News from the Interventional Council: Unbundling Left Bundle Branch Block | CardioSource WorldNews Interventions

By Manpreet Singh Sabharwal, MD; Syed Tanveer Rab, MD; and Jacqueline E. Tamis-Holland, MD

Patients with acute chest pain and left bundle branch block (LBBB) on electrocardiogram (ECG) are a constant challenge to physicians when considering acute reperfusion therapy. Historically, LBBB had been considered an ST-segment elevation myocardial infarction (STEMI) equivalent, and guidelines recommended that patients with new, or presumably new, LBBB be treated with fibrinolytic therapy or primary percutaneous coronary intervention (PCI).1 These guidelines were based on the early trials of fibrinolytic therapy that included patients with "bundle branch block" (BBB) as a criteria for trial eligibility. In a pooled analysis of fibrinolytic trials, the subgroup of patients with BBB on ECG demonstrated improved survival when treated with fibrinolytic therapy.2

With the increasing use of early angiography for patients with suspected STEMI, subsequent data have suggested that only a minority of patients who present with LBBB is referred emergently to the cardiac catheterization laboratory and is found to have an acute occlusion on coronary angiography.3-6

Thus, routinely treating all chest pain patients with new, or presumably new, LBBB as a STEMI equivalent would expose a large number of patients (who do not have an acute arterial occlusion) to unnecessary risks from fibrinolytic therapy or emergency invasive studies, and can result in needless utilization of health care resources. (This does not apply to patients with LBBB who meet Sgarbossa's criteria; these patients should be treated as a STEMI equivalent.)

LBBB in the Guidelines
In New York City, pre-hospital care for patients with suspected STEMI includes a pre-hospital ECG performed by emergency medical services personnel. In cases where the ECG demonstrates STEMI or new LBBB, patients are referred to the nearest PCI hospital. Since the institution of this protocol in January 2008, a total of 8,552 patients were directly transferred to PCI hospitals for consideration for primary PCI. Two thousand of these patients (23%) had presumably new LBBB on ECG. A review of hospital data, however, demonstrated that only 42 patients (2.1%) with LBBB on ECG ultimately were referred for emergency angiography.

As a result of the low yield for emergency angiography with new LBBB, the Regional Emergency Medical Service Council of New York City (REMAC) has now removed "new LBBB" from the transportation procedure guidelines for emergency medical care. In keeping with the ever-changing evidence regarding LBBB, the 2013 ACCF/AHA Guidelines for the Management of STEMI now recommend careful evaluation of patients with LBBB prior to instituting reperfusion therapy: "New or presumably new LBBB at presentation occurs infrequently, may interfere with ST-elevation analysis, and should not be considered diagnostic of acute myocardial infarction (MI) in isolation."7

Sorting Out Guidelines and Regulatory Agencies
Despite these guidelines, regulatory agencies have not changed their algorithms for grading hospitals on timely use of coronary angiography and primary PCI in patients with new or presumably new LBBB.

Case in point: when a patient came to the emergency room for a self-limiting episode of chest pain and was found to have a presumably new LBBB, the ER staff consulted the on-call cardiologist, who evaluated the patient. After a bedside echocardiogram was performed, the clinical diagnosis was felt to be consistent with a non-ST-elevation acute coronary syndrome. The patient was treated with dual antiplatelet therapy, intravenous heparin, beta-blockers, and statins. Serial cardiac enzymes demonstrated a mildly elevated troponin. The following day, coronary angiography revealed a severe stenosis of the distal left circumflex artery, which was treated with a drug-eluting stent. The case seemed to have been managed well since the patient had received guideline-directed optimal medical care.

However, when this case was reviewed by the hospital's quality improvement department, it appeared that, according to the Centers for Medicare and Medicaid Services and the Joint Commission specifications manual, standard of care was not met.

Using the Joint Commission algorithm for abstraction of data, abstractors need first to answer the following: "Is there documentation of ST-segment elevation or LBBB on the ECG performed closest to hospital arrival?" If the answer to the question is "yes" and the LBBB is not documented as "old," then the patient should be referred for emergency catheterization. Failure to do this—or failure to document why the patient was not treated in this way—can have serious financial repercussions for the hospital.

Unfortunately, cardiologists caring for patients like the one in this case often feel that the decision to not refer a patient for emergency angiography is implicit and therefore documentation in writing is not necessary.

LBBB's Impact on Reimbursement and Performance Metrics
This use of new LBBB as criteria to refer a patient for primary PCI is not limited to the Joint Commission review. The New York State Percutaneous Coronary Interventions Reporting System (PCIRS), the National Cardiovascular Data Registry (NCDR®), and other registries also use new LBBB as a criterion for inclusion in the "door-to-balloon" metric.

Yet, as the guidelines imply, the presence of LBBB in isolation should not be the sole criterion for instituting reperfusion therapy; in these cases, it is suggested that additional evaluation be performed when needed prior to committing to emergency catheterization or fibrinolytic therapy. Unless there is clear documentation in the chart that there was a delay to catheterization due to additional studies or evaluation, patients who are ultimately referred for emergency catheterization are included in the door-to-balloon time metric.

The data from the Joint Commission Core Measures are publicly reported and many insurance payers are moving toward using Core Measure results as a benchmark for contract negotiations. Performance on compliance with Core Measures is also used as a basis for Medicare Pay for Performance/ Value Based Purchasing.

Hence, while we all feel the timing of cardiac catheterization (or decision to refer for coronary angiography) in stable patients with new LBBB is implicit and needs no justification, our hospital systems are being penalized if such justification is not documented.

At present, with the tremendous financial strain that most hospitals face due to decreased reimbursement when performance is not on par with the national norms, it would be unfair to penalize a hospital for not taking a new LBBB for emergent catheterization when the care provided is supported by the most recent ACCF/AHA STEMI guidelines. This should provide a strong rationale for removing this ECG indicator from the assessment tools for quality performance metrics of door-to-balloon time. In the meantime, until new LBBB is removed from the metric, physicians must continue to provide clear documentation for decisions regarding referral (or deferral) for emergency angiography and primary PCI.


  1. Antman EM, Anbe DT, Armstrong PW, et al. J Am Coll Cardiol. 2004; 44:E1-E211.
  2. Fibrinolytic Therapy Trialists' (FTT) Collaborative Group. Lancet. 1994;343:311-22.
  3. Rokos IC, Rarkouh ME, Reiffel J, et al. Cath Cardiovasc Interv. 2012;79:1092-8.
  4. Chang AM, Shofer FS, Tabas JA, et al. Am J Emerg Med. 2009;27:916-21.
  5. Larson DM, Menssen KM, Sharkey SW, et al. JAMA.2007; 298:2754-60.
  6. Jain S, Ting HT, Bell M, et al. Am J Cardiol. 2011; 107:1111-6.
  7. O'Gara PT, Kushner FG, Ascheim DD, et al. J Am Coll Cardiol. 2013;61:e78-e140.

Manpreet Singh Sabharwal, MD, is a fellow at Mount Sinai St. Luke's-Roosevelt in New York, New York. Syed Tanveer Rab, MD, is an interventional cardiologist at Emory University Hospital in Atlanta, Georgia, and Councillor of the ACC's Georgia Chapter. Jacqueline E. Tamis-Holland, MD, is director of the cardiac catheterization laboratory at Mount Sinai St. Luke's-Roosevelt Hospital in New York.

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