Utility of left bundle branch block as a diagnostic criterion for acute myocardial infarction

The clinical utility of new or "presumably new" left bundle branch block (LBBB) as an electrocardiographic criterion equivalent to ST-segment elevation myocardial infarction in contemporary practice is not well established. The aim of this study was to investigate the hypothesis that new or presumably new LBBB in symptomatic patients frequently leads to an overdiagnosis of acute myocardial infarction (AMI). A retrospective analysis of data from consecutive patients in the Mayo Clinic's ST-segment elevation myocardial infarction network from July 2004 to August 2009 was conducted among 892 patients, 36 (4%) of whom had new LBBB. The frequency, clinical characteristics, serum troponin levels, coronary angiographic findings, and outcomes of patients with new LBBB suspected of having AMI were evaluated. Compared with patients without LBBB (n = 856), those with new LBBB were older (64.5 vs 72.9 years, p < 0.001), had higher Thrombolysis In Myocardial Infarction (TIMI) risk scores (22.7 vs 31.0, p < 0.005), were less likely to undergo primary percutaneous coronary intervention (86% vs 22%, p < 0.001), and had longer door-to-balloon times. Only 14 patients (39%) had final diagnoses of acute coronary syndromes, of which 12 were AMI, while 13 (36%) had cardiac diagnoses other than acute coronary syndrome and 9 (25%) had noncardiac diagnoses. Of the patients with AMI, 5 had occluded culprit arteries, of which 2 involved the left anterior descending coronary artery. A Sgarbossa score ≥ 5 had low sensitivity (14%) but 100% specificity in diagnosing AMI in the presence of new LBBB. In conclusion, new or presumably new LBBB in patients suspected of having AMI identifies a high-risk subgroup, but only a small number have AMI. Two thirds of these patients are discharged from the hospital with alternative diagnoses. The Sgarbossa criteria appear to have limited utility in clinical practice because of their low sensitivity.     

Evolving considerations in the management of patients with left bundle branch block and suspected myocardial infarction

Patients with a suspected acute coronary syndrome and left bundle branch block (LBBB) present a unique diagnostic and therapeutic challenge to the clinician. Although current guidelines recommend that patients with new or presumed new LBBB undergo early reperfusion therapy, data suggest that only a minority of patients with LBBB are ultimately diagnosed with acute myocardial infarction, regardless of LBBB chronicity, and that a significant proportion of patients will not have an occluded culprit artery at cardiac catheterization. The current treatment approach exposes a significant proportion of patients to the risks of fibrinolytic therapy without the likelihood of significant benefit and leads to increased rates of false-positive cardiac catheterization laboratory activation, unnecessary risks, and costs. Therefore, alternative strategies to those for patients with ST-segment elevation myocardial infarction are needed to guide selection of appropriate patients with a suspected acute coronary syndrome and LBBB for urgent reperfusion therapy. In this article, we describe the evolving epidemiology of LBBB in acute coronary syndromes and discuss controversies related to current clinical practice. We propose a more judicious diagnostic approach among clinically stable patients with LBBB who do not have electrocardiographic findings highly specific for ST-segment elevation myocardial infarction.     

Virtual histology-intravascular ultrasound assessment of lesion coverage after angiographically-guided stent implantation in patients with ST Elevation myocardial infarction undergoing primary percutaneous coronary intervention

An occlusion or severe stenosis (angiographic culprit lesion) of the infarct-related artery is frequently located at the site of the maximum thrombus burden, whereas the origin of the plaque rupture (the true culprit) can be situated proximal or distal to it. The aim of this study was to examine stent coverage of true culprit lesions in 20 patients who underwent primary percutaneous coronary intervention and had Thrombolysis In Myocardial Infarction (TIMI) grade 3 flow restored in the infarct-related artery by angiographically guided direct stenting. Images of lesions were obtained using virtual histology-intravascular ultrasound before and after intervention (blinded to the operator). Plaque rupture sites were identified by intravascular ultrasound in 12 lesions (60%), 11 proximal and 1 distal to the minimum luminal area (MLA). Maximum necrotic core sites were found proximal to the MLA in 16 lesions, at the MLA in 3 lesions, and distal to the MLA in 1 lesion. Plaque rupture sites were fully covered by stents in 11 lesions. Virtual histology-intravascular ultrasound-derived thin-cap fibroatheroma longitudinal geographic misses were found in 10 lesions, 7 in the proximal reference segment and in 3 patients in the proximal and distal reference segments. In conclusion, in about 50% of patients who undergo primary percutaneous coronary intervention for ST-segment elevation myocardial infarction with optimal angiographic results, the stent does not fully cover the maximum necrotic core site related to the culprit lesion.     

New method of intracoronary adenosine injection to prevent microvascular reperfusion injury in patients with acute myocardial infarction undergoing percutaneous coronary intervention

The aim of our study was to examine the role of a new, simple protocol of intracoronary adenosine administration performed during primary angioplasty on the immediate angiographic results and clinical course. A prospective, single-center, randomized, placebo-controlled trial of 70 consecutive patients (64 ± 14 years, 54 men) with acute myocardial infarction with ST-segment elevation undergoing primary percutaneous coronary intervention (PCI) was conducted. Patients were randomized to 2 groups. Group 1 (n = 35) received intracoronary adenosine (1 to 2 mg) with a hand injection through the guiding catheter 2 times: immediately after crossing the lesion of the infarct-related artery with guidewire and then after the first balloon inflation. Group 2 (n = 35) received placebo. The baseline clinical and angiographic characteristics of the 2 groups were similar. Percutaneous coronary intervention resulted in Thrombolysis In Myocardial Infarction grade 3 flow after PCI in 32 patients (91.4%) in the adenosine group and 27 patients (77.1%) in the placebo group (p = 0.059). Myocardial blush grade 3 was observed at the end of PCI in 23 patients (65.7%) in the adenosine group and 13 (37.1%) in the placebo group (p < 0.05). Resolution of ST-segment elevation (> 50%) was more frequently observed in the adenosine than in the placebo group: 27 (77%) versus 15 (43%), respectively (p < 0.01). In conclusion, intracoronary adenosine administration improved the angiographic and electrocardiographic results in patients with acute myocardial infarction with ST-segment elevation undergoing PCI. Adenosine administration seemed to be associated with a more favorable clinical course.     

Clinical outcomes of acute myocardial infarction with occluded left circumflex artery

Left circumflex artery (LCX) related acute myocardial infarction (AMI) has been known to be under diagnosed with 12-lead electrocardiogram (ECG). However, there were only a few studies that have focused on the clinical characteristics of LCX-related AMI. We studied the clinical characteristics and hospital mortality in patients with angiographically confirmed LCX-related AMI. A total of 2281 AMI patients with single acutely occluded culprit vessel in coronary angiography (pre-Thrombolysis In Myocardial Infarction flow: 0) were enrolled in the Korea Acute Myocardial Infarction Registry (KAMIR) from November 2005 to January 2008. These patients were divided into three groups according to culprit vessel [left anterior descending artery (LAD), right coronary artery (RCA), and LCX]. This study showed the patients with LCX-related AMI were less likely to present with ST elevation in ECG (46.3%, 87.0%, and 82.3%; p<0.001) and primary percutaneous coronary intervention (PCI) (43.4%, 78.9%, and 74.5%; p<0.001) and door to balloon time <90 min (31.3%, 52.8%, and 51.0%; p<0.001), compared with LAD and RCA. However, no statistical difference was found in hospital mortality among the three groups. Multivariate analysis showed primary PCI decreased the hospital mortality in patients with occluded coronary artery. In conclusion, AMI patients with an occluded LCX presented with less ST elevation and primary PCI. These results suggest that clinical physicians should be careful with patients presenting with chest pain but apparently normal ECG and must rule out LCX occlusion.     

Comparison of angiographic and other findings and mortality in non-ST-segment elevation versus ST-segment elevation myocardial infarction in patients undergoing early invasive intervention

We sought to compare the angiographic findings and mortality in patients with non-ST-segment elevation (NSTEMI) versus ST-segment elevation myocardial infarction (STEMI) undergoing early invasive intervention. Of 11,872 patients enrolled in the Korean Acute Myocardial Infarction Registry from November 2005 to January 2008, we studied patients with NSTEMI undergoing early invasive intervention (n = 1,486) and those with STEMI undergoing primary percutaneous coronary intervention (n = 4,392). Multivessel coronary disease, baseline Thrombolysis In Myocardial Infarction (TIMI) flow grade 3, and the left circumflex artery as a culprit lesion occurred more frequently in patients with NSTEMI than in those with STEMI. Those with NSTEMI had a significantly lower mortality rate than those with STEMI during a median follow-up of about 12 months (3.8% vs 6.7%, p <0.001). In the patients with NSTEMI, the independent predictors of mortality included postprocedural TIMI flow grade 0 to 2 (hazard ratio [HR] 3.07, 95% confidence interval [CI] 1.01 to 9.29, p = 0.047) and multivessel coronary disease (HR 3.83, 95% CI 1.36 to 10.81, p = 0.010) but not baseline TIMI flow or infarct location. However, baseline TIMI flow grade 0 to 2 (HR 1.56, 95% CI 1.03 to 2.36, p = 0.035), anterior infarction (HR 1.69, 95% CI 1.28 to 2.23, p <0.001), multivessel coronary disease (HR 1.45, 95% CI 1.10 to 1.91, p = 0.008), and postprocedural TIMI flow grade 0 to 2 (HR 2.00, 95% CI 1.42 to 2.82, p <0.001) were all independent predictors of mortality in the patients with STEMI. In conclusion, the angiographic findings in patients from NSTEMI differ from those in patients with STEMI. Postprocedural TIMI flow and multivessel coronary disease were independent predictors of mortality in patients with NSTEMI undergoing early invasive intervention.     

Association of culprit lesion calcium with angiographic and clinical outcomes in patients with ST-elevation myocardial infarction treated with fibrinolytic therapy

Coronary artery calcium has been associated with a greater extent of angiographically significant coronary artery stenoses, but the angiographic and clinical outcomes associated with culprit lesion calcium (CLC) have not been fully evaluated, particularly in the stetting of ST-elevation myocardial infarction. We hypothesized that CLC would be associated with adverse angiographic and clinical outcomes in patients who had ST-elevation myocardial infarction. Data were evaluated in 3,292 patients from 6 trials of fibrinolytic therapy for ST-elevation myocardial infarction; 243 culprit lesions (7.4%) were calcified. CLC was associated with advanced age, history of hypertension, previous coronary artery disease, greater extent of disease, angiographically evident residual thrombus, smaller minimum luminal diameter, and larger percent residual stenosis after fibrinolytic therapy. CLC was associated with lower rates of arterial patency after fibrinolytic therapy (63.3% vs 81.3% p <0.001), lower rates of Thrombolysis In Myocardial Infarction grade 3 flow (41.5% vs 57.2%, p <0.001), and higher (slower) Thrombolysis In Myocardial Infarction frame counts (52 vs 36 frames, p <0.0001, multivariate p = 0.02). CLC was also associated with increased 30-day mortality rates (6.2% vs 3.4%, p = 0.028) and 30-day rates of death, myocardial infarction, or congestive heart failure (16.5% vs 8.9%, p <0.001) and independently associated with 30-day rates of death, myocardial infarction, or congestive heart failure (odds ratio 1.6, p = 0.016) after multivariate adjustment for baseline clinical and lesion characteristics, epicardial flow, and performance of rescue/adjunctive percutaneous coronary intervention. In a model restricted to patients who had successful restoration of epicardial patency after fibrinolytic therapy, CLC was independently associated with 30-day mortality (odds ratio 2.2, p = 0.045). CLC is independently associated with indexes of poorer epicardial flow and a higher incidence of adverse clinical outcomes after fibrinolytic administration in patients who have ST-elevation myocardial infarction.     

Revisiting the culprit lesion in non-Q-wave myocardial infarction. Results from the VANQWISH trial angiographic core laboratory

OBJECTIVE: We sought to determine the underlying coronary anatomy and characterize the culprit lesion after non-Q-wave myocardial infarction (NQWMI). BACKGROUND: Although the culprit lesion and infarct-related artery often are easily identified with coronary angiography after Q-wave MI, the culprit lesion after NQWMI has not been well characterized. Small retrospective studies have suggested that the absence of Q-waves on an electrocardiogram is due to incomplete occlusion of the infarct-related artery. METHODS: Coronary angiograms from 350 patients randomized to the early invasive strategy in the Veterans Affairs Non-Q-Wave Infarction Strategies in-Hospital (VANQWISH) trial were systematically analyzed in an angiographic core laboratory. A consensus panel identified the culprit lesion and the infarct-related artery using prespecified criteria for complex lesion morphology and acute versus chronic occlusions. Severity of angiographic disease and left ventricular function also were analyzed. Patients with a single identified culprit lesion were compared with those who had multiple apparent culprits and those without an identifiable culprit lesion. RESULTS: A single culprit lesion was identified in only 49% of patients undergoing early angiography after NQWMI. The majority of patients either had no identifiable culprit (37%) or multiple apparent culprit lesions (14%). A single incomplete occlusion of the infarct-related artery was found in only 36% of patients, and an isolated acute occlusion of the infarct-related artery occurred in 13%. Patients without an identifiable culprit lesion had severe coronary disease (obstructive coronary artery disease [CAD] in 84%) but no complex lesion morphology. There was no difference in angiographic severity of disease comparing patients with and without identifiable culprit lesions. Patients with a single incomplete occlusion of the infarct-related artery were more likely to undergo percutaneous transluminal coronary angioplasty than other patients, whereas patients with multiple culprit lesions were more frequently treated with coronary artery bypass grafting. CONCLUSIONS: Coronary angiography early after NQWMI frequently identifies severe obstructive CAD, but a single identifiable culprit lesion was identified in <50% of patients. Multiple culprit lesions were seen in 14% of patients. An angiographic culprit lesion could not be identified in more than one-third of patients undergoing coronary angiography as part of an invasive strategy.     

Association of lesion complexity following fibrinolytic administration with mortality in ST-elevation myocardial infarction

Greater lesion complexity, according to the American College of Cardiology and American Heart Association, has been associated with decreased success rates of percutaneous coronary intervention. We hypothesized that greater lesion complexity after fibrinolytic administration for ST-segment elevation myocardial infarction would similarly be associated with increased mortality and other adverse events at 30 days. We studies 2,605 patients from the Thrombolysis In Myocardial Infarction 10B and 14, Integrilin and Tenecteplase in Acute Myocardial Infarction, ENTIRE, and FASTER studies. For all studies, angiographic outcomes were assessed immediately after fibrinolytic administration and clinical outcomes were assessed at 30 days. Greater lesion complexity was associated with poorer epicardial flow and decreased myocardial perfusion at 60 minutes and after percutaneous coronary intervention and with a higher risk of shock and mortality within 30 days. In a multivariate model, type C lesion complexity remained associated with an increased 30-day mortality rate.     

Current Smoking and Prognosis After Acute ST-Segment Elevation Myocardial Infarction: New Pathophysiological Insights

ObjectivesThe aim of this study was to mechanistically investigate associations among cigarette smoking, microvascular pathology, and longer term health outcomes in patients with acute ST-segment elevation myocardial infarction (MI).BackgroundThe pathophysiology of myocardial reperfusion injury and prognosis in smokers with acute ST-segment elevation MI is incompletely understood.MethodsPatients were prospectively enrolled during emergency percutaneous coronary intervention. Microvascular function in the culprit artery was measured invasively. Contrast-enhanced magnetic resonance imaging (1.5-T) was performed 2 days and 6 months post-MI. Infarct size and microvascular obstruction were assessed using late gadolinium enhancement imaging. Myocardial hemorrhage was assessed with T2* mapping. Pre-specified endpoints included: 1) all-cause death or first heart failure hospitalization; and 2) cardiac death, nonfatal MI, or urgent coronary revascularization (major adverse cardiovascular events). Binary logistic regression (odds ratio [OR] with 95% confidence interval [CI]) with smoking status was used.ResultsIn total, 324 patients with ST-segment elevation MI were enrolled (mean age 59 years, 73% men, 60% current smokers). Current smokers were younger (age 55 ± 11 years vs. 65 ± 10 years, p < 0.001), with fewer patients with hypertension (52 ± 27% vs. 53 ± 41%, p = 0.007). Smokers had better TIMI (Thrombolysis In Myocardial Infarction) flow grade (≥2 vs. ≤1, p = 0.024) and ST-segment resolution (none vs. partial vs. complete, p = 0.010) post–percutaneous coronary intervention. On day 1, smokers had higher circulating C-reactive protein, neutrophil, and monocyte levels. Two days post-MI, smoking independently predicted infarct zone hemorrhage (OR: 2.76; 95% CI: 1.42 to 5.37; p = 0.003). After a median follow-up period of 4 years, smoking independently predicted all-cause death or heart failure events (OR: 2.20; 95% CI: 1.07 to 4.54) and major adverse cardiovascular events (OR: 2.79; 95% CI: 2.30 to 5.99).ConclusionsSmoking is associated with enhanced inflammation acutely, infarct-zone hemorrhage subsequently, and longer term adverse cardiac outcomes. Inflammation and irreversible myocardial hemorrhage post-MI represent mechanistic drivers for adverse long-term prognosis in smokers. (Detection and Significance of Heart Injury in ST Elevation Myocardial Infarction. [BHF MR-MI]; NCT02072850)     

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.     

Comparison of ST-segment resolution with combined fibrinolytic and glycoprotein IIb/IIIa inhibitor therapy versus fibrinolytic alone (data from four clinical trials)

We compared combination fibrinolytic plus glycoprotein IIb/IIIa inhibitor therapy with stand-alone fibrinolysis with respect to speed and stability of reperfusion in patients who had acute ST-segment elevation myocardial infarction; data were obtained from 654 patients in 4 trials (Integrilin to Manage Platelet Aggregation to Combat Thrombosis in Acute Myocardial Infarction, Platelet Aggregation Receptor Antagonist Dose Investigation and Reperfusion Gain in Myocardial Infarction, Integrilin and Tenecteplase in Acute Myocardial Infarction, and the Fifth Global Use of Strategies to Open Occluded Coronary Arteries) that compared thrombolytics plus lamifiban, eptifibatide, or abciximab with standard thrombolysis. We found significantly faster and more stable ST-segment recovery with combination therapy starting at 60 minutes (56.7% vs 48.0% with >/=50% ST-segment resolution, p = 0.03) and sustained over 180 minutes after drug administration; this transient benefit may suggest a time frame when more optimal percutaneous coronary intervention can be performed.     

ST-segment deviation in lead aVR on admission is not associated with left ventricular function at predischarge in first anterior wall ST-segment elevation acute myocardial infarction

Previous studies have shown that the analysis of ST-segment deviation in lead aVR on admission provides useful information on angiographic coronary anatomy and risk stratification in acute coronary syndromes. However, the association between ST-segment deviation in lead aVR on admission and left ventricular (LV) function has not been fully investigated in anterior wall acute ST-segment elevation myocardial infarction. In this study, 237 patients with first anterior wall acute ST-segment elevation myocardial infarction were examined. The patients were divided into the following 3 groups according to ST-segment deviation in lead aVR on admission: 85 with ST-segment elevation ≥0.5 mm (group A), 106 without ST-segment deviation (group B), and 46 with ST-segment depression ≥0.5 mm (group C). LV ejection fractions at predischarge were compared among the 3 groups. Among the 3 groups, there were significant differences in the prevalences of proximal left anterior descending coronary artery (LAD) occlusion (group A 75.3%, group B 56.6%, group C 45.7%, p = 0.002), long LAD (group A 27.1%, group B 31.1%, group C 56.5%, p = 0.002), and good collaterals to the LAD (group A 40.0%, group B 25.4%, group C 17.4%, p = 0.01). LV ejection fractions at predischarge did not differ among the 3 groups (group A 56.4 ± 12.5%, group B 56.9 ± 12.7%, group C 53.3 ± 12.2%, p = 0.26). On a multiple regression analysis, establishment of Thrombolysis In Myocardial Infarction grade 3 flow, proximal LAD occlusion, and long LAD were associated with the LV ejection fraction at predischarge. In conclusion, ST-segment deviation in lead aVR on admission is not associated with LV function at predischarge in first anterior wall acute ST-segment elevation myocardial infarction.     

Can myocardial infarction be rapidly identified in emergency department patients who have left bundle-branch block?

STUDY OBJECTIVES: Fibrinolytic therapy is recommended for patients who have chest pain and left bundle-branch block (LBBB). However, the presence of baseline ECG abnormalities makes early accurate identification of acute myocardial infarction (AMI) difficult. The predictive ability of clinical and ECG variables for identifying patients with LBBB and AMI has not been well studied. We sought to determine the prevalence and predictors of myocardial infarction among patients presenting to the emergency department with LBBB on the initial ECG who were evaluated for myocardial infarction. METHODS: All patients presenting to the ED were prospectively risk stratified on the basis of clinical and historical variables. ECGs from patients with LBBB were compared retrospectively with previously published criteria for identification of AMI. The ability of a new LBBB to predict AMI was also determined. RESULTS: Twenty-four (13%) of the 182 patients with LBBB had AMI. Clinical and historical variables were similar in patients with and without AMI. A new LBBB had a sensitivity of 42% and a specificity of 65%. The presence of concordant ST-segment elevation or depression had specificities and positive predictive values of 100%; however, sensitivities were only 8% and 17%, respectively. The best diagnostic criterion was the presence of concordant ST-segment elevation or depression on the ECG or an initially elevated creatine kinase MB (sensitivity, 63%; specificity, 99%). CONCLUSION: ECG criteria for identifying patients with AMI and LBBB identify only a small minority of patients with AMI. Treating all patients with LBBB and chest pain with fibrinolytics would result in treatment of a significant number of patients without AMI.     

非心肌梗死冠心病患者运动致ST段抬高的临床意义

目的 研究运动致ST段抬高在非心肌梗死患者中发生率及其临床意义。方法 2004年6月至2006年6月共有4601例患者接受了运动平板试验,其中有15例非心肌梗死患者出现ST段抬高,对这15例患者的临床特点与冠状动脉造影结果进行分析。结果 15例（3．2‰）运动致ST段抬高患者中,男性13例,女性2例,年龄40-75岁。单支病变者6例（40％）,2支病变者6例（40％）,3支病变者3例（20％）;12例（80％）累及前降支,1例（6．6％）累及左主干,7例累及右冠状动脉,在累及前降支及左主干13例患者中有8例为重度狭窄病变（狭窄程度为90％-100％）,所有ST段抬高的导联均与病变血管的供血部位一致。结论 运动致ST段抬高在非心肌梗死患者中发生率非常低,多因冠状动脉有严重的固定性狭窄,特别是前降支,可根据出现ST段抬高的导联判断缺血心肌的部位。     

Diabetes mellitus, myocardial reperfusion, and outcome in patients with acute ST-elevation myocardial infarction treated with primary angioplasty (from HORIZONS AMI)

Diabetes mellitus (DM) increases mortality in acute ST-segment elevation myocardial infarction (STEMI) but the responsible mechanism is not fully elucidated. We compared the rate of successful myocardial reperfusion measured by tissue myocardial perfusion grade (TMPG) and outcomes in patients with and without DM undergoing primary percutaneous coronary intervention (PCI) for STEMI. Patients enrolled in the Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction (HORIZONS AMI) trial were analyzed according to presence of DM with respect to TMPG after PCI and outcomes at 30 days and 3 years. Multivariable logistic regression was performed to identify the independent contribution to mortality of DM and TMPG and the interaction between the 2 was assessed. Complete data were available for 3,265 patients, of whom 533 (16.3%) had DM. Diabetic patients were significantly older and heavier and had more risk factors for coronary disease and more previous MI, revascularization, and heart failure. There were no differences in rates of Thrombolysis In Myocardial Infarction grade 3 flow after PCI in the infarct artery or TMPG 2/3 between patients with and without DM. Compared to nondiabetics, mortality was significantly higher at 30 days and at 3 years in the DM group (1.8% vs 4.5%, p = 0.0002 and 5.4% vs 11.0%, p <0.0001, respectively). DM and TMPG were significantly associated with 3-year mortality, but there was no statistical interaction between DM and TMPG (p = 0.70). In conclusion, DM is associated with a significantly higher risk of death but this association is not mediated by impaired epicardial or myocardial reperfusion.     

Protection of Distal Embolization in High-Risk Patients with Acute ST-Segment Elevation Myocardial Infarction (PREMIAR)

Distal embolization may decrease myocardial reperfusion after primary percutaneous coronary intervention (PCI). Nonetheless, results of previous trials assessing the role of distal protection during primary PCI have been controversial. The Protection of Distal Embolization in High-Risk Patients with Acute ST-Segment Elevation Myocardial Infarction Trial (PREMIAR) was a prospective, randomized, controlled study designed to evaluate the role of filter-based distal protection during PCI in patients with acute ST-segment elevation myocardial infarction at high risk of embolic events (including only baseline Thrombolysis In Myocardial Infarction grade 0 to 2 flow). The primary end point was continuous monitoring of ST-segment resolution. Secondary end points included core laboratory analysis of angiographic myocardial blush, ejection fraction measured by cardiac ultrasound, and adverse cardiac events at 6 months. From a total of 194 enrolled patients, 140 subjects were randomized to PCI with or without embolic protection, and 54 were included in a registry arm due to the presence of angiographic exclusion criteria. Baseline characteristics were comparable between arms. The rate of complete ST-segment resolution (>or=70%) at 60 minutes was similar in patients treated with or without distal protection (61.2% vs 60.3%, respectively, p = 0.85). Angiographic myocardial blush (67% vs 70.7%, p = 0.73), in-hospital ejection fraction (47.4 +/- 9.9% vs 45.3 +/- 7.3%, p = 0.29), and combined end point of death, heart failure, or reinfarction at 6 months (14.3% vs 15.7%, p = 0.81) were consistently achieved in a similar proportion in the 2 groups. In conclusion, the use of filter-based distal protection is safe and effectively retrieves debris; however, such use does not translate into an improvement of myocardial reperfusion, left ventricular performance, or clinical outcomes.     

Stress-induced ST-segment elevation in patients without prior Q-wave myocardial infarction

Background

Stress-induced ST-segment elevation is an uncommon finding that usually occurs in patients with prior myocardial infarction (MI). Our purpose was to assess the angiographic and clinical significance of this finding in patients without prior MI.

Methods

Of the 29 002 consecutive ambulatory patients who underwent stress myocardial perfusion imaging over a 5-year period, 205 (0.7%) developed stress-induced ST-segment elevation, of whom 39 (19%) had no Q-wave MI in leads showing ST-segment elevation during either exercise (n = 31) or dipyridamole (n = 8) stress myocardial perfusion imaging. All 39 patients were hospitalized and underwent coronary angiography.

Results

Significant coronary artery disease was found in all 39 patients: 87% had critical (≥90%) stenosis, and 59% had multiple vessel disease. During hospitalization, 37 patients (95%) underwent revascularization.

Conclusions

In patients without prior Q-wave MI, stress-induced ST-segment elevation is associated with critical coronary artery disease. Therefore, these patients should be considered for early coronary investigation.     

Precordial ST-segment elevation caused by right coronary artery occlusion

Among 57 consecutive patients undergoing percutaneous transluminal coronary angioplasty (PTCA) of the right coronary artery, eight patients showed precordial ST-segment elevation in leads V1-3 during the procedure. The mechanism of this ST elevation was investigated reviewing the coronary angiographic findings. All patients had angina pectoris, but none had evidence of myocardial infarction. The balloon inflation time was limited to 60 sec, and 12 lead electrocardiograms were recorded every 15 sec. In the eight patients who had precordial ST-segment elevation, six had the anatomically dominant right coronary artery, and two had proportioned (balanced) left and right coronary arteries. Six patients, however, had functionally dominant left coronary arteries because of good collaterals supplying the right coronary artery from the left coronary artery. Thus, functionally, six had the dominant left coronary artery, one had proportioned coronary supply, and only one had the dominant right coronary artery. In all eight patients, the most proximal portion of the right coronary artery was occluded during PTCA, obstructing both the conus branches and the right ventricular branches. This often induced precordial ST-segment elevation in cases with the functionally dominant left or proportioned coronary artery. This ST-segment elevation seemed to represent right ventricular ischemia, as the inferior wall was protected from ischemia by good collaterals. However, precordial ST-segment elevation was rare in the functionally dominant right coronary artery even when the most proximal portion of the right coronary artery was occluded. This fact seemed due to masking of electrocardiographic manifestations of right ventricular ischemia by the dominant electrical forces of inferior wall ischemia.