An assessment of ST-segment measurement variability between two core electrocardiogram laboratories.

OBJECTIVES: We evaluated inter-reader agreement of the ST-segment between two electrocardiogram (ECG) core laboratories. BACKGROUND: Accurate measurement of the ST-segment is key to diagnosis and management of acute coronary syndromes (ACS). Clinical trials also rely on adherence to the pre-specified ECG eligibility criteria. METHODS: 150 patients (100 ST-segment elevation (STE)-ACS, 50 non-STE-ACS) were selected. An experienced ECG reader from each laboratory measured ST-segment deviation on the baseline ECGs (nearest 0.1mm). RESULTS: ∑ST-segment deviation showed excellent inter-reader agreement (R=0.965, intraclass correlation coefficient (ICC) 0.949, 95% CI (0.930-0.963)). Similar agreement was observed when ∑ST-segment elevation (∑STE) and ∑ST-segment depression (∑STD) were assessed separately. Better agreement was evident in STE-ACS cohort (ICC (95% CI): 0.968 (0.953-0.978, 0.969 (0.954-0.979), 0.931 (0.899-0.953)) compared to NSTE-ACS patients (ICC (95% CI): 0.860 (0.768-0.917), 0.816 (0.699-0.890), 0.753 (0.605-0.851) across measurement of ∑ST-segment deviation, ∑STE, and ∑STD. CONCLUSIONS: We demonstrated excellent agreement on ST-segment measurements between two experienced readers from two ECG core laboratories.

Aborted myocardial infarction after primary percutaneous coronary intervention: magnetic resonance imaging insights from the Assessment of Pexelizumab in Acute Myocardial Infarction (APEX-AMI) trial.

BACKGROUND: Aborted myocardial infarction (AbMI) in patients with ST-elevation MI defined by ST resolution with less than 2-fold elevation in biomarkers has been previously reported. We examined the association among AbMI, other metrics of infarct size, and left ventricular (LV) function defined by cardiac magnetic resonance (CMR). METHODS: A total of 5745 patients with ST-elevation MI enrolled in the APEX-AMI trial, and 73 who were part of the CMR substudy within 3 to 5 days of randomization were evaluated. Core laboratories analyzed electrocardiograms, angiograms, and CMR images. RESULTS: Aborted MI (peak creatine kinase/creatine kinase MB <2× upper limit of normal) with typical evolutionary electrocardiogram changes was observed in 11% (437/3938) overall and in 19% (14/73) of patients within the CMR study. Patients with AbMI were older (62 vs 60 years, P = .003) and tended to achieve complete STE-resolution post-percutaneous coronary intervention (≥70% resolution: 64% vs 32%; P = .076) compared with patients with MI. Cardiac magnetic resonance revealed that patients with AbMI had a smaller infarct size (4.7% vs 14.9% LV, P < .001), less "no reflow" (0.9% vs 1.7% LV, P = .017), enhanced LV function (ejection fraction 54.4% vs 46.5%, P = .064), smaller LV end-systolic volumes (46.5 mL vs 67.2 mL, P = .009), and less transmurality (21.4% vs 50.9% with at least 1 segment with >75% wall thickness, P = .046) when compared with patients with MI. CONCLUSIONS: Patients with AbMI had smaller subendocardial infarcts with enhanced LV size and function. Cardiac magnetic resonance provides corroborative evidence of AbMI and insights into its pathophysiology, specifically rapid successful reperfusion leading to limitation of the "wavefront" of infarct to the subendocardium.

Does silent myocardial infarction add prognostic value in ST-elevation myocardial infarction patients without a history of prior myocardial infarction? Insights from the Assessment of Pexelizumab in Acute Myocardial Infarction (APEX-AMI) Trial.

BACKGROUND: ST-elevation myocardial infarction (STEMI) patients with a prior MI history have worse outcomes. The prognostic significance of silent MI (pathologic Q waves outside the ST-elevation territory) in STEMI is unclear. METHODS: A total of 5,733 STEMI patients from 296 clinical centers in 17 countries were classified as (1) silent MI-baseline Q waves outside the infarct-related artery territory and no history of prior MI, (2) history of prior MI (HxMI), or (3) no prior MI. RESULTS: Of 5,733 STEMI patients, 419 (7.3%) had silent MI, 693 (12.1%) had HxMI, and 4,621 (80.6%) had no prior MI. Ninety-day death and death/congestive heart failure/shock were higher in patients with HxMI (8.4% and 15.3%, respectively) and silent MI (6.7% and 13.9%, respectively) compared with patients with no prior MI (4.0% and 9.1%, respectively) (P ≤ .001 for all). After baseline adjustment, patients with HxMI were at increased risk for 90-day death (adjusted hazard ratio [HR] 1.62, 95% CI 1.18-2.21), whereas both those with HxMI and those with silent MI had increased risk of 90-day death/congestive heart failure/shock compared with those with no prior MI (adjusted HR 1.54, 95% CI 1.23-1.93 and adjusted HR 1.46, 95% CI 1.10-1.93, respectively). CONCLUSIONS: Seven percent of STEMI patients had a silent MI. They represent a novel subgroup at increased risk comparable to those with known prior MI. Hence, in future studies, acquiring baseline Q wave data outside the distribution of acute injury should broaden the prognostic insights from STEMI patients with a prior MI.

[Effects of CO2 storage flux on carbon budget of forest ecosystem].

Carbon dioxide (CO2) storage flux in the air space below measurement height of eddy covariance is very important to correctly evaluate net ecosystem exchange of CO2 (NEE) between forest ecosystem and atmosphere. This study analyzed the dynamic variation of CO2 storage flux and its effects on the carbon budget of a temperate broad-leaved Korean pine mixed forest at Changbai Mountains, based on the eddy covariance flux data and the vertical profile of CO2 concentration data. The CO2 storage flux in this forest ecosystem had typical diurnal variation, with the maximum variation appeared during the transition from stable atmospheric layer to unstable atmospheric layer. The CO2 storage flux calculated by the change in CO2 concentration throughout a vertical profile was not significantly different from that calculated by the change in CO2 concentration at the measurement height of eddy covariance. The NEE of this forest ecosystem was underestimated by 25% and 19% at night and at daytime, respectively, without calculating the CO2 storage flux at half-hour scale, and was underestimated by 10% and 25% at daily scale and annual scale, respectively. Without calculating the CO2 storage flux in this forest ecosystem, the parameters of Michaelis-Menten equation and Lloyd-Taylor equation were underestimated, and the ecosystem apparent quantum yield (alpha) and the ecosystem respiration rate (Rref) at the reference temperature were mostly affected. The gross primary productivity (GPP) and ecosystem respiration (Re) of this forest ecosystem were underestimated about 20% without calculating the CO2 storage flux at half-hour, daily scale, and annual scale.

Do baseline atrial electrocardiographic and infarction patterns predict new-onset atrial fibrillation after ST-elevation myocardial infarction? Insights from the Assessment of Pexelizumab in Acute Myocardial Infarction Trial.

BACKGROUND: Atrial infarction reportedly occurs in 0.7% to 52% of ST-elevation myocardial infarctions (STEMIs), up to two thirds of whom develop atrial fibrillation and flutter (AF). Prospective validation of electrocardiographic atrial infarction patterns is lacking. Hence, in STEMI patients treated with primary percutaneous coronary intervention, we examined whether baseline atrial electrocardiographic changes or atrial infarction patterns predicted new AF or mortality. METHODS: Within the Assessment of Pexelizumab in Acute Myocardial Infarction trial, a nested case-control study was conducted. Patients with new AF were matched 1:1 with controls, and baseline atrial electrocardiographic variables were examined. RESULTS: Abnormal P wave morphology (Liu minor criterion for atrial infarction) was significantly associated with new AF (adjusted odds ratio, 1.68; 1.03-2.73). This was also independently associated with 90-day mortality in the overall case-control cohort (adjusted hazard rate, 1.90; 1.04-3.46) and among patient with new-onset AF (adjusted hazard rate, 2.43; 1.22-4.84). CONCLUSIONS: Abnormal P wave morphology significantly predicted new AF and 90-day mortality in STEMI patients.

Contribution of angiographic and electrocardiographic parameters of reperfusion to prediction of mortality and morbidity after acute ST-elevation myocardial infarction: Insights from the Assessment of Pexelizumab in Acute Myocardial Infarction trial.

BACKGROUND: Reperfusion with primary percutaneous intervention (PCI) in ST-segment elevation myocardial infarction leads to improved clinical outcomes. The contribution angiographic vs electrocardiographic reperfusion parameters confer on prognosis is unclear. METHODS: A prespecified subset of the APEX-AMI trial patients was analyzed by independent angiographic and electrocardiographic core laboratories (n = 1,018). Angiographic reperfusion after PCI and electrocardiogram 30 minutes post-PCI were assessed. RESULTS: Of the 941 patients in the angiographic substudy, 796 (85%) attained post-PCI Thrombolysis In Myocardial Infarction (TIMI) flow 3 and 852 (91%) had TIMI Myocardial Perfusion Grade (TMPG) 2/3. There were 664 (71%) patients with residual ST elevation (ST-E) <2 mm. Ninety-day mortality and death/CHF/shock were lower in patients with TIMI flow 3 vs <3 (1.9% vs 6.2%, P = .002; 5.8% vs 10.4%, P = .044) and those with TMPG 2/3 vs 0/1 (2.0% vs 7.9%, P = .001; 6.0% vs 11.9%, P = .028). Patients with residual ST-E <2 mm had similar rates of mortality as those with > or =2 mm (2.3% vs 3.3%, P = .374) but lower rates of death/CHF/shock (5.2% vs 9.6%, P = .013). After multivariable adjustment, only post-PCI TMPG 2/3 was significantly associated with survival (P = .001), whereas residual ST-E (P = .606) and post-PCI TIMI flow grade (P = .086) were not. Conversely, residual ST-E > or =2 mm (P = .012) rather than angiographic reperfusion was associated with the composite of death/CHF/shock events. CONCLUSION: Angiographic and electrocardiographic estimates of reperfusion with primary PCI in ST-segment elevation myocardial infarction provide different and complementary predictions of morbidity and mortality.

ST-segment recovery and outcome after primary percutaneous coronary intervention for ST-elevation myocardial infarction: insights from the Assessment of Pexelizumab in Acute Myocardial Infarction (APEX-AMI) trial.

BACKGROUND: Primary percutaneous coronary angioplasty is an effective and widely adopted treatment for acute myocardial infarction. A simple method of determining prognosis after primary percutaneous coronary intervention (PCI) would facilitate appropriate care and expedite hospital discharge. Thus, we determined the prognostic importance of various measures of ST-segment-elevation recovery after primary PCI in a large, contemporary cohort of patients with ST-elevation myocardial infarction. METHODS AND RESULTS: We analyzed ECG data describing the magnitude and extent of ST-segment elevation and deviation before and early after (ie, 30 minutes) primary PCI in the study cohort of 4866 subjects with electrocardiographically high-risk ST-elevation myocardial infarction enrolled in the Assessment of PEXelizumab in Acute Myocardial Infarction (APEX-AMI) trial. Associations among 6 methods for calculating ST-segment recovery, biomarker estimates of infarct size (ie, peak creatine kinase, creatine kinase-MB, and troponin I and T), and prespecified clinical outcomes (ie, rates of 90-day death and 90-day death, heart failure, or shock) were examined. All ST-segment-recovery methods provided strong prognostic information regarding clinical outcomes. A simple ST-segment-recovery method of residual ST-segment elevation measurement in the most affected lead on the post-PCI ECG performed as well as complex methods that required comparison of pre- and post-PCI ECGs or calculation of summed ST-segment deviation in multiple leads (ie, worst-lead residual ST elevation: adjusted hazard ratio for 90-day death rate [reference <1 mm]: 1 to <2 mm, 1.23 [95% CI 0.74 to 2.03]; > or =2 mm, 2.22 [95% CI 1.35 to 3.65], corrected c-index=0.832; 90-day death/congestive heart failure/shock [reference <1 mm]: 1 to <2 mm, 1.55 [95% CI 1.06 to 2.26]; > or =2 mm, 2.33 [95% CI 1.59 to 3.41], corrected c-index=0.802). Biomarker estimates of infarct size declined in association with enhanced ST-segment recovery. CONCLUSIONS: An ECG performed early after primary PCI is a simple, widely available, inexpensive, and powerful prognostic tool applicable to patients with ST-elevation myocardial infarction.

Forecasting mortality: dynamic assessment of risk in ST-segment elevation acute myocardial infarction.

AIMS: To demonstrate the feasibility and clinical utility of developing dynamic risk assessment models for ST-segment elevation myocardial infarction (STEMI) patients. METHODS AND RESULTS: In 6066 STEMI patients enrolled in the Assessment of the Safety and Efficacy of a New Thrombolytic-3 (ASSENT-3) trial with complete electrocardiographic data, we assessed the probability of 30-day mortality over the following forecasting periods beginning at day 0 (baseline), 3 h, day 2, and day 5 using multiple-logistic regression. These models were validated and simplified in independent samples of 1622 similar fibrinolytic-treated patients from the ASSENT-3 PLUS trial and in 814 STEMI patients undergoing primary percutaneous coronary intervention in the COMplement inhibition in Myocardial infarction treated with Angioplasty (COMMA) trial. The discriminatory power of these predictive models, from baseline to day 5, was excellent (c-statistics 0.80 to 0.87); and their predictive ability was supported by strong gradients in mortality outcomes as the risk score increased. Dynamic modelling also provided information on the change in prognosis over time which may be used to advise more appropriate therapeutic decisions, e.g. the identification of high-risk patients for possible co-interventions. CONCLUSION: Dynamic modelling for STEMI patients enhances the risk assessment and stratification and should provide valuable ongoing guidance for their management.

Unraveling the spectrum of left bundle branch block in acute myocardial infarction: insights from the Assessment of the Safety and Efficacy of a New Thrombolytic (ASSENT 2 and 3) trials.

BACKGROUND: Left bundle branch block (LBBB) complicates the diagnosis of acute myocardial infarction (AMI). The Sgarbossa criteria were developed from GUSTO I to surmount this diagnostic challenge but have not been prospectively validated in a large population with presumed AMI. We evaluated their utility in the diagnosis and risk stratification of AMI patients in ASSENT 2 & 3. METHODS: Baseline electrocardiograms (ECG) of LBBB patients were scored using Sgarbossa's criteria (0-10) by 2 readers blinded to the CK/CK-MB data and clinical outcomes; 267 (1.2%) patients had LBBB on their baseline ECG. RESULTS: Among 253 LBBB patients with available peak CK/CK-MB data, 158 (62.5%) had peak CK/CK-MB levels > 2x ULN, thereby qualifying for the diagnosis of AMI. A Sgarbossa score of 3 was shown in 48.7% of LBBB patients with elevated CK/CK-MB versus in 12.6% of those without a CK/CK-MB rise (P < .001). Patients with higher Sgarbossa scores, ie, 3, had a higher mortality compared with those with a score < 3, (23.5% vs 7.7% at 30 days P < .001; and 33.7% vs 20.2% at 1 year, P < .001, respectively). CONCLUSIONS: Our findings validate the utility of Sgarbossa criteria for diagnosing AMI in the setting of LBBB. These criteria provide a simple and practical diagnostic approach to risk stratify this diagnostically challenging high-risk group and optimize risk-benefit of acute therapy.

Aborted myocardial infarction in patients with ST-segment elevation: insights from the Assessment of the Safety and Efficacy of a New Thrombolytic Regimen-3 Trial Electrocardiographic Substudy.

OBJECTIVES: The investigators undertook a systematic, comprehensive analysis of the therapeutic response and clinical outcomes of reperfusion therapy for acute ST-segment elevation myocardial infarction (STEMI) in 5,470 patients from the Assessment of the Safety and Efficacy of a New Thrombolytic Regimen (ASSENT)-3 trial. BACKGROUND: Prompt effective reperfusion therapy for acute STEMI may attenuate major myocardial necrosis. METHODS: We prospectively collected sequential electrocardiographs and clinical data. Aborted myocardial infarction (MI) was defined as maximal creatine kinase < or =2x upper limit of normal coupled with typical evolutionary electrocardiographic changes. RESULTS: Of the patients, 727 (13.3%) had an aborted MI, with the highest frequency (25%) occurring in patients treated <1 h after symptom onset. As compared with MI patients, patients with aborted MI more often had complete ST-segment resolution at 60 min (56.3% vs. 30.2%, p < 0.001) and 180 min (61.5% vs. 53%, p < 0.001); they also had smaller infarct sizes based on QRS score at discharge (2.37 vs. 4.62, p <0.001). Mortality in aborted MI patients compared with those who had true MI was 3.9% versus 4.6% at 30-day and 7.0% versus 7.4% at 1-year. The baseline-adjusted mortality was significantly lower in patients with aborted MI (odds ratio [OR] 0.76, 95% confidence interval [CI] 0.63 to 0.92, p = 0.005 for 30-day and OR 0.70, 95% CI 0.50 to 0.98, p = 0.035 for one year). A very low-risk subset was identified with > or =70% ST-segment resolution at 60 min whose 30-day and 1-year mortality was 1.0% and 2.7%, respectively, compared with 5.9% and 9.3% in aborted MI patients with <70% ST-segment resolution at 60 min (all p < or = 0.002). CONCLUSIONS: Prompt fibrinolytic treatment improved the likelihood of aborted MI. The subgroup with complete 60-min ST-segment resolution had the best clinical outcomes.

International differences in evolution of early discharge after acute myocardial infarction.

BACKGROUND: Early discharge of low-risk patients with acute myocardial infarction is feasible and can be achieved at no additional risk of adverse events. We aimed to identify the extent to which countries have taken advantage of the opportunity for early discharge. METHODS: The study population consisted of 54174 patients enrolled in GUSTO-I, GUSTO-III, and ASSENT-2 studies (enrollment period 1990-98) in the USA, Canada, Australia, New Zealand, Belgium, France, Germany, Spain, and Poland. We identified patients with uncomplicated acute myocardial infarction who were eligible for early discharge on the basis of previously established criteria, and assessed the extent to which these patients were discharged early--defined as discharged alive within 4 days of admission. The economic consequences (defined as potentially unnecessary hospital days consumed per 100 patients enrolled) were also investigated. FINDINGS: Patients in all European countries had significantly longer stays than did those from non-European countries. Over the study period, the number of eligible patients discharged on or before day 4 increased in the USA, Canada, Australia, and New Zealand. Despite this increase, no more than 40% of patients who were eligible for early discharge were actually discharged early. The rate of early discharge of eligible patients was consistently low (<2%) in Belgium, France, Germany, Spain, and Poland. In ASSENT-2, which is the most recent trial in this study, the number of potentially unnecessary hospital days (per 100 patients enrolled) ranged from 65 in New Zealand to 839 in Germany. INTERPRETATION: Despite more than a decade of research, there is still a lot of variation between countries in international length-of-stay patterns in acute myocardial infarction. The potential for more efficient discharge of low-risk patients exists in all countries investigated, but was especially evident in the European countries included in the study (Belgium, France, Germany, Spain, and Poland).

Impact of on-site cardiac interventional facilities on management and outcome of patients with acute coronary syndromes.

OBJECTIVES: To investigate the impact of on-site cardiac interventional facilities on the management and outcome of patients with versus those without ST elevation acute coronary syndromes (ACS) in the Canadian-American Global Use of Strategies to Open Occluded Coronary Arteries (GUSTO) IIb population. METHODS: Data from 4605 patients were analyzed in relation to the admitting hospital's capability to perform coronary procedures (noninvasive, angiography-capable and interventional hospitals). Differences in medication use, revascularization rate and patient outcome were determined. RESULTS: Whereas medication use during hospitalization and at discharge differed between non-ST elevation ACS patients treated in the three groups, these were generally more comparable among ST elevation ACS patients. In both ST segment cohorts, patients treated in interventional hospitals underwent coronary procedures more often (angiography rate greater than 70% versus 40% for noninvasive hospitals) and sooner (median two to three days versus four days in noninvasive hospitals) than those treated in other hospitals. Recurrent ischemia was significantly less common in non-ST elevation ACS patients treated in interventional hospitals (32% versus 36% in angiography-capable and 40% in noninvasive hospitals, P<0.001) and tended to be less common among ST elevation ACS patients treated in interventional hospitals. Patients treated in interventional hospitals tended to have lower mortality in the non-ST elevation ACS cohort but significantly fewer died in the ST elevation ACS during hospitalization and at 30 days, six months and one year (8.8% versus 11% in angiography-capable and 15% in noninvasive hospitals, P=0.015). These differences in mortality persisted after adjustment for key baseline covariates. Separate analysis of Canadian and American patients revealed similar mortality patterns, as to the total population, in both ST segment cohorts. CONCLUSIONS: Presence of an on-site cardiac interventional facility favourably affected the management and outcome of ACS patients in both non-ST and ST elevation cohorts.