Infarct site-related mortality in patients with recurrent myocardial infarction. SPRINT Study Group

The role of the ECG in diagnosis, risk estimation, and catheterization laboratory activation in patients with acute coronary syndromes: a consensus document

The electrocardiogram (ECG) is the most widely used imaging tool helping in diagnosis and initial management of patients presenting with symptoms compatible with acute coronary syndrome. Acute ischemia affects the configuration of the QRS complexes, the ST segments and the T waves. The ECG should be read along with the clinical assessment of the patient. ST segment elevation (and ST depression in leads V1 -V3 ) in patients with active symptoms usually indicates acute occlusion of an epicardial artery with ongoing transmural ischemia. These patients should be triaged for emergent reperfusion therapy per current guidelines. However, many patients have ST segment elevation secondary to nonischemic causes. ST depression in leads other than V1 -V3 usually are indicative of subendocardial ischemia secondary to subocclusion of the epicardial artery, distal embolization to small arteries or spasm supply/demand mismatch. ST depression may also be secondary to nonischemic etiologies, such as left ventricular hypertrophy, cardiomyopathies, etc. Knowing the clinical scenario, comparison to previous ECG and subsequent ECGs (in cases that there are changes in the quality or severity of symptoms) may add in the diagnosis and interpretation in difficult cases. This review addresses the different ECG patterns, typically seen in patients with active symptoms, after resolution of symptoms and the significance of such changes when seen in asymptomatic patients.

Localization of prior myocardial infarction by repolarization variables

BACKGROUND

To find quantitative, automatically applicable electrocardiographic (ECG) variables for detecting prior myocardial infarction (MI) in different myocardial regions.

METHODS

Observational study. Body surface potential mapping (BSPM) was recorded at rest, and automatically analyzed with regard to ECG parameters, blinded to the clinical characteristics of the study subjects, 144 patients with prior MI and 75 healthy controls. MI location was determined by cine angiography or echocardiography as anterior (66 patients), inferoposterior (89 patients), and lateral (15 patients). Patients' 12-lead ECG was interpreted according to Minnesota code (Q-wave MI in 97 patients). The QRSSTT, QRS, and STT integrals, and the T-apex amplitude in detecting prior anterior and inferoposterior MI were analyzed.

RESULTS

The T-apex amplitude, QRSSTT integral, and STT integral were functional in detecting MI in all tested locations on a single-lead basis, with areas under receiver operating characteristic curves (AUC) of over 90% (p<0.001) in optimal sites. In the best leads AUC for the QRSSTT integral in anterior MI was 93% (CI 87-99%) and for the inferoposterior MI 92% (CI 88-97%). These repolarization variables outperformed the Minnesota code in all tested MI locations. They were also able to distinguish between anterior and inferoposterior MI with an AUC of >85% (p<0.001).

CONCLUSIONS

Quantitative, automatically applicable single-lead repolarization variables detect prior MI irrespective of its location. They may simplify the screening for and localization of old infarctions as compared to the conventional ECG methods.

Electrocardiographic Diagnosis of ST-elevation Myocardial Infarction

The ECG is an essential part of the initial evaluation of patients who have chest pain, especially in the immediate decision-making process in patients who have ST-elevation myocardial infarction. This article reviews and summarizes the current information that can be obtained from the admission ECG in patients who have ST-elevation acute myocardial infarction, with an emphasis on: (1) prediction of final infarct size, (2) estimation of prognosis, and (3) the correlations between various ECG patterns and the localization of the infarct and the underlying coronary anatomy.

Ischemia-induced ST-segment elevation: classification, prognosis, and therapy

The standard 12-lead electrocardiogram (ECG) remains the most useful tool for the diagnosis, early risk stratification, triage, and guidance of therapy in patients with acute coronary syndromes. However, the initial and the terminal part of the QRS complex, the ST segments, and the T waves are influenced by anatomical and metabolic factors such as the "myocardium at risk" and "severity" and "duration" of ischemia. Moreover, there are complex interactions between all these factors. The ECG can identify potential candidates for reperfusion therapy as well as the completeness and success of reperfusion, whereas it can also identify those patients who will have no benefit from reperfusion because of either late arrival or nonischemic etiologies of ECG changes. These patients may have a "pseudo" ST-elevation acute myocardial infarction (STEAMI) or "pseudo-pseudo" STEAMI. The presence of Q waves and additional ST-segment depression and T-wave inversion on the admission ECG in patients with STEAMI may provide us information regarding the potential myocardial reserves, and various ECG scoring systems are in current use for that purpose. The pattern and timing of changes in Q waves, ST segment, and T waves may all be markers of the patency status of the infarct-related artery. We review and discuss each of the dynamic ECG variables during ischemia and reperfusion: the initial QRS (Q and R waves), the terminal QRS (Sclarovsky-Birnbaum score), the ST segment, and the T waves.

The electrocardiogram in ST elevation acute myocardial infarction: correlation with coronary anatomy and prognosis

The electrocardiogram is considered an essential part of the diagnosis and initial evaluation of patients with chest pain. This review summarises the information that can be obtained from the admission electrocardiogram in patients with ST elevation acute myocardial infarction, with emphasis on: (1) prediction of infarct size, (2) estimation of prognosis, and (3) the correlations between various electrocardiographic patterns and the localisation of the infarct and the underlying coronary anatomy.

Hierarchy of risk based on history and location of prior myocardial infarction in the thrombolytic era. GUSTO-I Investigators

BACKGROUND

Among patients receiving thrombolytic therapy for myocardial infarction, the outcome for those with a history of infarction is dramatically worse than for those with their first event. Methods And Results We performed a post hoc analysis of patients with a history of myocardial infarction enrolled in the Global Utilization of Streptokinase and TPA for Occluded arteries (GUSTO)-I trial, focusing on the impact of the location of their current and prior events on mortality rates. Within the first 24 hours, mortality rate was greatest among patients with a current infarction in a territory remote from their previous event. By 48 hours after examination, mortality rates among patients with a second anterior infarct had overtaken that among patients with a current inferior/prior anterior infarct. This hierarchy of risk persisted at both 30 days and 1 year (mortality rate at 1 year: current anterior/prior inferior 23.2% +/- 1.4%, current anterior/prior anterior 20% +/- 1.5%, current inferior/prior anterior 17% +/- 1.2%, current inferior/prior inferior 10.8% +/- 0. 9%).

CONCLUSIONS

In patients with ST-elevation myocardial infarction on a background of prior infarction, the location of current and prior events predicts a hierarchy of short- and long-term risk of death.

Risk stratification after acute myocardial infarction in the reperfusion era

Historically, risk stratification for survivors of acute myocardial infarction (AMI) has centered on 3 principles: assessment of left ventricular function, detection of residual myocardial ischemia, and estimation of the risk for sudden cardiac death. Although these factors still have important prognostic implications for these patients, our ability to predict adverse cardiac events has significantly improved over the last several years. Recent studies have identified powerful predictors of adverse cardiac events available from the patient history, physical examination, initial electrocardiogram, and blood testing early in the evaluation of patients with AMI. Numerous studies performed in patients receiving early reperfusion therapy with either thrombolysis or primary angioplasty have emphasized the importance of a patent infarct related artery for long-term survival. The predictive value of a variety of noninvasive and invasive tests to predict myocardial electrical instability have been under active investigation in patients receiving early reperfusion therapy. The current understanding of the clinically important predictors of clinical outcomes in survivors of AMI is reviewed in this article.

Prognostic Importance of Previous Myocardial Infarction in Patients Receiving Thrombolytic Therapy for Acute Infarction

This study evaluated the prognostic significance of reinfarction location by considering the previous site or type of myocardial infarction (MI) among 1601 patients with a history of previous MI who took part in the International (non-Italian) tPA/STK trial and/or the Israeli GUSTO study population. These patients were accordingly divided and hospital mortality was compared by six location groups as follows: acute inferior with previous inferior (8.1% hospital mortality), acute inferior with previous anterior (12.8%), acute anterior with previous inferior (13.3%), acute anterior with previous anterior (11.1%), acute inferior with previous non-Q-wave MI (7.6%), and acute anterior with previous non-Q-wave MI (11.2%) (p = 0.17 for comparison between the six groups). Hospital mortality tended to increase among patients with an anterior reinfarction compared with those with an inferior one (12.1% vs. 9.5%, p = 0.12). Among patients with a reinfarction at a different ECG location from the previous event, mortality tended to be higher compared with patients with two MIs at the same location (13.1% vs. 9.7%, p = 0.07). Recurrent MI following a previous Q-wave MI did not cause a higher mortality compared with a previous non-Q-wave type of MI (11.5% vs. 9.5%, p = 0.24). Among patients sustaining reinfarction, overall mortality did not differ between STK- and tPA-treated patients (11.0% vs. 11.4%, p = NS). In conclusion, the current study identified trends for higher mortality rates in patients with anterior compared with inferior reinfarction, with remote compared with the same ECG location of the two infarctions but not following a previous non-Q-wave compared with Q-wave MI. However, no particular combination of successive MIs location was significantly associated with a higher risk for hospital mortality.

Characteristics, clinical course, and in-hospital mortality of non-insulin-dependent diabetic and nondiabetic patients with acute myocardial infarction in Argentina

The characteristics and clinical course of 1040 cases of acute myocardial infarction (AMI) among non-insulin-dependent diabetics (146) and nondiabetics (894) were compared. Patients with non-insulin-dependent diabetes mellitus (NIDDM) historically showed a greater percentage of AMI, angina, and risk factors than nondiabetic patients. Although the degree of left-ventricular function upon admission (according to the Killip and Kimball scores) was similar in both the diabetic and nondiabetic groups, the prevalence of hypertension and hypercholesterolemia was significantly higher in the NIDDM patients. All told, NIDDM cases were 1.73 [relative risk (RR)] times more likely to die of AMI than nondiabetic patients. The age factor and the presence of shock of any type also significantly increased the case-fatality rate. Diabetic patients showed signs of successful reperfusion less often than control subjects, an event that was closely associated with their case-fatality rate. In the NIDDM group, both the age and gender factor as well as a history of either casual or in-hospital clinical events such as cardiogenic shock, reinfarction, unsuccessful reperfusion, and incidence of anterior AMI along with either pain or previous angina were clear prognosticators of poor outcome from AMI. In the nondiabetic group, cardiogenic shock and hypertension were indicators of poor prognosis. These results would suggest that an improvement in the incidence of successful reperfusion in NIDDM patients, particularly in the face of clinical indicators of poor AMI prognosis, could decrease the high AMI mortality currently observed in these patients.