Electrocardiographic predictors of culprit artery in acute inferior ST elevation myocardial infarction

Background

In acute inferior ST-segment elevation myocardial infarction (STEMI), multiple electrocardiographic algorithms have been proposed to predict the culprit artery. Our purpose is to review these and compare them to ST depression in lead aVR to predict culprit artery in inferior STEMI.

Methods

In 106 patients with acute inferior STEMI who underwent emergent coronary angiography, we correlated electrocardiographic and angiographic findings pertaining to the culprit artery. We then reviewed the algorithms proposed by Fiol et al and Tierala et al, and applied them and our own from Kanei et al using ST depression in aVR for predicting the left circumflex artery (LCx) as the culprit, to the population. Finally, we compared the sensitivities and specificities of the respective algorithms for predicting the culprit artery.

Results

The sensitivity and specificity of ST depression in lead aVR to predict LCx as the culprit were 53% and 86%, respectively, and 86% and 55%, respectively for predicting the right coronary artery (RCA) as the culprit. When their algorithms were applied to our population, the sensitivities and specificities of Fiol et al and Tierala et al were slightly higher.

Conclusion

Compared to other proposed algorithms, ST depression in aVR is a simple method with satisfactory sensitivity and specificity to predict the culprit artery in inferior STEMI.     

Determinants of ST-segment level in lead aVR in anterior wall acute myocardial infarction with ST-segment elevation

Background

This study aimed to clarify the determinants of ST-segment level in lead aVR in anterior wall acute myocardial infarction (AAMI).

Methods

We analyzed ST-segment levels in all 12 leads on admission and emergency coronary angiographic findings in 261 patients with a first AAMI with ST-segment elevation. The length of the left anterior descending coronary artery (LAD) was classified as follows: short = not reaching the apex; medium = perfusing less than 25% of the inferior wall; long = perfusing 25% or more of the inferior wall.

Results

The ST-segment level in lead aVR correlated significantly with the ST-segment levels in leads I, II, III, aVF, V₁, and V_3-6, especially with those in leads II and V₆ (r = −0.63, P < .001; r = −0.61, P < .001; respectively). Patients with a proximal LAD occlusion had a greater ST-segment level in lead aVR than those with a distal LAD occlusion (P < .001). Patients with a long LAD had a lower ST-segment level than those with a short or medium LAD (P < .05).

Conclusions

The ST-segment levels, especially in leads II and V₆, the site of the LAD occlusion, and the length of the LAD affect the ST-segment level in lead aVR in ST-segment elevation AAMI.     

The relationship between initial ST-segment deviation and final QRS complex changes related to the posterolateral wall in acute inferior myocardial infarction

Objectives

The aim of this study was to assess the relationship between initial ST-segment deviation and final QRS complex changes related to the posterolateral left ventricular wall in patients with acute inferior myocardial infarction receiving reperfusion therapy. The secondary aim was to determine if this relationship is stronger for patients who present early in the ischemia/infarction process in comparison with patients who present late.

Methods

The ST-segment depression in the leads V₁, V2, and −V6 were measured in the electrocardiograph (ECG) just before initiation of myocardial reperfusion. These leads were chosen because they represent the posterolateral wall in the Selvester score. In addition, the Anderson-Wilkins acuteness score was calculated in the admission ECG. Selvester criteria related to the posterolateral wall were identified in the ECG performed before hospital discharge to assess final infarct size.

Results

Fifty-six patients were included in this study. No significant relationship was found between the sum of initial ST-segment depression in the leads V₁, V₂, and −V₆, and final infarct size in the posterolateral left ventricular wall for the total study population (r = 0.19, P = .16). Patients were subgrouped by Anderson-Wilkins acuteness score of less than 3 vs 3 or more. In those with a low acuteness score, the amount of ST-segment depression had no relationship with final infarct size (r = −0.16, P = .41). However, the correlation was statistically significant for those with a high acuteness score (r = 0.42, P = .04).

Conclusion

The initial ST-segment depression in leads V₁, V₂, and −V₆ can predict ECG-estimated amount of infarction in the posterolateral left ventricular wall in patients with acute inferior myocardial infarction receiving reperfusion therapy, but only in those who present early in the ischemia/infarction process.     

Electrocardiographic characteristics in angiographically documented occlusion of the dominant left circumflex artery with acute inferior myocardial infarction: limitations of ST elevation III/II ratio and ST deviation in lateral limb leads

Background

The prognosis of dominant left circumflex artery (LCx) occlusion-related inferior acute myocardial infarction (AMI) patients is poor, but the electrocardiographic (ECG) characteristics of this AMI entity have not been described.

Methods

One hundred thirty-five patients with first dominant right coronary artery (RCA) or dominant LCx-related inferior AMI were included. The characteristics of ECG obtained on admission for 55 patients with culprit lesions proximal to the first major right ventricular (RV) branch of dominant RCA (group proximal dominant RCA), 62 patients with culprit lesions distal to the first major RV branch of dominant RCA (group distal dominant RCA), and 18 patients with culprit lesions in dominant LCx (group dominant LCx) were compared.

Results

There were no significant differences among the 3 groups in the prevalence regarding an S/R ratio greater than 1:3 in aVL, ST elevation in aVR (ST↑_aVR), ST depression in aVR (ST↓_aVR) of 1 mm or more, and atrioventricular block. Greater ST elevation in lead III than in II and greater ST depression in aVL than I showed specificity of 17% and 44% to identify dominant RCA as culprit lesion, respectively. All 3 groups could be distinguished on the basis of ST↑_V4R, ST↓_V4R, ST↓_V3/ST↑_III of 1.2 or less, and ST↓_V3/ST↑_III of more than 1.2.

Conclusions

Greater ST elevation in lead III than in II, greater ST depression in aVL than I, and an S/R ratio of greater than 1:3 in aVL were not useful to discriminate between dominant RCA and dominant LCx occlusion-related inferior AMI. ST-segment deviation in lead V₄R and the ratio of ST↓_V3/ST↑_III were useful in predicting the dominant artery occlusion-related inferior AMI.     

Primary percutaneous coronary intervention for patients presenting with ST-segment elevation myocardial infarction: process improvement in a rural ST-segment elevation myocardial infarction receiving center

Background

Rural ST-segment elevation myocardial infarction (STEMI) care networks may be particularly disadvantaged in achieving a door-to-balloon time (D2B) of less than or equal to 90 minutes recommended in current guidelines.

ST-Elevation Myocardial Infarction Process Upgrade Project

A multidisciplinary STEMI process upgrade group at a rural percutaneous coronary intervention center implemented evidence-based strategies to reduce time to electrocardiogram (ECG) and D2B, including catheterization laboratory activation triggered by either a prehospital ECG demonstrating STEMI or an emergency department physician diagnosing STEMI, single-call catheterization laboratory activation, catheterization laboratory response time less than or equal to 30 minutes, and prompt data feedback.

Evaluating success

An ongoing regional STEMI registry was used to collect process time intervals, including time to ECG and D2B, in a consecutive series of STEMI patients presenting before (group 1) and after (group 2) strategy implementation. Significant reductions in time to first ECG in the emergency department and D2B were seen in group 2 compared with group 1.

Conclusions

Important improvement in the process of acute STEMI patient care was accomplished in the rural percutaneous coronary intervention center setting by implementing evidence-based strategies.     

Electrocardiographic markers predict left ventricular wall motion improvement in patients with acute myocardial infarction receiving thrombolysis

Background

In patients with ST-elevation myocardial infarction (STEMI) treated with fibrinolysis, prediction of early left ventricular wall motion changes is important for prognosis.

Materials and Methods

In 106 patients with STEMI treated with thrombolysis, we analyzed the degrees of total and maximal ST-segment resolution at 3 hours and changes in sums of T-wave amplitudes in leads with ST elevation 3 and 48 hours after thrombolysis as the predictors of the echocardiographic left ventricular wall motion score index (WMSI) improvement.

Results

Wall motion score index improvement was best predicted by total ST-segment resolution of more than 44% in anterior infarctions (sensitivity, 81%; specificity, 62%) and more than 59% in nonanterior infarctions (sensitivity, 100%; specificity, 42%) and by difference in sums of T-wave amplitudes between electrocardiograms at 48 hours and baseline less than −28 mm (sensitivity, 68%; specificity, 76%).

Conclusion

In STEMI, the total ST-segment resolution 3 hours and T-wave changes at 48 hours after thrombolysis are the reliable predictors of the left ventricular WMSI improvement.     

Significance of a prominent Q wave in lead negative aVR (−aVR) in acute anterior myocardial infarction

Purpose

The aim of this study was to clarify the significance of a Q wave in lead negative aVR (−aVR) in anterior wall acute myocardial infarction (AMI).

Methods

Eighty-seven patients with a first anterior wall AMI were classified into 2 groups according to the presence (n = 17, group A) or absence (n = 70, group B) of a prominent Q wave (duration ≥20 milliseconds) in lead −aVR at predischarge. Group A had a higher prevalence of a long left anterior descending coronary artery (LAD), a lower left ventricular ejection fraction, and more reduced regional wall motion in the apical and inferior regions than group B. None of group A patients had an LAD that did not reach the apex.

Conclusion

A prominent Q wave in lead −aVR in anterior wall AMI is related to severe regional wall motion abnormality in the apical and inferior regions, with an LAD wrapping around the apex.     

Value of lead aVR in predicting acute occlusion of proximal left anterior descending coronary artery and in-hospital outcome in ST-elevation myocardial infarction: an electrocardiographic predictor of poor prognosis

Background

We aimed to investigate the value of ST elevation in lead aVR (ST↑aVR) in predicting the left anterior descending coronary artery (LAD) occlusion site proximal to first septal perforator (S₁) and its effect on in-hospital outcome in ST-elevation myocardial infarction (STEMI).

Methods

The study included 950 patients with STEMI. Patients were divided into 2 groups as aVR(+) and aVR(−) according to the presence of an ST↑aVR of 0.5 mm or greater.

Results

ST elevation in lead aVR was seen in 155 (16%) patients, and LAD occlusion proximal to S₁ was detected in 52% of patients in the aVR(+) group and in 9% of patients in the aVR(−) group. aVR positivity was associated with higher heart rate, lower systolic blood pressure and ejection fraction, and worse Killip class at the hospital admission. In-hospital mortality was 19% in the aVR(+) group and 5% in the aVR(−) group. aVR positivity was an independent predictor of in-hospital death.

Conclusion

This study revealed that ST↑aVR was not only a good indicator of LAD occlusion proximal to S₁ but also a source of valuable information about in-hospital outcome in patients with STEMI.     

Ischemic ST-segment episodes during the initial 24 hours of ST elevation myocardial infarction predict prognosis at 1 and 5 years

Objectives

The aims of the study were to assess the prognostic value of recurrent ischemic episodes during the first 24 hours in ST elevation myocardial infarction (STEMI) treated with thrombolysis and to explore those episodes as a part of a low-risk prognostic feature.

Design

Two hundred twenty patients with STEMI treated with thrombolysis were monitored for 24 hours with continuous online vectorcardiography assessing ST vector changes to record recurrent ischemic events.

Results

Ischemic events measured as an increase in ST-change vector magnitude (STC-VM) more than 50 μV for at least 2 minutes during 4- to 24-hour predicted mortality in a 5-year follow-up based on a multivariable analysis (hazard ratio, 1.18/episode; confidence interval, 1.01-1.37). The more episodes there were, the worse the prognosis. A low-risk group with a 1-year mortality of 1.9% could be identified.

Conclusion

Continuous ST-segment monitoring during the first 24 hours of a myocardial infarction is a valuable tool for identifying high- and low-risk patients. The STC-VM events during 4 to 24 hours of the first day of a myocardial infarction predict mortality within 5 years.     

In-hospital outcomes of a regional ST-segment elevation myocardial infarction acute transfer and repatriation program

Background

Primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) presents challenges in a large geographic area for achieving treatment time targets and creates demands on the PCI centre resources.

Objective

We compare the in-hospital mortality rate of patients presenting with STEMI and referred for PCI from 11 transfer hospitals with those presenting to the cardiac centre in a regional STEMI program with a selective repatriation strategy.

Methods

Between June 1, 2003, and June 30, 2007, clinical and procedural data of all STEMI patients who were referred to the catheterization laboratory were prospectively collected. Patients who sustained prolonged cardiac arrest were excluded.

Results

A total of 1154 patients from regional hospitals and 325 patients initially presenting to the PCI centre were referred for acute intervention. There was no significant in-hospital mortality difference between the 2 groups (3.7% vs 4.0%, respectively; P = 0.87). Multiple logistic regression analysis showed that advanced age, female gender, multivessel coronary disease, history of hypertension, low ejection fraction, increased left ventricular end-diastolic pressure, and thrombolytic pretreatment, but not transfer status, were independent predictors for mortality. Among the 1154 transfer patients, 937 patients (81.2%) returned immediately post procedure and had a lower mortality rate than the remaining 217 patients (18.2%) who required admission to the PCI centre following cardiac catheterization (1.9% vs 11.5%, P < 0.001).

Conclusion

A regional system of STEMI care based on rapid patient transfer to a PCI centre and repatriation was feasible and safe.     

Overcoming barriers to developing seamless ST-segment elevation myocardial infarction care systems in the United States: recommendations from a comprehensive Prehospital 12-lead Electrocardiogram Working Group

Background

Reducing time to reperfusion treatment for patients with ST-segment elevation myocardial infarction (STEMI) improves patient outcomes. Few medical systems consistently meet current benchmarks regarding timely access to treatment. Studies have widely demonstrated that prehospital 12-lead electrocardiography can facilitate early catheterization laboratory activation and is the most effective means of decreasing patients' time to treatment.

Methods

We gathered experts to examine the barriers to implementation of prehospital 12-lead electrocardiographic monitoring and transmission to in-hospital cardiologists in creating seamless STEMI care systems (STEMI-CS) and propose multidisciplinary approaches to overcoming these barriers.

Results and Conclusions

Physicians, hospital systems, and emergency medical services often lack coordination of care delivery and receive fragmented funding and oversight. Clinical and regulatory guidelines do not emphasize local solutions to achieving clinical benchmarks, do not target incentives at all components of the STEMI-CS, and underemphasize risk-based approaches to protecting patient health. Integration of the multiple complex components involved in STEMI-CS is essential to improving care delivery.     

Electrocardiography cannot reliably differentiate transient left ventricular apical ballooning syndrome from anterior ST-segment elevation myocardial infarction

Objective

The presentation and electrocardiographic (ECG) characteristics of transient left ventricular apical ballooning syndrome (TLVABS) can be similar to that of anterior ST-segment elevation myocardial infarction (STEMI). We tested the hypothesis that the ECG on presentation could reliably differentiate these syndromes.

Subjects and Methods

Between January 1, 2002 and July 31, 2004, we identified 18 consecutive patients with TLVABS who were matched with 36 subjects presenting with acute anterior STEMI due to atherothrombotic left anterior descending coronary artery occlusion.

Results

All patients with TLVABS were women (mean age, 72.0 ± 13.1 years). The heart rate, PR interval, QRS duration, and corrected QT interval were similar between groups. Distribution of ST elevation was similar, but patients with anterior STEMI exhibited greater ST elevation. Regressive partitioning analysis indicated that the combination of ST elevation in lead V₂ of less than 1.75 mm and ST-segment elevation in lead V₃ of less than 2.5 mm was a suggestive predictor of TLVABS (sensitivity, 67%; specificity, 94%). Conditional logistic regression indicated that the formula: (3 × ST-elevation lead V₂) + (ST-elevation V₃) + (2 × ST-elevation V₅) allowed possible discrimination between TLVABS and anterior STEMI with an optimal cutoff level of less than 11.5 mm for TLVABS (sensitivity, 94%; specificity, 72%). Patients with TLVABS were less likely to have concurrent ST-segment depression (6% vs 44%; P = .003).

Conclusions

Women presenting with TLVABS have similar ECG findings to patients with anterior infarct but with less-prominent ST-segment elevation in the anterior precordial ECG leads. These ECG findings are relatively subtle and do not have sufficient predictive value to allow reliable emergency differentiation of these syndromes.     

Optimization of the precordial leads of the 12-lead electrocardiogram may improve detection of ST-segment elevation myocardial infarction

Background

For the assessment of patients with chest pain, the 12-lead electrocardiogram (ECG) is the initial investigation. Major management decisions are based on the ECG findings, both for attempted coronary artery revascularization and risk stratification. The aim of this study was to determine if the current 6 precordial leads (V₁-V₆) are optimally located for the detection of ST-segment elevation in ST-segment elevation myocardial infarction (STEMI).

Methods

We analyzed 528 (38% anterior [200], 44% inferior [233], and 18% lateral [95]) patients with STEMI with both a 12-lead ECG and an 80-lead body surface map (BSM) ECG (Prime ECG, Heartscape Technologies, Bangor, Northern Ireland). Body surface map was recorded within 15 minutes of the 12-lead ECG during the acute event and before revascularization. ST-segment elevation of each lead on the BSM was compared with the corresponding 12-lead precordial leads (V₁-V₆) for anterior STEMI. In addition, for lateral STEMI, leads I and aVL of the BSM were also compared; and limb leads II, III, aVF of the BSM were compared with inferior unipolar BSM leads for inferior STEMI. Leads with the greatest mean ST-segment elevation were selected, and significance was determined by analysis of variance of the mean ST segment.

Results

For anterior STEMI, leads V₁, V₂, 32, 42, 51, and 57 had the greatest mean ST elevation. These leads are located in the same horizontal plane as that of V₁ and V₂. Lead 32 had a significantly greater mean ST elevation than the corresponding precordial lead V₃ (P = .012); and leads 42, 51, and 57 were also significantly greater than corresponding leads V₄, V₅, V₆, respectively (P < .001). Similar findings were also found for lateral STEMI. For inferior STEMI, the limb leads of the BSM (II, III, and aVF) had the greatest mean ST-segment elevation; and lead III was significantly superior to the inferior unipolar leads (7, 17, 27, 37, 47, 55, and 61) of the BSM (P < .001).

Conclusion

Leads placed on a horizontal strip, in line with leads V₁ and V₂, provided the optimal placement for the diagnosis of anterior and lateral STEMI and appear superior to leads V₃, V₄, V₅, and V₆. This is of significant clinical interest, not only for ease and replication of lead placement but also may lead to increased recruitment of patients eligible for revascularization with none or borderline ST-segment elevation on the initial 12-lead ECG.     

ST-segment resolution assessed immediately after primary percutaneous coronary intervention correlates with infarct size and left ventricular function in cardiac magnetic resonance at 1-year follow-up

Background

Little is known about the predictive value of electrocardiographic ST-segment resolution (STR) assessed immediately after primary percutaneous coronary intervention (PCI). The aim of the study was to analyze the value of STR and maximum single-lead ST-segment elevation assessed immediately after primary PCI in prediction of infarct size and left ventricular function in cardiac magnetic resonance (CMR) at 1-year follow-up.

Methods and results

A total of 28 patients with anterior wall ST-segment elevation myocardial infarction treated with primary PCI entered the study. There was a significant correlation of STR and maximum single-lead ST-segment elevation assessed immediately after primary PCI and CMR infarct size and left ventricular function after 1 year. When analyzed according to standard optimal reperfusion cutoff (70% for STR and 1 mm for single-lead elevation), both electrocardiographic parameters were also good predictors of CMR infarct size and left ventricular function after 1 year.

Conclusions

ST-segment resolution and the single-lead maximum ST-segment elevation assessed immediately after primary PCI for ST-segment elevation myocardial infarction are good predictors of infarct size and left ventricular function in 1-year follow-up.     

The prognostic value of the Tpeak-Tend interval in patients undergoing primary percutaneous coronary intervention for ST-segment elevation myocardial infarction

Introduction

The Tpeak-Tend interval (TpTe) has been linked to increased arrhythmic risk. TpTe was investigated before and after primary percutaneous coronary intervention (pPCI) in patients with ST-segment elevation myocardial infarction (STEMI).

Method

Patients with first-time STEMI treated with pPCI were included (n = 101; mean age 62 years; range 39-89 years; 74% men). Digital electrocardiograms were taken pre- and post-PCI, respectively. Tpeak-Tend interval was measured in leads with limited ST-segment deviation. The primary end point was all-cause mortality during 22 ± 7 months (mean ± SD) of follow-up.

Results

Pre- and post-PCI TpTe were 104 milliseconds [98-109 milliseconds] and 106 milliseconds [99-112 milliseconds], respectively (mean [95% confidence interval], P = .59). A prolonged pre-PCI TpTe was associated with increased mortality (hazard ratio, 10.5 [1.7-20.4] for a cutoff value of 100 milliseconds). Uncorrected QT and heart rate-corrected QT intervals (Fridericia-corrected QT) were prolonged after PCI (QT: 401 vs 410 milliseconds, P = .022, and Fridericia-corrected QT: 430 vs 448 milliseconds, P < .0001).

Conclusion

In patients with STEMI undergoing pPCI, pre-PCI TpTe predicted subsequent all-cause mortality, and the QT interval was increased after the procedure.     

Referral of patients with ST-segment elevation acute myocardial infarction directly to the catheterization suite based on prehospital teletransmission of 12-lead electrocardiogram

Background

Time from symptom onset to reperfusion is essential in patients with ST-segment elevation acute myocardial infarction. Prior studies have indicated that prehospital 12-lead electrocardiogram (ECG) transmission can reduce time to reperfusion.

Purpose

Determine 12-lead ECG transmission success rates, and time saved by referring patients directly to primary percutaneous coronary intervention (pPCI) bypassing local hospitals and emergency departments.

Methods

Prehospital 12-lead ECG was recorded in patients with symptoms suggesting acute coronary syndrome during a 1-year pilot phase and transmitted to the attending cardiologist's mobile phone. Transmission success rates were determined, and prehospital and hospital delays were recorded and compared to historic controls.

Results

Transmission was attempted in 152 patients and was successful in 89%. Twenty-seven patients were referred directly for pPCI. Median hospital arrival to pPCI was 22 vs 94 minutes in the control group (P < .01).

Conclusions

Transmission of prehospital ECG is technically feasible and reduces time to pPCI in ST-segment elevation acute myocardial infarction patients.     

Effects of ischemic preconditioning and arterial collateral flow on ST-segment elevation and QRS complex prolongation in a canine model of acute coronary occlusion

Background

During acute myocardial infarction, both ST elevation and QRS distortion on the initial electrocardiogram (ECG) have been correlated with poorer prognosis. Studies in dogs and humans suggest that these ECG markers provide information about myocardial protection from both collateral blood flow and ischemic preconditioning.

Methods

In a protocol designed to precondition the heart with ischemia, we examined both ST-segment elevation and QRS complex prolongation in lead II of the ECG in 23 mongrel dogs during the first and fourth episode of 5 minutes of left circumflex artery occlusion. Myocardial collateral flow was measured during each of these episodes by injection of radioactive microspheres 2.5 minutes into the episode of ischemia.

Results

During ischemia, the degree of elevation of the ST segments was reduced markedly in hearts preconditioned with ischemia and/or in hearts with the greatest amounts of collateral arterial flow. During the first episode of ischemia, the ST segments increased to a similar extent in severe and moderate ischemia, but less in hearts in which the ischemia was mild. However, marked QRS prolongation was present only in hearts with severe ischemia, and decreased when the hearts were preconditioned. In addition, large ischemic beds exhibited the most marked QRS prolongation, whereas small but even severely ischemic beds showed little or no change in QRS duration.

Conclusion

Both ST elevation and QRS prolongation are reduced by the presence of collateral flow and ischemic preconditioning. The QRS complex merits further study as an important marker of the degree of myocardial protection during human acute myocardial ischemia/infarction.     

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.     

Excess heparin dosing among fibrinolytic-treated patients with ST-segment elevation myocardial infarction

Background

Although the use of heparin with fibrinolytics is associated with more rapid ST-segment resolution and increased infarct-related artery patency among patients with ST-segment elevation myocardial infarction (STEMI), its associated increase in bleeding risk is well documented and might be augmented by excess heparin dosing.

Methods

We sought to characterize the incidence and associated bleeding risk of excess heparin dosing among patients with STEMI treated with fibrinolysis who were enrolled in the Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes with Early Implementation of the American College of Cardiology/American Heart Association Guidelines initiative. Excess dosing was defined as a bolus more than 60 U/kg or an infusion more than 12 U/kg/h per American College of Cardiology/American Heart Association guidelines and was further stratified into major and mild excess (major defined as a bolus > 70 U/kg or infusion >15 U/kg/h).

Results

Among 964 fibrinolytic-treated patients with STEMI, 758 (79%) received adjunctive unfractionated heparin therapy. Of these, 368 patients (49%) received excess dosing of unfractionated heparin and 137 patients (18%) received major excess heparin dosing. Factors significantly associated with excess dosing included low body weight and female sex. Patients who received major excess dosing had higher unadjusted rates of major bleeding (19.2% vs 12.4%, P = .004) and transfusion (13.5% vs 4.7%, P = .0002) than patients without excess dosing. After adjustment, a trend persisted for the association with higher transfusion risk (odds ratio 1.39 [0.61-3.14]).

Conclusion

Approximately half of fibrinolytic-treated patients with STEMI in contemporary practice received an excess dose of unfractionated heparin. Careful attention to dosing is needed to limit the compounded bleeding risk when heparin is added to fibrinolytic therapy.     

Grade 3 ischemia on admission electrocardiogram and chest pain duration predict failure of ST-segment resolution after primary percutaneous coronary intervention for acute myocardial infarction

Objectives

ST resolution (STR) is a surrogate marker of myocardial tissue reperfusion and a predictor of outcome after primary percutaneous coronary intervention (pPCI) for ST-elevation myocardial infarction (STEMI). Terminal QRS distortion (grade 3 ischemia) has been shown to predict failure of STR after thrombolysis for STEMI, but the ability of grade 3 ischemia to predict STR with pPCI is unclear.

Methods

We retrospectively analyzed 155 patients who underwent pPCI and compared grade 2 ischemia (ST elevation without terminal QRS distortion; n = 89) to grade 3 ischemia (n = 66) on admission for baseline characteristics, in-hospital course, and STR immediately after pPCI and at 18 to 24 hours.

Results

Patients with grade 3 ischemia were older (60 ± 12 vs 56 ± 11 years; P = .018), had more anterior STEMI (42% vs 17%; P = .0004), and were less often smokers (41% vs 90%; P = .004). The grade 3 ischemic group had significantly less complete STR (35% vs 75% [P < .00001] immediately after pPCI and 33% vs 79% [P < .00001] 18-24 hours after pPCI), a longer hospital stay (6.4 ± 4.1 vs 4.9 ± 1.9 days; P = .008), and higher peak CKMB (292 ± 231 vs 195 ± 176 ng/mL; P = .0005). Duration of symptoms before pPCI (odds ratio [OR], 0.838; 95% confidence interval [CI], 0.724-0.969; P = .017) and grade 3 ischemia (OR, 0.181; 95% CI, 0.068-0.480; P < .001) were negative predictors of complete STR, whereas nonanterior STEMI (OR, 5.95; 95% CI, 2.154-16.436; P < .001) and initial sum of ST elevation (OR, 3.132; 95% CI, 1.140-8.605; P = .027) were positive predictors.

Conclusion

Grade 3 ischemia on presentation of STEMI and duration of chest pain are strong independent predictors of failure to achieve complete STR after pPCI.