The open artery hypothesis: beneficial effects and long-term prognostic importance of patency of the infarct-related coronary artery

There seem to be additional mechanisms of benefit in patients receiving late reperfusion therapy in a time when the opportunity for myocardial salvage has been missed. Previous studies have demonstrated that the restoration of blood flow in the infarct-related coronary artery in patients with acute myocardial infarction improves left ventricular function and reduces mortality. Initially, it was thought that survival was improved because viable myocardium was salvaged. However, data obtained over the past several years have suggested that the restoration of antegrade flow in the infarct-related artery may improve survival via a mechanism independent of the influence on left ventricular function. Clinical interest in the open artery hypothesis has recently resurfaced owing to a substantial improvement in technical aspects of percutaneous coronary interventions (PCI). Observational data suggest a role for late intervention as safer and more effective mechanical reperfusion practices have emerged. Long-term clinical benefits have been shown from balloon angioplasty late after myocardial infarction (MI). Therefore, patients with failed thrombolysis or those with late-presenting MI may still benefit from PCI by mechanisms independent of myocardial salvage. There is accumulative evidence on this matter. Possible mechanisms include reduction of ventricular remodeling, diminished ventricular instability reducing the incidence of arrhythmias, and provision of collaterals to other territories in the event of further coronary artery occlusion. However, caution must be exercised in interpreting the results of studies examining the open artery hypothesis. This hypothesis can be tested in its purest sense in animal experiments; however, the clinical situation is much more complex. Patients may have acute-on-chronic coronary artery occlusion in the presence of multivessel disease and well-developed collateral channels. The pattern of necrosis may also be different with areas of necrosis separated by islands of ischemic, stunned, hibernating, or normal cells. Therefore, the patency of the infarct-related coronary artery in single or multivessel disease days to weeks after infarction markedly influences long-term prognosis unrelated to improvement of left ventricular function. Current technology has made it feasible to open and maintain patency of most occluded infarct-related arteries. However, the hypothesis that late mechanical reperfusion in patients with asymptomatic occluded infarct-related artery will improve long-term clinical outcomes remains to be proved and is currently being tested in a large randomized trial.     

Percutaneous transluminal coronary angioplasty in evolving acute myocardial infarction

In 29 patients with evolving acute myocardial infarction, acute reperfusion of the infarct-related coronary artery was attempted using percutaneous transluminal coronary angioplasty (PTCA). Before PTCA, angiography showed 23 totally occluded and 6 severely stenotic infarct-related coronary arteries. PTCA was initially successful in 25 of 29 patients (86%). Reocclusion occurred in 4 patients within 12 hours after successful PTCA and was associated with new electrocardiographic changes or recurrence of symptoms. In 17 patients the infarct-related coronary artery remained patent at early follow-up; late stenosis occurred in 4 patients. Recurrence of stenosis was accompanied by development of angina. No clinical or angiographic features distinguished those with ultimate vessel patency, occlusion or recurrence of stenosis. On follow-up, ventricular function appeared better preserved or improved in those with a patent infarct-related coronary artery than in those with an occluded infarct-related coronary artery. Further studies are warranted to compare PTCA and streptokinase as primary reperfusion modalities in evolving acute myocardial infarction.     

The Late Open Infarct‐related Artery Hypothesis: Evidence‐based Medicine or Not?

Randomized clinical trials have clearly shown that early reperfusion of coronary arteries is the established treatment of myocardial infarction preserving left ventricular function and reducing mortality. However, late patency of the infarct-related artery is an independent predictor of survival leading to the late open-artery hypothesis. This concept implies restoration of antegrade blood flow of the infarct-related artery in patients with myocardial infarction to improve survival by mechanisms less time-dependent or even time-independent. Possible explanations for this benefit include improved left ventricular function and electrical stability by perfusion of hibernating myocardium, accelerated infarct healing and limitation of ventricular remodeling. This review focuses on the evidence of late recanalization of occluded infarct-related arteries in patients with coronary artery disease.     

Early reperfusion, late reperfusion, and the open artery hypothesis: an overview

Randomized clinical trials have clearly shown the beneficial effects of early reperfusion within 12 hours, and possibly up to 24 hours, after acute myocardial infarction (AMI). The data on late reperfusion beyond 24 hours are less convincing. Many studies show that an open infarct-related artery after MI, irrespective of the initial reperfusion strategy, is independently associated with improved long-term clinical outcome. However, similar analysis of the large Global Utilization of Streptokinase and tPA for Occluded Arteries (GUSTO) I study did not confirm this finding. It is unclear whether mechanical reperfusion of an occluded infarct-related artery late after MI (>24 hours) in asymptomatic patients will confer long-term benefits. The late open artery hypothesis, which proposes several mechanisms by which late reperfusion may offer benefit, remains to be tested in a large clinical trial. This overview focuses on the definitions of early reperfusion, late reperfusion, the relationship between timing of reperfusion and prognosis after AMI, and the late open artery hypothesis. Copyright © 2000 by W.B. Saunders Company

Progress in Cardiovascular Diseases, Vol. 42, No. 6 (May/June), 2000: pp 397-404     

Patency of the infarct-related coronary artery and ventricular geometry.

The pathogenesis of acute myocardial infarction (AMI) involves a sudden thrombotic occlusion of a coronary artery. Spontaneous or pharmacologic thrombolysis may lead to myocardial salvage if patency is achieved within a narrow time window. However, patients in whom thrombolysis occurs late seem to demonstrate improved left ventricular (LV) function and prognosis, which may be independent of myocardial salvage. Preservation of normal LV geometry by reducing expansion of the infarcted segment is a likely mechanism for this benefit. Infarct expansion is most pronounced in patients with anterior wall AMI who have a persistently occluded infarct-related vessel. This process of expansion leads to early increases in LV volume and distortions of LV contour (abnormal LV geometry). Patients whose infarct segment is largest, patients who have manifested infarct expansion, and patients with a persistently occluded infarct-related artery are at highest risk for progressive LV dilation. Experimental data support the concept that reperfusion of occluded vessels that occurs too late for myocardial salvage will preserve LV geometry by limiting infarct expansion. Prospective clinical trials should address whether there is a late, "second time window" during which infarct expansion and distortions of LV geometry may be reduced by (1) therapy with thrombolytic agents applied late after infarction, (2) late mechanical reperfusion with percutaneous transluminal coronary angioplasty (PTCA) or related methods, and (3) load-reducing agents to decrease remodeling, such as angiotensin-converting enzyme inhibitors or nitroglycerin.     

Effects of reperfusion obtained two to six months after acute myocardial infarction on myocardial electrical stabilization in patients with an occluded infarct-related coronary artery

To assess the changes in electrical stability markers in patients with previous myocardial infarction after very late reopening of the infarct-related artery, we studied QT dispersion, corrected-QT dispersion, and late potentials before and 1, 3, and 6 months after an attempt at late percutaneous coronary intervention (PCI) in 31 consecutive patients with single-vessel disease (infarct-related artery occlusion or subocclusion) diagnosed > or = 4 weeks after the ST-elevation myocardial infarction. Patients underwent PCI 3.9 +/- 2 months after ST-elevation myocardial infarction. PCI was successful in 24 patients (group A) and unsuccessful in 7 (group B). The 2 groups were similar in clinical and angiographic characteristics, as well as the prevalence of basal late potentials, average QT dispersion, and corrected-QT dispersion. One month after PCI, the successful reperfusion group had a significant 67% decrease in the prevalence of late potentials and average QT dispersion and corrected QT dispersion (51 +/- 9 vs 72 +/- 11 ms, p <0.00001, and 51 +/- 10 vs 76 +/- 15 ms, p <0.00001, respectively). These benefits remained stable at 3 and 6 months after PCI. Conversely, the unsuccessful group did not show any improvement in electrical stability markers after PCI failed. Thus, reperfusion obtained very late after ST-elevation myocardial infarction confers significant electrical stabilization that may contribute to a better outcome in patients with patent infarct-related arteries.     

急性心肌梗死的治疗进展--从再通到再灌注

对于急性心肌梗死患者冠状动脉的再灌注治疗已得到广泛开展。然而,由于微循环无复流现象的存在,使得梗死相关血管的再通并不完全意味着心肌水平再灌注的实现。几项研究发现,超过 25%的急性心肌梗死患者经成功的溶栓或经皮冠脉介入术后都存在无复流现象,即未达到充分的心肌再灌注。所以,我们应把更多的注意力和研究重点转移到对心肌微循环再灌注的实现,而非冠状动脉的再通。     

Late potentials on signal-averaged electrocardiograms and patency of the infarct-related artery in survivors of acute myocardial infarction

This study evaluated the relation between patency of the infarct-related artery and the presence of late potentials on the signal-averaged electrocardiogram (ECG) in 124 consecutive patients (98 men, 26 women; mean age 59 years) with acute myocardial infarction receiving thrombolytic therapy, acute percutaneous transluminal coronary angioplasty or standard care. All patients were studied by coronary angiography, measurement of ejection fraction and signal-averaged ECG. The infarct-related artery was closed in 51 patients and open in 73. Among patients with no prior myocardial infarction undergoing early attempted reperfusion therapy, a patent artery was associated with a decreased incidence of late potentials (20% versus 71%; no significant difference in ejection fraction). In the 48 patients receiving thrombolytic agents within 4 h of symptom onset, the incidence of late potentials was 24% and 83% among patients with an open or closed artery, respectively (p less than 0.04). The most powerful predictors of late potentials were the presence of a closed infarct-related artery, followed by prior infarction and patient age. Among patients receiving thrombolytic agents within 4 h of symptom onset, the only variable that was predictive of the presence of late potentials was a closed infarct-related artery. These data imply that reperfusion of an infarct-related artery has a beneficial effect on the electrophysiologic substrate for serious ventricular arrhythmias that is independent of change in left ventricular ejection fraction as an index of infarct size. These findings might explain, in part, the low late mortality rate in survivors of myocardial infarction with documented reperfusion of the infarct-related artery.     

Aortic Counterpulsation May Improve Late Patency of the Occluded Coronary Artery in Patients With Early Failure of Thrombolytic Therapy

Objectives. Using a prospective, randomized design, we tested our hypothesis that the augmentation of diastolic pressure by intraaortic balloon counterpulsation (IABP) would improve the late patency of the occluded coronary artery in patients with early failure of thrombolytic therapy.Background. Rescue angioplasty is often performed in patients in whom thrombolysis has failed, although 30% to 60% of the infarct-related arteries that are closed early after thrombolytic therapy will open later with conservative therapy.Methods. The study included 45 patients in whom thrombolysis had failed, despite treatment with intravenous tissue-type plasminogen activator (alteplase 0.75 mg/kg body weight) delivered over 60 min within 12 h of the onset of symptoms. All patients underwent coronary angiography 60 min after initiation of thrombolytic therapy (baseline), and Thrombolysis in Myocardial Infarction (TIMI) grade 0, 1 or 2 flow was defined as failed thrombolysis. The patients were randomized to groups receiving IABP for 48 h (n = 23) or conservative therapy (n = 22, control subjects) at the end of cardiac catheterization. The late patency of the infarct-related artery, the primary end point of the study, was evaluated 3 weeks after myocardial infarction. Stenosis of the infarct-related artery was measured using a computer-assisted quantitative angiographic system in blinded manner. Data are expressed as mean value ± SEM.Results. There was no difference with regard to the baseline value for TIMI flow grade between the groups. However, 3 weeks after myocardial infarction, the patients treated with IABP had a significantly higher frequency of TIMI flow grade 3, lower residual percent stenosis and larger minimal lumen diameter of the infarct-related artery than did the control subjects (74% vs. 32%, p < 0.05; 42 ± 5% vs. 68 ± 6%, p < 0.01; and 1.6 ± 0.1 vs. 0.9 ± 0.2 mm, p < 0.01, respectively).Conclusions. These findings suggest that in patients with early failure of thrombolytic therapy, IABP may improve late patency of the occluded coronary artery, probably due to augmented perfusion pressure.     

Immediate and long-term results of delayed recanalization of occluded acute myocardial infarction-related arteries using coronary angioplasty.

Recent evidence suggests that late reperfusion of an occluded infarct-related artery after acute myocardial infarction (AMI) may convey a better prognosis. The clinical outcome of percutaneous transluminal coronary angioplasty (PTCA) as a means of mechanical reperfusion in this particular setting has not been clearly delineated. Ninety-seven patients with AMI underwent PTCA of the occluded infarct-related artery after the acute phase of the AMI (48 hours to 2 weeks, mean 8 +/- 4 days). The study consisted of 72 men (74%) (mean age 56.5 +/- 12 years) and 25 women. Seventy-seven patients (79%) had a Q-wave AMI and 20 patients (21%) a non-Q-wave AMI. Seventy-six patients (79%) had angina after AMI and 4 had previously undergone coronary bypass surgery. Clinical success was achieved in 85 patients (87%). Angiographic success was obtained in 90 of the 97 occluded arteries (93%) and was similar for all 3 major vessels: right coronary 97%, left anterior descending 93% and circumflex 85% (p = not significant). Major complications (AMI, emergency bypass and death) occurred in 3 patients (3.1%). Long-term follow up (3.7 +/- 0.8 years) revealed symptomatic recurrence in 20 (23%), whereas 51 (58%) remained asymptomatic. Most recurrences (16 of 20) were in the form of restenosis rather than reocclusion, with a high success rate for repeat dilation (93%). These results indicate that mechanical reperfusion of an occluded infarct artery, performing PTCA 48 hours to 2 weeks after AMI, has a high success rate, a low complication rate and low symptomatic restenosis.     

Reperfusion arrhythmia: a marker of restoration of antegrade flow during intracoronary thrombolysis for acute myocardial infarction

We studied the effects of coronary recanalization on arrhythmogenesis in patients undergoing intracoronary thrombolysis during the early hours of myocardial infarction. Catheterization, ventriculography, coronary angiography, and intracoronary streptokinase infusion were performed in 22 patients. Twenty-one of 22 had thrombotic total occlusion of the infarct-related transient thrombolysis with reocclusion by the end of the procedure. In 12 of these 17 patients, restoration of antegrade coronary flow was accompanied by transient arrhythmia. In these 12 patients coronary angiography within seconds of onset of arrhythmia showed vessel patency in a previously totally occluded coronary artery. Two additional patients developed arrhythmias during streptokinase infusion but after reperfusion had already been established. Accelerated idioventricular rhythm was most often noted. Sinus bradycardia and atrioventricular block with hypotension occurred during restoration of flow in arteries supplying the inferoposterior left ventricle. These arrhythmias may be useful noninvasive markers of successful reperfusion during thrombolytic therapy in acute myocardial infarction.     

Occluded infarct-related arteries and clinical events

Late patency of the infarct-related artery has been shown to be associated with improved long-term survival rates in observational cohort studies. However, there is a dearth of randomized trials correlating the opening of persistently occluded infarct-related arteries with clinical outcomes. Recent technological advances have improved the success and safety of percutaneous revascularization, resulting in lower restenosis and reocclusion rates. A large randomized trial is needed to evaluate clinical outcomes with percutaneous revascularization versus medical management of occluded infarct-related arteries in the absence of inducible ischemia. Copyright © 2000 by W.B. Saunders Company

Progress in Cardiovascular Diseases, Vol. 42, No. 6 (May/June), 2000: pp 405-418     

Relation between late patency of the infarct-related artery, left ventricular function, and clinical outcomes after primary percutaneous intervention for acute myocardial infarction (CADILLAC trial)

The importance of sustained patency of the infarct-related artery after primary percutaneous coronary intervention for acute myocardial infarction is controversial. We examined serial measures of left ventricular function and clinical outcomes in 280 patients with an initially occluded infarct artery in whom Thrombolysis In Myocardial Infarction trial grade 3 flow was achieved and routine follow-up angiography was performed 7 months after percutaneous coronary intervention. Reocclusion of the infarct artery was associated with decreased event-free survival, and the degree of restenosis was an independent predictor of the lack in improvement in left ventricular ejection fraction over time.     

Late coronary artery recanalization effects on left ventricular remodelling and contractility by magnetic resonance imaging.

AIMS: To assess the recanalization effects of post-myocardial infarction (MI) on left ventricular (LV) remodelling and contractility in relation to conservative therapy. METHODS AND RESULTS: Thirty-six patients with occluded infarct-related artery between 12 h and 14 days post-anterior MI were randomized to percutaneous coronary intervention (PCI group) or conservative therapy (no-PCI group). Magnetic resonance imaging was performed at enrollment and after 6 months. The left ventricle was divided into infarct, adjacent, and remote segments. There was no difference in relation to LV volume between groups at the 6 month follow-up. Change in LV ejection fraction was favourable to the PCI group: 5.00% vs. -0.76%, P=0.012. Change in circumferential shortening (Ecc) of the remote segments in the PCI group was significantly better than in the no-PCI group: -1.67+/-6.30% vs. 0.29+/-6.02%, P<0.001. Infarct size and LV mass were similar between groups. CONCLUSIONS: Late recanalization improved LV ejection fraction and myocardial contractility in late follow-up, but did not change the ventricular volumes. Improvement in the left ventricle global and regional contractility may benefit the long-term outcome in post-MI patients with sustained patency of the infarct-related artery.     

Appropriate invasive and conservative treatment strategies for patients with ST elevation myocardial infarction

PURPOSE OF REVIEW: The goal of treatment strategies for patients with ST elevation myocardial infarction is to reperfuse the occluded coronary artery, as rapidly and safely as possible. This review discusses evidence regarding the appropriate treatment strategy for patients with ST elevation myocardial infarction taking into consideration geographical and logistical barriers. RECENT FINDINGS: Primary percutaneous coronary intervention is considered the gold standard of myocardial reperfusion. As therapy is time dependent, logistical barriers limit its use to no more than 29% of ST elevation myocardial infarction patients worldwide. Most patients with ST elevation myocardial infarction who undergo primary angioplasty achieve mechanical reopening of the infarct-related artery beyond the established time limit from which left ventricular preservation and clinical benefit are less probable. In contrast, early administration of newer fibrin-specific thrombolytics is at least as effective as primary angioplasty, and can abort infarction and dramatically reduce mortality when given during the first 1-2 hours of onset. Consequently, key elements from the current guidelines recommend that patients with ST elevation myocardial infarction should be reperfused either by primary percutaneous coronary intervention performed 90 minutes after the first medical contact or by thrombolysis within 30 minutes of presentation to hospital. These advantages and disadvantages should generate distinct viewpoints on reperfusion strategies for patients with infarction. For patients admitted in a hospital with primary percutaneous coronary intervention facilities, this should be considered the reperfusion strategy. Options for patients admitted to community hospitals without percutaneous coronary intervention facilities include administration of fibrinolysis or transfer to a tertiary care center for primary percutaneous coronary intervention. SUMMARY: Implementation of reperfusion strategies should vary based on the mode of transportation of the patient and capabilities at the receiving hospital.     

Rescue angioplasty during myocardial infarction has a beneficial effect on mortality: a tenable hypothesis.

HYPOTHESIS: Rescue percutaneous transluminal coronary angioplasty (PTCA) reduces mortality during myocardial infarction. OBJECTIVE: To determine if PTCA after failed thrombolytic therapy results in reduced mortality. DESIGN: Twenty-eight patients with a persistently occluded infarct artery following thrombolytic therapy more than 3 h after symptom onset were randomized to rescue PTCA (n = 16) or conservative treatment (n = 12) as part of a prospective randomized trial of reperfusion therapy during myocardial infarction in 184 patients. Hospital mortality was assessed in these groups as well as in the 177 patients with known infarct artery status after initial attempts at reperfusion. MAIN RESULTS: There was one death among the 16 patients in the rescue PTCA group versus four deaths in the 12 patients treated conservatively (P = 0.13). Moreover, the death in the rescue PTCA group occurred in one of three patients in whom the procedure failed. Mortality in the entire study group was 10.3% (19 of 184); 4.2% (six of 142) in patients in whom patency was achieved after thrombolysis and/or PTCA and 34.3% (12 of 35) in those in whom reperfusion was not achieved (P less than 0.001). In patients with anterior myocardial infarction, mortality was 6.7% (four of 60) in those with reperfusion and 47.1% (eight of 17) in those with a persistently occluded artery (P less than 0.001). In patients with inferior myocardial infarction, 2.4% (two of 82) with reperfusion and 22.2% (four of 18) with a persistently occluded artery died (P less than 0.01). CONCLUSIONS: Although the number of patients in the randomized groups was small, the trend toward a lower mortality after rescue PTCA supports the hypothesis that rescue PTCA may be beneficial. The mortality results in relation to presence or absence of reperfusion from the entire study population underscores the importance of achieving patency during myocardial infarction.     

Follow-up after coronary arterial reperfusion with intravenous streptokinase in relation to residual myocardial infarct artery narrowings

Short- and long-term changes in residual stenosis of the myocardial infarct-related coronary arteries in patients with successful reperfusion by intravenous streptokinase have not been determined until now. In 15 patients the residual diameter stenosis decreased significantly from 62 +/- 9% after 24 hours to 55 +/- 13% in the fourth week (p less than 0.005). Quantitative angiographic analyses in 61 patients with patent infarct-related coronary arteries in the fourth week revealed a mean diameter stenosis of 61 +/- 13%. The patients were followed up 34 +/- 10 months. Sixteen had elective coronary artery bypass surgery or percutaneous transluminal coronary angioplasty (PTCA). Eighteen without coronary artery bypass surgery or PTCA had undergone repeat angiography after 26 +/- 9 months. Twenty-five (41%) have had a residual diameter stenosis greater than 65% in the fourth week. A stenosis greater than 65% was found in: 4 of 5 patients with late reinfarction; 3 of 7 with 1-vessel coronary artery disease and persistent angina, compared with none of 11 with a stenosis less than 65%; 6 of 7, whose silent reocclusion had been found at long-term follow-up compared with 1 of 9 with a residual stenosis less than 65%. In 8 patients with persistent patency of the infarct artery, the stenosis had decreased significantly from 55 +/- 6% to 36 +/- 12% (p less than 0.005). Correspondingly, there was a significant improvement in the infarct-related left ventricular wall motion disorders.(ABSTRACT TRUNCATED AT 250 WORDS)     

Long-term prognosis of late spontaneous reperfusion after failed thrombolysis for acute myocardial infarction

BACKGROUND: Early reperfusion improves left ventricular (LV) function and survival after acute myocardial infarction (MI). Thrombolytic therapy achieves early patency of the infarct artery in about two-thirds of patients. In nearly half of the remaining patients, in whom early reperfusion was not achieved with thrombolytic therapy, the infarct artery might reopen by the time of predischarge angiography. However, the impact of such late spontaneous reperfusion after failed thrombolytic therapy on LV function and long-term survival remained unclear. HYPOTHESIS: This study was undertaken to assess implication of late spontaneous reperfusion after failed thrombolytic therapy on LV function and long-term survival after acute MI. METHODS: The study consisted of 198 patients with anterior acute MI who underwent thrombolytic therapy and predischarge angiography: 160 patients with infarct artery patent early and late after therapy (persistent patency), 17 patients with infarct artery occluded early after therapy but patent at predischarge angiography (late spontaneous reperfusion), and 21 patients with infarct artery occluded early and late after therapy (persistent occlusion). RESULTS: Persistent patency was associated with enhanced improvement in LV ejection fraction (7.7 +/- 11.8%) compared with late spontaneous reperfusion (0.0 +/- 9.6%, p = 0.03) and persistent occlusion (-1.4 +/- 9.7%, p = 0.003). Persistent patency was associated with better long-term survival than with late spontaneous reperfusion (p < 0.001) and persistent occlusion (p < 0.001). Multivariate analysis comparing persistent patency and late spontaneous reperfusion showed that early reperfusion was an independent predictor of long-term survival. CONCLUSION: Late spontaneous reperfusion after failed thrombolytic therapy was associated with poor LV function and long-term survival, emphasizing the importance of early reperfusion.     

Impact of late coronary artery reperfusion on left ventricular function one month after acute myocardial infarction (results from the ISAM study)

To evaluate the impact of late reperfusion of an infarct-related coronary artery on left ventricular (LV) function in the month after myocardial infarction, findings from 368 patients in the Intravenous Streptokinase in Myocardial Infarction study are presented. All patients had a late peaking in the creatine kinase-MB serum time-activity curve, suggesting absence of early reperfusion. Contrast angiography was performed 1 month after the acute event. The infarct-related coronary artery was patent in 74 of 116 (64%) streptokinase-treated patients and 141 of 252 (56%) patients treated with anticoagulant therapy (placebo group). In all baseline variables, including the actually developed enzymatic and electrocardiographic infarct sizes, there were no differences between the patent- or occluded-artery groups. A patent infarct artery 1 month after infarction was associated with significantly better LV function regardless of the vessel involved and whether or not patients had been treated with streptokinase. Ejection fraction in patients with patent versus occluded artery was 56 +/- 13 versus 50 +/- 14 (p less than 0.0005). Most benefit was noted in patients in whom the proximal left anterior descending coronary artery was affected: ejection fraction was 52 +/- 14 versus 36 +/- 12% (p less than 0.0005). Our data confirm that restoration of adequate flow through an infarct-related coronary artery beyond the time window for actual salvage of ischemic myocardium has a definite beneficial effect on LV function.