The 12-lead electrocardiogram as a predictive tool of mortality after acute myocardial infarction: current status in an era of revascularization and reperfusion

A cross-sectional study determining prevalence and factors associated with ST-segment elevation myocardial infarction and non-ST segment elevation myocardial infarction in Iran: results from fasa registry on acute myocardial infarction (FaRMI)

BACKGROUND

Acute myocardial infarction is still a leading cause of death worldwide, accounting for roughly three million deaths yearly. This study aimed to investigate the prevalence and factors associated with ST-Segment Elevation Myocardial Infarction and Non-ST Segment Elevation Myocardial Infarction in Iran.

METHODS

This cross-sectional study was conducted using the databases of the Fasa Registry on Acute Myocardial Infarction (FaRMI) and the Fasa Adult Cohort Study (FACS). chi-squared and one-way ANOVA tests were utilized to calculate the unadjusted associations between the study variables. A multivariate multinomial logistic regression model was also employed to determine the adjusted association of each independent variable with the risk of ST-elevation myocardial infarction (STEMI).

RESULTS

The prevalence of STEMI and non-STEMI was 31.60% and 11.80%, respectively. Multinomial logistic regression showed that older age, anemia, high WBC, and high creatinine levels were associated with higher odds of STEMI and non-STEMI compared to healthy individuals. In addition, based on the analysis being a woman(OR = 0.63,95%CI:0.51-0.78), anemia(OR = 0.67,95%CI:0.54-0.63)and hypertension (OR = 0.80,95%CI:0.65-0.97)decreased the likelihood of STEMI occurrence compared to non-STEMI, while high WBC(OR = 1.19,95%CI:1.15-1.23)increased the odds.

CONCLUSION

In this study, significant predictors of MI risk included age, gender, anemia, lipid profile, inflammation, and renal function. Subsequent investigations ought to prioritize the comprehensive understanding of the underlying mechanisms that drive these connections and assess the effectiveness of specific interventions aimed at diminishing the occurrence of MI and improving patient outcomes.

ECG Markers of Acute Melatonin Treatment in a Porcine Model of Acute Myocardial Ischemia

In myocardial ischemia, melatonin confers antiarrhythmic action, but its electrocardiographic expression is unclear. We aimed to evaluate the effects of melatonin treatment on electrocardiogram (ECG) parameters reflecting major arrhythmogenic factors and to test the association of these parameters with ventricular fibrillation (VF) incidence. Myocardial ischemia was induced by 40 min coronary artery occlusion in 25 anesthetized pigs. After induction of ischemia, 12 and 13 animals were given melatonin or placebo, respectively. Twelve-lead ECGs were recorded and durations of QRS, QT, Tpeak-Tend intervals and extrasystolic burden were measured at baseline and during occlusion. During ischemia, VF episodes clustered into early and delayed phases (<10 and >20 min, respectively), and QRS duration was associated with VF incidence. QT interval and extrasystolic burden did not differ between the groups. The Tpeak-Tend interval was progressively prolonged, and the prolongation was less pronounced in the treated animals. QRS duration increased, demonstrating two maxima (5−10 and 25 min, respectively). In the melatonin group, the earlier maximum was blunted, and VF development in this period was prevented. Thus, acute melatonin treatment prevented excessive prolongation of the QRS and Tpeak-Tend intervals in the porcine myocardial infarction model, and QRS duration can be used for the assessment of antiarrhythmic action of melatonin.

Sex Disparity in Characteristics, Management, and In-Hospital Outcomes of Patients with ST-Segment Elevated Myocardial Infarction: Insights from Henan STEMI Registry

Background

Women hospitalized with ST-elevation myocardial infarction (STEMI) experience higher risk of early mortality than men. We aimed to investigate the potential impact of risk factors, clinical characteristics, and management among gender-related risk differences.

Method

We analyzed 5063 STEMI patients prospectively enrolled from 66 hospitals during 2016-2018 and compared sex differences in mortality, death, or treatment withdrawal and main adverse cardiovascular and cerebrovascular events (MACCE) using the generalized linear mixed model, following sequential adjustment for covariates.

Results

Women were older and had a higher prevalence of hypertension (53.3% vs. 41.1%, P < 0.001) and diabetes (24.5% vs. 15.2%, P < 0.001). Eligible women were less likely to receive reperfusion therapy (56.1% vs. 62.4%, P < 0.001); the onset to first medical contact (FMC) (255 vs. 190 minutes, P < 0.001), onset to fibrinolysis (218 vs. 185 minutes, P < 0.001), and onset to percutaneous coronary intervention (PCI) (307 vs. 243 minutes, P < 0.001) were significantly delayed in women. The incidence of in-hospital death (6.8% vs. 3.0%, P < 0.001), death or treatment withdrawal (14.5% vs. 5.6%, P < 0.001), and MACCE (18.5% vs. 9.4%, P < 0.001) were notably higher. The gender disparities persist in death (OR: 1.61, 95% CI: 1.12-2.33), death or treatment withdrawal (OR: 1.68, 95% CI: 1.26-2.24), and MACCE (OR: 1.37, 95% CI: 1.08-1.74) after adjustment for covariates. Among possible explanatory factors, age (-58.46%, -59.04%, -62.20%) and cardiovascular risk factors (-40.77%, -39.36%, -41.73%) accounted for most of the gender-associated risk differences.

Conclusions

Women experienced worse in-hospital outcomes, and age and cardiovascular risk factors were major factors influencing sex-related differences. The sex disparity stressed the awareness and importance of quality improvement efforts against female patients in clinical practice.

Recent Non-Invasive Parameters to Identify Subjects at High Risk of Sudden Cardiac Death

Cardiovascular diseases remain among the leading causes of death worldwide and sudden cardiac death (SCD) accounts for ~25% of these deaths. Despite its epidemiologic relevance, there are very few diagnostic strategies available useful to prevent SCD mainly focused on patients already affected by specific cardiovascular diseases. Unfortunately, most of these parameters exhibit poor positive predictive accuracy. Moreover, there is also a need to identify parameters to stratify the risk of SCD among otherwise healthy subjects. This review aims to provide an update on the most relevant non-invasive diagnostic features to identify patients at higher risk of developing malignant ventricular arrhythmias and SCD.

In-Hospital Prognostic Value of Electrocardiographic Parameters Other Than ST-Segment Changes in Acute Myocardial Infarction: Literature Review and Future Perspectives

Electrocardiography (ECG) remains an irreplaceable tool in the management of the patients with myocardial infarction, with evaluation of the QRS and ST segment being the present major focus. Several ECG parameters have already been proposed to have prognostic value with regard to both in-hospital and long-term follow-up of patients. In this review, we discuss various ECG parameters other than ST segment changes, particularly with regard to their in-hospital prognostic importance. Our review not only evaluates the prognostic segments and parts of ECG, but also highlights the need for an integrative approach in big data to re-assess the parameters reported to predict in-hospital prognosis. The evolving importance of artificial intelligence in evaluation of ECG, particularly with regard to predicting prognosis, and the potential integration with other patient characteristics to predict prognosis, are discussed.

Gender-related differences in men and women with ST-segment elevation myocardial infarction and incomplete infarct-related artery flow restoration: a multicenter national registry

INTRODUCTION

Little is known about gender-related differences in ST-segment elevation myocardial infarction (STEMI) and incomplete infarct-related artery (IRA) reperfusion after primary percutaneous coronary intervention (pPCI).

AIM

To evaluate gender-related differences in clinical characteristics and prognosis in patients with STEMI and incomplete IRA reperfusion after pPCI.

MATERIAL AND METHODS

From 42,752 STEMI patients hospitalized between 2009 and 2011 in Poland we analyzed a group of 984 (36%) females and 1,746 (64%) males with less than Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow following pPCI.

RESULTS

Women were older than men (72.0 ±11.3 vs. 64.0 ±11.7 years; p < 0.0001) and in age-adjusted analysis they were more likely to present with hypertension (73.7% vs. 67%; p = 0.0003), diabetes (33% vs. 22.6%; p < 0.0001) and obesity (28.1% vs. 22.6%; p = 0.0016). Heart rate > 100 beats/min was more common in women, while men were more often smokers and presented with sudden cardiac arrest. The most common IRA in women was the left anterior descending artery, and the right coronary artery in men. After adjusting for age statistically significant differences in pharmacotherapy concerned only the use of insulin (OR = 1.31, 95% CI: 1.02-1.68). High risk of death, rehospitalization due to heart failure or cardiac causes, were observed in all patients during the 6-month and 12-month follow-up periods. The risk of heart failure was significantly higher in women than in men. The most significant decrease in survival rates was observed in the in-hospital period.

CONCLUSIONS

Among patients with STEMI and post-interventional TIMI flow grade < 3 women have unfavorable baseline characteristics and an adverse short- and long-term prognosis when compared to men.

Causal Pathways from Blood Pressure to Larger Qrs Amplitudes a Mendelian Randomization Study

Abnormal QRS duration and amplitudes on the electrocardiogram are indicative of cardiac pathology and are associated with adverse outcomes. The causal nature of these associations remains uncertain and could be due to QRS abnormalities being a symptom of cardiac damage rather than a factor on the causal pathway. By performing Mendelian randomization (MR) analyses using summary statistics of genome wide association study consortia with sample sizes between 20,687 and 339,224 individuals, we aimed to determine which cardiovascular risk factors causally lead to changes in QRS duration and amplitude (Sokolow-Lyon, Cornell and 12-leadsum products). Additionally, we aimed to determine whether QRS traits have a causal relationship with mortality and longevity. We performed inverse-variance weighted MR as main analyses and MR-Egger regression and weighted median estimation as sensitivity analyses. We found evidence for a causal relationship between higher blood pressure and larger QRS amplitudes (systolic blood pressure on Cornell: 55SNPs, causal effect estimate per 1 mmHg = 9.77 millimeters·milliseconds (SE = 1.38,P = 1.20 × 10⁻¹²) and diastolic blood pressure on Cornell: 57SNPs, causal effect estimate per 1 mmHg = 14.89 millimeters·milliseconds (SE = 1.82,P = 3.08 × 10⁻¹⁶), but not QRS duration. Genetically predicted QRS traits were not associated with longevity, suggesting a more prominent role of acquired factors in explaining the well-known link between QRS abnormalities and outcome.

Comparison of automated measurements of electrocardiographic intervals and durations by computer-based algorithms of digital electrocardiographs

BACKGROUND AND PURPOSE

Automated measurements of electrocardiographic (ECG) intervals are widely used by clinicians for individual patient diagnosis and by investigators in population studies. We examined whether clinically significant systematic differences exist in ECG intervals measured by current generation digital electrocardiographs from different manufacturers and whether differences, if present, are dependent on the degree of abnormality of the selected ECGs.

METHODS

Measurements of RR interval, PR interval, QRS duration, and QT interval were made blindly by 4 major manufacturers of digital electrocardiographs used in the United States from 600 XML files of ECG tracings stored in the US FDA ECG warehouse and released for the purpose of this study by the Cardiac Safety Research Consortium. Included were 3 groups based on expected QT interval and degree of repolarization abnormality, comprising 200 ECGs each from (1) placebo or baseline study period in normal subjects during thorough QT studies, (2) peak moxifloxacin effect in otherwise normal subjects during thorough QT studies, and (3) patients with genotyped variants of congenital long QT syndrome (LQTS).

RESULTS

Differences of means between manufacturers were generally small in the normal and moxifloxacin subjects, but in the LQTS patients, differences of means ranged from 2.0 to 14.0 ms for QRS duration and from 0.8 to 18.1 ms for the QT interval. Mean absolute differences between algorithms were similar for QRS duration and QT intervals in the normal and in the moxifloxacin subjects (mean ≤6 ms) but were significantly larger in patients with LQTS.

CONCLUSIONS

Small but statistically significant group differences in mean interval and duration measurements and means of individual absolute differences exist among automated algorithms of widely used, current generation digital electrocardiographs. Measurement differences, including QRS duration and the QT interval, are greatest for the most abnormal ECGs.

Acute myocardial infarction complicated by shock: outcome analysis based on initial electrocardiogram

OBJECTIVES

To assess the relation between initial ECG findings, presence of risk factors, coronary angiography findings, and clinical outcomes in patients with acute myocardial infarction complicated by cardiogenic shock (CS).

DESIGN

Data from a total of 5572 acute myocardial infarction patients admitted to the four tertiary hospitals during a period of 3 years were analyzed. CS on admission was present in 358 patients (6.4%). They were divided into four groups based on the admission ECG: ST-segment elevation (STEMI), ST-segment depression (STDMI), bundle branch block (BBBMI), and other ECG acute myocardial infarction.

RESULTS

CS developed most frequently among BBBMI patients (in 12.1% of all BBBMIs, p < 0.001 vs. STEMI), followed by STEMI (6.7%), STDMI (4.4%), and other ECG acute myocardial infarction (2.3%). The risk of CS development was similar in patients with left bundle branch block (LBBB) (13.3%) and right bundle branch block (RBBB) (11.2%). The one-year mortality was highest among RBBBMI patients (66.7%, p < 0.001), followed by LBBBMI (48.6%), other ECG (47.1%), STEMI (41.7%), and STDMI patients (38.1%).

CONCLUSIONS

RBBB on admission ECG is associated with the highest risk of CS development, frequent left main coronary artery affection, and unsuccessful revascularization. It is also an independent predictor of one-year mortality.

Early- and late-term clinical outcome and their predictors in patients with ST-segment elevation myocardial infarction and non-ST-segment elevation myocardial infarction

BACKGROUNDS

The disparity between ST-segment elevation myocardial infarction (STEMI) and non-STEMI (NSTEMI) remains controversial. We compared clinical outcomes and prognostic factors between STEMI and NSTEMI using large-scale registry data.

METHODS

We recruited 28,421 patients with STEMI (n=16,607) and NSTEMI (n=11,814) between November 2005 and April 2010 from a nationwide registry in Korea. We performed landmark analysis of cardiac death, recurrent acute myocardial infarction (re-AMI), revascularization, and major adverse cardiac events (MACE) at 30 days (early term) and 1 year (late term) after admission.

RESULTS

Patients with NSTEMI had a greater number of co-morbidities than STEMI patients. Early term MACE (6.9% vs. 4.5%, p<0.001) and cardiac death (6.1% vs. 3.7%, p<0.001) were higher in STEMI patients. However, late-term MACE (8.0% vs. 9.1%, p=0.007), cardiac death (1.9% vs. 2.6%, p=0.001), and re-AMI (0.6% vs. 1.3%, p<0.001) were lower in the STEMI group. The independent predictors of cardiac death were old age, renal dysfunction, LV dysfunction, Killip class, post-thrombolysis in myocardial infarction (TIMI) flow, and major bleeding in both groups. Female gender, previous ischemic heart disease, diabetes, current smoking, multivessel disease, and body mass index were MI type- or time-dependent predictors.

CONCLUSION

The STEMI group displayed poor early term clinical outcome, whereas the NSTEMI group displayed poor late-term clinical outcome. The STEMI and NSTEMI groups had different predictor profiles for cardiac death, suggesting that different strategies are required for improving the late-term outcome of STEMI and NSTEMI patients.

Long-term prognosis of first myocardial infarction according to the electrocardiographic pattern (ST elevation myocardial infarction, non-ST elevation myocardial infarction and non-classified myocardial infarction) and revascularization procedures

The aim of this study was to describe differences in the characteristics and short- and long-term prognoses of patients with first acute myocardial infarction (MI) according to the presence of ST-segment elevation or non-ST-segment elevation. From 2001 and 2003, 2,048 patients with first MI were consecutively admitted to 6 participating Spanish hospitals and categorized as having ST-segment elevation MI (STEMI), non-ST-segment elevation MI (NSTEMI), or unclassified MI (pacemaker or left bundle branch block) according to electrocardiographic results at admission. The proportions of female gender, hypercholesterolemia, hypertension, and diabetes were higher among NSTEMI patients than in the STEMI group. NSTEMI 28-day case fatality was lower (2.99% vs 5.26%, p = 0.02). On multivariate analysis, the odds ratio of 28-day case fatality was 2.23 for STEMI patients compared to NSTEMI patients (95% confidence interval 1.29 to 3.83, p = 0.004). The multivariate adjusted 7-year mortality for 28-day survivors was higher in NSTEMI than in STEMI patients (hazard ratio 1.31, 95% confidence interval 1.02 to 1.68, p = 0.035). However, patients with unclassified MI presented the highest short- and long-term mortality (11.8% and 35.4%, respectively). The excess of short-term mortality in unclassified and STEMI patients was mainly observed in those patients not treated with revascularization procedures. In conclusion, patients with first NSTEMI were older and showed a higher proportion of previous coronary risk factors than STEMI patients. NSTEMI patients had lower 28-day case fatality but a worse 7-year mortality rate than STEMI patients. Unclassified MI presented the worst short- and long-term prognosis. These results support the invasive management of patients with acute coronary syndromes to reduce short-term case fatality.

Electrocardiogram-based predictors of sudden cardiac death in patients with coronary artery disease

Current recommendations on which patients with coronary artery disease (CAD) should be offered an implantable cardioverter defibrillator for the primary prevention of sudden cardiac death (SCD) rely heavily on the presence of depressed left ventricular ejection fraction. Because the majority of SCD victims with CAD have preserved left ventricular function, additional cardiac investigations are likely to play an increasing role in the risk stratification of CAD patients. A number of studies have demonstrated that certain parameters on the traditional 12-lead electrocardiogram (ECG) and other ECG-based investigations (such as signal-averaged ECG, heart rate turbulence, T-wave alternans) can provide important information on the underlying cardiac substrate abnormality that may predispose to ventricular arrhythmias and SCD. This article reviews some of the evidence for these ECG-based tests as predictors of SCD in patients with CAD and addresses their advantages and limitations.

QRS prolongation in patients with acute coronary syndromes

BACKGROUND

QRS prolongation with or without bundle branch block (BBB) has been associated with adverse outcome in myocardial infarction; we examined the relationship between QRS duration and outcome in a broad spectrum of patients with acute coronary syndrome (ACS).

METHOD AND RESULTS

Core laboratory evaluation of the presenting electrocardiogram in Canadian ACS Registry patients (n = 5,003) showed 4,289 (85.7%) had QRS <120 milliseconds, 202 (4.0%) patients had QRS > or =120 milliseconds without BBB, 262 (5.2%) had left BBB (LBBB), and 250 (5.0%) had right BBB. Compared to patients with QRS <120 milliseconds, patients with QRS > or =120 milliseconds without BBB had higher in-hospital (3.5% vs 1.9%, odds ratio [OR] 1.87, 95% CI 0.85-4.09, P = .12) and 1-year mortality (14.9% vs 7.7%, OR 2.10, 95% CI 1.38-3.18, P = .001). In-hospital and 1-year mortality was significantly higher in patients with BBB (eg, LBBB compared with QRS <120 milliseconds) (5.0% vs 1.9%, OR 2.71, 95% CI 1.49-4.94, P = .001, and 23.8% vs 7.7%, OR 3.74, 95% CI 2.72-5.13, P < .001). Analyzed as a continuous variable and after adjustment for validated prognosticators, QRS duration was an independent predictor of 1-year death (OR 1.11, 95% CI 1.06-1.16, P < .001) and death/myocardial infarction (OR 1.06, 95% CI 1.02-1.11, P = .003). However, when using clinically applicable QRS duration evaluation, only LBBB was an independent predictor of 1-year mortality (OR 1.93, 95% CI 1.28-2.90, P = .002).

CONCLUSIONS

In patients presenting with a broad spectrum of suspected ACS, QRS prolongation-particularly in the setting of LBBB-is an independent predictor of in-hospital and 1-year mortality.

Effect of beta-blockers on the risk of atrial fibrillation in patients with acute myocardial infarction

INTRODUCTION

Oral beta-blockers improve the prognosis of patients with acute myocardial infarction, while atrial fibrillation worsens the prognosis of this population. The reduction of atrial fibrillation incidence in patients treated with beta-blockers could at least in part explain the benefits of this drug.

OBJECTIVE

To investigate the effect of beta-blockers on the incidence of atrial fibrillation in patients with acute myocardial infarction.

METHODS

We analyzed 1401 patients with acute myocardial infarction and evaluated the occurrence or absence of atrial fibrillation, the use of oral beta-blockers and mortality during the first 24 hours.

RESULTS

a) The use of beta-blockers was inversely correlated with the presence of atrial fibrillation (rho = 0.004; OR = 0.54). b) Correlations with mortality were as follows: 31.5% in patients with atrial fibrillation, 9.2% in those without atrial fibrillation (rho < 0.001; Odds Ratio = 4.52), and 17.5% in patients not treated with beta-blockers and 6.7% in those who received the drug (rho < 0.001; OR = 0.34). c) Adjusted Models: The presence of atrial fibrillation was independently correlated with mortality (OR = 2.48, rho = 0.002). The use of beta-blockers was inversely and independently correlated with mortality (OR = 0.53; rho = 0.002). The patients who used beta-blockers showed a lower risk of atrial fibrillation (OR = 0.59; rho = 0.029) in the adjusted model.

CONCLUSION

The presence of atrial fibrillation and the absence of oral beta-blockers increased in-hospital mortality in patients with acute myocardial infarction. Oral beta-blockers reduced the incidence of atrial fibrillation, which might be at least partially responsible for the drug's benefit.

Impact of metabolic syndrome on future cardiovascular events in patients with first acute myocardial infarction

The prevalence of metabolic syndrome (MetS) is increasing worldwide and patients with MetS have increased risk of cardiovascular events. Recent studies in different populations showed higher prevalences of MetS in patients with acute myocardial infarction (MI) and identified MetS as an independent predictor of future cardiac events. This study sought to determine the prevalence of MetS in patients with acute MI and investigate the impact of MetS on adverse cardiovascular events after acute MI. One hundred and eighty-eight patients (155 men, 33 women) admitted with first acute MI were enrolled into the study. Of the total patients, 80 (42.6%) patients were diagnosed with MetS according to the National Cholesterol Education Program Adult Treatment Panel III criteria with modifications for high blood pressure and high fasting plasma glucose. Kaplan-Meier curves showed that the cumulative event-free survival rates did not differ between the patients with and without MetS during a median follow-up period of 27.7 (min:14, max:42) months (P>0.05). On multivariate Cox regression analysis controlling for hypertension, diabetes mellitus, glucose, MetS, and waist-to-hip ratio, there was no association between the major adverse coronary events and the presence of MetS (P>0.05), whereas Killip class (relative risk: 2.853, 95% confidence interval: 1.606-5.070; P<0.001) was identified as the only independent predictor of long-term cardiovascular outcomes. This study shows that MetS has no effect on long-term prognosis after MI. However, Killip class was identified as an independent predictor of major cardiac events.

Prognostic impact of left bundle-branch block in the early stable phase after acute myocardial infarction

BACKGROUND

Diagnostic marker parameters are needed to enable timely identification of high risk patients after acute myocardial infarction (MI). We assessed risk factors for death and sudden death in stable revascularized patients undergoing guideline-based therapy during an in-patient rehabilitation program more than 3 weeks after acute myocardial infarction.

METHODS

During an in-patient rehabilitation program, 939 patients with a recent myocardial infarction were prospectively included. Besides demographic and clinical data, ejection fraction (EF), Holter ECG, standard 12-lead electrocardiogram (ECG) and baseline laboratory values were determined. Patients were followed up for 18 months.

RESULTS

Among multiple variables, left bundle-branch block (LBBB) was the most significant parameter affecting the outcome (combination endpoint of death, resuscitation or ventricular tachycardia (VT)), hazard ratio 7.74 (3.2-18.7, P<0.0001). 42% of the 24 patients with LBBB but only 11.5% of the 62 patients with a left ventricular EF </=30% died during follow-up (P<0.001).

CONCLUSION

LBBB observed during a rehabilitation program following an acute MI indicates a grave prognosis with a high mortality rate (mainly caused by sudden death). Future studies are required to establish whether this simple marker characterizes a group of patients that will profit from preventive defibrillator implantation and/or biventricular pacing.

Distortion of the terminal portion of the QRS is predictor of shock after primary percutaneous coronary intervention for acute myocardial infarction

BACKGROUND

Although invasive management of ST segment elevation myocardial infarction has improved the clinical outcome, cardiogenic shock (CS) remains an important issue. Our purpose was to asses the utility of the initial electrocardiogram in detecting patients who are at increased risk of CS after percutaneous coronary intervention for acute myocardial infarction.

METHODS

We evaluated 508 consecutive patients admitted in our Coronary Unit and treated by primary angioplasty within 12 h of an ST segment elevation myocardial infarction. Patients with cardiogenic shock at admission were excluded. Two groups were defined according to the presence of distortion of the terminal portion of the QRS in two or more adjacent leads (group 1) or the absence of this pattern (group 2).

RESULTS

There were 99 patients (20%) in group 1 and 409 (80%) in group 2. CS developed in 38 patients, 18 in group 1 (18%) and 20 in group 2 (5%), p<0.001. Seventeen patients died in hospital, 6 in group 1 (6%) and 11 in group 2 (3%), p 0.094. Multivariate analysis including clinical, electrocardiographic and angiographic variables showed distortion of the QRS as an independent predictor of cardiogenic shock (odds ratio 3.17, 95% confidence interval 1.44 to 6.96, p 0.004), together with Killip class at admission and TIMI 3 flow after revascularization.

CONCLUSIONS

Distortion of the terminal portion of the QRS complex is a strong predictor of cardiogenic shock in STEMI patients. Close hemodynamic monitoring should be warranted in patients showing this electrocardiographic pattern.

The electrocardiogram as a prognostic tool for predicting major cardiac events

Among patients with cardiac disease, the identification of those who are at low risk and those who are at high risk for major cardiac events is crucial for a rational clinical management of individual patients. A correct noninvasive risk stratification of cardiac patients, in particular, has relevant clinical implications because it would avoid unnecessary exposure to potentially risky invasive diagnostic or interventional procedures in low-risk patients, whereas it would allow an appropriate aggressive diagnostic and therapeutic approach in high-risk patients. Furthermore, the appropriate identification of low- and high-risk patients would also have social and economic implications by favoring optimization of resource distribution and costs. A large number of studies in previous decades provided evidence that several methods and variables derived from the analysis of the electrocardiogram (ECG) are powerful predictors of major cardiac events in several clinical conditions. Despite that, there has been limited attention about how several of these findings can be used in clinical practice. Furthermore, in recent years, most studies about risk stratification of cardiac patients have mainly been focused on the use of a number of serum/plasma biomarkers with reduced attention to ECG variables. Surprisingly, however, there have been few attempts to establish whether the various proposed risk markers add any significant information to that obtainable from ECG methods. In this article, the evidence for the prognostic value of variables derived from the assessment of the ECG signal by several methods and techniques will be briefly reviewed. Because of the largeness of the topic, this review will be necessarily incomplete. Because most of the clinical research in this field concerned risk stratification of patients with coronary artery disease, the article will be largely focused on this population of patients. The role of ECG methods in specific cardiac diseases and, in particular, in the general population of asymptomatic subjects will be briefly discussed when believed appropriate and helpful. Furthermore, only major clinical events (ie, cardiac death, arrhythmic events, acute myocardial infarction) will be taken into account as end points in this article. Minor clinical events (eg, coronary revascularization procedures, coronary artery restenosis, recurrences of symptoms) are indeed less robust as end points because they are widely biased by subjective judgments.

Characteristics and outcome of patients with acute myocardial infarction according to presenting electrocardiogram (from the MONICA/KORA Augsburg Myocardial Infarction--Registry)

Acute myocardial infarctions (AMIs) are categorized according to presenting electrocardiography into ST-elevation (STE), non-STE, and bundle branch block AMIs. Data on the characteristics and risks of these categories originate mainly from voluntary registries or clinical trials and may be hampered by selection and information bias. This study evaluated these different categories, with the additional differentiation of non-STE AMIs into ST-depression (STD) AMIs and those with nonspecific electrocardiographic signs (no-ST) in an unselected cohort. From 1985 to 2004, all consecutive patients aged 25 to 74 years who were hospitalized with AMI at the study region's major clinic were registered prospectively. A total of 6,748 patients were identified, of whom 45.8% had STE, 14.0% STD, 32.4% no-ST, and 7.8% bundle branch block AMIs, respectively. There were substantial differences in medical history, presentation, and therapy among the AMI types. Even after adjusting for the latter factors, the odds ratios of 28-day case fatality compared with no-ST were 1.26 (95% confidence interval 1.01 to 1.59) for STE, 1.84 (95% confidence interval 1.39 to 2.44) for STD, and 3.18 (95% confidence interval 2.37 to 4.27) for bundle branch block. In conclusion, after considering in-hospital therapy, the difference between STE and no-ST was nonsignificant, whereas the case-fatality difference between no-ST and STD persisted, suggesting some other unknown underlying factors associated with STD.