Left ventricular function at 3 months after successful thrombolysis. Impact of reocclusion without reinfarction on ejection fraction, regional function, and remodeling

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.

Long-term outcome of acute myocardial infarction patients treated with stents versus balloon angioplasty: results from randomized trials

AIM

To examine the impact of primary stent implantation versus balloon angioplasty on long-term outcome (median 8 years) in 117 patients with ST-elevation myocardial infarction (STEMI) from randomized trials.

METHODS

Enrolled patients were those presenting with STEMI within 12 h of symptom onset. Patients were randomized to either Palmaz-Schatz stent implantation (N=25) or balloon angioplasty (N=23) between January and November 1996; or Palmaz-Schatz (N=26), or Cordis coil stent implantation (N=24) or balloon angioplasty (N=19) between February 1998 and March 1999.

RESULTS

Patients (67+/-11 years) arrived to the hospital within median 2.5 h of symptom onset with Killip 1/2/3/4 grade (72/19/7/2%, respectively). The culprit lesion was located in the left anterior descending (50%), right (39%), or left circumflex coronary artery (11%) with TIMI 0/1/2/3 flow (81/5/12/2%, respectively). Clinical/angiographic features were comparable between the 2 groups. During follow-up, there was a significant reduction in cardiac mortality in the stent group (5%) compared to the angioplasty group (17%, log-rank test p=0.04). In addition, the stent group had a lower target lesion revascularization rate (28% versus 52%, p=0.008), and a significantly lower major adverse cardiac event rate (37% versus 67%, p=0.005), than the angioplasty group.

CONCLUSION

Compared to balloon angioplasty, primary stenting resulted in a sustained beneficial effect on cardiac mortality at 8 years.

Severity of residual stenosis of infarct-related lesion and left ventricular function after single-vessel anterior wall myocardial infarction: implication of ST-segment elevation in lead aVL of the admission electrocardiograms

BACKGROUND

The relationship between the severity of chronic-phase stenosis of infarct-related lesions (IRLs) and chronic left ventricular function in anterior acute myocardial infarctions (AMI) has not been adequately investigated.

HYPOTHESIS

This study investigated whether ST elevation in lead aVL of admission electrocardiogram (ECG) would be a determinant factor of the relationship between the severity of stenosis of the IRL and chronic left ventricular function after anterior wall AMI.

METHODS

One month after AMI, the IRL was evaluated by coronary angiography in 98 patients with anterior AMI, and left ventricular ejection fraction (LVEF) was determined using multigated radionuclide angiocardiography. Patients were classified according to the severity of the IRL: patients with 100% occlusion (Group O), patients with 90 to 99% stenosis (Group H), and patients with < or =75% stenosis (Group L). Patients with ST elevation > or =0.1 mV in the aVL lead on their admission ECG were included in the ST-elevation group, and those with ST elevation <0.1 mV were included in the non-ST-elevation group.

RESULTS

The LVEF was greater in the non-ST-elevation group than in the ST-elevation group (p<0.0001), and the LVEF in a whole group as follows: Group L LVEF>Group H LVEF>Group O LVEF (p = 0.0160). In the ST-elevation group, LVEF was higher in Group L than in the other groups (p = 0.0251). There were three independent predictors of a reduced LVEF: ST-elevation in aVL [odds ratio (OR): 3.38, p = 0.0044], IRL stenosis > or =90% (OR: 2.90, p = 0.0044), and the IRL occurring in the left anterior descending artery proximal to the first diagonal branch (OR: 6.31, p = 0.0024).

CONCLUSION

Left ventricular function was preserved, regardless of the severity of residual stenosis, in patients without ST elevation in aVL if the IRL was not totally occluded. In patients with ST elevation in aVL, LVEF was lower in patients with more severe stenosis, even if the IRL was patent.

Sustained coronary patency after fibrinolytic therapy as independent predictor of 10-year cardiac survival Observations from the Antithrombotics in the Prevention of Reocclusion in COronary Thrombolysis (APRICOT) trial

BACKGROUND

Whether late coronary patency after myocardial infarction has prognostic impact independent of left ventricular function remains a matter of debate. Reocclusion rates in the first year after fibrinolysis vary between 20% and 30%. Of all reocclusions, about 30% present as clinical reinfarction, associated with a 2-fold-increased risk of mortality. The clinical impact of reocclusion that presents without reinfarction has not been studied; but an association has been demonstrated with impaired contractile recovery of left ventricular function, the strongest prognosticator of long-term outcome. We therefore studied the impact of 3-month coronary patency after successful fibrinolysis on 10-year cardiac survival.

METHODS

In the APRICOT-1 trial, 248 ST-elevation myocardial infarction patients with an open infarct artery 24 hours after fibrinolysis had 3-month repeated angiography. Ten-year clinical follow-up was complete in 99.6%.

RESULTS

The reocclusion rate was 29% (71/248). Of these reocclusions, 24% presented as clinical reinfarction (17/71). Cardiac survival at 10 years was 73% in patients with a reoccluded infarct artery and 88% in patients with sustained patency (P < .01). This difference was also present in patients in whom reocclusion was only detected as a result of systematic repeated angiography, that is, in the absence of reinfarction or ischemic symptoms between angiograms (70% vs 86%, P < .03). Multivariable analysis identified sustained patency at 3-month angiography as independent predictor of 10-year cardiac survival (hazard ratio 2.10, 95% CI 1.10-4.02) together with left ventricular ejection fraction.

CONCLUSIONS

Sustained infarct artery patency in the first 3 months after successful fibrinolysis is a strong predictor of 10-year cardiac survival, independent of left ventricular function. Notably, this also holds true when reocclusion occurs without signs of clinical reinfarction or recurrent ischemia. Therefore, future preventive strategies should also focus on "clinically silent" reocclusions. Additional studies on better antithrombotic regimens and the combination with a routine invasive strategy early after successful fibrinolysis are warranted.

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.

Percutaneous coronary intervention for late reperfusion after myocardial infarction in stable patients

BACKGROUND

Results of randomized trials that have compared mechanical coronary artery recanalization versus medical therapy for total occlusion late after myocardial infarction (MI) have been conflicting.

METHODS

We performed a meta-analysis of randomized trials comparing percutaneous coronary intervention (PCI) with medical therapy in stable patients with an occluded artery 1 to 45 days after MI. Six trials and one substudy were included with data on 2617 patients for the clinical outcomes and 653 patients for determination of ejection fraction (EF) during follow-up. Outcomes included death, MI, death or MI, congestive heart failure (CHF), and change in left ventricular EF.

RESULTS

There were no statistically significant differences for any clinical outcome, with trends for an increase in MI (risk ratio 1.26, P = .19) and decrease in CHF (risk ratio 0.67, P = .19) in the PCI arm. The PCI arm showed a slight superiority in left ventricular EF (2%, 95% CI 0.1%-2.8%). Early smaller studies showed formally statistically significant benefits for CHF and EF, but the much larger Occluded Artery Trial and Total Occlusion Study of Canada 2 found no benefit. For CHF, the difference between early smaller studies and Occluded Artery Trial was beyond chance (P = .02).

CONCLUSIONS

Percutaneous coronary intervention does not seem to confer any benefits when used for late revascularization of occluded arteries after MI in stable patients.

Coronary intervention for persistent occlusion after myocardial infarction

BACKGROUND

It is unclear whether stable, high-risk patients with persistent total occlusion of the infarct-related coronary artery identified after the currently accepted period for myocardial salvage has passed should undergo percutaneous coronary intervention (PCI) in addition to receiving optimal medical therapy to reduce the risk of subsequent events.

METHODS

We conducted a randomized study involving 2166 stable patients who had total occlusion of the infarct-related artery 3 to 28 days after myocardial infarction and who met a high-risk criterion (an ejection fraction of <50% or proximal occlusion). Of these patients, 1082 were assigned to routine PCI and stenting with optimal medical therapy, and 1084 were assigned to optimal medical therapy alone. The primary end point was a composite of death, myocardial reinfarction, or New York Heart Association (NYHA) class IV heart failure.

RESULTS

The 4-year cumulative primary event rate was 17.2% in the PCI group and 15.6% in the medical therapy group (hazard ratio for death, reinfarction, or heart failure in the PCI group as compared with the medical therapy group, 1.16; 95% confidence interval [CI], 0.92 to 1.45; P=0.20). Rates of myocardial reinfarction (fatal and nonfatal) were 7.0% and 5.3% in the two groups, respectively (hazard ratio, 1.36; 95% CI, 0.92 to 2.00; P=0.13). Rates of nonfatal reinfarction were 6.9% and 5.0%, respectively (hazard ratio, 1.44; 95% CI, 0.96 to 2.16; P=0.08); only six reinfarctions (0.6%) were related to assigned PCI procedures. Rates of NYHA class IV heart failure (4.4% vs. 4.5%) and death (9.1% vs. 9.4%) were similar. There was no interaction between treatment effect and any subgroup variable (age, sex, race or ethnic group, infarct-related artery, ejection fraction, diabetes, Killip class, and the time from myocardial infarction to randomization).

CONCLUSIONS

PCI did not reduce the occurrence of death, reinfarction, or heart failure, and there was a trend toward excess reinfarction during 4 years of follow-up in stable patients with occlusion of the infarct-related artery 3 to 28 days after myocardial infarction. (ClinicalTrials.gov number, NCT00004562 [ClinicalTrials.gov].).

Early and long-term outcome of elective stenting of the infarct-related artery in patients with viability in the infarct-area: Rationale and design of the Viability-guided Angioplasty after acute Myocardial Infarction-trial (The VIAMI-trial)

Background

Although percutaneous coronary intervention (PCI) is becoming the standard therapy in ST-segment elevation myocardial infarction (STEMI), to date most patients, even in developed countries, are reperfused with intravenous thrombolysis or do not receive a reperfusion therapy at all. In the post-lysis period these patients are at high risk for recurrent ischemic events. Early identification of these patients is mandatory as this subgroup could possibly benefit from an angioplasty of the infarct-related artery.

Since viability seems to be related to ischemic adverse events, we initiated a clinical trial to investigate the benefits of PCI with stenting of the infarct-related artery in patients with viability detected early after acute myocardial infarction.

Methods

The VIAMI-study is designed as a prospective, multicenter, randomized, controlled clinical trial. Patients who are hospitalized with an acute myocardial infarction and who did not have primary or rescue PCI, undergo viability testing by low-dose dobutamine echocardiography (LDDE) within 3 days of admission. Consequently, patients with demonstrated viability are randomized to an invasive or conservative strategy. In the invasive strategy patients undergo coronary angiography with the intention to perform PCI with stenting of the infarct-related coronary artery and concomitant use of abciximab. In the conservative group an ischemia-guided approach is adopted (standard optimal care).

The primary end point is the composite of death from any cause, reinfarction and unstable angina during a follow-up period of three years.

Conclusion

The primary objective of the VIAMI-trial is to demonstrate that angioplasty of the infarct-related coronary artery with stenting and concomitant use of abciximab results in a clinically important risk reduction of future cardiac events in patients with viability in the infarct-area, detected early after myocardial infarction.

High-grade infarct-related stenosis after successful thrombolysis: strong predictor of reocclusion, but not of clinical reinfarction

BACKGROUND

After successful thrombolysis, a high-grade stenosis at 24-hour angiography is strongly predictive of reocclusion and is often believed to result in high reinfarction rates. However, routine angioplasty did not reduce death or reinfarction in past trials. Systematic angiographic follow-up shows that reocclusion often occurs without clinical reinfarction. This study investigates whether the increased risk for reocclusion associated with a high-grade lesion translates into impaired clinical outcome.

METHODS

In the ischemia-guided Antithrombotics in the Prevention of Reocclusion in COronary Thrombolysis (APRICOT-1) trial, 240 patients with ST-elevation MI who had an open infarct artery 24 hours after thrombolysis had 3-month repeat angiography to assess reocclusion, with clinical follow-up at 3 months and 3 years.

RESULTS

On the basis of the optimal discriminative stenosis severity, the reocclusion rate was 40% (47/118) in patients with a high-grade residual stenosis and 16% (20/122) in patients with a low-medium-grade lesion (risk ratio [RR], 2.43; 95% CI, 1.54-3.84; P <.01). Three-month death and reinfarction rates did not differ: 6% (7/118) versus 9% (11/122; RR, 0.66; 95% CI, 0.26-1.64; P = not significant). Systematic angiographic follow-up revealed that reocclusion of a high-grade lesion occurred in the absence of clinical reinfarction in 85% (40/47) of patients, as compared with 45% (9/20) in patients with a low-medium-grade stenosis (RR, 1.89; 95% CI, 1.15-3.12; P <.01). Despite an independent association with reocclusion, a high-grade stenosis was not predictive of either short- or long-term death and reinfarction.

CONCLUSIONS

After successful thrombolysis and adopting an ischemia-guided revascularization strategy, patients with a high-grade stenosis experience death/reinfarction rates similar to that of patients with a low-medium-grade lesion. This is true despite a 2- to 3-fold higher risk for reocclusion. The finding that reocclusion of a high-grade lesion often occurs without clinical reinfarction explains the absence of a relationship between a severe stenosis and death/reinfarction. Appreciation of these observations may contribute to an optimal design of a future randomized trial to re-evaluate the impact of a routine invasive strategy.

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.

The effect of statin therapy on ventricular late potentials in acute myocardial infarction

AIMS

To determine whether early statin therapy in acute myocardial infarction has any effect on ventricular late potentials which are considered as a noninvasive tool for evaluation of arrhythmogenic substrate.

METHODS AND RESULTS

Study population consisted of prospectively enrolled 72 patients presenting with acute myocardial infarction (<6 h). Thirty-four of the patients were randomized to pravastatin (40 mg/day) on admission irrespective of lipid levels. All patients received thrombolytic therapy. Signal-averaged ECG recordings were obtained serially prior to thrombolytic therapy, 48 h after and 10 days later. Late potentials were defined as positive if signal-averaged ECG met at least two of Gomes criteria: filtered total QRS duration >114 ms, root mean square voltage of the last 40 ms of the QRS <20 mV, or the duration of the terminal low (<40 mV) amplitude signals >38 ms. Changes observed in signal-averaged ECG recordings after thrombolysis were evaluated statistically with regard to statin usage. There were no significant differences between the clinical characteristics of the two randomized groups. There was a significant decrease in the rates of late potentials between the first and third signal-averaged ECG recordings after thrombolytic therapy in pravastatin group. Pravastatin group also had lower incidence of ventricular arrhythmias compared with control group (26 vs. 63%, P=0.021). The in-hospital cardiovascular event rates were also lower in statin group.

CONCLUSION

Early use of pravastatin reduces the incidence of late potentials following thrombolytic therapy in acute myocardial infarction. Statin therapy also seems to be reducing the incidence of in-hospital ventricular arrhythmias. These beneficial effects of statins might be explained through prevention of new myocardial ischemic episodes due to early plaque stabilization or regulation of endothelial and platelet functions.

Early prediction of improvement in ejection fraction after acute myocardial infarction using low dose dobutamine echocardiography

OBJECTIVE

To evaluate the relation between changes in ejection fraction during the first three months after acute myocardial infarction and myocardial viability.

PATIENTS

Myocardial viability was assessed using low dose dobutamine echocardiography in 107 patients at mean (SD) 3 (1) days after acute myocardial infarction. Cross sectional echocardiography was repeated three months later. Left ventricular volumes and ejection fraction were determined from apical views using the Simpson biplane formula.

RESULTS

In patients with viability, ejection fraction increased by 4.4 (4.3)%; in patients without viability it remained unchanged (0.04 (3.6)%; p < 0.001). A > or = 5% increase in ejection fraction was present in 21 of 107 patients (20%). Receiver operating characteristic analysis showed that myocardial viability in > or = 2 segments predicted this increase in ejection fraction with a sensitivity of 81% and a specificity of 65%. Multivariate logistic regression analysis was used to define which clinical and echocardiographic variables were related to > or = 5% improvement in ejection fraction. Myocardial viability, non-Q wave infarction, and anterior infarction all emerged as independent predictors, myocardial viability being the best (chi(2) = 14.5; p = 0.0001). Using the regression equation, the probability of > or = 5% improvement in ejection fraction for patients with a non-Q wave anterior infarct with viability was 73%, and for patients with a Q wave inferior infarct without viability, only 2%.

CONCLUSIONS

Myocardial viability after acute myocardial infarction is the single best predictor of improvement in ejection fraction. In combination with infarct location and Q wave presence, the probability of > or = 5% improvement can be estimated in individual patients at the bedside.

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.

Safety of coronary stenting early after thrombolysis in patients with acute myocardial infarction: one- and six-month clinical and angiographic evolution

To determine the feasibility and safety of early posthrombolysis coronary stenting and the incidence of further reocclusion, we followed 99 consecutive patients with acute myocardial infarction thrombolyzed with rt-PA 2.0 +/- 0.8 hr after onset. Culprit artery was stented 14.0 +/- 7.0 hr after thrombolysis. All patients underwent clinical and angiographic follow-up at 1 and 6 months. Angiographic success was achieved in 99% of cases. Neither major cardiac events nor bleeding or vascular complications occurred during hospital stay. At 30 days, no events occurred and normal flow persisted in all stented arteries. At 6 months, only one artery reoccluded (1%), resulting in a nonfatal reinfarction. Restenosis rate was 21%. Contribution of the infarcted area to left ventricular function significantly increased from baseline to 30-day and to 6-month evaluations. Thus, early posthrombolysis stenting is a safe strategy with a low reocclusion rate, which seems to allow functional recovery of the infarcted area. Further studies are necessary to define its impact on survival and cost-effectiveness.

Keeping the coronary arteries open: current opportunities

Thrombolysis has reduced mortality from myocardial infarction, but effective opening of the artery with normal flow continues to be an important goal. Thrombolysis is not always as successful as it should be; alternatives include adjunctive therapy and mechanical opening of the arteries. In patients with acute coronary occlusion opening the artery should continue to be the primary aim.

The late open artery hypothesis--a decade later

BACKGROUND

Early reperfusion after myocardial infarction has been proved to preserve left ventricular function and reduce mortality. However, a significant number of patients have persistent occlusion of the infarct-related artery late (days to weeks) after myocardial infarction because of ineligibility for thrombolytic therapy, failure of reperfusion, or reocclusion.

METHODS

In this report we review the data on the potential mechanisms and benefits of late reperfusion and present prospective data on the incidence of and current practice patterns for the management of persistently occluded infarct-related arteries late after myocardial infarction.

RESULTS

Although several studies have associated late patency of the infarct-related artery with improved long-term clinical outcome, they were nonrandomized and reflect selection bias. Furthermore, data on late patency from the largest study, Global Utilization of Steptokinase and Tissue Plasminogen Activator for Occluded Arteries (GUSTO-I), failed to confirm independent benefits of an open infarct-related artery 1 year after myocardial infarction. The randomized data on the effects of percutaneous transluminal coronary angioplasty for occluded infarct-related arteries late after myocardial infarction are limited and inconclusive.

CONCLUSIONS

The hypothesis that late reperfusion by percutaneous coronary intervention days to weeks after myocardial infarction results in improved long-term clinical outcomes in asymptomatic patients with occluded infarct-related artery is currently being tested in the randomized, multicenter Occluded Artery Trial.

Full recovery of contraction late after acute myocardial infarction: determinants and early predictors

OBJECTIVES

To assess the relative value of electrocardiographic, echocardiographic, angiographic, and in-hospital therapeutic indices for predicting late functional recovery after acute myocardial infarction, and to determine the variables associated with absence of recovery, partial recovery, and full recovery.

DESIGN

Prospective observational follow up study.

SETTING

Teaching hospital.

PATIENTS

74 consecutive patients with a first uncomplicated acute myocardial infarct.

INTERVENTIONS

Dobutamine-atropine stress echocardiography was performed mean (SD) 5 (2) days after the acute event. Quantitative angiography was available in all patients before hospital discharge. A follow up resting echocardiogram was obtained 12 (2) months later.

RESULTS

Functional recovery (partial, n = 18; full, n = 27) was observed in 45 of the 74 patients. Recovery was associated with earlier thrombolytic treatment (p = 0.008), earlier peak concentration of creatine kinase (p = 0.009), greater contractile reserve (p = 0.0001), non-Q wave acute myocardial infarction (p = 0.002), and more frequent elective angioplasty of the infarct related vessel (p = 0.0004). Three independent variables were selected stepwise from multivariate analysis for predicting late recovery: contractile reserve (chi(2) = 24.2, p < 0.0001); non-Q wave infarction (chi(2) = 15.7, p = 0.0001); and the time from symptom onset to thrombolysis (chi(2) = 4.94, p = 0.026). Three independent variables predicted full recovery: contractile reserve (chi(2) = 17.2, p = 0.0001); non-Q wave infarction (chi(2) = 10.1, p = 0.0016); and elective angioplasty of the infarct related artery (chi(2) = 4.53, p = 0.033). Only contractile reserve (chi(2) = 17.0, p < 0.001) was selected from the multivariate analysis for its ability to distinguish between partial recovery and absence of recovery.

CONCLUSIONS

Late recovery of contraction relates to earlier treatment, which is associated with lower infarct size unmasked by a non-Q wave event and the presence of contractile reserve. Elective coronary angioplasty of the infarct related artery before hospital discharge is associated with full recovery.

Full recovery of contraction late after acute myocardial infarction: determinants and early predictors

OBJECTIVES

To assess the relative value of electrocardiographic, echocardiographic, angiographic, and in-hospital therapeutic indices for predicting late functional recovery after acute myocardial infarction, and to determine the variables associated with absence of recovery, partial recovery, and full recovery.

DESIGN

Prospective observational follow up study.

SETTING

Teaching hospital.

PATIENTS

74 consecutive patients with a first uncomplicated acute myocardial infarct.

INTERVENTIONS

Dobutamine–atropine stress echocardiography was performed mean (SD) 5 (2) days after the acute event. Quantitative angiography was available in all patients before hospital discharge. A follow up resting echocardiogram was obtained 12 (2) months later.

RESULTS

Functional recovery (partial, n = 18; full, n = 27) was observed in 45 of the 74 patients. Recovery was associated with earlier thrombolytic treatment (p = 0.008), earlier peak concentration of creatine kinase (p = 0.009), greater contractile reserve (p = 0.0001), non-Q wave acute myocardial infarction (p = 0.002), and more frequent elective angioplasty of the infarct related vessel (p = 0.0004). Three independent variables were selected stepwise from multivariate analysis for predicting late recovery: contractile reserve (χ2 = 24.2, p < 0.0001); non-Q wave infarction (χ2 = 15.7, p = 0.0001); and the time from symptom onset to thrombolysis (χ2 = 4.94, p = 0.026). Three independent variables predicted full recovery: contractile reserve (χ2 = 17.2, p = 0.0001); non-Q wave infarction (χ2 = 10.1, p = 0.0016); and elective angioplasty of the infarct related artery (χ2 = 4.53, p = 0.033). Only contractile reserve (χ2 = 17.0, p < 0.001) was selected from the multivariate analysis for its ability to distinguish between partial recovery and absence of recovery.

CONCLUSIONS

Late recovery of contraction relates to earlier treatment, which is associated with lower infarct size unmasked by a non-Q wave event and the presence of contractile reserve. Elective coronary angioplasty of the infarct related artery before hospital discharge is associated with full recovery.

Early patency of the infarct-related artery after myocardial infarction preserves diastolic filling

A patent infarct-related artery (IRA) following myocardial infarction has been associated with lower mortality, increased systolic function, decreased left ventricular remodeling, and electrical stability. The purpose of this study was to determine whether coronary artery patency early after myocardial infarction is associated with greater early diastolic filling than a closed artery. Radionuclide ventriculograms were performed at a central laboratory on 167 patients who received alteplase for an acute myocardial infarction and had infarct artery patency determined by cardiac catheterization. The peak early filling rate (PEFR) was assessed by 4 different methods: (1) PEFR (EDV/s)--normalized to the end-diastolic volume; (2) PEFR (SV/s)--normalized to the stroke volume; (3) PEFR (ml/s/m(2))--an absolute diastolic filling rate; and (4) PEFR (PER)--normalized to the peak ejection rate. Patients with a closed IRA (n = 16, Thrombolysis In Myocardial Infarction [TIMI] 0 or 1 flow) and patients with an open IRA (n = 151, TIMI 2 or 3 flow) had similar ages, ejection fractions, and cardiac volumes. However, among patients with an occluded IRA, the PEFR was decreased by 12% to 18% by the 4 measures of diastolic filling (3 of 4 methods, p <0.05). PEFR (EDV/s) was 1.69 +/- 0.9 in the occluded group versus 2.06 +/- 0.4 EDV/s in the open artery group (p = 0.005). By multivariate analysis, IRA patency was an independent predictor of the PEFR by all 4 methods. Early coronary artery patency after an acute myocardial infarction preserves diastolic filling. Improved diastolic function may in part explain part of the long-term benefits of a patent IRA after thrombolytic therapy when there is no documented improvement in the ejection fraction.

Prediction of functional recovery of viable myocardium after delayed revascularization in postinfarction patients: accuracy of dobutamine stress echocardiography and influence of long-term vessel patency

OBJECTIVES

We sought to evaluate dobutamine stress echocardiography (DSE) for predicting recovery of viable myocardium after revascularization with cineangiography as a gold standard for left ventricular (LV) function. We studied the influence of late vessel reocclusion on regional LV function.

BACKGROUND

Dobutamine stress echocardiography is a well established evaluation method for myocardial viability assessment. In previous studies the reference method for assessing LV recovery was echocardiography, long-term vessel patency has not been systematically addressed.

METHODS

Sixty-eight patients with a first acute myocardial infarction (AMI) and residual stenosis of the infarct related artery (IRA) underwent DSE (mean +/- standard deviation) 21 +/- 12 days after AMI to evaluate myocardial viability. Revascularization of the IRA was performed in 54 patients by angioplasty (n = 43) or bypass grafting (n = 11). Coronary angiography and LV cineangiography were repeated at four months to assess LV function and IRA patency.

RESULTS

Sensitivity and specificity of DSE for predicting myocardial recovery after revascularization were 83% and 82%. In the case of late IRA patency, specificity increased to 95%, whereas sensitivity remained unchanged. In the 16 patients with myocardial viability and late IRA patency, echocardiographic wall motion score index decreased after revascularization from 1.83 +/- 0.15 to 1.36 +/- 0.17 (p = 0.0001), and left ventricular ejection fraction (LVEF) increased from 0.52 +/- 0.06 to 0.57 +/- 0.06 (p = 0.0004), whereas in five patients, reocclusion of the IRA prevented improvement of segmental or global LV function despite initially viable myocardium.

CONCLUSIONS

Dobutamine stress echocardiography is reliable to predict recovery of viable myocardium after revascularization in postinfarction patients. Late reocclusion of the IRA may prevent LV recovery and influence the accuracy of DSE.

Coronary artery flow ten weeks after myocardial infarction or unstable angina: effects of combined warfarin and aspirin therapy

Forty-three patients presenting with unstable angina or myocardial infarction were randomised double blind to warfarin [target international normalised ratio (INR), 2.0 to 2.5] and aspirin (150 mg) daily or placebo plus aspirin (150 mg) daily. Coronary flow was assessed with the thrombolysis in myocardial infarction (TIMI) flow grade and corrected TIMI frame count (CTFC). Coronary artery flow was reduced (higher CTFC) at baseline in culprit arteries (mean +/-SD, 37.1+/-15.4 frames) compared to nonculprit arteries (22.5+/-6.7 frames, P<0.0001). In patients with a patent artery at follow-up, coronary flow was unchanged after ten weeks of warfarin and aspirin (-2.0+/-19.9 frames) or aspirin alone (3.8+/-10.4 frames, P = 0.20). Patients randomised to aspirin alone were more likely to progress to total occlusion [aspirin, 7 of 19 (37%) vs. warfarin and aspirin, 1 of 24 (4%); P = 0.01). Higher baseline culprit artery CTFC was also associated with an increased risk of late occlusion [+10 frames; odds ratio (OR), 1.65; 95% CI, 1.01 to 2.33]. Coronary flow remained impaired ten weeks after presentation with myocardial infarction or unstable angina. Combination warfarin and aspirin therapy did not improve flow in vessels that remained patent but did reduce the risk of progression to occlusion.

Long-term arterial patency after coronary reperfusion

Coronary reocclusion is a frequent event after reperfusion and may be responsible for the deterioration of left ventricular function. It may occur early as well as in the chronic phase after hospital discharge. Current, evidence based, strategies to prevent reocclusion include antiplatelet and anticoagulant agents as well as the use of intracoronary stenting in those patients who are treated by PTCA. The combination of aspirin and ticlopidine adds on the results of stenting. Further treatments are currently investigated and may significantly improve the long-term coronary patency.

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.

Ventricular dilatation in the absence of ACE inhibitors: influence of haemodynamic and neurohormonal variables following myocardial infarction

OBJECTIVE

To examine the relation between patterns of ventricular remodelling and haemodynamic and neurohormonal variables, at rest and during symptom limited exercise, in the year following acute myocardial infarction in patients not receiving angiotensin converting enzyme (ACE) inhibitors.

DESIGN

A prospective observational study.

PATIENTS

65 patients recruited following hospital admission with a transmural anterior myocardial infarction.

METHODS

Central haemodynamics and neurohormonal activation at rest and during symptom limited treadmill exercise were measured at baseline before hospital discharge, one month later, and at three monthly intervals thereafter. PATIENTS were classified according to individual patterns of change in left ventricular end diastolic volumes at rest, assessed at each visit using transthoracic echocardiography.

RESULTS

In most patients (n = 43, 66%) ventricular volumes were unchanged or reduced. Mean (SEM) treadmill exercise capacity and peak exercise cardiac index increased at month 12 by 200 (24) seconds (p < 0.001 v baseline) and by 0.8 (0.4) l/min/m2 (p<0.05 v baseline), respectively, in this group. In patients with limited ventricular dilatation (n = 11, 17%) exercise capacity increased by 259 (52) seconds (p < 0.001 v baseline) and peak exercise cardiac index improved by 0.8 (0.7) l/min/m2 (NS). In the remaining 11 patients with progressive left ventricular dilatation, exercise capacity increased by 308 (53) seconds (p< 0. 001 v baseline) and peak exercise cardiac index similarly improved by 1.3 (0.7) l/min/m2 (NS). There were trends towards increased atrial natriuretic factor (ANF) secretion at rest and at peak exercise in this group.

CONCLUSIONS

Ventricular dilatation after acute myocardial infarction is a heterogeneous process that is progressive in only a minority of patients. Compensatory mechanisms, including ANF release, appear capable of maintaining and improving exercise capacity in most patients for at least 12 months, even in those with a progressive increase in ventricular size.

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.

Multicenter trial on prognostic value of inducible ischemia, assessed by dobutamine stress echocardiography and exercise electrocardiography test, in patients with uncomplicated myocardial infarction, treated with thrombolytic therapy

BACKGROUND

Thrombolysis has reduced early and longterm mortality by about 20%; sometimes, however, there is a re-occlusion of the infarct related artery or an unsuccessful thrombolysis. In these situations, there is a possible increase in detrimental events in the follow-up.

OBJECTIVES

The aim of the study was to compare the prognostic value of dobutamine echocardiography (DET) and ECG exercise test (EET) in pts submitted to thrombolysis.

METHODS

One hundred and fifty-one pts, with acute uncomplicated myocardial infarction, were enrolled. The pts were able to perform EET and had a sufficient echocardiographic window; 58 had anterior myocardial infarction (38%), 79 had inferior (52%), 2 had lateral (1%), 12 had non-Q (8%). EET was performed with an initial load of 25 Watt, and thereafter, 25 W every two minutes. DET was performed with step-wise infusion every three minutes (5, 10, 20, 30 and 40 mcg/kg/min.). If the target heart rate was not reached, a further dose of 40 mcg/kg/min. together with atropine 0.25-1 mg was administered, in the absence of signs and symptoms of ischemia.

RESULTS

During a mean (+/- SD) follow-up period of 8 +/- 4.5 months (range 1-23), 16 spontaneous events happened (4 deaths, 5 non-fatal re-infarctions, 7 unstable angina). One-hundred and three EET (68%) were negative for ongoing ischaemia, while 48 were positive, 79 DET (52%) were negative for ongoing ischaemia and 72 were positive (48%). Statistical results: DET and EET had a sensitivity of 41% and 54%, a specificity of 57% and 74%, a positive predictive value of 7% and 14%, a negative predictive value of 91% and 95%, an accuracy of 56% and 73%. Kaplan-Maier survival curves demonstrated that patients with Peak Wall motion > 1.8 and EET score > 3, had the higher risk of spontaneous events.

CONCLUSION

A few spontaneous events happened in the follow-up. These data demonstrate that patients treated with thrombolysis are not at high risk of spontaneous events. DET and EET, therefore, have had a high negative predictive value. For this reason, we can conclude that pts with negative tests can be considered at low risk and do not need any further investigations.

Thrombolysis in acute myocardial infarction improves prognosis and prolongs life but will increase the prevalence of heart failure in the geriatric population

This paper will review the hypothesis that early complete thrombolytic therapy in acute myocardial infarction reduces mortality and improves prognosis. ACE inhibitors improve remodelling and anti-platelet drugs or interventional procedures prevent reocclusion of the infarct related coronary artery. Most patients are left with significant myocardial damage and this effect is cumulative with subsequent infarction. The average age of death has increased by 10 years in the last three decades, so that many older patients survive. They have survived acute myocardial infarction and we now have a significant population with important heart failure despite good thrombolytic therapy.

Abnormal coronary flow in infarct arteries 1 year after myocardial infarction is predicted at 4 weeks by corrected Thrombolysis in Myocardial Infarction (TIMI) frame count and stenosis severity

Because 24% to 30% of patent infarct-related arteries occlude in the year following thrombolytic therapy for acute myocardial infarction, angiographic factors including corrected Thrombolysis in Myocardial Infarction (TIMI) frame count which may predict abnormal infarct-artery flow, require definition. We examined changes in coronary flow and infarct-artery lesion severity by computerized quantitative angiography over 1 year in 154 patients with a patent infarct-related artery 4 weeks after myocardial infarction. These patients were randomized to receive either ongoing daily therapy of 50 mg aspirin and 400 mg dipyridamole, or placebo. All angiograms were interpreted blind in our core angiographic laboratory. Infarct-artery flow, assessed by corrected TIMI frame counts, was normal (< or = 27) in 46% and 45% of patients at 4 weeks and 1 year, respectively. At 4 weeks, patients with corrected TIMI frame counts < or = 27 had higher ejection fractions (60+/-11% vs 56+/-12%; p = 0.04) than those with corrected TIMI frame counts >27. On multivariate analysis, corrected TIMI frame count and stenosis severity were predictive of late abnormal infarct-artery flow (TIMI 0 to 2 flow, both p <0.01). Only stenosis severity at 4 weeks predicted reocclusion at 1 year (p <0.0001). Aspirin and dipyridamole had no effect on flow or reocclusion. Thus, corrected TIMI frame count and stenosis severity at 4 weeks was highly correlated with infarct-artery flow at 1 year.

Dissociation between changes in intramyocardial function and left ventricular volumes in the eight weeks after first anterior myocardial infarction

OBJECTIVES

We sought to examine the relation between regional changes in intramyocardial function and global left ventricular (LV) remodeling in the first 8 weeks after reperfused first anterior myocardial infarction (MI).

BACKGROUND

Because of limitations in imaging methods used to date, this relation has not been thoroughly evaluated.

METHODS

We studied 26 patients (21 men, 5 women; mean age 51 years) by magnetic resonance imaging (MRI) on day 5 +/- 2 (mean +/- SD) and week 8 +/- 1 after their first anterior MI. All patients had single-vessel left anterior descending coronary artery disease and although they had received reperfusion therapy, all had regional LV dysfunction and an initial ejection fraction (EF) < or = 50%. Short-axis magnetic resonance tagging was performed spanning the LV. Percent intramyocardial circumferential shortening (%S) on a topographic basis, LV mass index, LV end-diastolic volume index (LVEDVI), LV end-systolic volume index and LV ejection fraction (LVEF) were measured.

RESULTS

Left ventricular mass index tended to decrease, whereas the LVEDVI increased from 82 +/- 24 to 96 +/- 27 ml/m2 (p = 0.002). Left ventricular end-systolic volume index remained unchanged, whereas LVEF increased from 39 +/- 12% to 45 +/- 14% (p = 0.002). Apical %S improved from 9 +/- 6% to 13 +/- 5% (p < 0.0001), as it did in the midanterior (6 +/- 6% to 10 +/- 7%, p < 0.02) and midseptal regions (8 +/- 7% to 12 +/- 6%, p < 0.02). Early dysfunction in remote midinferior and basal lateral regions resolved by 8 weeks. By multivariate analysis, the only significant predictor of an increase in LVEDVI over the study period was peak creatine kinase (p = 0.04).

CONCLUSIONS

In the first 8 weeks after a large, reperfused anterior MI, %S improved in the apex, midanterior and midseptal regions and normalized in remote noninfarct-related regions, but LV end-diastolic volumes also increased. This increased LVEDVI correlated with infarct size by peak creatine kinase and was not related to changes in global and regional LV function.

Assessment of myocardial viability in patients with previous myocardial infarction by using single-photon emission computed tomography with a new metabolic tracer: [123I]-16-iodo-3-methylhexadecanoic acid (MIHA). Comparison with the rest-reinjection thallium-201 technique

OBJECTIVES

We compared the ability of rest single-photon emission computed tomography (SPECT) with [123I]-16-iodo-3-methylhexadecanoic acid (MIHA) and the thallium-201 (Tl-201) rest-reinjection technique to detect myocardial viability after infarction.

BACKGROUND

After myocardial infarction, MIHA frequently shows increased uptake in the areas with exercise Tl-201 defects (mismatch), even in patients with an irreversible Tl-201 reinjection defect. Whether such increased uptake is indicative of ischemic but viable myocardium is not known.

METHODS

We studied 38 patients who 1) underwent exercise SPECT Tl-201 with rest-reinjection and rest SPECT with MIHA before undergoing percutaneous transluminal coronary angioplasty (PTCA) of an infarct-related coronary artery, and 2) were found to have successful revascularization at follow-up angiography. The relation between SPECT results before PTCA and subsequent improvement in left ventricular wall motion was assessed.

RESULTS

A mismatch was evident before PTCA in 51 of 76 infarct-related segments and correlated with subsequent improvement in wall motion (overall accuracy 71%), even for the 27 segments whose exercise defects remained irreversible after Tl-201 reinjection (overall accuracy 81%). The finding of a mismatch clearly enhanced the results provided by the finding of > or = 50% Tl-201 uptake as determined at redistribution (p < 0.05), but not as determined at reinjection, although there was a trend toward a better specificity for the findings of a mismatch.

CONCLUSIONS

MIHA is an efficient marker of viability inside exercise-underperfused areas after infarction, even in patients with irreversible Tl-201 reinjection defects. Assessment by conventional SPECT of a mismatch between results obtained with a metabolic tracer (MIHA) and a flow tracer analyzed at exercise (Tl-201) as a marker of myocardial viability is a promising area of research.

Progression of the culprit lesion in unstable coronary artery disease with warfarin and aspirin versus aspirin alone: preliminary study

OBJECTIVES

This study assessed whether combination therapy with aspirin and warfarin for 10 weeks reduces the risk of progression or reocclusion of the unstable coronary artery lesion.

BACKGROUND

Reocclusion of the culprit coronary artery occurs in up to one third of patients during the 3 months after myocardial infarction (MI) or unstable angina and is associated with increased morbidity and mortality.

METHODS

Fifty-seven patients presenting with unstable angina or MI who had an identifiable culprit lesion at coronary angiography were randomized in double-blind manner to receive warfarin (target international normalized ratio [INR] 2.0 to 2.5) or placebo in addition to aspirin (150 mg daily). Changes in the culprit lesion were assessed by quantitative angiography in 50 patients after 10 weeks of therapy or after a clinical event. Progression of the culprit lesion was defined as a decrease in minimal lumen diameter > 0.4 mm or a new total occlusion. Regression was defined as an increase in minimal lumen diameter > 0.4 mm.

RESULTS

In subjects randomized to receive warfarin, the culprit lesion was less likely to progress (1 [4%] vs. 8 [33%]) and more likely to regress (5[19%] vs. 2[9%]) than in subjects receiving placebo (p = 0.02). Recurrent MI or a new occlusion at angiography occurred in 2 (7%) of 29 patients receiving warfarin versus 11 (39%) of 28 patients receiving placebo (p = 0.005).

CONCLUSIONS

In patients with an acute coronary syndrome, combined therapy with aspirin and warfarin with a target INR of 2.0 to 2.5 for 10 weeks reduces the risk of progression or reocclusion of the culprit coronary lesion.

Changing paradigms in thrombolysis in acute myocardial infarction

Acute myocardial infarction occurs when a ruptured coronary artery plaque causes sudden thrombotic occlusion of a coronary artery and cessation of coronary artery blood flow. This paper reviews the underlying coronary pathology in progressive coronary atherosclerosis, mechanisms of plaque rupture and arterial occlusion and the time relationship between coronary occlusion and myocardial necrosis. Reperfusion can be achieved by chemical thrombolysis with different thrombolytic agents. Early lysis is achieved best by prehospital administration, a transtelephonic monitor, a mobile intensive care unit, active general practitioner treatment or by warning the emergency room of impending arrival of a patient. Thrombolytic therapy may be unsuccessful and not achieve Grade III TIMI flow in less than 4 h (or even 2 h) due to inadequate or intermittent perfusion or reocclusion. Adjuvant therapy includes aspirin and platelet receptor antagonists. Bleeding is a constant danger. Direct percutaneous transluminal coronary angioplasty (PTCA) may be as effective or better than chemical thrombolysis. Reperfusion protects the myocardium and salvages viable tissue. It also improves mechanical remodelling of the ventricle. Long-term follow-up has shown that quantum leaps of fresh coronary occlusion causes step-wise progression in patient disability and that further early, prompt reperfusion can salvage myocardium and prevent this inexorable progress of the disease.

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.

Impact of severity of coronary artery stenosis and the collateral circulation on the functional outcome of dyssynergic myocardium after revascularization in patients with healed myocardial infarction and chronic left ventricular dysfunction

The aim of this study was to assess the influence of the severity of coronary artery stenosis and the grade of collateral circulation on myocardial viability in patients with chronic left ventricular (LV) dysfunction undergoing coronary artery bypass grafting. Forty patients (age 59 +/- 8 years) with old myocardial infarction were studied by dobutamine stress echocardiography (DSE) before coronary artery bypass grafting. LV function was assessed using a 16-segment, 5-grade score model. Viability and functional recovery were respectively defined as a reduction in wall motion score > or = 1 at low-dose DSE and at follow-up echocardiograms obtained 3 months after surgery. There were 56 stenotic coronary arteries subtending severely dyssynergic myocardial segments, of which 38 were occluded. Among 186 severely dyssynergic segments, functional recovery occurred in 42 (23%). There was no significant difference between myocordial regions with patent or occluded coronary arteries with respect to prevalence of viability or functional recovery and percentage of viable or recovered segments relative to the total number of dyssynergic segments. In patients with total occlusion, these parameters were not different between regions with different collateral grades. Sensitivity, specificity, and accuracy of low-dose DSE for prediction of regional functional recovery were 71%, 90%, and 86%, respectively. It is concluded that in patients with chronic LV dysfunction, the presence of total occlusion of coronary arteries supplying severely dyssynergic regions does not imply a lower prevalence or extent of functional recovery after revascularization, regardless of the grade of angiographically visualized collaterals. Low-dose DSE can identify myocardial regions with a high probability of functional improvement after revascularization regardless of the severity of underlying coronary stenosis or collateralization of the involved coronary vessel.

Effect of late percutaneous angioplastic recanalization of total coronary artery occlusion on left ventricular remodeling, ejection fraction, and regional wall motion

The clinical benefit of late recanalization of complete coronary occlusion is debated. Left ventricular (LV) function and volumes are major prognostic determinants in patients with coronary artery disease. We sought to assess comprehensively the evolution of global and regional LV function and LV volumes after percutaneous recanalization of chronic complete coronary artery occlusions. A consecutive series of 55 patients who underwent successful percutaneous recanalization of a chronic (> or = 10 days), total (Thrombolysis in Myocardial Infarction trial flow grade 0) occlusion of the left anterior descending or dominant right coronary arteries, and in whom a complete angiographic evaluation was available before angioplasty and at follow-up was studied. At follow-up, 38 patients had a patent artery (group 1) and 17 had a reocclusion (group 2). Baseline parameters were similar in the 2 groups. In group 1, LV ejection fraction increased from 55 +/- 14% to 62 +/- 13% (p <0.001), with an increase in fractional shortening in the occluded artery territory (0.43 +/- 0.30 to 0.71 +/- 0.34, p <0.001), while LV end-diastolic volume remained unchanged. In group 2, ejection fraction and regional wall motion were unchanged, while LV end-diastolic volume index increased (86 +/- 22 ml/m2 to 99 +/- 34 ml/m2, p <0.02). The evolution in LV global and regional function was similar in patients with or without previous myocardial infarction; however, prevention of LV remodeling was observed only in patients with previous infarction. Maintained potency after successful recanalization of totally occluded coronary arteries improves global and regional LV function and, in patients with previous myocardial infarction, avoids LV remodeling.

Reduction of reinfarction and angina with use of low-molecular-weight heparin therapy after streptokinase (and heparin) in acute myocardial infarction

This study examined whether extending the anticoagulation effect of heparin by low-molecular-weight heparin (clexane) can prevent recurrent myocardial infarction (AMI) treated by streptokinase. On the fifth day after AMI and after heparin therapy cessation, 103 patients were randomly assigned to either treatment with low-molecular-weight heparin (40 mg subcutaneously per day for 25 days, n=43) or control (no treatment, n=60). All patients were followed carefully for 6 months after the infarction date. A total of 32 patients (31%) sustained a cardiac event during the 6-month observation period. There were 12 patients (20%) with reinfarction in the control group versus 2 patients (4.6%) in the low-molecular-weight heparin group during the first 30 days of the study (p=0.02). One additional patient sustained reinfarction at 3 months of followup in the control group, which yielded a total of 13 patients (21.6%) sustaining reinfarction in the control group versus 2 patients (4.6%) in the low-molecular-weight heparin group during 6 months of followup (p=0.01). Angina pectoris after AMI was diagnosed in 13 control patients (21.6%) versus 4 low-molecular-weight heparin-treated patients (9.3%) (p=0.078) during the study period. No major bleeding events were reported in either low-molecular-weight heparin-treated or control patients. Among patients with recently diagnosed AMI treated by streptokinase, extending the anticoagulant effect of heparin for 25 days may prevent recurrent coronary events for at least one month.

Reocclusion: the flip side of coronary thrombolysis

Since the introduction of thrombolytic therapy for acute myocardial infarction, the incidence of coronary artery reocclusion has been intensively studied. Also, the prediction and diagnosis of reocclusion by angiographic and clinical variables, as well its invasive and pharmacologic prevention, have gained much attention. By angiographic definition, reocclusion requires three angiographic observations: one with an occluded artery, one with a reperfused artery and a third for the assessment of subsequent occlusion (true reocclusion). Since the introduction of early intravenous reperfusion therapy, most studies use only two angiograms: one with a patent and one with a nonpatent infarct-related artery. A search for all published reocclusion studies revealed 61 studies (6,061 patients) with at least two angiograms. The median time interval between the first angiogram after thrombolysis and the second was 16 days (range 0.1 to 365). Reocclusion was observed in 666 (11%) of 6,061 cases. Interestingly, the 28 true reocclusion studies showed an incidence of reocclusion of 16 +/- 10% (mean +/- SD), and the 33 studies with only two angiograms 10 +/- 8% (p=0.04), suggesting that proven initial occlusion of the infarct-related artery is a risk factor for reocclusion after successful thrombolysis. The other predictors for reocclusion are probably severity of residual stenosis of the infarct-related artery after thrombolysis and perhaps the flow state after lysis. Reocclusion is most frequently seen in the early weeks after thrombolysis. The clinical course in patients with reocclusion is more complicated than in those without this complication. Left ventricular contractile recovery after thrombolysis is hampered by reocclusion. Routine invasive strategies have not been proven effective against reocclusion. In the prevention of reocclusion, both antiplatelet and antithrombin strategies have been tested, including hirudin and hirulog, but the safety of these agents in thrombolysis is still questionable. Thus, reocclusion after thrombolysis is an early phenomenon and is more frequent after proven initial occlusion of the infarct-related artery. Reocclusion can be predicted by angiography after thrombolysis. Because reocclusion is detrimental, strategies to prevent it should be developed and carried out after thrombolytic therapy for acute myocardial infarction as soon as they are deemed safe.

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.

Non-invasive assessment of reperfusion of the infarct-related artery during coronary thrombolysis and its relation with left ventricular function

We monitored ST segment continuously for at least 3 h after the beginning of lytic treatment in 103 patients undergoing early coronary thrombolysis for acute myocardial infarction in order to ascertain whether this technique, which has been shown to be useful to assess recanalization of the infarct-related artery, is also able to identify the improvement in left ventricular function associated with successful reperfusion. Global left ventricular function (assessed in the 30 degrees right anterior oblique projection with the area/length method) and infarct zone wall motion (studied with the centerline method) were evaluated at least 4 weeks after the event. Reperfusion was thought to be achieved when ST segment elevation dropped > 50% relative to the most abnormal peak documented at any time in the study. Eighty patients (78%) met the criterium for successful reperfusion (group 1), and 23 (22%) did not (group 2). Both groups had similar clinical and angiographic characteristics. All indexes of global left ventricular function were significantly better in group 1 than in group 2 patients (end-diastolic volume: 176 +/- 51 vs. 209 +/- 76 ml, end-systolic volume: 66 +/- 40 vs. 97 +/- 55 ml, ejection fraction: 65 +/- 13 vs. 57 +/- 11%, respectively, all P < 0.02). Also the severity (-1.6 +/- 1.3 vs. -2.6 +/- 1.01 S.D./chord, respectively, P < 0.001) and the extension of hypokinesia in the infarct zone (number of chords with > 2 S.D.: 13 +/- 16 vs. 28 +/- 17, respectively, P < 0.0001) were less in group 1 than in group 2 patients. Furthermore, in reperfused patients, both global left ventricular function and regional wall motion were better in those admitted < 60 min from onset of pain. In conclusion, patients with rapid ( > 50%) decrease of ST segment elevation have smaller infarct size and better global left ventricular function than patients without electrocardiographic signs of reperfusion as assessed by continuous ST segment monitoring. This suggests that this non-invasive technique is a powerful tool able to identify patients most benefiting from thrombolytic therapy.