Late reperfusion for acute myocardial infarction limits the dilatation of left ventricle without the reduction of infarct size

Coronary collateral circulation: Effects on outcomes of acute anterior myocardial infarction after primary percutaneous coronary intervention

Background

To investigate the effects of collateral coronary circulation on the outcome of the patients with anterior myocardial infarction (MI) with left anterior desending artery occlusion abruptly.

Methods

Data of 189 patients with acute anterior MI who had a primary percutaneous coronary intervention (PCI) in the first 12 h from the onset of symptoms between January 2004 and December 2008 were retrospective analyzed. Left anterior descending arteries (LAD) of all patients were occluded. LADs were reopened with primary PCI. According to the collateral circulation, all patients were classified to two groups: no collateral group (n = 111), patients without angiographic collateral filling of LAD or side branches (collateral index 0) and collateral group (n = 78), and patients with angiographic collateral filling of LAD or side branches (collateral index 1, 2 or 3). At one year's follow-up, the occurrence of death, reinfarction, stent thrombosis (ST), target vessel revascularization and readmission because of heart failure were observed.

Results

At one year, the mortality was lower in patients with collateral circulation compared with those without collateral circulation (1% vs. 8%, P = 0.049), whereas there were no differences in the occurrence of reinfarction, ST, target vessel revascularization and readmission because of heart failure. The occurrence of composite of endpoint was lower in patients with collateral circulation compared with those without collateral circulation (12% vs. 26%; P = 0.014).

Conclusions

Pre-exist collateral circulation may prefigure the satisfactory prognosis to the patients with acute anterior MI after primary PCI in the first 12 h of MI onset.

Infarct tissue characteristics of patients with versus without early revascularization for acute myocardial infarction: a contrast-enhancement cardiovascular magnetic resonance imaging study

Histopathological studies have suggested that early revascularization for acute myocardial infarction (MI) limits the size, transmural extent, and homogeneity of myocardial necrosis. However, the long-term effect of early revascularization on infarct tissue characteristics is largely unknown. Cardiovascular magnetic resonance (CMR) imaging with contrast enhancement (CE) allows non-invasive examination of infarct tissue characteristics and left ventricular (LV) dimensions and function in one examination. A total of 69 patients, referred for cardiac evaluation for various clinical reasons, were examined with CE-CMR >1 month (median 6, range 1-213) post-acute MI. We compared patients with (n = 33) versus without (n = 36) successful early revascularization for acute MI. Cine-CMR measurements included the LV end-diastolic and end-systolic volumes (ESV), LV ejection fraction (LVEF, %), and wall motion score index (WMSI). CE images were analyzed for core, peri, and total infarct size (%), and for the number of transmural segments. In our population, patients with successful early revascularization had better LVEFs (46 ± 16 vs. 34 ± 14%; P < 0.01), superior WMSIs (0.53, range 0.00-2.29 vs. 1.42, range 0.00-2.59; P < 0.01), and smaller ESVs (121 ± 70 vs. 166 ± 82; P = 0.02). However, there was no difference in core (9 ± 6 vs. 11 ± 6%), peri (9 ± 4 vs. 10 ± 4%), and total infarct size (18 ± 9 vs. 21 ± 9%; P > 0.05 for all comparisons); only transmural extent (P = 0.07) and infarct age (P = 0.06) tended to be larger in patients without early revascularization. CMR wall motion abnormalities are significantly better after revascularization; these differences are particularly marked later after infarction. The difference in scar size is more subtle and does not reach significance in this study.

Folic acid mitigated cardiac dysfunction by normalizing the levels of tissue inhibitor of metalloproteinase and homocysteine-metabolizing enzymes postmyocardial infarction in mice

Myocardial infarction (MI) results in significant metabolic derangement, causing accumulation of metabolic by product, such as homocysteine (Hcy). Hcy is a nonprotein amino acid generated during nucleic acid methylation and demethylation of methionine. Folic acid (FA) decreases Hcy levels by remethylating the Hcy to methionine, by 5-methylene tetrahydrofolate reductase (5-MTHFR). Although clinical trials were inconclusive regarding the role of Hcy in MI, in animal models, the levels of 5-MTHFR were decreased, and FA mitigated the MI injury. We hypothesized that FA mitigated MI-induced injury, in part, by mitigating cardiac remodeling during chronic heart failure. Thus, MI was induced in 12-wk-old male C57BL/J mice by ligating the left anterior descending artery, and FA (0.03 g/l in drinking water) was administered for 4 wk after the surgery. Cardiac function was assessed by echocardiography and by a Millar pressure-volume catheter. The levels of Hcy-metabolizing enzymes, cystathionine β-synthase (CBS), cystathionine γ-lyase (CSE), and 5-MTHFR, were estimated by Western blot analyses. The results suggest that FA administered post-MI significantly improved cardiac ejection fraction and induced tissue inhibitor of metalloproteinase, CBS, CSE, and 5-MTHFR. We showed that FA supplementation resulted in significant improvement of myocardial function after MI. The study eluted the importance of homocysteine (Hcy) metabolism and FA supplementation in cardiovascular disease.

Left ventricular function in acute myocardial infarction treated with thrombolysis followed by early versus late invasive strategy

BACKGROUND

Thrombolysis remains the treatment of choice in acute ST-segment elevation myocardial infarction (STEMI) when primary percutaneous coronary intervention (PCI) cannot be performed within 90 to 120 minutes. The optimal treatment after thrombolysis is still debated, but several studies have shown improved clinical outcomes with early transfer for PCI. The aim of this study was to investigate whether an early invasive strategy after thrombolysis preserved left ventricular function better than a late invasive strategy.

METHODS

This was a substudy of the NORwegian study on DIstrict treatment of ST-Elevation Myocardial Infarction. Patients with STEMI of <6 hours of duration and >90 minutes of expected transfer delays to PCI were treated with aspirin, tenecteplase, enoxaparin, and clopidogrel and randomized to early or late invasive strategy (N = 266). Left ventricular volumes and ejection fraction were assessed by single-photon emission computed tomography, echocardiography, and magnetic resonance imaging 3 months after the index infarction.

RESULTS

Noninvasive imaging was completed in 241 patients (91%). Median end-diastolic and end-systolic volumes after 3 months did not differ between groups. Median ejection fraction was well preserved and also without differences: 63% (interquartile range 51-70) in the early invasive versus 65% (interquartile range 55-71) in the late invasive group when assessed by single-photon emission computed tomography (P = .30), 55% versus 55% when assessed by echocardiography (P = .88), and 57% versus 57% when assessed by magnetic resonance imaging (P = .99).

CONCLUSION

In this group of STEMI patients treated with thrombolysis, no difference in left ventricular function after 3 months was found between patients treated with early versus late invasive strategy.

Beneficial effect of reperfusion therapy beyond the preservation of left ventricular function in patients with acute ST-segment elevation myocardial infarction

BACKGROUND

Reperfusion therapy has been shown to improve mortality in patients with acute ST-segment elevation myocardial infarction. However, in randomized clinical trials there was only a modest improvement in left ventricular ejection fraction with reperfusion therapy, despite a larger improvement in mortality.

METHODS

In the prospective MITRA-Plus registry we compared 1-year mortality of inhospital survivors of ST-segment elevation myocardial infarction (STEMI) divided into nine groups with preserved (>55%), moderately reduced (41-55%) and severely reduced (≤40%) left ventricular ejection fraction (LVEF) and treated with no early reperfusion therapy, fibrinolysis or primary percutaneous coronary intervention (PCI) within 24 h after admission.

RESULTS

A total of 5867 patients were included in this analysis, 1026 (18%) without early reperfusion, 2462 (42%) with fibrinolysis and 2379 (40%) with primary PCI. After adjustment for confounding variables in a propensity score analysis, reperfusion therapy (Odds ratio and 95% CI: 0.27, 0.15-0.48; 0.50, 0.32-0.79; 0.64, 0.44-0.93), fibrinolysis (Odds ratio and 95% CI: 0.27, 0.14-0.52; 0.58, 0.35-0.95; 0.60, 0.39-0.93) and primary PCI (Odds ratio and 95% CI: 0.22, 0.11-0.44; 0.34, 0.19-0.59; 0.56, 0.36-0.88) remained independent predictors of survival in comparison to no reperfusion therapy in the patients with preserved, moderately reduced and severely reduced LVEF, respectively.

CONCLUSIONS

These results suggest a beneficial effect of early reperfusion therapy beyond the preservation of left ventricular function, however the mechanisms need further study.

Intracardiac injection of erythropoietin induces stem cell recruitment and improves cardiac functions in a rat myocardial infarction model

Erythropoietin (EPO) protects the myocardium from ischaemic injury and promotes beneficial remodelling. We assessed the therapeutic efficacy of intracardiac EPO injection and EPO-mediated stem cell homing in a rat myocardial infarction (MI) model. Following MI, EPO (3000 U/kg) or saline was delivered by intracardiac injection. Compared to myocardial infarction control group (MIC), EPO significantly improved left ventricular function (n =11-14, P < 0.05) and decreased right ventricular wall stress (n = 8, P < 0.05) assessed by pressure-volume loops after 6 weeks. MI-EPO hearts exhibited smaller infarction size (20.1 +/- 1.1% versus 27.8 +/- 1.2%; n = 6-8, P < 0.001) and greater capillary density (338.5 +/- 14.7 versus 259.8 +/- 9.2 vessels per mm2; n = 6-8, P < 0.001) than MIC hearts. Direct EPO injection reduced post-MI myocardial apoptosis by approximately 41% (0.27 +/- 0.03% versus 0.42 +/- 0.03%; n = 6, P= 0.005). The chemoattractant SDF-1 was up-regulated significantly assessed by quantitative realtime PCR and immunohistology. c-Kit(+) and CD34(+) stem cells were significantly more numerous in MI-EPO than in MIC at 24 hrs in peripheral blood (n = 7, P < 0.05) and 48 hrs in the infarcted hearts (n = 6, P < 0.001). Further, the mRNAs of Akt, eNOS and EPO receptor were significantly enhanced in MI-EPO hearts (n = 7, P < 0.05). Intracardiac EPO injection restores myocardial functions following MI, which may attribute to the improved early recruitment of c-Kit(+) and CD34(+) stem cells via the enhanced expression of chemoattractant SDF-1.

The comparison of early and late outcome of direct and conventional stenting of patients with st elevation myocardial infarction

Background: The aim of this study was to compare direct and conventional stenting procedure in the subacute stable phase on short- and long-term results in patients with ST elevation myocardial infarction.

Methods: Eighty-eight clinically stable ST-segment elevation myocardial infarction (STEMI) patients were enrolled into the study. The patients were classified as group I (direct stenting) and group II (conventional stenting — stenting after balloon dilatation). Baseline characteristics of patients were scanned from hospital records. Coronary angiograms before and after the revascularization procedure were evaluated with the quantitative coronary angiogram technique. Patients were followed for 5 years for clinical outcomes. The study population consisted of 58 patients (65%) in group I and 30 patients (35%) in group II. Mean ages were 55.8 ± 10.8 and 57.3 ± 9.8, respectively.

Results: There were no significant differences between the two groups regarding clinical characteristics (hypertension, diabetes mellitus, family history of cardiovascular disease, smoking and dyslipidemia). The thrombus score was similar in both groups. Diameter stenosis was lower in group I (54.8 ± 12.7 versus 61.4 ± 12.6; p = 0.023) and TFC (Thrombolysis in Myocardial Infarction frame count) was higher in group II (30.7 ± 14.5 versus 40.8 ± 26.7; p = 0.02) before the percutaneous coronary intervention (PCI). Other quantitative angiographic parameters were not different. For all angiographic criteria, the difference between pre- and post-PCI parameters was significantly different in both groups. However, the change in TFC was higher within the group II compared to pre-PCI TFC rates. This difference was statistically significant ( p = 0.002). Procedural success was statistically different between groups (69% in group I, 43% in group II; p50.01). Immediate clinical and angiographic results were similar. At 5-year follow-up the incidence of major adverse cardiac events including death, angina pectoris and myocardial infarction were similar for direct stenting versus conventional angioplasty.

Conclusions: Direct stenting is safe and feasible for the treatment in patients with STEMI at the subacute phase. Immediate clinic, angiographic and late clinical results are similar for direct stenting and conventional stenting following balloon angioplasty. Although conventional stenting improved TFC better than direct stenting, this did not translate to better clinical outcomes.

The optimal time of elective percutaneous coronary intervention for stable patients after ST elevation myocardial infarction

OBJECTIVE

To find the optimal time (early: < or =3 days; late: >3 days) for revascularization in ST elevation myocardial infarction (STEMI) patients in the subacute phase.

METHODS

Ninety-nine STEMI patients who were admitted to Gazi University Faculty of Medicine between 2000 and 2004 were enrolled into this study. Patients were divided into 2 groups according to time from the beginning of symptoms to the percutaneous coronary intervention. Coronary angiograms before and after the revascularization were evaluated using the quantitative coronary angiogram technique.

RESULTS

45 early (group I) and 54 late (group II) revascularized patients were evaluated. There were no significant differences between the 2 groups regarding demographic properties, thrombus score, success of the procedure, quantitative angiographic parameters, and clinical results of the procedure.

CONCLUSIONS

Waiting for the development of stable phase in STEMI to apply PCI has no obvious benefit for angiographic and clinical results.

Usefulness of plasma brain natriuretic peptide concentration for predicting subsequent left ventricular remodeling after coronary angioplasty in patients with acute myocardial infarction

To determine the relation between plasma brain natriuretic peptide (BNP) and remodeling in terms of infarct-related artery (IRA) patency, 106 patients with a first anterior wall acute myocardial infarction with a patent IRA at 1 month were studied. The IRA reoccluded at 6 months in 17 patients (reoccluded IRA) and was patent in 89 patients (patent IRA). The 2 groups did not differ with respect to clinical characteristics, hemodynamic variables, and left ventricular function at 1 month, except for left ventricular end-diastolic and systolic volumes, which were significantly greater in the reoccluded IRA group. Plasma BNP concentration in the reoccluded IRA group (336 +/- 288 pg/ml) was significantly higher than that in the patent IRA group (116 +/- 106 pg/ml) at 1 month. BNP concentration decreased significantly at 6 months in the 2 groups (reoccluded IRA vs patent IRA 152 +/- 162 vs 44 +/- 58 pg/ml, p <0.05). The increase in left ventricular volume from 1 to 6 months was significantly correlated with plasma BNP concentration at 1 month in the patent IRA group (r = 0.314, p < 0.01) and the reoccluded group (r = 0.634, p < 0.01). Linear regression analysis showed that the correlation between the 2 parameters in the 2 groups was similar. Based on stepwise multivariate linear regression analysis, only plasma BNP concentration was significantly correlated with the increase in left ventricular volume from 1 to 6 months in the 2 groups. In conclusion, these results suggest that plasma BNP concentration predicts left ventricular dilation independently of IRA patency.

Improvement in left ventricular function following coronary stenting in patients with acute myocardial infarction: 6-month and 3-year follow-up

BACKGROUND

This study assesses hemodynamic and angiographic changes in patients with a patent infarct-related artery (IRA) after acute myocardial infarction (AMI).

METHODS

One hundred and seventy-seven patients with first AMI, who received a predischarge stenting to the IRA and sustained a patent IRA over 3 years, were stratified into 3 groups according to the baseline left ventricular ejection fraction (LVEF): group A included 63 patients with a LVEF of >49%, group B 73 patients with a LVEF of 40%-49%, and group C 41 patients with a LVEF of <40%. The hemodynamic and angiographic parameters were compared at baseline, 6-month and 3-year follow-up.

RESULTS

The LV end-diastolic volume index increased 1, 4 and 4 ml/m(2) at 6 months and 4, 5 and 10 ml/m(2) at 3 years, respectively in group A, B and C. The LVEF increased 4%, 7% and 12% at 6 months and 6%, 8% and 14% at 3 years, respectively in group A, B and C. The stroke volume index increased 3, 7 and 12 ml/m(2) at 6 months and 6, 8 and 15 ml/m(2) at 3 years, respectively in group A, B and C. The LV wall motion score decreased 2, 3 and 3 at 6 months and was unchanged at 3 years, respectively in group A, B and C. The LV end-diastolic pressure decreased 2, 3 and 4 mm Hg, respectively in group A, B and C, at 6-month follow-up and remained stable at 3 years.

CONCLUSIONS

Long-term beneficial effects in patients receiving a late predischarge intracoronary stenting following first AMI were seen and these may be related to patent IRA. A progressive improvement in left ventricular remodeling occurs in all patients regardless of their initial left ventricular function and the improvement continues for at least 3 years.

Erythropoietin Enhances Neovascularization of Ischemic Myocardium and Improves Left Ventricular Dysfunction After Myocardial Infarction in Dogs

OBJECTIVES

We investigated the effects of erythropoietin (EPO) on neovascularization and cardiac function after myocardial infarction (MI).

BACKGROUND

Erythropoietin exerts antiapoptotic effects and mobilizes endothelial progenitor cells (EPCs).

METHODS

We intravenously administered EPO (1,000 IU/kg) immediately [EPO(0) group], 6 h [EPO(6h) group], or 1 week [EPO(1wk) group] after the permanent ligation of the coronary artery in dogs. Control animals received saline immediately after the ligation.

RESULTS

The infarct size 6 h after MI was significantly smaller in the EPO(0) group than in the control group (61.5 +/- 6.0% vs. 22.9 +/- 2.2%). One week after MI, the circulating CD34-positive mononuclear cell numbers in both the EPO(0) and the EPO(6h) groups were significantly higher than in the control group. In the ischemic region, the capillary density and myocardial blood flow 4 weeks after MI was significantly higher in both the EPO(0) and the EPO(6h) groups than in the control group. Four weeks after MI, left ventricular (LV) ejection fraction in the EPO(6h) (48.6 +/- 1.9%) group was significantly higher than that in either the control (41.9 +/- 0.9%) or the EPO(1wk) (42.6 +/- 1.2%) group but significantly lower than that in the EPO(0) group (56.1 +/- 2.3%). The LV end-diastolic pressure 4 weeks after MI in both the EPO(0) and the EPO(6h) groups was significantly lower than either the control or the EPO(1wk) group. Hematologic parameters did not differ among the groups.

CONCLUSIONS

In addition to its acute infarct size-limiting effect, EPO enhances neovascularization, likely via EPC mobilization, and improves cardiac dysfunction in the chronic phase, although it has time-window limitations.

Complete rupture of the posterior papillary muscle caused by late reperfusion for acute myocardial infarction

We describe a patient with acute mitral regurgitation due to complete rupture of the papillary muscle immediately after successful late reperfusion for inferior myocardial infarction. An 81-year-old woman was admitted complaining of mild chest discomfort. Although the electrocardiograms, biochemical test results, and her clinical history showed that several days had passed since the onset of acute myocardial infarction, a late coronary stenting was performed. Immediately after successful stenting, she suddenly developed acute pulmonary edema, leading to cardiogenic shock. In addition to high pulmonary capillary wedge pressure (mean 35 mmHg), color Doppler imaging revealed massive mitral regurgitation caused by complete rupture of the posterior papillary muscle. Emergent mitral valve replacement with a prosthetic valve was performed, saving the patient. Hence, late reperfusion should be considered carefully when treating a patient with a high risk, such as an elderly patient or a patient with single-vessel disease or initial transmural myocardial infarction.

Serial changes in plasma brain natriuretic peptide concentration at the infarct and non-infarct sites in patients with left ventricular remodelling after myocardial infarction

OBJECTIVES

To clarify the role of infarct and non-infarct sites on left ventricular (LV) remodelling after myocardial infarction by measuring brain natriuretic peptide (BNP) from each site.

METHODS AND RESULTS

BNP from the aorta and the anterior interventricular vein (AIV) was measured in 45 patients with first anterior myocardial infarction at one, six, and 18 months. The LV was significantly dilated (> 10 ml/m(2) of end diastolic volume from one to 18 months) in 20 patients (remodelling (R) group) but not in 25 others (non-remodelling (NR) group). Patient characteristics and LV functions did not differ significantly at one month but plasma BNP concentration was higher in group R than in group NR (336 (288) v 116 (106) pg/ml, p < 0.01), predicting the degree of LV dilatation. The difference in BNP concentration between the aortic root and AIV (DeltaBNP), reflecting BNP secreted from the infarct site, did not differ at one month. In both groups BNP and DeltaBNP significantly decreased from one to six months (p < 0.05) and decreased from six months to 18 months, but the change was not significant. BNP and DeltaBNP were significantly higher in group R than in group NR after six months, when LV dilatation was not evident in both groups.

CONCLUSION

Enhanced BNP secretion at one month in the non-infarct and infarct ventricular sites predicts subsequent LV dilatation (that is, remodelling). The slower process of LV remodelling decreased BNP secretion at both sites. Thus, BNP concentration should be useful for monitoring ventricular remodelling after infarction.

Reduced collateral circulation to the infarct-related artery in elderly patients with acute myocardial infarction

OBJECTIVES

The purpose of this study was to investigate the hypothesis that circulation via collateral vessels to an infarct-related artery (IRA) is impaired with aging in patients with acute myocardial infarction (AMI).

BACKGROUND

Animal experiments have shown that advanced age blunts the development of new vessels in response to angiogenic cytokines.

METHODS

Of 3,573 consecutive patients with AMI, 1,934 patients who fulfilled the following criteria were enrolled in this study: 1) coronary angiograms were obtained within 72 h after the onset of AMI; and 2) IRA showed complete occlusion (Thrombolysis In Myocardial Infarction [TIMI] flow grade 0 or 1). Collaterals to the IRA were angiographically evaluated using the Rentrop score. Rentrop scores 1 to 3 were defined as demonstrating significant collaterals.

RESULTS

The prevalence of collaterals decreased with age, from 47.9%, 45.8%, 43.4%, to 34.0% in patients <50 years, 50 to 59 years, 60 to 69 years, > or =70 years, respectively (p < 0.001). Advanced age was an independent factor predicting the absence of collateral circulation to the IRA. In contrast, time to catheterization, history of angina pectoris, and preinfarction angina were independent predictors for the presence of collaterals. Multivariate analysis showed that the absence of collaterals was an independent predictor of in-hospital mortality in elderly patients > or =70 years (odds ratio, 15.6; 95% confidence interval, 3.5 to 69.6), although this finding was not significant in patients <70 years.

CONCLUSIONS

Advanced age is associated with decreased angiographic presence of collaterals to the IRA in patients with AMI. This abnormality may contribute to the poor prognosis of elderly patients with AMI.

Long-Term Beneficial Effect of Infarct-Related Artery Patency in Acute Anterior Myocardial Infarction in Patients With Poor Myocardial Viability in the Region-at-Risk

BACKGROUND

Several studies have demonstrated the benefit of the patency of infarct-related artery (IRA) in acute myocardial infarction (AMI). However those studies have not been concerned with myocardial viability in the region-at-risk. In the present study the effect of the patency of IRA was investigated in the setting of anterior AMI with poor viable myocardium in the risk region.

METHODS AND RESULTS

From 1993 to 1996 patients with a first time anterior AMI and poor viable myocardium in the region-at-risk at 1 month after onset were identified and enrolled. Patients with a totally occluded IRA were included in the Non-Open group (n=44), and patients with a reperfused IRA were included in the Open group (n=49). At 5 years after onset, left ventricular function was better preserved in the Open group than in the Non-Open group (p<0.05). Kaplan-Meier survival curves for cardiac mortality and event-free survival curves revealed poor prognoses in the Non-Open group over a 5-year period (p<0.05, respectively). The advantages of a patent IRA were further seen in health-related quality-of-life outcomes (p<0.05).

CONCLUSIONS

Even in patients with poor myocardial viability after an anterior AMI, the patency of the IRA is strongly associated with improved long-term survival, independent of residual myocardium viability.

Effect of successful late reperfusion by primary coronary angioplasty on mechanical complications of acute myocardial infarction

It has been suggested that early treatment decreases, but late treatment increases, the risk of mechanical complications for a thrombolytic strategy. However, few studies have evaluated whether late reperfusion (LR) by primary coronary angioplasty decreases the risk of mechanical complications. A total of 2,209 patients with acute myocardial infarction treated with primary coronary angioplasty within 24 hours after the onset of symptoms were divided into 3 groups: early reperfusion (ER; < or =12 hours, n = 1,647), LR (>12 hours, n = 219), and failed reperfusion (FR; n = 343). We evaluated the incidence, risk ratio, and predictors of mechanical complications. The overall incidence of mechanical complications was 2.0%. The incidence of mechanical complications was highest in the FR group (ER 1.4%, LR 1.8%, FR 5.0%; p <0.01). After adjusting for clinical variables, the risk ratio for mechanical complications increased in the FR group compared with the LR group (risk ratio 7.34, 95% confidence interval [CI] 1.02 to 52.80; p = 0.04). Predictors of an increased risk of mechanical complications by multivariate analysis were age > or =70 years (odds ratio [OR] 3.68, 95% CI 1.56 to 8.64; p <0.01), Killip class > or =II (OR 3.73, 95% CI 1.53 to 9.12; p <0.01), absence of collateral vessels (OR 4.09, 95% CI 1.17 to 14.26; p = 0.03), and FR (OR 2.68, 95% CI 1.09 to 6.61; p = 0.03). In conclusion, successful LR by primary coronary angioplasty is associated with the reduced risk of mechanical complications in patients with acute myocardial infarction.

Effect of intraaortic balloon pumping on left ventricular function in patients with persistent ST segment elevation after revascularization for acute myocardial infarction

The purpose of the present study was to assess the impact of intraaortic balloon pumping (IABP) in patients with persistent ST elevation who underwent revascularization within 6 h of their first acute anterior myocardial infarction (AMI). Persistent ST elevation after revascularization was defined as being > or =50% of the initial value on return to the coronary care unit. Twenty-four patients were treated without IABP (control group) and 27 patients were treated with IABP (IABP group). There was no significant difference between the 2 groups in pretreatment left ventricular ejection fraction (LVEF), end-diastolic volume index or end-systolic volume index. After 137+/-46 days, the change in the LVEF was significantly higher in the IABP group than in the control group (5+/-13% vs 13+/-15%, p=0.04). However, the left ventricular end-diastolic volume index was similar between the 2 groups during follow-up (pretreatment: 77+/-19 ml/m(2) vs 74+/-13 ml/m(2), p=0.54; follow-up: 86+/-22 ml/m(2) vs 83+/-18 ml/m(2), p=0.60). These data suggest that IABP enhances the improvement in LVEF independent of remodeling in AMI patients with persistent ST elevation after revascularization.

Late intervention after anterior myocardial infarction: effects on left ventricular size, function, quality of life, and exercise tolerance: results of the Open Artery Trial (TOAT Study)

OBJECTIVE

We sought to conduct a randomized trial comparing late revascularization with conservative therapy in symptom-free patients after acute myocardial infarction (AMI).

BACKGROUND

In the absence of ischemia, the benefits of reperfusion late after AMI remain controversial. However, the possibility exists that an open infarct related artery benefits healing post AMI.

METHODS

Of 223 patients enrolled with Q-wave anterior AMI, 66 with isolated persistent occlusion of the left anterior descending coronary artery (LAD) were randomized to the following treatments: 1) medical therapy (closed artery group; n = 34) or 2) late intervention and stent to the LAD + medical therapy (open artery group; n = 32). The study was powered to compare left ventricular (LV) end-systolic volume between the two groups 12 months post AMI.

RESULTS

Late intervention 26 +/- 18 days post AMI resulted in significantly greater LV end-systolic and end-diastolic volumes at 12 months than medical therapy alone (106.6 +/- 37.5 ml vs. 79.7 +/- 34.4 ml, p < 0.01 and 162.0 +/- 51.4 ml vs. 130.1 +/- 46.1 ml, p < 0.01, respectively). Exercise duration and peak workload significantly increased in both groups from 6 weeks to 12 months post AMI, although absolute values were greater in the open artery group. Quality of life scores tended to deteriorate during this time interval in the closed artery patients but remained unchanged in the open artery patients. Coronary angiography at 1 year documented a low incidence of intergroup cross-over (spontaneous recanalization in 19% and closure in 11%).

CONCLUSIONS

In the present study, recanalization of occluded infarct-related arteries in symptom-free patients approximately 1 month post AMI had an adverse effect on remodeling but tended to increase exercise tolerance and improve quality of life.

Comparison of time of reperfusion during anterior wall acute myocardial infarction to left ventricular volume one month and 20 months later

We studied 95 patients with a first anterior wall acute myocardial infarction who received successful reperfusion within 72 hours after the onset. The patients were divided into 4 groups based on the time required to achieve reperfusion; <3 hours (n = 23), 3 to 6 hours (n = 42), 6 to 24 hours (n = 17), and >24 to 72 hours (n = 13). The infarct size, as evaluated by thallium-201 single-photon emission computed tomography, at 1 month after the infarct was significantly larger (p <0.05) in >24 to 72 hours (1,593 +/- 652 U) than that in <3 hours (749 +/- 650 U), but was not significantly different from that at 3 to 6 hours (1,353 +/- 770 U) or 6 to 24 hours (1,371 +/- 561 U). The end-diastolic volume index at 1 month did not differ among the 4 groups. However, the end-diastolic volume index during the follow-up period (20 +/- 8 months) in >24 to 72 hours (93 +/- 23 ml/m(2)) was significantly larger than that in the other 3 groups (<3 hours [65 +/- 21 ml/m(2)], 3 to 6 hours [65 +/- 22 ml/m(2)], and 6 to 24 hours [70 +/- 25 ml/m(2)]). Similar findings were observed in end-systolic volume index. In conclusion, although infarct size reduction was not observed by late reperfusion, left ventricular volumes at 1 month were comparable among patients with successful reperfusion within 3 and up to >24 hours. Left ventricular volumes 2 years after acute myocardial infarction were significantly larger in patients who did not under reperfusion for >24 hours.

Benefits of late reperfusion in the treatment of acute myocardial infarction

Early reperfusion of the infarct-related coronary artery is very much effective to treat the patients with acute myocardial infraction. However, there are many clinical as well as experimental evidences supporting the efficacy of late reperfusion therapy. In this article, effects of late reperfusion on mortality, left ventricular function, left ventricular dilatation and remodeling, or electrical stability were summarized. Also, the possible mechanisms for benefits of late reperfusion were discussed and the special role of epicardial rim bring about those benefits was emphasized.

Primary angioplasty and selection bias inpatients presenting late (>12 h) after onset of chest pain and ST elevation myocardial infarction

OBJECTIVES

This study was designed to compare the in-hospital outcome of patients presenting with >12 h from onset of chest pain and acute ST elevation myocardial infarction (AMI) who received either immediate invasive or conservative therapy.

BACKGROUND

The benefits of fibrinolytic therapy diminish in patients presenting with AMI and onset of chest pain >12 h. Primary angioplasty has been suggested as a possible treatment for such patients, but they have been excluded from most trials of primary angioplasty. It remains unclear if an invasive treatment strategy is beneficial to these patients.

METHODS

Patients presenting with >12 h of chest pain and AMI were identified from the National Registry of Myocardial Infarction 2 database. Patients receiving invasive therapy <6 h after hospital admission were compared with those receiving conservative therapy. Short-term outcomes were compared on the basis of the initial therapy received. To help control for baseline differences in the groups, patients were matched with controls by propensity score methodology.

RESULTS

On preliminary analysis, in-hospital outcome was improved in terms of recurrent ischemia, angina, myocardial infarction and mortality in patients receiving initial invasive therapy (odds ratio [OR] = 0.67; 95% confidence interval [CI] 0.49 to 0.92 for mortality). After matching by propensity score, the mortality benefit persisted on bivariate analysis (3.5% vs. 5.0%, p = 0.036), though on multivariate analysis, only a non-significant but strong trend toward decreased mortality remained (OR = 0.73; 95% CI 0.53 to 1.01).

CONCLUSIONS

Patients receiving early invasive therapy had lower risk features on presentation. Selection bias may play an important role in choosing these patients' course of treatment and their subsequent outcomes. Certain patients presenting with AMI and duration of chest pain >12 h may benefit from early invasive therapy. These patients could be characterized in a randomized trial.

Late Reperfusion (6-24 Hours After Onset) Improves Left Ventricular Function in Patients With Acute Myocardial Infarction

The TAMI-6 trial has demonstrated that coronary reperfusion >6h after onset (ie, late reperfusion) in patients with acute myocardial infarction (AMI) does not improve left ventricular (LV) function during the chronic phase of infarction. However, the low patency rate (only 60%) of the infarct-related artery (IRA) during the chronic phase in the TAMI-6 trial raises a new hypothesis that late reperfusion with a higher patency rate may improve LV function during the chronic phase. Forty-four patients with AMI, who were admitted to hospital 6-24h after the symptom onset and in whom emergency coronary angiography revealed a total occlusion of the IRA, were randomly assigned to either the late reperfusion group (n=22) or the non-reperfusion group (n=22). The initial success rate of reperfusion therapy in the late reperfusion group was 86% and the chronic patency rate of the IRA was 91%. The improvements in ejection fraction and chord shortening in the infarct region from the acute phase to the chronic phase were significantly greater in the late reperfusion group than in the non-reperfusion group. Late reperfusion with a high patency rate of the IRA significantly improves LV global and regional function in patients with AMI.

Ventricular function and cardiac hypertrophy after coronary thrombolysis with tissue-type plasminogen activator (t-PA) in dogs with coronary artery thrombi

Subacute prognosis of cardiac function after thrombolysis with a modified tissue-type plasminogen activator (t-PA) YM866 was determined in dogs with coronary artery thromboses induced by injection of a thrombin, fibrinogen and autogenous blood mixture. The left ventricular ejection fraction (LVEF) decreased 30 min after occlusion and had not improved 1 week later. Examination after sacrifice revealed myocardial infarction as well as increases in both the left ventricular myocardial area and heart mass. Occluded coronary arteries reperfused by YM866 (0.1 mg kg(-1) i.v.) treatment 30 min after occlusion, by contrast, had improved LVEF and inhibited myocardial infarction development. In addition, the left ventricular myocardial area and heart mass were significantly reduced compared with the vehicle control group 1 week after administration. Although occluded coronary arteries reperfused by YM866 (0.1 mg kg(-1) i.v.) treatment 3 h after occlusion did not show an improvement in the LVEF or inhibition of myocardial infarction development, the left ventricular myocardial area and heart mass decreased significantly compared with the vehicle control group 1 week after administration. In conclusion, early reperfusion by t-PA treatment 30 min after occlusion improved the ventricular function and cardiac hypertrophy, whereas late reperfusion by t-PA treatment 3 h after occlusion did not improve the ventricular function but did inhibit hypertrophy in dogs with coronary artery thrombi.

Time course of left ventricular remodeling after myocardial infarction: a two-dimensional echocardiographic study

In order to forecast the clinical course of acute myocardial infarction (MI), the time course of the functional changes of the left ventricular myocardium that result in remodeling was evaluated with two-dimensional echocardiography (2DE). The study group comprised 45 patients with anterior MI treated with successful percutaneous transluminal coronary angioplasty. 2DE studies were performed on days 1, 3, 7 and 14; months 1 and 3 and 1 year after MI, and the following parameters were recorded: (1) infarcted wall thickness, (2) traced length of the endocardium and of the epicardium on end-diastolic apical long axis images, and (3) wall motion score (total of asynergy scores of 16 segments of left ventricle (LV); normal: 0, hypokinesis: 1, akinesis: 2, dyskinesis: 3). According to the peak creatine kinase (CK) level, patients were classified into L group (CK > or =8000 U/L, n=16), M group (8000> CK > or =4000, n=13) and S group (CK <4000, n=16). The following results were obtained. (1) There was progressive thinning of the infarcted myocardium up to 1 month after (1 day: 9.3+/-1.7, 14 days: 6.3+/-1.7 vs 1 month: 5.9+/-1.8 mm, p<0.05; vs 1 year: 5.9+/-1.9 mm, NS). (2) Dilatation of the LV cavity occurred shortly after MI and continued up to 14 days (endocardium at 14 days: 176.8+/-13.6 vs 1 day: 164.1+/-11.4 mm, p<0.01; vs 1 year: 176.3+/-12.7 mm, NS). (3) The wall motion score improved rapidly by 14 days, and continued to improve gradually to 1 year (1 day: 12.2+/-3.4, 14 days: 6.8+/-4.0, 1 year: 4.6+/-3.1). (4) The expansion ratio (endocardial length at 14 days/1 day) was significantly greater in the L group than in the S group (p<0.05). Comparing the groups, the LV cavity of the L group remained dilated up to 14 days, whereas that of the S and M groups was dilated up to 7 days (L group 14 days: 179.3+/-11.9 vs 1 day: 156.9+/-9.2mm, p<0.01; vs 1 year: 180.0+/-14.1 mm, NS) (S group 7 days: 171.7+/-13.6 vs 1 day: 161.5+/-7.2 mm, p<0.01; vs 1 year: 172.7+/-14.4 mm, NS) (M group 7 days: 170.5+/-10.5 vs 1 day: 157.7+/-14.5 mm, p<0.05; vs 1 year: 177.08+/-9.6 mm, NS). Serial 2DE on days 1 and 14 after MI were useful for evaluating the course of LV remodeling and to forecast cardiac function in the chronic phase of MI. Determining the length of hospital stay on the basis of infarction size is justified.

Beneficial effect of prodromal angina pectoris is lost in elderly patients with acute myocardial infarction

BACKGROUND

Prodromal angina pectoris occurring shortly before the onset of acute myocardial infarction is associated with a favorable outcome by the mechanism of ischemic preconditioning. Recent experiments have reported that the beneficial effect of ischemic preconditioning are reversed in the aged heart.

METHODS

We studied 990 patients who underwent coronary angiography within 12 hours after the onset of acute myocardial infarction. Patients were divided into 2 groups: those aged <70 years (nonelderly patients, n = 722) and those aged >/=70 years (elderly patients, n = 268). Prodromal angina in the 24 hours before infarction was found in 190 of 722 nonelderly patients and in 66 of 268 elderly patients (26% vs 25%, P =.61).

RESULTS

In nonelderly patients, prodromal angina was associated with lower peak creatine kinase levels (2438 +/- 1939 IU/L vs 2837 +/- 2341 IU/L, P =.04), lower in-hospital mortality rates (3.7% vs 8.8%, P =.02), and better 5-year survival rates (P =. 007). On the contrary, in elderly patients there was no significant difference in peak creatine kinase levels (2427 +/- 2142 IU/L vs 2256 +/- 1551 IU/L, P =.51), in-hospital mortality rate (21.2% vs 17. 4%, P =.49), and 5-year survival rates (P =.47). A multivariate analysis showed that prodromal angina in the 24 hours before infarction was associated with 5-year survival rate in nonelderly patients (odds ratio 0.49, P =.009) but not in elderly patients (odds ratio l.12, P =.65).

CONCLUSIONS

In nonelderly patients, prodromal angina in the 24 hours before infarction was associated with a smaller infarct size and better short- and long-term survival, suggesting a relation to ischemic preconditioning. However, such a beneficial effect was not observed in elderly patients.

Early angiotensin converting enzyme inhibitor therapy enhances the benefits of late coronary artery reperfusion on infarct expansion

BACKGROUND

Individually, both late reperfusion and early angiotensin converting enzyme (ACE) inhibitor treatment prevent infarct expansion after acute myocardial infarction.

OBJECTIVE

To examine the effect and mechanism of early post-myocardial infarction ACE inhibitor treatment, when used in combination with late coronary artery reperfusion, on infarct expansion.

METHODS

Sprague-Dawley rats underwent 8 h of coronary occlusion followed by permanent reperfusion. The treatment group received enalapril, started 1 h after coronary occlusion and continued for 13 days. A control group received placebo. Two weeks after acute myocardial infarction, hemodynamic, morphometric and histologic analyses were performed.

RESULTS

Hemodynamic parameters were similar in both groups (P = NS). Infarct size was similar in the ACE inhibitor and placebo treatment groups (44 +/- 4% compared with 39 +/- 4%, P = NS). Septal thickness was also similar in the two groups (2.8 +/- 0.3 mm compared with 2.7 +/- 0.3 mm, P = NS). The ACE inhibitor-treated group had thicker infarcts than those in the placebo-treated group (0.93 +/- 0.07 mm compared with 0.76 +/- 0.04 mm, P < 0.05) and these infarcts were less expanded (expansion index 1.17 +/- 0.12 compared with 1.57 +/- 0.12, P < 0.05). ACE inhibitor treatment was associated with hypertrophy of viable myocytes within the scar compared with placebo treatment (cell diameter 11.1 +/- 0.5 microns compared with 8.9 +/- 0.4 microns, P < 0.01).

CONCLUSIONS

Early post-myocardial infarction ACE inhibitor treatment enhances the benefits of late coronary reperfusion on infarct expansion. The benefits may be related to hypertrophy of still-viable myocytes within the infarcted zone.

Regional and temporal profiles of phorbol 12,13-dibutyrate binding after myocardial infarction in rats: effects of captopril treatment

Phosphoinositide turnover and protein kinase C (PKC) mediate the signaling of angiotensin II, which plays a pivotal role in ventricular remodeling after myocardial infarction (MI). To determine whether PKC is activated after MI, rat hearts after MI were subjected to in vitro quantitative autoradiography with [3H]phorbol 12,13-dibutyrate (PDBu), which is highly selective for PKC. [3H]PDBu binding in the infarcted area increased significantly compared with the non-infarcted region 7 and 21 days after MI, but not 1 and 3 days and 10 months after MI. [3H]PDBu binding in the noninfarcted area was similar to that in the sham-operated rats. Immunohistochemical analysis revealed that abundant macrophages (7 days after MI), fibroblasts, and myofibroblasts (7 and 21 days after MI) occupied the infarcted region. To investigate whether myocardial [3H]PDBu binding is affected by captopril, hearts were subjected to in vitro autoradiography with [3H]PDBu after 1- or 3-week captopril treatment or no treatment. Captopril treatment significantly suppressed [3H]PDBu binding in the infarcted area 3 weeks after MI, but not 1 week after MI nor in the noninfarcted areas. These results suggest that PKC is upregulated during the healing and fibrogenic process after MI and that captopril treatment suppresses the upregulation in the infarcted area.

Myocardial infarction and remodeling in mice: effect of reperfusion

Anatomic and functional changes after either a permanent left anterior descending coronary artery occlusion (PO) or 2 h of occlusion followed by reperfusion (OR) in C57BL/6 mice were examined and compared with those in sham-operated mice. Both interventions generated infarcts comprising 30% of the left ventricle (LV) measured at 24 h and equivalent suppression of LV ejection velocity and filling velocity measured by Doppler ultrasound at 1 wk. Serial follow-up revealed that the ventricular ejection velocity and filling velocity returned to the levels of the sham-operated controls in the OR group at 2 wk and remained there; in contrast, PO animals continued to display suppression of both systolic and diastolic function. In contrast, ejection fractions of PO and OR animals were depressed equivalently (50% from sham-operated controls). Anatomic reconstruction of serial cross sections revealed that the percentage of the LV endocardial area overlying the ventricular scar (expansion ratio) was significantly larger in the PO group vs. the OR group (18 +/- 1.7% vs. 12 +/- 0.9%, P < 0.05). The septum that was never involved in the infarction had a significantly (P < 0.002) increased mass in PO animals (22.5 +/- 1.08 mg) vs. OR (17.8 +/- 1.10 mg) or sham control (14.8 +/- 0.99 mg) animals. Regression analysis demonstrated that the extent of septal hypertrophy correlated with LV expansion ratio. Thus late reperfusion appears to reduce the degree of infarct expansion even under circumstances in which it no longer can alter infarct size. We suggest that reperfusion promoted more effective ventricular repair, less infarct expansion, and significant recovery or preservation of ventricular function.

Modulation of left ventricular diastolic distensibility by collateral flow recruitment during balloon coronary occlusion

OBJECTIVES

The goals of this study were to elucidate the scaffolding effect of blood-filled coronary vasculature and to determine the functional role of recruited collateral flow in modulating left ventricular (LV) distensibility during balloon coronary occlusion (BCO).

BACKGROUND

Although LV distensibility is an important factor affecting acute dilation after myocardial infarction, the response of LV diastolic pressure-volume (P-V) relations to coronary occlusion is inconsistent in humans.

METHODS

Micromanometer and conductance derived LV P-V loops were serially obtained from 16 patients undergoing percutaneous transluminal coronary angioplasty. Coronary collateral flow recruitment was angiographically evaluated by contralateral and ipsilateral contrast injection during BCO.

RESULTS

In the group with poor collateral flow (grades 0-I; n = 8), BCO resulted in a downward and rightward shift of the diastolic P-V relations, where end-diastolic volume (EDV) increased by 13% (p < 0.05) without appreciable change in end-diastolic pressure (EDP; 18 +/- 6 to 18 +/- 8 mm Hg). In contrast, BCO in the group with good collateral flow (grades II-III; n = 8) shifted the diastolic P-V relations upward to the right with a concomitant increase in minimal pressure (min-P; 6 +/- 4 to 10 +/- 5 mm Hg, p < 0.05), EDP (15 +/- 7 to 21 +/- 9 mm Hg, p < 0.05) and EDV (+/- 10%, p < 0.05). Reactive hyperemia after balloon deflation caused a rapid and parallel upward shift of the diastolic P-V relations with a marked increase in min-P and EDP, especially in the group with poor collateral flow, before any improvement in LV contraction or relaxation abnormalities.

CONCLUSIONS

Grades of coronary filling, either retrograde or anterograde, abruptly modulate LV distensibility through the rapid scaffolding effect of coronary vascular turgor.

Spontaneous late improvement of myocardial viability in the chronic infarct zone is possible, depending on persistent TIMI 3 flow and a low grade stenosis of the infarct artery

OBJECTIVE

In the chronic phase of myocardial infarction, the relation between myocardial recovery and infarct related artery status remains unclear. The spontaneous changes in rest-redistribution thallium defect size were prospectively studied over six months in 52 patients with chronic Q wave myocardial infarction.

DESIGN

Changes in rest thallium defect size, thallium uptake in the infarct area, and radionuclide left ventricular ejection fraction were compared to the quantitative coronary angiogram data. Two groups of patients were considered: patients with a percentage of stenosis below 100% (group 1, n = 31); and patients with an occluded artery (group 2, n = 21).

RESULTS

In the overall population, the mean (SD) defect size decreased from 28.2 (17.2)% to 24.9 (19.3)% of the whole myocardium (p = 0.01), while, in this area, the thallium uptake increased from 62.9 (13.7)% to 66. 9 (15.6)% (p < 0.001). At the time of inclusion, the defect size, thallium uptake, and ejection fraction were similar in both groups. In group 1 patients only, the reduction in defect size correlated with the improvement in ejection fraction (r = 0.41, p = 0.02) and was related to the percentage of coronary artery stenosis. TIMI 3 patients reduced the defect size while other patients increased this defect (-5.1 (7.0)% v +11.0 (14.4)%, p < 0.001). In contrast, no significant relations were found in group 2 patients.

CONCLUSION

Late spontaneous recovery in thallium defect can occur in patients with a patent infarct related artery, depending on the TIMI flow grade and a low grade stenosis of the infarct related artery, and is associated with functional improvement.

Heterogeneous fate of perfusion and contraction after anterior wall acute myocardial infarction and effects on left ventricular remodeling

After acute myocardial infarction, patency of infarct vessel and extent of left venticular (LV) dysfunction are major determinants of ventricular remodeling. Spontaneous, delayed reperfusion in the infarct zone occurs in a sizeable number of patients well after the subacute phase. The aim of this study was to determine the relation between the occurrence of this spontaneous, delayed reperfusion and LV remodeling. In 84 patients, resting LV volumes, topography, regional function, and perfusion were quantitatively evaluated by 2-dimensional echocardiography and sestamibi tomography 5 weeks (study 1) and 7 months (study 2) after anterior Q-wave infarction. At study 2, LV end-diastolic volume increased by > 15% in 17 patients (20%, LV remodeling); they had already had at study 1 significantly larger LV volumes, more severe hypoperfusion and wall motion abnormalities, and greater regional dilation than patients with stable LV volumes. Delayed reperfusion occurred in 8 of 17 patients with and in 42 of 67 patients without LV remodeling (47% vs 63%; p=NS). At study 2, LV regional dilation and end-diastolic volumes were stable in patients with, but increased in patients without, spontaneous reperfusion (from 25+/-24% to 29+/-26% at study 2 [p<0.05] and from 65+/-14 to 68+/-18 ml/m2 [p <0.05]). At multivariate analysis, however, regional ventricular dilation at study 1 was the sole predictor of further LV remodeling. Thus, after acute myocardial infarction, spontaneous reperfusion occurring after 5 weeks plays only a minor role in influencing LV remodeling. Benefits from delayed reperfusion seem limited to patients with preserved LV volumes; patients with an enlarged left ventricle 5 weeks after acute infarction are prone to further LV remodeling, irrespective of delayed reperfusion.

Routine Coronary Arteriography Following Thrombolytic Therapy for Acute Myocardial Infarction: An Unsettled Controversy

Although coronary artery disease remains the leading cause of death in industrialized countries, the management of patients recovering from acute myocardial infarction varies significantly. The issue of routine arteriography and revascularization following thrombolytic therapy remains controversial despite substantial evidence associating infarct-related artery patency with improved cardiac function and survival. Randomized trials of routine intervention after myocardial infarction have generally failed to demonstrate advantages of this invasive approach but methodological problems limit their application to current practice. High-risk patients should be referred for arteriography. While awaiting definitive trials addressing the influence of routine arteriography on patient survival and its cost effectiveness, the management of other patient groups must be individualized.

Quantification of the benefit of earlier thrombolytic therapy: five-year results of the Grampian Region Early Anistreplase Trial (GREAT)

OBJECTIVES

This report presents the 5-year results of the Grampian Region Early Anistreplase Trial (GREAT) and quantifies the benefit of earlier thrombolysis in terms that are generally applicable.

BACKGROUND

Although it is accepted that the earlier thrombolytic therapy is given for acute myocardial infarction the greater the benefit, there are widely differing estimates of the magnitude of the time-related benefit of thrombolysis because of inappropriate trial design and analysis.

METHODS

In a previously reported randomized trial, anistreplase (30 U) was given intravenously either before hospital admission or in the hospital, at a median time of 105 and 240 min, respectively, after onset of symptoms. Intention to treat and multivariate analyses of the 5-year results were performed.

RESULTS

By 5 years, 41 (25%) of 163 patients had died in the prehospital treatment group compared with 53 (36%) of 148 in the hospital treatment group (log-rank test, p < 0.025). Delaying thrombolytic treatment by 1 h increases the hazard ratio of death by 20%, equivalent to the loss of 43/1,000 lives within the next 5 years (95% confidence interval 7 to 88, p = 0.012). Delaying thrombolytic treatment by 30 min reduces the average expectation of life by approximately 1 year.

CONCLUSIONS

The magnitude of the benefit from earlier thrombolysis is such that giving thrombolytic therapy to patients with acute myocardial infarction should be accorded the same degree of urgency as treatment of cardiac arrest. Policies should be developed for giving thrombolytic therapy on-site if practicable and by the first qualified person to see the patient.

Mitral insufficiency as a complication of acute myocardial infarction and left ventricular remodeling

The presence of mitral insufficiency after acute myocardial infarction (AMI) often leads to hemodynamic impairment and heart failure. This study was designed to examine the relationship between mitral regurgitation (MR), an indicator of mitral insufficiency, and the course of recovery from AMI. We evaluated the course of MR after AMI in 223 patients by color Doppler echocardiography. MR was detected in 21% (47/223) of patients at the onset of AMI, and developed in 18% (40/223) of patients during follow-up. Patients were grouped according to the course of MR as well as the success of acute recanalization therapy. No correlation was observed between the presence or course of MR and the site of infarction. The incidence of successful recanalization was higher in patients with MR that improved during follow-up than in patients with MR that was unchanged or that worsened during follow-up. Although no significant differences in hemodynamic variables were noted among the groups at admission, the group with unsuccessful recanalization and unimproved MR (BS-) showed a significantly greater left ventricular end-diastolic diameter (LVDd), left ventricular end-systolic diameter, and left ventricular end-diastolic volume (LVEDV) as well as a lower left ventricular ejection fraction than patients with successful recanalization and no MR (CS+) during the convalescent period. The extent of change in LVDd and LVEDV between admission and convalescence was significantly greater in the BS(-) group than in the CS(+) group. The results suggest that successful recanalization after AMI reduces the incidence of MR. Acute recanalization therapy after AMI may prevent left ventricular remodeling, resulting in a secondary improvement of MR.

Comparable uptake of thallium-201 and technetium-99m MIBI in hibernating and "maimed" myocardium

Thallium-201 and technetium-99m-MIBI uptake are comparable in "maimed" (i.e., partially viable) and hibernating myocardium. The appreciation of myocardial viability should be based not only on the presence of a regional contractility improvement, but also on the evaluation of the initial level of contractility and of tracer uptake in the concerned area.

Implications of prodromal angina pectoris in anterior wall acute myocardial infarction: acute angiographic findings and long-term prognosis

OBJECTIVES

This study was undertaken to assess how prodromal angina affects long-term prognosis after acute myocardial infarction.

BACKGROUND

Although it has been reported that prodromal angina occurring shortly before the onset of acute myocardial infarction has protective effects against ischemia, its implication for long-term prognosis remains unclear.

METHODS

We studied consecutive 350 patients with anterior myocardial infarction who underwent coronary angiography within 24 h after the onset of chest pain. Follow-up was achieved for 340 patients (97%).

RESULTS

Eighty-nine patients had one or more episodes of angina within 24 h before infarction. On initial angiography, patients with prodromal angina in the 24 h before infarction had a patent infarct-related artery more frequently than did those without prodromal angina (34% vs. 22%, p = 0.03). Among 213 patients who underwent thrombolytic therapy for an occluded infarct-related artery, reperfusion was more frequently achieved in patients with prodromal angina in the 24 h before infarction (76% vs. 56%, p = 0.01). Prodromal angina in the 24 h before infarction was associated with a lower in-hospital mortality rate (6% vs. 14%, p = 0.02) and better 5-year survival (p = 0.009). There was no significant difference in survival between patients with previous angina at any time (n = 202) and those without. Multivariate analysis showed that prodromal angina in the 24 h before infarction was an independent factor related to 5-year survival after acute myocardial infarction (odds ratio 0.49, p = 0.04).

CONCLUSIONS

Prodromal angina occurring shortly before the onset of infarction, but not previous angina itself, has a beneficial effect on long-term prognosis after infarction, suggesting a relation to ischemic preconditioning.

Role of infarction artery status in left ventricular remodeling after acute myocardial infarction

The aim of this study was to evaluate the relation between the infarction artery status and left ventricular volumes, independently of regional ventricular dysfunction, at 4-6 weeks after a first myocardial infarction. The study group consisted of 100 patients, of whom 80 received thrombolytic treatment. Coronary and contrast left ventricular angiograms were performed at 36+/-5 days postinfarction. Left ventricular end-diastolic and end-systolic volumes were measured. The centerline chord motion method was used to calculate the extent of wall motion abnormality (percentage of chords with hypokinetic motion) and its severity (maximum units of S.D. below the normal wall motion reference). Minimum lumen diameter, patency and collateral flow in the infarction artery were also analyzed. Eight patients (group I) showed occlusion with poor collateral flow in the infarction artery, 22 patients (group II) occlusion with good collateral flow, 38 patients (group III) severe residual stenosis (minimum lumen diameter < or = 1 mm), and 32 patients (group IV) non-severe residual stenosis (minimum lumen diameter > 1 mm). Patients from group I presented greater wall motion abnormality in terms of both extent (P=0.005) and severity (P=0.007), and greater end-diastolic (P=0.07) and end-systolic (P=0.0008) volumes; there were no differences among groups II, III and IV. By stepwise multivariate regression analysis, the extent of wall motion abnormality was the main determinant of end-diastolic (P=0.0001) and end-systolic (P=0.0001) volumes; occlusion with poor collateral flow was also a significant independent factor for end-systolic volume (P=0.03). Total occlusion (including both with and without collaterals) and the minimum lumen diameter did not correlate with end-diastolic and end-systolic volumes. We concluded that (A) the extent of regional dysfunction is the primary determinant of left ventricular volumes at 4-6 weeks postinfarction. (B) The status of the infarction artery is a weak predictor of end-diastolic volume, which is the best descriptor of ventricular remodeling, although occlusion with poor collateral flow is associated to larger end-systolic volume.

Collateral channels that develop after an acute myocardial infarction prevent subsequent left ventricular dilation

OBJECTIVES

We sought to evaluate the effect of collateral channels that develop late after a first anterior myocardial infarction on left ventricular dilation and function.

BACKGROUND

Collateral channels in an infarct-related artery may develop long after occlusion of the artery. Well visualized collateral channels that appear immediately after a myocardial infarction reduce infarct size and preserve left ventricular function. However, the functional significance of collateral channels that develop late after myocardial infarction has not been evaluated in terms of left ventricular function.

METHODS

We studied 21 patients with a first anterior myocardial infarction and an infarct-related artery that remained totally occluded after reperfusion therapy and did not reopen within 1 month of infarction. No collateral channels were observed during the acute period. Patients were classified into two groups according to the extend of collateral formation 1 month after infarction: group C, patients with well developed collateral channels (n = 11), and group NC, patients with absent or poorly developed collateral channels (n = 10). Infarct size was determined by peak creatine kinase activity and thallium-201 single-photon emission computed tomography. Global and regional left ventricular function and left ventricular volumes were assessed by left ventriculography. These measurements were identical in both groups 1 month after infarction. Left ventricular function was reevaluated after 2.12 +/- 0.79 years (mean +/- SD).

RESULTS

There were no significant changes in global and regional left ventricular function between the two groups during the long-term follow-up period. However, the end-diastolic volume index of group NC increased from 71 +/- 14 to 85 +/- 19 ml/m2, whereas that of group C decreased from 64 +/- 18 to 59 +/- 12 ml/m2. This important change during the long-term follow-up period resulted in a significant difference (p = 0.0006) in the end-diastolic volume index between the groups 2 years after onset (p = 0.002), whereas 1 month after infarction the difference was not significant (p = 0.36). A similar pattern was observed for the end-systolic volume index (group C: 38 +/- 16 to 35 +/- 14 ml/m2; group NC: 45 +/- 12 to 58 +/- 18 ml/m2, p = 0.018). The power of the tests to detect the observed differences showing nonsignificant results ranged from 0.05 to 0.38, whereas the power of the tests indicating a significant difference in end-diastolic and end-systolic volume indexes was >0.88.

CONCLUSIONS

Collateral channels that develop after a myocardial infarction do not reduce the infarct size or prevent left ventricular dilation within 1 month of infarction. In contrast, such collateral channels prevent subsequent ventricular dilation and the deterioration of left ventricular function over 2 years. However, our results may have been biased because of the small number of patients.

Benefits of late coronary artery reperfusion on infarct expansion progressively diminish over time: relation to viable islets of myocytes within the scar

To define the time limit and mechanism of the effects of late coronary artery reperfusion on infarct expansion, rats were randomized into one of four groups: permanent left coronary artery occlusion; and 2, 8, and 16 hours of left coronary artery occlusion followed by reperfusion. Two weeks after coronary occlusion, morphometric and histologic analyses were performed. Benefits of late reperfusion on infarct expansion progressively diminished after increasingly long periods of coronary occlusion and were minimal but present after 16 hours of coronary occlusion. The extent of the benefits of late reperfusion on infarct expansion were related to preservation and hypertrophy of small islets of still viable myocytes located mainly in the subepicardium of the scar.

Adverse long-term effects of reocclusion after coronary thrombolysis

OBJECTIVES

This study sought to assess the long-term clinical consequences of reocclusion after coronary thrombolysis.

BACKGROUND

After acute myocardial infarction successfully treated with thrombolysis, reocclusion occurs in approximately 30% of patients and leads to poorer in-hospital outcome. However, the long-term effects of reocclusion are unknown.

METHODS

Three hundred patients with no history of coronary surgery and with a patent infarct-related artery at coronary angiography within 48 h after thrombolysis were enrolled in the Antithrombotics in the Prevention of Reocclusion in Coronary Thrombolysis (APRICOT) trial. At a mean (+/- SD) of 77 +/- 23 days after thrombolysis, 248 patients (87%) underwent follow-up angiography. Reocclusion was observed in 71 (29%) of 248 patients. To compare outcome between 71 patients with and 177 without reocclusion an analysis of event-free survival, defined as a clinical course without death, reinfarction and revascularization, was performed.

RESULTS

Over a 3-year follow-up period, event-free survival was significantly better in patients without reocclusion: At 1 year it was 63% for patients with and 83% for those without reocclusion (p < 0.001). In the first year, two or more cardiac-related events occurred in 24% of patients with and 6% of those without reocclusion (p < 0.001). Patients with reocclusion had a markedly higher reinfarction and revascularization rate. At 1 year the reinfarction rate was 23% for patients with and 5% for those without reocclusion (p < 0.001).

CONCLUSIONS

This analysis shows the adverse influence of reocclusion on long-term clinical outcome in relation to reinfarction and need for revascularization. To further optimize prognosis after thrombolysis, prevention of reocclusion should become a main priority. Future research should focus on the criteria and timing of elective revascularization procedures in the prevention of coronary reocclusion.