Patients With Prolonged Ischemic Chest Pain and Presumed-New Left Bundle Branch Block Have Heterogeneous Outcomes Depending on the Presence of ST-Segment Changes

Clinical Outcomes According to ECG Presentations in Infarct-Related Cardiogenic Shock in the Culprit Lesion Only PCI vs Multivessel PCI in Cardiogenic Shock Trial

BACKGROUND

The impact of ECG presentations of acute myocardial infarction (AMI) in cardiogenic shock is unknown.

RESEARCH QUESTION

In myocardial infarction with cardiogenic shock, is there a difference in the outcomes and effect of revascularization strategies between non-ST-segment elevation myocardial infarction (NSTEMI) and left bundle branch block myocardial infarction (LBBBMI) vs ST-segment elevation myocardial infarction (STEMI)?

STUDY DESIGN AND METHODS

Cardiogenic shock patients from the CULPRIT-SHOCK trial with NSTEMI or LBBBMI were compared with STEMI patients for 30-day and 1-year all-cause mortality. The interaction between ECG presentation and the effect of revascularization strategies on outcomes was evaluated.

RESULTS

Of 665 cardiogenic shock patients analyzed, 55.9% demonstrated STEMI, 29.3% demonstrated NSTEMI, and 14.7% demonstrated LBBBMI. Patients differed in mean age (68.0 years in STEMI patients, 71.0 years in NSTEMI patients, and 73.5 years in LBBBMI patients; P = .015), cardiovascular risk factors, and angiographic severity. No difference was found in the 30-day risk of death between NSTEMI and STEMI patients (48.7% vs 43.0%; adjusted OR [aOR], 1.05; 95% CI, 0.66-1.67; P = .85), nor between LBBBMI and STEMI patients (59.2% vs 43.0%; aOR, 1.31; 95% CI, 0.73-2.34; P = .36). Although the univariate risk of death by 1 year was higher in NSTEMI and LBBBMI patients compared with STEMI patients, ECG presentation was not an independent risk factor of mortality after adjustment (NSTEMI vs STEMI: 56.4% vs 46.8%; aOR, 1.21; 95% CI, 0.76-1.92; P = .42; LBBBMI vs STEMI: 69.4% vs 46.8%; aOR, 1.59; 95% CI, 0.89-2.84; P = .12). ECG presentation did not modify the effect of the revascularization strategy on 30-day and 1-year mortality (P = .91 and P = .97 for interaction).

INTERPRETATION

In patients with cardiogenic shock, NSTEMI and LBBBMI presentations reflect higher-risk profiles than STEMI presentations, but are not independent risk factors of mortality. ECG presentations did not modify the treatment effect, supporting culprit-lesion-only percutaneous coronary intervention as the preferred strategy across the AMI spectrum.

In the transition from fibrinolysis to primary PCI, the HERO trials help refine STEMI ECG interpretation and Q wave analysis potentially alters future management

Electrocardiogram sub-studies from the Hirulog Early Reperfusion/Occlusion 1 and 2 trials, which tested bivalirudin as an adjunctive anticoagulant to fibrinolysis in ST-elevation myocardial infarction, have contributed to the literature. The concept of using the presence of infarct lead Q waves to determine reperfusion benefit has subsequently been explored in multiple primary percutaneous coronary intervention studies. The angiographic findings before percutaneous coronary intervention combine with the baseline electrocardiogram to accurately diagnose ST-elevation myocardial infarction and evaluate its potential territory. This review discusses the relative merits of the presence of infarct lead Q waves versus time duration from symptom onset using observational data from cohorts of patients from multiple clinical trials. The presence of infarct lead Q waves at presentation has been repeatedly shown to be superior to time duration from symptom onset in determining prognosis, despite that continuous variable (time duration) statistically should be more powerful than dichotomous variable (Q wave). If quantitative or semi-quantitative measurement of Q waves correlates well with irreversible myocardial injury in vivo (a research goal of many cardiac magnetic resonance imaging studies), Q waves measurements by mirroring ST-elevation myocardial infarction evolution better than the current metric of time duration of symptoms will impact future ST-elevation myocardial infarction reperfusion management. Newer methodology will more quickly capture and transmit electrocardiogram information including infarct lead Q waves potentially before first medical contact, and help differentiate new evolving Q waves of the ongoing ST-elevation myocardial infarction from old changes. Q waves as the new metric in ST-elevation myocardial infarction reperfusion should be tested in upcoming trials.

Assessment of Smith Algorithms for the Diagnosis of Acute Myocardial Infarction in the Presence of Left Bundle Branch Block

INTRODUCTION AND OBJECTIVES

Recently, a new electrocardiography algorithm has shown promising results for the the diagnosis of acute myocardial infarction in the presence of left bundle branch block (LBBB). We aimed to assess these new electrocardiography rules in a cohort of patients referred for primary percutaneous coronary intervention (pPCI).

METHODS

Retrospective observational cohort study that included all patients with suspected myocardial infarction and LBBB on the presenting electrocardiogram, referred for pPCI to 4 tertiary hospitals in Barcelona, Spain.

RESULTS

A total of 145 patients were included. Fifty four (37%) had an ST-segment elevation myocardial infarction (STEMI) equivalent. Among patients with STEMI, 25 (46%) presented in Killip class III or IV, and in-hospital mortality was 15%. Smith I and II rules performed better than Sgarbossa algorithms and showed good specificity (90% and 97%, respectively) but their sensitivity was 67% and 54%, respectively. In a strategy guided by Smith I or Smith II rules, 18 (33%) or 25 (46%) patients with STEMI would have not received a pPCI, respectively. Moreover, the severity and prognosis of STEMI patients was similar regardless of the positivity of Smith rules. Cardiac biomarkers were positive in 54% of non-STEMI patients, limiting their usefulness for initial diagnostic screening.

CONCLUSIONS

Diagnosis of STEMI in the presence of LBBB remains a challenge. Smith rules can be useful but are limited by suboptimal sensitivity. The search for new electrocardiography algorithms should be encouraged to avoid unnecessary aggressive treatments in the majority of patients, while providing timely reperfusion to a high-risk subgroup of patients.

New or presumed new left bundle branch block in patients with suspected ST-elevation myocardial infarction

AIMS

Using a comprehensive large prospective regional ST-elevation myocardial infarction (STEMI) system database, we evaluated the prevalence, clinical and angiographic characteristics, and outcomes in patients with ischemic symptoms and new or presumed new left bundle branch block (LBBB). We then tested a new hierarchical diagnosis and triage algorithm to identify more accurately new LBBB patients with an acute culprit lesion.

METHODS AND RESULTS

From March 2003 to June 2013, 3903 consecutive STEMI patients were treated using the Minneapolis Heart Institute regional STEMI protocol including 131 patients (3.3%) with new LBBB. These patients had fewer culprit arteries (54.2% vs. 86.4%; P<0.001), were older, more commonly women, with a lower ejection fraction, and more frequently presented with cardiac arrest or heart failure than those without new LBBB. At 1 year follow-up, all-cause mortality accounting for baseline differences was higher in patients with new LBBB (hazard ratio 1.73, 95% confidence interval 1.17-2.58; P=0.007). The new algorithm yielded high sensitivity (97%) and negative predictive value (94%) for identification of a culprit lesion. Using the definition of new LBBB with either hemodynamically unstable features or Sgarbossa concordance criteria on electrocardiogram (ECG), 45% of new LBBB patients would have been treated as 'STEMI equivalent'.

CONCLUSION

Patients with acute ischemic symptoms and new LBBB represent a high-risk population with unique clinical challenges. If validated in an independent dataset, the new algorithm may improve the diagnostic accuracy regarding reperfusion therapy for new LBBB patients.

Simplifying electrocardiographic assessment in STEMI reperfusion management: Pros and cons

Current guidelines on STEMI reperfusion management do not incorporate further electrocardiographic details over the presence of significant ST elevation. Fibrinolysis is considered an alternative therapy to primary PCI if there is a long PCI-related delay, but the 2 therapies should not be combined. Meanwhile, reperfusion for ischemic stroke has evolved on mechanistic understanding - reperfusion benefit being greatest in the patient with small "core" infarct and large ischemic "penumbra". Fibrinolysis is not regarded as an alternative to mechanical thrombectomy, and the 2 therapies can be combined. In this article describing how reperfusion regimes have evolved along different paths for STEMI and for ischemic stroke, a new concept is made that in STEMI infarct lead Q waves can be the counterpart of the "core" and ST elevation the "penumbra". Suggestions to modify STEMI treatment algorithms are made, exploring further the relative role of (pre-hospital) fibrinolysis versus PCI particularly in younger patients presenting at the onset of their STEMI (no Q waves). In contrast, some patients particularly the older ones with more evolved STEMI (large Q waves present) may be much more suited for PCI despite expecting a long delay. The article finishes by describing potential future alterations in the method of reperfusion. Despite primary PCI being the well-established therapy, there are rooms for further research to optimize STEMI outcomes.

Diagnosis of myocardial infarction and ischemia in the setting of bundle branch block and cardiac pacing

The diagnosis of myocardial infarction (MI) in the presence of left bundle branch block (LBBB) or during ventricular pacing (VP) is challenging because of inherent changes in the sequence of ventricular depolarization and repolarization associated with both conditions. Although LBBB and right ventricular (RV) pacing may both produce abnormalities in the ECG, it is often possible to diagnose an acute MI (AMI) or an old MI based on selected morphologic changes. Primary ST-segment changes scoring 3 points or greater according to the Sgarbossa criteria are highly predictive of an AMI in patients with LBBB or RV pacing. The modified Sgarbossa criteria are useful for the diagnosis of AMI in patients with LBBB; however, these criteria have not yet been studied in the setting of RV pacing. Although changes of the QRS complex are not particularly sensitive for the diagnosis of an old MI in the setting of LBBB or RV pacing, the qR complex and Cabrera sign are highly specific for the presence of an old infarct. Diagnosing AMI in the setting of biventricular (BiV) pacing is challenging. To date there is minimal evidence suggesting that the traditional electrocardiographic criteria for diagnosis of AMI in bundle branch block may be applicable to patients with BiV pacing and positive QRS complexes on their ECG in lead V1. This report is a careful review of the electrocardiographic criteria facilitating the diagnosis of acute and remote MI in patients with LBBB and/or VP.

Troponin I Assay for Identification of a Significant Coronary Stenosis in Patients with Suspected Acute Myocardial Infarction and Wide QRS Complex

Background

Common ECG criteria such as ST-segment changes are of limited value in patients with suspected acute myocardial infarction (AMI) and bundle branch block or wide QRS complex. A large proportion of these patients do not suffer from an AMI, whereas those with ST-elevation myocardial infarction (STEMI) equivalent AMI benefit from an aggressive treatment. Aim of the present study was to evaluate the diagnostic information of cardiac troponin I (cTnI) in hemodynamically stable patients with wide QRS complex and suspected AMI.

Methods

In 417 out of 1818 patients presenting consecutively between 01/2007 and 12/2008 in a prospective multicenter observational study with suspected AMI a prolonged QRS duration was observed. Of these, n = 117 showed significant obstructive coronary artery disease (CAD) used as diagnostic outcome variable. cTnI was determined at admission.

Results

Patients with significant CAD had higher cTnI levels compared to individuals without (median 250ng/L vs. 11ng/L; p<0.01). To identify patients needing a coronary intervention, cTnI yielded an area under the receiver operator characteristics curve of 0.849. Optimized cut-offs with respect to a sensitivity driven rule-out and specificity driven rule-in strategy were established (40ng/L/96ng/L). Application of the specificity optimized cut-off value led to a positive predictive value of 71% compared to 59% if using the 99^th percentile cut-off. The sensitivity optimized cut-off value was associated with a negative predictive value of 93% compared to 89% provided by application of the 99^th percentile threshold.

Conclusion

cTnI determined in hemodynamically stable patients with suspected AMI and wide QRS complex using optimized diagnostic thresholds improves rule-in and rule-out with respect to presence of a significant obstructive CAD.

Pre-hospital management of patients with chest pain and/or dyspnoea of cardiac origin. A position paper of the Acute Cardiovascular Care Association (ACCA) of the ESC

Chest pain and acute dyspnoea are frequent causes of emergency medical services activation. The pre-hospital management of these conditions is heterogeneous across different regions of the world and Europe, as a consequence of the variety of emergency medical services and absence of specific practical guidelines. This position paper focuses on the practical aspects of the pre-hospital treatment on board and transfer of patients taken in charge by emergency medical services for chest pain and dyspnoea of suspected cardiac aetiology after the initial assessment and diagnostic work-up. The objective of the paper is to provide guidance, based on evidence, where available, or on experts’ opinions, for all emergency medical services’ health providers involved in the pre-hospital management of acute cardiovascular care.

Left bundle branch block and suspected myocardial infarction: does chronicity of the branch block matter?

BACKGROUND

Our aim was to investigate if patients with suspected myocardial infarction (MI) and a new or presumed new left bundle branch block (nLBBB) were treated according to the ESC reperfusion guidelines and to compare them with patients having a previously known LBBB (oLBBB). Furthermore, we investigated the prevalence of ST-segment concordance in this population.

METHODS

Retrospective data was collected from the Swedeheart registry for patients admitted to the cardiac care unit at Örebro University Hospital with LBBB and suspected MI during 2009 and 2010. The patients were divided in two age groups; <80 or ≥80 years and analysed for LBBB chronicity (nLBBB or oLBBB), MI, and reperfusion treatment. We also compared our data with the national Swedeheart database for 2009.

RESULTS

A total of 99 patients fulfilled the inclusion criteria. A diagnosis of MI was significantly more common in the group ≥80 years compared to the group <80 years (53.8 vs. 25%, p=0.007). The rate of MI was similar in the groups with nLBBB and oLBBB (33 and 37% respectively, p=0.912). Of the 36 patients with a final diagnosis of MI, only eight (22%) had nLBBB. Reperfusion treatment, defined as an acute coronary angiography with or without intervention, was significantly more often performed in patients with nLBBB compared to patients with oLBBB (42 vs. 8%, p<0.001). The rate of MI and reperfusion treatment did not differ between our institution and the Swedish national data. ST-concordance was present in only two cases, one of which did not suffer an MI.

CONCLUSIONS

The proportion of patients receiving reperfusion treatment was low, but higher in nLBBB, reflecting a partial adherence to the guidelines. We found no correlation between LBBB chronicity and MI. Furthermore, only a minority of the MIs occurred in patients with nLBBB. ST-concordance was found in only one of 36 MI cases, indicating lack of sensitivity for this test.

Reperfusion therapy for ST-segment elevation myocardial infarction: has ECG information been underutilized?

This perspective makes a contentious viewpoint that ECG information is underutilized in ST-segment elevation myocardial infarction (STEMI) and the next breakthrough rests on its full utilization. This is to better diagnose difficult cases such as ST changes during bundle branch block, posterior ST elevation and right-sided ST elevation during normal conduction, and aVR ST elevation. More importantly, this is to better characterize the STEMI for tailored reperfusion. The proposal is to develop a system capable of recording from multiple electrodes that one can apply onto oneself, and having analysis coordinated centrally via phone-internet transmission. This provides 'longitudinal' in addition to 'cross-sectional' ECG information. STEMI will be classified on a gray-scale according to its potential size and speed of Q wave evolution. The hypothesis is that large rapidly progressive STEMI is best treated by on-site fibrinolysis with prompt transferral to a percutaneous coronary intervention center; while small stuttering STEMI is best treated by primary percutaneous coronary intervention despite a long delay.

Synopsis and Review of the American College of Cardiology Foundation/American Heart Association 2013 ST-Elevation Myocardial Infarction Guideline

The “2013 ACCF/AHA Guideline for the Management of ST-Elevation Myocardial Infarction: A Report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines” is a major revision of the 2004 guideline. This article provides a synopsis and review of the guideline focusing on changes in patient care and implementing processes to ensure quality care. The implementation of this guideline provides nursing with a unique opportunity to affect patients and families primarily by recognition of the event and education about lifestyle modification and disease management. Regionalization of emergency systems provides a novel situation for nursing to develop interdepartmental and system protocols

Difficult ECGs in STEMI: lessons learned from serial sampling of pre- and in-hospital ECGs

Prehospital interpretation of electrocardiograms (ECGs) is crucial to ensure early diagnosis and optimal treatment of patients with ST elevation myocardial infarction (STEMI). Recognition of ST-segment elevations (STE) by qualified personnel in the prehospital phase has successfully reduced the delay from the first medical contact to reperfusion. A few other ECG patterns without true STE, referred to as "STEMI equivalents", bear the same prognostic significance, reflect imminent or ongoing transmural ischemia, but are less easily identified. Hyperacute T waves, de Winter ST-T complex, Wellens' syndrome, and posterior STEMI, as well as myocardial infarction in the presence of left bundle branch block, paced rhythm or left ventricular hypertrophy, among others are diagnostic challenges. This article reviews some critical examples of ischemic ECG patterns that may be ephemeral, misinterpreted by medical staff or not identified by automated ECG algorithms, and it emphasizes the importance of serial ECG acquisition.

New ST-depression: an under-recognized high-risk category of 'complete' ST-resolution after reperfusion therapy

AIM

It is not known if there is an association between resolution of ST-elevation to ST-depression following fibrinolysis and 30-day mortality.

METHODS

In an ECG substudy of HERO-2, which compared bivalirudin to unfractionated heparin following streptokinase in 12,556 patients with ST-elevation myocardial infarction ECGs were recorded at baseline and at 60 minutes after commencing fibrinolysis. The main outcome measure was 30-day mortality.

RESULTS

Using summed ST-segment elevation and five categories of changes in the infarct leads, further ST-elevation, 0-30% ST-resolution, >30-70% (partial) ST-resolution, >70% (complete) ST-resolution, and new ST-depression occurred in 21.7, 24.9, 36.8, 14.8, and 1.8% of patients, with 30-day mortality of 12.3, 11.7, 8.0, 4.2, and 8.1%, respectively. For the comparison of new ST-depression with complete ST-resolution and no ST-depression, p<0.01 with 24-hour mortality 4.5 vs. 1.3%, respectively (p=0.0003). Patients with new ST-depression had similar peak cardiac enzyme elevations as patients with complete ST-resolution without ST-depression. On multivariate analysis including summed ST-elevation at baseline, age, sex, and infarct location, new ST-depression was a significant predictor of 30-day mortality (OR 1.82, 95% CI 1.42-4.29).

CONCLUSIONS

In patients with complete ST-resolution following fibrinolysis, new ST-depression at 60 minutes developed in 10.8% of patients. These patients had higher mortality than patients with complete ST-resolution without ST-depression and represent a high-risk group which could benefit from rapid triage to early angiography and revascularization as appropriate.

The left bundle-branch block puzzle in the 2013 ST-elevation myocardial infarction guideline: from falsely declaring emergency to denying reperfusion in a high-risk population. Are the Sgarbossa Criteria ready for prime time?

Prompt and accurate identification of ST-elevation myocardial infarction (STEMI) in the presence of left bundle-branch block (LBBB) remains difficult. The 2004 STEMI guideline recommended emergent reperfusion therapy to patients with suspected ischemia and new or presumably new LBBB. These recommendations have led to frequent false catheterization laboratory activation and inappropriate fibrinolytic therapy because most patients with suspected ischemia and new or presumably new LBBB do not have acute coronary artery occlusion on angiography. The new 2013 STEMI guideline makes a drastic change by removing previous recommendations. Therefore, patients with suspected ischemia and new or presumably new LBBB would no longer be treated as STEMI equivalent. The new guideline fails to recognize that some patients with suspected ischemia and LBBB do have STEMI, and denying reperfusion therapy could be fatal. The Sgarbossa electrocardiography criteria are the most validated tool to aid in the diagnosis of STEMI in the presence of LBBB. A Sgarbossa score of ≥3 has a superb specificity (98%) and positive predictive value for acute myocardial infarction and angiography-confirmed acute coronary occlusion. Thus, we propose a diagnosis and triage algorithm incorporating the Sgarbossa criteria to quickly and accurately identify, among patients presenting with chest pain and new or presumably new LBBB, those with acute coronary artery occlusion. This is a high-risk population in which reperfusion therapy would be denied by the 2013 STEMI guideline. Our algorithm will also significantly reduce false catheterization laboratory activation and inappropriate fibrinolytic therapy, the inevitable consequence of the 2004 STEMI guideline.

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

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

Automatic classification of long-term ambulatory ECG records according to type of ischemic heart disease

BACKGROUND

Elevated transient ischemic ST segment episodes in the ambulatory electrocardiographic (AECG) records appear generally in patients with transmural ischemia (e. g. Prinzmetal's angina) while depressed ischemic episodes appear in patients with subendocardial ischemia (e. g. unstable or stable angina). Huge amount of AECG data necessitates automatic methods for analysis. We present an algorithm which determines type of transient ischemic episodes in the leads of records (elevations/depressions) and classifies AECG records according to type of ischemic heart disease (Prinzmetal's angina; coronary artery diseases excluding patients with Prinzmetal's angina; other heart diseases).

METHODS

The algorithm was developed using 24-hour AECG records of the Long Term ST Database (LTST DB). The algorithm robustly generates ST segment level function in each AECG lead of the records, and tracks time varying non-ischemic ST segment changes such as slow drifts and axis shifts to construct the ST segment reference function. The ST segment reference function is then subtracted from the ST segment level function to obtain the ST segment deviation function. Using the third statistical moment of the histogram of the ST segment deviation function, the algorithm determines deflections of leads according to type of ischemic episodes present (elevations, depressions), and then classifies records according to type of ischemic heart disease.

RESULTS

Using 74 records of the LTST DB (containing elevated or depressed ischemic episodes, mixed ischemic episodes, or no episodes), the algorithm correctly determined deflections of the majority of the leads of the records and correctly classified majority of the records with Prinzmetal's angina into the Prinzmetal's angina category (7 out of 8); majority of the records with other coronary artery diseases into the coronary artery diseases excluding patients with Prinzmetal's angina category (47 out of 55); and correctly classified one out of 11 records with other heart diseases into the other heart diseases category.

CONCLUSIONS

The developed algorithm is suitable for processing long AECG data, efficient, and correctly classified the majority of records of the LTST DB according to type of transient ischemic heart disease.

The prognostic meaning of the full spectrum of aVR ST-segment changes in acute myocardial infarction

AIMS

ST-elevation in lead aVR is known to be associated with a worse prognosis in patients with acute ST elevation myocardial infarction (MI) but the significance of ST depression in lead aVR has been unclear. Infarction of the inferior apex of the left ventricle may not be appreciated on the standard 12-lead electrocardiogram (ECG) except by observing ST depression in lead aVR which is reciprocal to lead V(7). We therefore determined the prognostic value of the full spectrum of aVR ST changes in patients presenting with acute ST elevation MI.

METHODS AND RESULTS

Lead aVR ST level was measured on randomization and 60 min ECGs in 15 315 patients with normal conduction from the HERO-2 trial. The outcome measure was 30-day mortality. aVR ST elevation ≥1 mm was associated with higher 30-day mortality for both inferior (22.5% for ≥1.5 mm and 13.2% for 1 mm) and anterior (23.5% for ≥1.5 mm and 11.5% for 1 mm) infarction. In contrast, deeper aVR ST depression (0, 0.5, 1, and ≥1.5 mm) was associated with higher mortality for anterior infarction (9.8, 13.2, 12.8, and 16.8%, respectively, trend P-value <0.0001) but not for inferior infarction. The resolution of aVR ST depression and ST elevation 60 min after fibrinolysis was associated with lower mortality.

CONCLUSION

There is a U-shaped relationship between 30-day mortality and aVR ST level in patients presenting with anterior but not inferior ST elevation MI.

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

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

Outcomes in patients with chronicity of left bundle-branch block with possible acute myocardial infarction

INTRODUCTION

Guidelines derived from patients in clinical trials indicate that emergency department patients with likely myocardial infarction (MI) who have new left bundle-branch block (LBBB) should undergo rapid reperfusion therapy. Whether this pertains to lower risk emergency department patients with LBBB is unclear.

METHODS

A total of 401 consecutive patients with LBBB undergoing an MI rule-out protocol were included. Left bundle-branch blocks were classified as chronic; new; or, if no prior electrocardiogram (ECG) was available, as presumably new. Left bundle-branch blocks were considered concordant if there was ≥1 mm concordant ST elevation or depression. Rates of MI, peak MB values in MI patients, and 30-day mortality were compared across groups.

RESULTS

A majority of patients (64%) had new (37%) or presumably new LBBB (27%). A total of 116 patients (29%) had MI, with no significant difference in prevalence or size of MI among the 3 ECG groups. Myocardial infarction was diagnosed in 86% of patients with concordant ECG changes versus 27% of patients without concordant ECG changes (P < .01). Peak MB was >5× normal in 50% who had concordant ST changes compared to none of those who did not. Concordant ST changes were the most important predictor of MI (odds ratio 17, 95% CI 3.4-81, P < .001) and an independent predictor of mortality (odds ratio 4.3, 95% CI 1.3-15, P < .001); new or presumably new LBBB was neither.

CONCLUSIONS

Most patients with possible MI with new or presumably new LBBB do not have MI. Concordant ECG changes were an important predictor of MI and death. Current guidelines regarding early reperfusion therapy for patients with LBBB should be reconsidered.

Prognostic value of lead V1 ST elevation during acute inferior myocardial infarction

BACKGROUND

Lead V(1) directly faces the right ventricle and may exhibit ST elevation during an acute inferior myocardial infarction when the right ventricle is also involved. Leads V(1) and V(3) indirectly face the posterolateral left ventricle, and ST depression ("mirror-image" ST elevation) in V(1) through V(3) may reflect concomitant posterolateral infarction. The prognostic significance of V(1) ST elevation during an acute inferior myocardial infarction may therefore be dependent on V(3) ST changes.

METHODS AND RESULTS

In 7967 patients with acute inferior myocardial infarction in the Hirulog and Early Reperfusion or Occlusion-2 (HERO-2) trial, V(1) ST levels were analyzed with adjustment for lead V(3) ST level for predicting 30-day mortality. V(1) ST elevation at baseline, analyzed as a continuous variable, was associated with higher mortality. Unadjusted, each 0.5-mm-step increase in ST level above the isoelectric level was associated with approximately 25% increase in 30-day mortality; this was true whether V(3) ST depression was present or not. The odds ratio for mortality was 1.21 (95% confidence interval, 1.07 to 1.37) after adjustment for inferolateral ST elevation and clinical factors and 1.24 (95% confidence interval, 1.09 to 1.40) if also adjusted for V(3) ST level. In contrast, lead V(1) ST depression was not associated with mortality after adjustment for V(3) ST level. V(1) ST elevation >or=1 mm, analyzed dichotomously in all patients, was associated with higher mortality. The odds ratio was 1.28 (95% confidence interval, 1.01 to 1.61) unadjusted, 1.51 (95% confidence interval, 1.19 to 1.92) adjusted for V(3) ST level, and 1.35 (95% confidence interval, 1.04 to 1.76) adjusted for ECG and clinical factors. Persistence of V(1) ST elevation >or=1 mm 60 minutes after fibrinolysis was associated with higher mortality (10.8% versus 5.5%, P=0.001).

CONCLUSIONS

V(1) ST elevation identifies patients with acute inferior myocardial infarction who are at higher risk.

aVR ST elevation: an important but neglected sign in ST elevation acute myocardial infarction

AIM

This study evaluated the prognostic implications of aVR ST elevation during ST elevation acute myocardial infarction (AMI).

METHODS AND RESULTS

The Hirulog and Early Reperfusion/Occlusion-2 study randomized 17 073 patients with acute ST elevation AMI within 6 h of symptom onset to receive either bivalirudin or heparin, in addition to streptokinase and aspirin. The treatments had no effect on the primary endpoint of 30-day mortality. Electrocardiographic recordings were performed at randomization and at 60 min after commencing streptokinase. aVR ST elevation > or =1 mm was associated with higher 30-day mortality in 15 315 patients with normal intraventricular conduction regardless of AMI location (14.7% vs. 11.2% for anterior AMI, P = 0.0045 and 16.0% vs. 6.4% for inferior AMI, P < 0.0001). After adjusting for summed ST elevation and ST depression in other leads, associations with higher mortality were found with aVR ST elevation of > or =1.5 mm for anterior [odds ratio 1.69 (95% CI 1.16 to 2.45)] and of > or =1 mm for inferior AMI [odds ratio 2.41 (95% CI 1.76 to 3.30)]. There was a significant interaction between aVR ST elevation and infarct location. Thirty-day mortality was similar with anterior and inferior AMI when aVR ST elevation was present (11.5% vs. 13.2%, respectively, P = 0.51 with 1 mm and 23.5% vs. 22.5% respectively, P = 0.84 with > or = 1.5 mm ST elevation). After fibrinolytic therapy, resolution of ST elevation in aVR to <1 mm was associated with lower mortality, while new ST elevation > or =1 mm was associated with higher mortality.

CONCLUSION

aVR ST elevation is an important adverse prognostic sign in AMI.

Underuse of thrombolytic therapy in acute myocardial infarction and left bundle branch block

Thrombolytic therapy reduces mortality in patients with acute myocardial infarction (AMI) and left bundle branch block (LBBB). The difficulty in accurately diagnosing AMI in patients with LBBB, however, might result in their undertreatment. Among 3,890 patients hospitalized with chest pain, 241 (6.2%) had LBBB at presentation. The only variable independently associated with AMI among patients with LBBB was in-hospital left ventricular failure (odds ratio [OR]: 4.32, 95% confidence interval [CI]: 1.95-9.57, p < 0.0005). Only 16 (29%) of the LBBB patients with AMI received thrombolytic therapy compared with 583 (78%) of the 747 patients with ST-elevation AMI (p < 0.0005). A further 19 (10%) LBBB patients without AMI also received thrombolysis. Difficulty in making an accurate early diagnosis in patients with LBBB ensures that the majority of those with AMI fail to receive thrombolytic therapy while others without AMI are treated inappropriately. Improved diagnostic and therapeutic strategies are needed for patients with acute coronary syndromes and LBBB.

Stress-induced cardiomyopathy: A review

In clinical practice it is essential to bear stress-induced cardiomyopathy (SICMP) in mind as it is an insufficiently known cardiac pathology that mimics acute coronary syndromes (ACS), often with signs of cardiac failure. In the chronic phase, it poses differential diagnostic problems with regard to coronary artery pathology. Taxonomic confusion, due to the pathology also being called "takotsubo" or "ampulla cardiomyopathy", has resulted in inappropriate diagnoses and therapy. Available evidence strongly suggests that, in the presence of several cardiac risk factors, excessive sympathetic stimulation may induce this cardiomyopathy. The predilection of this cardiomyopathy for Mediterranean and Indo-Asian women, who represent 85% of cases, is probably explained by the fact that there is a significant correlation between female gender, a short (<158 cm) stature, a small (<1.9 m(2)) body surface area, and hypoplastic coronary arteries. Furthermore, 40% of SICMP patients have a hypoplastic branching of the coronary arteries in the apical region of the heart. This anomaly strongly favors the apical localization of the dyskinesia. The prognosis of SICMP is good as far as life expectancy is concerned. However, in most cases, the symptoms become chronic, medical treatment rarely improves dyspnea and chest pain, and the quality of life is, therefore, reduced. In this paper, we address diagnostic misunderstandings and we review the clinical and pathophysiological features of SICMP.

Long-term outcomes of left bundle branch block in high-risk survivors of acute myocardial infarction: The VALIANT experience

BACKGROUND

In survivors of myocardial infarction (MI), new left bundle branch block (LBBB) is associated with adverse outcomes, but its impact is not well described in post-MI patients with left ventricular (LV) systolic dysfunction and/or heart failure (HF).

OBJECTIVES

The aim of this study was to determine if new LBBB is an independent predictor of long-term fatal and nonfatal outcomes in high-risk survivors of MI by reviewing data from the VALsartan In Acute myocardial iNfarcTion (VALIANT) trial.

METHODS

In VALIANT, 14,703 patients with LV systolic dysfunction and/or HF were randomized to valsartan, captopril, or both a mean of 5 days after MI. Baseline ECG data were available from 14,259 patients. We assessed the predictive value of new LBBB for death and major cardiovascular outcomes after 3 years, adjusting for multiple baseline covariates including LV ejection fraction.

RESULTS

At follow-up, patients with new LBBB (608 [4.2%]) compared with patients without new LBBB had more comorbidities and increased adjusted risk of death (hazard ratio [HR] 1.3, 95% confidence interval [CI] 1.2-1.6), cardiovascular death (HR 1.4, 95% CI 1.2-1.7), HF (HR 1.3, 95% CI 1.1-1.6), MI (HR 1.5, 95% CI 1.2-1.9), and the composite of death, HF, or MI (HR 1.4, 95% CI 1.2-1.6).

CONCLUSION

In post-MI survivors with LV systolic dysfunction and/or HF, new LBBB was an independent predictor of all major adverse cardiovascular outcomes during long-term follow-up. This readily available ECG marker should be considered a major risk factor for long-term cardiovascular complications in high-risk patients after MI.

Effect of Clopidogrel on Midterm Graft Patency following Off-Pump Coronary Revascularization Surgery

OBJECTIVE

The aim of the study was to evaluate the effect of clopidogrel on midterm graft patency following off-pump coronary revascularization surgery.

DESIGN

Ninety-four consecutive patients who underwent off-pump coronary artery bypass grafting between 1997 and 2002 were studied (58 men, 36 women; 61.7 +/- 9.8 years). The initial 36 patients (control group) received 75 to 160 mg acetyl salicylic acid (ASA) as an antiplatelet agent, whereas the consecutive 58 patients (clopidogrel group) received 75 mg clopidogrel postoperatively in addition to ASA. Intraoperatively, graft flow was assessed with transit-time flowmetry in all patients and the peripheral anastomoses were assessed with epicardial ultrasound in 28 patients. Sixty-two patients underwent angiography after a mean of 185 +/- 92 days. A total of 82 grafts were evaluated angiographically. Grafts with TIMI flow 2 and 3 were assessed as patent.

RESULTS

At angiographic follow-up, the overall graft patency rate was 84% (31/37) in the control group and 93% (42/45) in the clopidogrel group (P value was not significant [ns]). Graft patency rates for left internal mammary artery (LIMA) grafts were 92% (23/25) versus 96% (28/29) (ns), and for saphenous vein grafts were 66% (7/11) versus 87% (14/16) (ns), respectively.

CONCLUSION

The observed trend toward higher patency rates in patients treated with clopidogrel did not reach statistical significance. Further larger studies are necessary to confirm these preliminary results.

Risk Stratification of Patients With Acute Anterior Myocardial Infarction and Right Bundle-Branch Block

BACKGROUND

Patients with an acute anterior ST-segment elevation myocardial infarction and right bundle-branch block (RBBB) have a high mortality risk, which may be stratified by early ECG changes.

METHODS AND RESULTS

In the Hirulog Early Reperfusion Occlusion (HERO-2) trial, 17 073 patients with acute myocardial infarction (AMI) within 6 hours of symptom onset were treated with streptokinase and randomized to receive bivalirudin or heparin. There was no difference in the primary end point of 30-day mortality. ECGs were recorded at randomization and 60 minutes after fibrinolytic therapy was begun. The 30-day mortality rate was 31.6% in the 415 patients with RBBB and anterior AMI at randomization and 33% in the 100 patients who developed new RBBB at 60 minutes from normal baseline conduction accompanying an anterior AMI. An increase in QRS duration by 20-ms increments was associated with increasing 30-day mortality rate in both RBBB groups on multivariable analyses with covariates of age, Killip class, systolic blood pressure, pulse, and prior infarction. Patients with QRS duration > or = 160 ms had higher 30-day mortality rate than those with QRS duration < 160 ms (37.2% versus 27.2%, P = 0.03, and 46.2% versus 24.5%, P = 0.025, in the 2 groups, respectively). For the patients with RBBB and anterior MI at randomization, RBBB resolved at 60 minutes in 40 patients, but 30-day mortality rate was unchanged. For those with persisting RBBB at 60 minutes, 30-day mortality rate was lower if ST-segment elevation had resolved by > or = 50% (20.4% versus 35.3%, P = 0.006).

CONCLUSIONS

In patients with anterior AMI and RBBB, increasing QRS duration is associated with increasing 30-day mortality. Early ST-segment resolution after fibrinolytic therapy despite persisting RBBB is associated with lower mortality rate.

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.

Electrocardiographic Diagnosis of Myocardial Infarction during Left Bundle Branch Block

The electrocardiographic diagnosis of myocardial infarction (MI) in the presence of left bundle branch block (LBBB) has long been considered problematic or even almost impossible. Many proposed ECG markers in the old literature have now been discarded. However, the advent of reperfusion therapy has generated greater interest in the ECG diagnosis of acute MI in LBBB where ST-segment deviation is the only useful sign. As such, the ST-segment criteria cannot be used to rule out MI, but they can help to rule it in. Criteria for old MI (based on QRS changes) have not been reevaluated for almost 20 years and continue to exhibit low sensitivity, but high specificity.