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

doi:10.1016/j.ahj.2011.01.008

American Heart Journal

Volume 161, Issue 4, April 2011, Pages 698-704

https://doi.org/10.1016/j.ahj.2011.01.008 Get rights and content

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.

Section snippets

Methods

The chest pain protocol used at our institution has been described in detail previously.¹² Patients with possible myocardial ischemia undergo an evaluation by emergency department (ED) physicians, with further treatment and evaluation dictated based on the initial risk stratification.¹² Patients were included in this analysis if they presented with possible myocardial ischemia, underwent serial marker assessment, and had an LBBB on the initial ED ECG. Data were collected prospectively as part

Clinical characteristics

From 1994 to 2009, 401 consecutive patients who underwent evaluation for possible acute coronary syndrome had LBBB on the initial ECG and were included in this analysis. In general, the patient population was older (median age 66 years), with frequent comorbidities (Table I). Ejection fraction (EF) was available in 360 patients (90%), of whom 76% had an EF <50% and with 61%, <40%.

A majority of patients (64%) had either a new LBBB (36%) or presumed new LBBB (28%). Clinical characteristics of

Discussion

We found that there was no difference in the incidence of MI based on the chronicity of the LBBB on the presenting ECG. Patients who had concordant ST changes had a high likelihood of MI. In addition, concordant ECG changes were the most important independent predictor of MI as well as an independent predictor of 30-day mortality.

Administration of fibrinolytic therapy to patients with AMI and ST-segment elevation decreases mortality.¹⁵ The results of the Fibrinolytic Collaborative Group, which

Limitations

Although patient data from an extended period were used, the criteria for emergent reperfusion in patients with LBBB have been present because guidelines were published in 1996. We used CK and CK-MB to estimate peak MI size because of the multiple different TnI assays used during the study period. In addition, use of CK and CK-MB allows comparison across other studies, a technique used in clinical trials.

Despite these limitations, our study has several strengths. These include the large

Conclusions

Most patients who present to the ED with possible AMI who have an underlying LBBB do not have an MI. In those who do, MI size is relatively small and therefore are unlikely to benefit from emergent reperfusion treatment. The diagnostic use of a new LBBB was low. Specific ECG criteria, concordant ST depression or elevation, had a high specificity and identified patients who had large MIs. The use of emergent reperfusion treatment in patients with new LBBB as a performance indicator should be

Disclosures

Funded, in part, from research funds from the Pauley Heart Center.

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Cited by (32)

How to best use high-sensitivity cardiac troponin in patients with suspected myocardial infarction
2018, Clinical Biochemistry
Citation Excerpt :
While chronic LBBB has become more common, incident LBBB in MI has decreased [103]. Several studies have demonstrated no difference in the prevalence of MI between patients with presumably new or known LBBB, suggesting that true MI related LBBB is indeed rare [104,105]. Due to their high specificity, specific ECG criteria including Sgarbossa, Smith and Selvester criteria should be used to triage patients towards rule-in of MI and immediate coronary angiography such as patients with STEMI [106,107].
High-sensitivity cardiac troponin (hs-cTn) assays have been used clinically by thousands of physicians in many countries throughout the world since their clinical introduction seven years ago. In the early diagnosis of myocardial infarction (MI), beyond doubt the most important indication of hs-cTn assays, these simple, inexpensive and highly reproducible tools complement detailed clinical assessment including chest pain characteristics and the electrocardiogram. Hs-cTn assays for the first time allowed the precise quantification of cardiomyocyte injury around the 99th percentile and thereby substantially increased the accuracy of MI detection from blood obtained at presentation to the emergency department (ED). Higher accuracy at ED presentation enabled the development and extensive validation of early hs-cTn-based diagnostic algorithms, which substantially reduced the time required for the safe rule-out or rule-in of MI. This review summarizes key principles underlying the safe and effective use of hs-cTn in the ED in patients with suspected MI.
Clinical Use of High-Sensitivity Cardiac Troponin in Patients With Suspected Myocardial Infarction
2017, Journal of the American College of Cardiology
Citation Excerpt :
Although chronic LBBB has become more common, incident LBBB in MI has decreased (101). Several studies have demonstrated no difference in the prevalence of MI between patients with presumably new or known LBBB, suggesting that true MI related LBBB is indeed rare (102,103). Due to their high specificity, specific ECG criteria including Sgarbossa, Smith, and Selvester criteria should be used to triage patients toward rule-in of MI and immediate coronary angiography such as patients with STEMI (104,105).
High-sensitivity cardiac troponin (hs-cTn) assays have been used clinically by thousands of physicians in many countries throughout the world since their clinical introduction 7 years ago. In the early diagnosis of myocardial infarction (MI), beyond doubt, the most important indication of hs-cTn assays, these simple, inexpensive, and highly reproducible tools complement detailed clinical assessment including chest pain characteristics and the electrocardiogram. Hs-cTn assays for the first time allowed the precise quantification of cardiomyocyte injury around the 99th percentile and thereby substantially increased the accuracy of MI detection from blood obtained at presentation to the emergency department (ED). Higher accuracy at ED presentation enabled the development and extensive validation of early hs-cTn–based diagnostic algorithms, which substantially reduced the time required for the safe rule-out or rule-in of MI. This review summarizes key principles underlying the safe and effective use of hs-cTn in the ED in patients with suspected MI.
The prognostic value of a new left bundle branch block in patients with acute myocardial infarction: A systematic review and meta-analysis
2017, Heart and Lung: Journal of Acute and Critical Care
To assess the prognostic value of new left bundle branch block (LBBB) in patients with acute myocardial infarction (AMI).
LBBB develops in many cardiac conditions, including AMI. The empirical evidence for the contribution of LBBB to mortality in AMI is not consistent.
Medline, PubMed, CINAHL, and EMBASE were searched. Inverse variance meta-analysis was performed with odds ratios as the effect estimates. The I² statistic and risk of bias were assessed.
Eight studies involving 105,861 participants were eligible. New LBBB was associated with higher mortality at 30 days (OR: 2.10, 95% CI 1.27 to 3.48) and 1-year follow up (OR: 2.81, 95% CI 1.64 to 4.80), and increased heart failure risk (OR: 2.64, 95% CI 1.84 to 3.77).
AMI patients with new LBBB are a high risk group and must be treated accordingly. Yet, more research is needed given the limitations of studies.
Outcomes of Patients With ST-Elevation Myocardial Infarction Receiving and Not Receiving Reperfusion Therapy: The Importance of Examining All Patients
2016, Canadian Journal of Cardiology
Hospitals treating patients with ST-elevation myocardial infarction (STEMI) may show good results with reperfusion treatment (fibrinolysis or primary percutaneous coronary intervention [PPCI]), but a comprehensive evaluation should factor in outcomes of patients with STEMI who do not receive reperfusion. We compared outcomes of patients receiving and not receiving reperfusion within a complete system of STEMI care by hospital type: PPCI centres, fibrinolysis centres, centres that only transfer for PPCI, and centres providing a mix of fibrinolysis and PPCI transfer.
All patients presenting to 82 Quebec hospitals with characteristic symptoms, a final diagnosis of acute myocardial infarction, and core-laboratory confirmed STEMI over two 6-month periods were studied.
Of the total 3731 patients with STEMI, 2918 (78.2%) received reperfusion treatment (81% PPCI, 19% fibrinolysis); 813 (21.8%) did not. For reperfusion-treated patients, 30-day mortality was 5.4% in PPCI centres, 5.4% in fibrinolysis centres, 6.9% in transfer PPCI centres, and 6.0% in mixed centres (P = 0.55). For untreated patients, 30-day mortality was 15.7% (PPCI centres), 16.1% (fibrinolysis centres), 21.8% (transfer PPCI), and 24.6% (mixed) (P = 0.08). Adjusted mortality odds ratios for all patients were 1.00 (PPCI centres), 1.50 (95% CI: 0.97-2.32; fibrinolysis centres), 1.30 (0.95-1.78; transfer PPCI centres), and 1.58 (1.09-2.29; mixed centres). PPCI was within recommended delays in 35.4%, 11.9%, and 1.2% of PPCI, transfer, and mixed centres, respectively.
Mixed centres had the highest crude and adjusted all-patient 30-day STEMI mortality. Relatively good outcomes of reperfusion-treated patients, despite long treatment delays, can misrepresent overall performance if untreated patients are not examined.
Les hôpitaux qui traitent les patients atteints d’un infarctus du myocarde (IM) avec sus-décalage du segment ST montrent de bons résultats avec le traitement par reperfusion (fibrinolyse ou intervention coronarienne percutanée primaire [ICPP]), mais une évaluation exhaustive devrait prendre en compte les résultats cliniques des patients atteints d’un IM avec sus-décalage du segment ST qui ne reçoivent pas la reperfusion. Nous avons comparé les résultats cliniques des patients qui reçoivent ou non la reperfusion dans un programme complet de soins de l’IM avec sus-décalage du segment ST par type d’hôpitaux : les centres d’ICPP, les centres de fibrinolyse, les centres qui transfèrent seulement pour les ICPP, et les centres mixtes qui proposent la fibrinolyse et le transfert pour ICPP.
Nous avons étudié tous les patients admis dans les 82 hôpitaux du Québec qui présentaient des symptômes caractéristiques, un diagnostic final d’infarctus aigu du myocarde et d’IM avec sus-décalage du segment ST confirmé par un laboratoire central au cours de 2 périodes de 6 mois.
Parmi les 3731 patients atteints d’un IM avec sus-décalage du segment ST, 2918 (78,2 %) ont reçu un traitement de reperfusion (81 % l’ICPP, 19 % la fibrinolyse); 813 (21,8 %) n’en ont pas reçu. Pour les patients traités par reperfusion, la mortalité à 30 jours était de 5,4 % dans les centres d’ICPP, de 5,4 % dans les centres de fibrinolyse, de 6,9 % dans les centres de transfert pour l’ICPP et de 6,0 % dans les centres mixtes (P = 0,55). Pour les patients non traités, la mortalité à 30 jours était de 15,7 % dans les centres d’ICPP, de 16,1 % dans les centres de fibrinolyse, de 21,8 % dans les centres de transfert pour l’ICPP et de 24,6 % dans les centres mixtes (P = 0,08). Les rapports de cotes de mortalité ajustés de tous les patients étaient de 1,00 (centres d’ICPP), de 1,50 (IC à 95 % : 0,97-2,32; centres de fibrinolyse), de 1,30 (0,95-1,78; centres de transfert pour l’ICPP) et de 1,58 (1,09-2,29; centres mixtes). L’ICPP était réalisée dans les délais recommandés dans les centres d’ICPP, de transfert et mixtes à 35,4 %, 11,9 % et 1,2 % respectivement.
Les centres mixtes avaient les taux bruts et ajustés de mortalité à 30 jours de tous les patients atteints d’IM avec sus-décalage du segment ST les plus élevés. En dépit des longs délais de traitement, les résultats cliniques relativement bons des patients traités par reperfusion peuvent faussement représenter la performance globale si les patients non traités ne sont pas examinés.
Validation of the modified Sgarbossa criteria for acute coronary occlusion in the setting of left bundle branch block: A retrospective case-control study
2015, American Heart Journal
The modified Sgarbossa criteria were proposed in a derivation study to be superior to the original criteria for diagnosing acute coronary occlusion (ACO) in left bundle branch block (LBBB). The new rule replaces the third criterion (5 mm of excessively discordant ST elevation [STE]) with a proportion (at least 1 mm STE and STE/S wave ≤−0.25). We sought to validate the modified criteria.
This retrospective case-control study was performed by chart review in 2 tertiary care center emergency departments (EDs) and 1 regional referral center. A billing database was used at 1 site to identify all ED patients with LBBB and ischemic symptoms between May 2009 and June 2012. In addition, all 3 sites identified LBBB ACO patients who underwent emergent catheterization.
We measured QRS amplitude and J-point deviation in all leads, blinded to outcomes. Acute coronary occlusion was determined by angiographic findings and cardiac biomarker levels, which were collected blinded to electrocardiograms. Diagnostic statistics of each rule were calculated and compared using McNemar's test.
Our consecutive cohort search identified 258 patients: 9 had ACO, and 249 were controls. Among the 3 sites, an additional 36 cases of ACO were identified, for a total of 45 ACO cases and 249 controls.
The modified criteria were significantly more sensitive than the original weighted criteria (80% vs 49%, P < .001) and unweighted criteria (80% vs 56%, P < .001). Specificity of the modified criteria was not statistically different from the original weighted criteria (99% vs 100%, P = .5) but was significantly greater than the original unweighted criteria (99% vs 94%, P = .004).
The modified Sgarbossa criteria were superior to the original criteria for identifying ACO in LBBB.
New ST-segment elevation myocardial infarction criteria for left bundle branch block based on QRS area
2013, Journal of Electrocardiology
ECG detection of ST-segment elevation myocardial infarction (STEMI) in the presence of left bundle-branch block (LBBB) is challenging due to ST deviation from the altered conduction. The purpose of this study was to introduce a new algorithm for STEMI detection in LBBB and compare the performance to three existing algorithms.
Source data of the study group (143 with acute MI and 239 controls) comes from multiple sources. ECGs were selected by computer interpretation of LBBB. Acute MI reference was hospital discharge diagnosis. Automated measurements came from the Philips DXL algorithm. Three existing algorithms were compared, (1) Sgarbossa criteria, (2) Selvester 10% RS criteria and (3) Smith 25% S-wave criteria. The new algorithm uses an ST threshold based on QRS area. All algorithms share the concordant ST elevation and anterior ST depression criteria from the Sgarbossa score. The difference is in the threshold for discordant ST elevation. The Sgarbossa, Selvester, Smith and Philips discordant ST elevation criteria are (1) ST elevation ≥ 500 μV, (2) ST elevation ≥ 10% of |S|-|R| plus STEMI limits, (3) ST elevation ≥ 25% of the S-wave amplitude and (4) ST elevation ≥ 100 μV + 1050 μV/Ash * QRS area. The Smith S-wave and Philips QRS area criteria were tested using both a single and 2 lead requirement. Algorithm performance was measured by sensitivity, specificity, and positive likelihood ratio (LR +).
Algorithm performance can be organized in bands of similar sensitivity and specificity ranging from Sgarbossa score ≥ 3 with the lowest sensitivity and highest specificity, 13.3% and 97.9%, to the Selvester 10% rule with the highest sensitivity and lower specificity of 30.1% and 93.2%. The Smith S-wave and Philips QRS area algorithms were in the middle band with sensitivity and specificity of (20.3%, 94.9%) and (23.8%, 95.8%) respectively.
As can be seen from the difference between Sgarbossa score ≥ 3 and other algorithms for STEMI in LBBB, a discordant ST elevation criterion improves the sensitivity for detection but also results in a drop in specificity. For applications of automated STEMI detection that require higher sensitivity, the Selvester algorithm is better. For applications that require a low false positive rate such as relying on the algorithm for pre-hospital activation of cardiac catheterization laboratory for urgent PCI, it may be better to use the 2 lead Philips QRS area or Smith 25% S-wave algorithm.

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

Introduction

Methods

Results

Conclusions

Section snippets

Methods

Clinical characteristics

Discussion

Limitations

Conclusions

Disclosures

J Am Coll Cardiol

J Am Coll Cardiol

Ann Emerg Med

Ann Emerg Med

Am J Emerg Med

J Am Coll Cardiol

Am Heart J

Am J Emerg Med

Ann Emerg Med

Am J Cardiol

J Am Coll Cardiol