI were present in only a few patients. Patients receiving either acute or long-term treatment with β-adrenergic blocking agents were not included. The average follow up was 59 months (range 12 to 120). The cumulative mortality during the first 5 years for the patients with inferior AMI without VF (6%, 11%, 13%, 13% and 13%) was modest and not significantly different from that of inferior AMI complicated by VF (6%, 11%, 20%, 20%, and 26%). In contrast, a striking difference appeared when the cumulative mortality of patients with anterior AMI without VF (9%, 13%, 17%, 27% and 29%) was compared with that of patients with anterior AMI complicated by VF (32%, 40%, 46%, 49% and 54%) (p < 0.005). This group also had a high incidence of sudden death (71%), particularly in the first year after AMI. This finding is in contrast with the current view that VF does not modify the long-term post-AMI prognosis. In conclusion, patients who are discharged alive after an anterior AMI complicated by VF represent a subgroup at very risk of sudden cardiac death. For patients with an inferior AMI, the occurrence of VF in the acute phase does not modify the long-term prognosis.

Measurement of myocardial infarct size by technetium pyrophosphate single-photon tomography

The primary determinant of prognosis after acute myocardial infarction (AMI) is the size of the acute infarct. The present study evaluates 46 patients with different infarct distributions and sizes to test the hypothesis that single photon emission computed tomography with technetium-99m pyrophosphate (Tc-99m-PPi) and blood pool overlay allows measurements of AMI size that provide insight into prognosis irrespective of infarct location. Identical Tc-99m-PPi and ungated blood pool projections were acquired over 180 degrees with a rotating gamma camera. Reconstructed sections were color-coded and superimposed for purposes of infarct localization. Areas of increased pyrophosphate uptake within myocardial infarcts were thresholded at 65% of peak activity. The blood pool was thresholded at 50% and subtracted so as to determine an endocardial border for the left ventricle. Using this method, myocardial infarcts weighed 2.5 to 81.2 g. The correlation of infarct mass with prognosis showed that patients without previous AMI and with acute infarcts that weighed more than 40 g had an increased frequency of death and congestive heart failure (p less than 0.001). The correlation of measured infarct mass with peak serum creatine kinase level was significant (r = 0.83, p less than 0.001; y = 0.015x + 13.20). The correlation coefficients for anterior, inferior and nontransmural AMI were not significantly different from those for the entire group. In conclusion, tomographically determined infarct mass data correlate with subsequent clinical prognosis, and Tc-99m-PPi tomography with blood pool overlay is a safe and effective means of sizing infarcts in patients with AMI.