Korean Circ J.  2017 Mar;47(2):263-269. 10.4070/kcj.2016.0359.

Prognostic Implication of the QRS Axis and its Association with Myocardial Scarring in Patients with Left Bundle Branch Block

• Park CS
• Cha MJ
• Choi EK
• Oh S

• KMID: 2377468
• DOI: http://doi.org/10.4070/kcj.2016.0359

Abstract

BACKGROUND AND OBJECTIVES
Left bundle branch block (LBBB) with left axis deviation (LAD) has a worse prognosis than LBBB with a normal axis, and myocardial dysfunction has been suggested as a cause of left axis deviation. This study investigated the prognostic significance of the QRS axis in patients with LBBB and analyzed its relationship with the amount of myocardial scarring.
SUBJECTS AND METHODS
A total of 829 patients were diagnosed with LBBB at Seoul National University Hospital from October 2004 to June 2014. Of these, 314 who were asymptomatic and had no previous history of cardiac disease were included in the present study. Myocardial scarring was calculated using the Selvester QRS scoring system, and LAD was defined as a QRS axis between -180° and -30°.
RESULTS
Of the total patients, 91 (29%) had LAD, and patients were followed for a median of 30 months. During follow-up, two patients were hospitalized for de novo heart failure, four had pacemaker implants, and 10 died. There was a significant inverse correlation between myocardial scar score and the QRS axis (r=-0.356, p<0.001). Patients with concomitant LAD had a higher rate of major cardiac adverse events compared with patients with a normal axis (5.5% vs. 1.3%, log-rank p=0.010); the prognostic value was attenuated in multivariable analysis (hazard ratio 4.117; 95% confidence interval 0.955-17.743; p=0.058).
CONCLUSION
Concomitant LAD is an indicator of poor prognosis for patients with LBBB and may be associated with greater myocardial scarring.

Keyword

Bundle branch block; Electrocardiography; Electrophysiology; Prognosis

MeSH Terms

Bundle-Branch Block*
Cicatrix*
Electrocardiography
Electrophysiology
Follow-Up Studies
Heart Diseases
Heart Failure
Humans
Prognosis
Seoul

Figure

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  Fig. 1 Flow chart of this study. LBBB: left bundle branch block, ECG: electrocardiogram, ICD: implantable cardioverter defibrillator, CRT: cardiac resynchronization therapy, MACE: major adverse cardiac event.

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  Fig. 2 Association between QRS axis and myocardial scar score. (A) There was an inverse correlation between QRS axis and myocardial scar score. (B) Receiver-operating curves analysis: area under the curve of myocardial scar score to predict left axis deviation.

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  Fig. 3 Kaplan-Meier curves of major adverse cardiovascular event incidence according to QRS axis in left bundle branch block patients.

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