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

Abstract

Background and ObjectivesLeft 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 MethodsA 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°.ResultsOf 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).ConclusionConcomitant LAD is an indicator of poor prognosis for patients with LBBB and may be associated with greater myocardial scarring.

Clinical Profile of the Patients with Newly Detected Left Bundle Branch Block in the Outpatient Department

“…Park et al study which reported that LBBB with left axis deviation has an inferior prediction than LBBB with a normal axis. The myocardial disease has been suggested as a significant cause of left axis deviation [12]. We found that the left axis deviation in ECG is more common among patients with structural heart disease.…”

“…Sometimes it is the only manifestation of acute myocardial infarction [11]. LBBB with left axis deviation has a worse diagnosis than LBBB with a normal axis, and common causes of left axis deviation include myocardial dysfunction [12]. Some studies have revealed a correlation between LBBB and left ventricle systolic and diastolic dysfunction in patients [13].…”

Prognostic Significance of Left Axis Deviation in Acute Heart Failure Patients with Left Bundle branch block: an Analysis from the Korean Acute Heart Failure (KorAHF) Registry

“… 11) 19) Also, in patients with HF and LBBB who undergo successful implantations of CRT devices, the presence of LAD suggests a poor clinical outcome, including all-cause mortality and HF re-hospitalizations or events. 6) 20) Park et al 12) recently reported that LAD is associated with myocardial scarring and major adverse cardiac event in patients with LBBB. On the other hand, in patients with HF and LBBB who undergo ICD implantations, LAD does not predict all-cause mortality or HF events.…”

“… 10) A previous study showed that patients with LBBB with LAD had greater incidence of cardiomegaly, HF, advanced conduction disease, cardiovascular mortality, and major adverse cardiac event than those with a normal axis. 11) 12) Another study indicated that LBBB with LAD does not confer a significant mortality risk, but those with a normal axis who developed LAD during the study period had a significantly higher mortality. 13) However, limited data is available regarding the prognostic significance of LAD in acute heart failure syndrome (AHFS) patients with LBBB.…”

Left Axis Deviation in Patients with Acute Heart Failure with Left Bundle Branch Block: Does It Really Matter?

“…Although the study population was small (n=102), among patients with LBBB, those with LAD had an increased incidence of myocardial dysfunction, more advanced conduction disease, and greater cardiac death compared to those with normal axis 2). Also, myocardial scar score as calculated by the Selvester QRS scoring system was reported to be higher in those with concomitant LAD and LBBB 3). Recently, large population study (n=2,794, median follow-up duration 20 months) reported that LAD did not have significant association with mortality in patients with LBBB 4).…”