The late open artery hypothesis--a decade later

Improvement of the frontal QRS-T angle after successful percutaneous coronary revascularization in patients with chronic total occlusion

BACKGROUND

The QRS-T angle (QRS-Ta) is a novel marker of myocardial repolarization heterogeneity which is related to adverse cardiovascular events. Our aim in this study was to investigate the effect of successful percutaneous coronary intervention (PCI) on frontal QRS-Ta in patients with chronic total occlusion (CTO).

MATERIALS AND METHODS

A total of 132 patients undergoing PCI for CTO were included in this study. Successful PCI of CTO segment was performed in 84 patients (group 2) while 48 who failed CTO were observed (group 1). Baseline demographic and clinical variables were evaluated and, 12-lead surface ECGs of all subjects were recorded before performing coronary angiography and 1-month and 6-month after the index procedure.

RESULTS

QRS-Ta values significantly decreased during follow-up visits compared to baseline values [92.5 (63.25-110.75); 85.0 (59.0-101.0); 80.0 (53.0-99.0), P < 0.001] in group 2 patients. Moreover, there was no significant difference in frontal QRS-Ta measurements in group 1 patients in their clinical 6-month follow-up [87.0 (48.25-103.0); 86.5 (46.0-101.75); 84.0 (49.0-103.75); P = 0.320]. First month frontal QRS-Ta values [92.5 (63.25-110.75); 85.0 (59.0-101.0), P = 0.002] and sixth month frontal QRS-Ta values [92.5 (63.25-110.75); 80.0 (53.0-99.0), P < 0.001] were lower than baseline values while sixth month values [85.0 (59.0-101.0); 80.0 (53.0-99.0), P = 0.002] was lower compared to first month values. Additionally, a decrease in frontal QRS-Ta was observed regardless of target vessel or Rentrop classification.

CONCLUSION

Successful percutaneous revascularization of CTO was effective in ventricular repolarization. Frontal QRS-Ta significantly decreased after successful PCI on CTO patients at a 6-month follow-up.

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.

Can heart function lost to disease be regenerated by therapeutic targeting of cardiac scar tissue?

Myocardial infarction results in scar tissue that cannot actively contribute to heart mechanical function and frequently causes lethal arrhythmias. The healing response after infarction involves inflammation, biochemical signaling, changes in cellular phenotype, activity, and organization, and alterations in electrical conduction due to variations in cell and tissue geometry and alterations in protein expression, organization, and function - particularly in membrane channels. The intensive research focus on regeneration of myocardial tissues has, as of yet, only met with modest success, with no near-term prospect of improving standard-of-care for patients with heart disease. An alternative concept for novel therapeutic approach is the rejuvenation of cardiac electrical and mechanical properties through the modification of scar tissue. Several peptide therapeutics, locally applied genetic therapies, or delivery of genetically modified cells have shown promise in improving the characteristics of the fibrous scar and post-myocardial infarction prognosis in experimental models. This review highlights several factors that contribute to arrhythmogenesis in scar formation and how these might be targeted to regenerate some of the electrical and mechanical function of the post-MI scar.

Left ventricular remodeling after late revascularization correlates with baseline viability

The ideal management of stable patients who present late after acute ST-elevation myocardial infarction (STEMI) is still a matter of conjecture. We hypothesized that the extent of improvement in left ventricular function after successful revascularization in this subset was related to the magnitude of viability in the infarct-related artery territory. However, few studies correlate the improvement of left ventricular function with the magnitude of residual viability in patients who undergo percutaneous coronary intervention in this setting. In 68 patients who presented later than 24 hours after a confirmed first STEMI, we performed resting, nitroglycerin-enhanced, technetium-99m sestamibi single-photon emission computed tomography-myocardial perfusion imaging (SPECT-MPI) before percutaneous coronary intervention, and again 6 months afterwards. Patients whose baseline viable myocardium in the infarct-related artery territory was more than 50%, 20% to 50%, and less than 20% were divided into Groups 1, 2, and 3 (mildly, moderately, and severely reduced viability, respectively). At follow-up, there was significant improvement in end-diastolic volume, end-systolic volume, and left ventricular ejection fraction in Groups 1 and 2, but not in Group 3. We conclude that even late revascularization of the infarct-related artery yields significant improvement in left ventricular remodeling. In patients with more than 20% viable myocardium in the infarct-related artery territory, the extent of improvement in left ventricular function depends upon the amount of viable myocardium present. The SPECT-MPI can be used as a guide for choosing patients for revascularization.

Impact of percutaneous coronary intervention on biomarker levels in patients in the subacute phase following myocardial infarction: the Occluded Artery Trial (OAT) biomarker ancillary study

BACKGROUND

The purpose of the Occluded Artery Trial (OAT) Biomarker substudy was to evaluate the impact of infarct related artery (IRA) revascularization on serial levels of N-terminal prohormone of brain natriuretic peptide (NT-proBNP) and dynamics of other biomarkers related to left ventricular remodeling, fibrosis and angiogenesis.

METHODS

Patients were eligible for OAT-Biomarker based on the main OAT criteria. Of 70 patients (age 60.8 ± 8.8, 25% women) enrolled in the substudy, 37 were randomized to percutaneous coronary intervention (PCI) and 33 to optimal medical therapy alone. Baseline serum samples were obtained prior to OAT randomization with follow up samples taken at one year. The primary outcome was percent change of NT-proBNP from baseline to 1 year. The secondary outcomes were respective changes of matrix metalloproteinases (MMP) 2 and 9, tissue inhibitor of matrix metalloproteinase 2 (TIMP-2), Vascular Endothelial Growth Factor (VEGF), and Galectin-3.

RESULTS

Paired (baseline and one-year) serum samples were obtained in 62 subjects. Baseline median NT-proBNP level was 944.8 (455.3, 1533) ng/L and decreased by 69% during follow-up (p < 0.0001). Baseline MMP-2 and TIMP-2 levels increased significantly from baseline to follow-up (p = 0.034, and p = 0.027 respectively), while MMP-9 level decreased from baseline (p = 0.038). Levels of VEGF and Galectin-3 remained stable at one year (p = NS for both). No impact of IRA revascularization on any biomarker dynamics were noted.

CONCLUSIONS

There were significant changes in measured biomarkers related to LV remodeling, stress, and fibrosis following MI between 0 and 12 month. Establishing infarct vessel patency utilizing stenting 24 hours-28 days post MI did not however influence the biomarkers' release.

Causes of death in early MI survivors with persistent infarct artery occlusion: results from the Occluded Artery Trial (OAT)

AIMS

OAT randomised patients with an occluded infarct artery three to 28 days after myocardial infarction (MI). The study demonstrated that PCI did not reduce the occurrence of the primary composite endpoint of death, re-MI, and New York Heart Association class IV heart failure in comparison with patients assigned to optimal medical therapy alone (MED). In view of prior literature in similar cohorts showing fewer sudden cardiac deaths and less left ventricular (LV) remodelling, but excess re-MI with PCI, causes of death were analysed in more detail.

METHODS AND RESULTS

Stepwise Cox regression was used to examine baseline variables associated with causes of death. The immediate and primary cause of death did not differ between 1,101 PCI and 1,100 MED patients. One-year cardiovascular death rates were 3.8% for the PCI group, and 3.7% for the MED group, and 0.9% per year for the next four years in both groups. Five of six cases of cardiac rupture occurred in patients undergoing PCI.

CONCLUSIONS

In stable post-MI patients with occlusion of the infarct-related artery, PCI did not change the rate or cause of death. The observation that the majority of cardiac ruptures occurred in patients undergoing PCI deserves further investigation.

Percutaneous coronary intervention in the Occluded Artery Trial: procedural success, hazard, and outcomes over 5 years

BACKGROUND

The Occluded Artery Trial (OAT) was a 2,201-patient randomized clinical trial comparing routine stent-based percutaneous coronary intervention (PCI) versus optimal medical therapy alone in stable myocardial infarction (MI) survivors with persistent infarct-related artery occlusion identified day 3 to 28 post MI. Intent-to-treat analysis showed no difference between strategies with respect to the incidence of new class IV congestive heart failure, MI, or death. The influence of PCI failure, procedural hazard, and crossover on trial results has not been reported.

METHODS

Study angiograms were analyzed and adjudicated centrally. Factors associated with PCI failure were examined. Time-to-event analysis using the OAT primary outcome was performed by PCI success status. Landmark analysis (up to and beyond 30 days) partitioned early hazard versus late outcome according to treatment received.

RESULTS

Percutaneous coronary intervention was adjudicated successful in >87%. Percutaneous coronary intervention failure rates were similar in US and non-US sites, and did not significantly influence outcome at 60 months (hazard ratio for success vs fail 0.79, 99% CI 0.45-1.40, P = .29). Partitioning of early procedural hazard revealed no late benefit for PCI (hazard ratio for PCI success vs medical therapy alone 1.06, 99% CI 0.75-1.50, P = .66).

CONCLUSIONS

Percutaneous coronary intervention failure and complication rates in the OAT were low. Neither PCI failure nor early procedural hazard substantively influenced the primary trial results.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

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

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

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

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

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

Systematic review of fibrinolytic-facilitated percutaneous coronary intervention: potential benefits and future challenges

BACKGROUND

Facilitated percutaneous coronary intervention (PCI) is defined as the administration of fibrinolytic therapy and/or glycoprotein (GP) IIb/IIIa inhibitors to minimize myocardial ischemia time while waiting for PCI. A pooled meta-analysis suggested that facilitated PCI was associated with higher rates of mortality and morbidity compared with nonfacilitated PCI.

OBJECTIVE

The heterogeneous and complex trials of facilitated PCI were systematically reviewed to identify where this strategy may be beneficial and deserving of further research.

METHODS

MEDLINE, EMBASE, the Cochrane database, the Internet and conference proceedings were searched to obtain relevant trials. Human studies that randomly assigned patients to fibrinolytic-facilitated PCI (administration of fibrinolytic therapy alone or in combination with GP IIb/IIIa inhibitors before angiography) versus nonfacilitated PCI were included.

RESULTS

Nine trials encompassing 3836 patients were reviewed. The facilitated PCI strategy was fibrinolytic therapy alone in seven trials and half-dose fibrinolytic therapy plus GP IIb/IIIa inhibitors in two trials. In patients who had fibrinolysis less than 2 h after symptom onset (mainly in the prehospital setting) and/or slightly delayed PCI 3 h to 24 h after fibrinolysis, facilitated PCI was associated with the greatest Thrombolysis In Myocardial Infarction (TIMI) grade 3 flow and a trend toward reduced mortality. Overall, facilitated PCI was associated with increased intracranial hemorrhage and reinfarction. Combining half-dose fibrinolytic therapy and GP IIb/IIIa inhibitors reduced reinfarction but increased major bleeding.

CONCLUSIONS

Facilitated PCI cannot be recommended outside of experimental protocols at this time. Further research should focus on selecting patients with higher benefit-to-risk ratios and performing prehospital fibrinolysis with optimal antiplatelet or antithrombin therapy, as well as slightly delayed PCI in patients who are stable or geographically removed from PCI facilities.

Electrophysiological effects of late percutaneous coronary intervention for infarct-related coronary artery occlusion: the Occluded Artery Trial-Electrophysiological Mechanisms (OAT-EP)

BACKGROUND

The Occluded Artery Trial-Electrophysiological Mechanisms (OAT-EP) tested the hypothesis that opening a persistently occluded infarct-related artery by percutaneous coronary intervention and stenting (PCI) after the acute phase of myocardial infarction compared with optimal medical therapy alone reduces markers of vulnerability to ventricular arrhythmias.

METHODS AND RESULTS

Between April 2003 and December 2005, 300 patients with an occluded native infarct-related artery 3 to 28 days (median, 12 days) after myocardial infarction were randomized to PCI or optimal medical therapy. Ten-minute digital Holter recordings were obtained before randomization, at 30 days, and at 1 year. The primary end point was the change in alpha1, a nonlinear heart rate variability parameter, between baseline and 1 year. Major secondary end points were the changes in the filtered QRS duration on the signal-averaged ECG and variability in T-wave morphology (T-wave variability) between baseline and 1 year. There were no significant differences in the changes in alpha1 (-0.04; 95% CI, -0.12 to 0.04), filtered QRS (2.2 ms; 95% CI, -1.4 to 5.9 ms), or T-wave variability (3.0 microV; 95% CI, -4.8 to 10.7 microV) between the PCI and medical therapy groups (medical therapy change minus PCI change). Multivariable analysis revealed that the results were unchanged after adjustment for baseline clinical variables and medication treatments during the Holter recordings.

CONCLUSIONS

PCI with stenting of a persistently occluded infarct-related artery during the subacute phase after myocardial infarction compared with medical therapy alone had no significant effect on changes in heart rate variability, the time-domain signal-averaged ECG, or T-wave variability during the first year after myocardial infarction. These findings are consistent with the lack of clinical benefit, including no reduction in sudden death, with PCI for stable patients with persistently occluded infarct-related arteries after myocardial infarction in the main OAT.

Lack of benefit from percutaneous intervention of persistently occluded infarct arteries after the acute phase of myocardial infarction is time independent: insights from Occluded Artery Trial

AIMS

The Occluded Artery Trial (OAT) (n = 2201) showed no benefit for routine percutaneous intervention (PCI) (n = 1101) over medical therapy (MED) (n = 1100) on the combined endpoint of death, myocardial infarction (MI), and class IV heart failure (congestive heart failure) in stable post-MI patients with late occluded infarct-related arteries (IRAs). We evaluated the potential for selective benefit with PCI over MED for patients enrolled early in OAT.

METHODS AND RESULTS

We explored outcomes with PCI over MED in patients randomized to the </=3 calendar days and </=7 calendar days post-MI time windows. Earlier, times to randomization in OAT were associated with higher rates of the combined endpoint (adjusted HR 1.04/day: 99% CI 1.01-1.06; P < 0.001). The 48-month event rates for </=3 days, </=7 days post-MI enrolled patients were similar for PCI vs. MED for the combined and individual endpoints. There was no interaction between time to randomization defined as a continuous (P = 0.55) or categorical variable with a cut-point of 3 days (P = 0.98) or 7 days (P = 0.64) post-MI and treatment effect.

CONCLUSION

Consistent with overall OAT findings, patients enrolled in the </=3 day and </=7 day post-MI time windows derived no benefit with PCI over MED with no interaction between time to randomization and treatment effect. Our findings do not support routine PCI of the occluded IRA in trial-eligible patients even in the earliest 24-72 h time window.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Late Intervention on an Occluded Infarct-Related Artery: A Meta-analysis of the Randomized Controlled Trials

Context

Late intervention to open an occluded infarct-related artery (IRA) after initial acute myocardial infarction was postulated to lead to clinical benefit.

Objective

To conduct a meta-analysis of the randomized trials.

Study Selection

Eligibility criteria were: 1) randomized trials comparing percutaneous coronary intervention (PCI) in a totally occluded artery (TIMI flow 0-1) versus medical therapy, 2) in stable post myocardial infarction (MI) patients without spontaneous or low level exercise induced ischemia, 3) trials with a time from the onset of symptoms to randomization >24 hours, but <6 weeks, and 4) trials reporting mortality and recurrent MI as an endpoint. Of 961 citations reviewed, 3 disagreements were easily resolved by discussion and 6 trials were selected for inclusion.

Data Synthesis

The primary endpoint was the composite of recurrent MI or death. The secondary endpoints were the development of heart failure or recurrent myocardial infarction. In a meta-analysis of the 6 trials, which included 2642 patients, late intervention of an IRA had a RR of death or recurrent MI of 1.12 (95% CI 0.91-1.38). Data regarding the development of heart failure was available for 4 trials. In a meta-analysis of these 4 trials, which included 2527 patients, late intervention of an IRA had a RR of 0.79 (95% CI 0.58-1.08). Data regarding the occurrence of recurrent MI was available for 5 trials. In a meta-analysis of these 5 trials, which included 2598 patients, late intervention of an IRA had a RR of 1.28 (95% CI 0.91-1.79).

Conclusions

Our meta-analysis of the currently available randomized data addressing late intervention of an occluded IRA failed to reveal clinical benefit with regard to the clinical endpoints of death, heart failure or reinfarction. The trend towards an increase in reinfarction among the PCI treated patients suggested by the Open Artery Trial (OAT) investigators persisted, but did not achieve statistical significance.

Multidetector row computed tomography can identify and characterize the occlusive culprit lesions in patients early (within 24 hours) after acute myocardial infarction

BACKGROUND

The reliable noninvasive assessment of occluded disrupted plaques and thromboses in culprit vessels could constitute an important step forward in risk stratification of patients early after acute myocardial infarction (AMI). However, noninvasive identification of patency of culprit vessels remains a challenging issue. This prospective study was designed to identify the occluded culprit vessels by multidetector row computed tomography (MDCT) and to compare the stenotic and occlusive culprit lesions by MDCT in patients early (within 24 hours) after AMI.

METHODS

We enrolled 62 patients with first Q-wave AMI (54 males). Multidetector row computed tomography was performed 16.5 +/- 7.1 hours after the onset of chest pain without any complication. Coronary angiography was done within 6 hours after MDCT. Patients were divided into 2 groups according to angiographic findings: stenotic group (35 patients) and occluded group (27 patients). The following MDCT data were collected: luminal artery stenosis, remodeling index, plaque burden, and lesion attenuation.

RESULTS

Compared to coronary angiography, MDCT detected occluded culprit vessels with sensitivity, specificity, negative predict value, and positive predict value of 92.6%, 88.6%, 93.9%, and 86.2%, respectively. Compared with the stenotic group, culprit lesions in the occlusive group had significantly longer length (18.9 +/- 9.7 vs 11.9 +/- 6.2 mm; P = .024) and higher MDCT lesion attenuation (38.8 +/- 15.6 vs 29.2 +/- 12.9 Hounsfield unit; P = .008). Multidetector row computed tomography attenuation was negatively correlated with thrombolysis in myocardial infarction flow (Spearman rho = -0.46; P < .001).

CONCLUSIONS

Multidetector row computed tomography could accurately and safely identify occluded culprit lesions in patients early after AMI, providing important information to aid in risk stratification.

Clinical trials update from the American Heart Association 2006: OAT, SALT 1 and 2, MAGIC, ABCD, PABA-CHF, IMPROVE-CHF, and percutaneous mitral annuloplasty

This article provides information and a commentary on trials presented at the American Heart Association meeting held in November 2006, relevant to the pathophysiology, prevention and treatment of heart failure. All reports should be considered as preliminary data, as analyses may change in the final publication. The OAT study failed to show a benefit of PCI over optimal medical therapy in patients with persistent total occlusion of the infarct related artery following a myocardial infarction. In SALT 1 and 2, tolvaptan was found to correct hyponatraemia of various aetiologies; however, whether this has an impact on heart failure prognosis requires further evaluation. A placebo controlled study of myocardial implantation of skeletal myoblasts in patients with moderate to severe LVSD (MAGIC) showed equivocal/uncertain effects, long term follow-up data are awaited. The ABCD study which compared the ability of an invasive and a non-invasive test to identify patients at risk of arrhythmic events prior to ICD implantation, suggested that the two strategies were comparable, although the practical value of either test remains uncertain and the study had many major flaws. The PABA-CHF study hinted that pulmonary vein antrum isolation might be more effective than AV node ablation with bi-ventricular pacing for the treatment of patients with heart failure in atrial fibrillation. In IMPROVE-CHF, an NT-pro BNP guided treatment strategy was found to reduce the cost of managing patients with acute breathlessness.

Effect of percutaneous coronary intervention of nonacute total coronary artery occlusions on QT dispersion

BACKGROUND

Myocardial ischemia is one of several potential causes of increased QT dispersion (QTd) in patients with nonacute total coronary artery occlusions (TCOs). We sought to assess the effect of percutaneous revascularization (PCI) of TCO on QTd and the relationship between QTd and long-term vessel patency.

METHODS

Seventy patients enrolled in the TOSCA were analyzed. Patients were undergoing PCI of a TCO > 72 hours' duration. Two independent reviewers measured QTd from electrocardiograms done immediately before PCI (PRE), 12 to 18 hours after PCI (POST), and then at 6 months (6M). Follow-up angiography was performed at 6 months.

RESULTS

Mean QTd decreased from PRE (77 +/- 29 milliseconds) to POST (66 +/- 26 milliseconds, P < .001) and 6M (65 +/- 25 milliseconds, P < .001). Patients with the same or longer QTd at 6 months compared with POST (POST < or = 6M) had significantly higher risk of failed target-vessel patency (odds ratio 10.3, 95% CI 1.24-84.8) than patients with QTd reduction at 6M versus POST values.

CONCLUSION

Revascularization of TCO resulted in a decrease in QTd, which was sustained at 6M. This suggests that PCI to a TCO has a beneficial effect on stabilization of the underlying ischemic substrate. Furthermore, absence of QTd reduction at 6M versus POST was associated with increased risk of failed target-vessel patency.

Design and methodology of the Occluded Artery Trial (OAT)

Experimental and clinical studies have suggested that late opening of an infarct-related artery (IRA) after myocardial infarction (MI) could improve clinical outcome. However, the suggestive observational data are limited by selection biases. Indeed, most small randomized studies have not demonstrated benefit. Thus, there is no recommendation for routine late opening of the IRA in current national guidelines for management of stable post-MI patients. The OAT is designed to test the hypothesis that opening a totally occluded IRA 3 to 28 days after MI in high-risk asymptomatic patients will improve clinical outcome and be cost-effective. The primary end point is the first occurrence of recurrent MI, hospitalization/treatment of New York Heart Association class IV congestive heart failure, or death. Trial background, design, and preliminary baseline characteristics of 2027 randomized patients are presented. Eligible patients are randomly assigned in equal proportions to optimal evidence-based medical care or optimal care plus late opening of the IRA using percutaneous coronary intervention of the occluded IRA. Treatment groups will be compared using intent-to-treat analysis. The results of OAT should have broad clinical impact by defining an evidence-based approach to the asymptomatic, high-risk, post-MI patient with an occluded IRA. If the efficacy and cost-effectiveness of percutaneous coronary intervention are established, then a policy of routinely seeking and opening persistently occluded IRAs could be advocated. If not, this strategy should be avoided in this large subgroup of post-MI patients.

Infarct zone viability influences ventricular remodelling after late recanalisation of an occluded infarct related artery

OBJECTIVE

To investigate the influence of infarct zone viability on remodelling after late recanalisation of an occluded infarct related artery.

METHODS

A subgroup of 26 volunteers from TOAT (the open artery trial) underwent dobutamine stress cardiovascular magnetic resonance at baseline to assess the amount of viable myocardium present with follow up to assess remodelling at one year. TOAT studied patients with left ventricular dysfunction after anterior myocardial infarction (MI) associated with isolated proximal occlusion of the left anterior descending coronary artery with randomisation to percutaneous coronary intervention (PCI) with stent at 3.6 weeks after MI (PCI group) or to medical treatment alone (medical group).

RESULTS

In the PCI group there was a significant relation between the number of viable segments within the infarct zone and improvement in end systolic volume index (-7.7 ml/m2, p = 0.02) and increased ejection fraction (4.1%, p = 0.03). The relation between viability and improvements in end diastolic volume index (-8.8 ml/m2, p = 0.08) and mass index (-6.3 g/m2, p = 0.01) did not reach significance (p = 0.27 and p = 0.8, respectively). In the medical group, there was no significant relation between the number of viable segments in the infarct zone and the subsequent changes in end diastolic (p = 0.84) and end systolic volume indices (p = 0.34), ejection fraction (p = 0.1), and mass index (p = 0.24).

CONCLUSION

The extent of viable myocardium in the infarct zone is related to improvements in left ventricular remodelling in patients who undergo late recanalisation of an occluded infarct related artery.

Angiography and revascularization in patients with heart failure following fibrinolytic therapy for ST-elevation acute myocardial infarction

We evaluated the use of coronary angiography and clinical outcomes among patients who had heart failure and were enrolled in the Intravenous Novel Plasminogen Activator (NPA) for the Treatment of Infarcting Myocardium Early study, a large international trial of fibrinolytic therapy in ST-elevation myocardial infarction.

The ‘Open-Artery Hypothesis’: New Clinical and Pathophysiologic Insights

The open-artery hypothesis states that myocardial reperfusion, even if late for myocardial salvage, provides benefits and prevents adverse cardiac remodeling. While observational data in humans regarding the deleterious impact of a permanent infarct-related artery occlusion and the benefits of spontaneous reperfusion are quite consistent, the reports regarding late revascularization are inconclusive in order to prove such a hypothesis. The observational studies tend to have selection biases, while randomized trials to date are too small to be conclusive. Moreover, the pathophysiological mechanisms underlying presumed benefits of reperfusion are still unclear. However, although the open-artery hypothesis remains unproven, the current evidence suggesting benefits calls for additional studies. Limitations of ischemic left ventricular dilatation and myopathy could markedly reduce cardiovascular morbidity and mortality after acute myocardial infarction.

Randomized comparison of percutaneous transluminal coronary angioplasty and medical therapy in stable survivors of acute myocardial infarction with single vessel disease: a study of the Arbeitsgemeinschaft Leitende Kardiologische Krankenhausärzte

BACKGROUND

Percutaneous transluminal coronary angioplasty of the infarct-related artery in stable survivors of acute myocardial infarction is often performed, even in patients without any symptoms or residual ischemia. Despite the lack of randomized studies, it is widely believed that this intervention will improve the clinical outcome of these patients.

METHODS AND RESULTS

Three hundred patients with single vessel disease of the infarct vessel and no or minor angina pectoris in the subacute phase (1 to 6 weeks) after an acute myocardial infarction were randomized to angioplasty (n=149) or medical therapy (n=151). Primary end point was the survival free of reinfarction, (re)intervention, coronary artery bypass surgery, or readmission for severe angina pectoris at 1 year. The event-free survival at 1 year was 82% in the medical group and 90% in the angioplasty group (P=0.06). This difference was mainly driven by the difference in the need for (re)interventions (20 versus 8, P=0.03). At long-term follow-up (mean, 56 months), survival was 89% and 96% (P=0.02). Survival free of reinfarction, (re)intervention, or coronary artery bypass surgery was 66% and 80% in the medically and interventionally treated patients, respectively (P=0.05). The use of nitrates was significantly lower in the angioplasty group, both at 1 year (38% versus 67%, P=0.001) and at long-term follow-up (36% versus 55%, P=0.006).

CONCLUSIONS

Percutaneous revascularization of the infarct-related coronary artery in stable patients with single vessel disease improves clinical outcome at long-term follow-up and reduces the use of nitrates. The results of our study should be reproduced in a confirmatory study with a larger sample size before percutaneous coronary intervention in this low-risk patient subgroup, after myocardial infarction can be recommended as routine treatment in clinical practice.

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

OBJECTIVE

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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