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Left Bundle Branch Block in Acute Cardiac Events

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Between 1991 and 2013, we evaluated the demographics, presentations, and final diagnosis of patients hospitalized with acute cardiac events and left bundle branch block (LBBB). Of 50 992 patients, 768 (1.5%) had LBBB. Compared with non-LBBB patients, patients with LBBB were mostly older, female, diabetic, and had hypertension and chronic kidney failure (CKF; P < .001 for all). Dyspnea (P < .001) and dizziness (P = .037) were more frequent in patients with LBBB. The most frequent cause of admission with LBBB was congestive heart failure (CHF; 54.2%), followed by ST-elevation myocardial infarction (STEMI; 13.3%), valvular heart disease (9.4%), unstable angina (8.3%) and Non-STEMI (7.7%). On multivariate analysis, CKF (odds ratio [OR]: 2.02, 95% confidence interval [CI]: 1.09-3.70) and LBBB (OR: 2.96, 95% CI: 2.01-4.42) were predictors of in-hospital mortality in the entire study population. Further analysis of patients with LBBB showed that CKF (OR: 2.93, 95% CI: 1.40-6.12) was the only predictor of in-hospital mortality. Regardless the presenting symptoms, CHF was the final diagnosis in most cases with LBBB.
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DOI: 10.1177/0003319714560223
published online 3 December 2014ANGIOLOGY
and Abdulrahman Arabi
Fahad Alkindi, Ayman El-Menyar, Jassim Al-Suwaidi, Ashfaq Patel, Abdurrazzak A. Gehani, Rajvir Singh, Hajar Albinali
Left Bundle Branch Block in Acute Cardiac Events: Insights From a 23-Year Registry
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Original Article
Left Bundle Branch Block in Acute Cardiac
Events: Insights From a 23-Year Registry
Fahad Alkindi, MD
1
, Ayman El-Menyar, MBChB, MSc, FRCP
2,3,4
,
Jassim Al-Suwaidi, MD
1
, Ashfaq Patel, MD
1
,
Abdurrazzak A. Gehani, MD, FRCP(Edin)
1
, Rajvir Singh, PhD
5
,
Hajar Albinali, MD
1
, and Abdulrahman Arabi, MD
1
Abstract
Between 1991 and 2013, we evaluated the demographics, presentations, and final diagnosis of patients hospitalized with acute
cardiac events and left bundle branch block (LBBB). Of 50 992 patients, 768 (1.5%) had LBBB. Compared with non-LBBB patients,
patients with LBBB were mostly older, female, diabetic, and had hypertension and chronic kidney failure (CKF; P< .001 for all).
Dyspnea (P< .001) and dizziness (P¼.037) were more frequent in patients with LBBB. The most frequent cause of admission with
LBBB was congestive heart failure (CHF; 54.2%), followed by ST-elevation myocardial infarction (STEMI; 13.3%), valvular heart
disease (9.4%), unstable angina (8.3%) and Non-STEMI (7.7%). On multivariate analysis, CKF (odds ratio [OR]: 2.02, 95% confi-
dence interval [CI]: 1.09-3.70) and LBBB (OR: 2.96, 95% CI: 2.01-4.42) were predictors of in-hospital mortality in the entire study
population. Further analysis of patients with LBBB showed that CKF (OR: 2.93, 95% CI: 1.40-6.12) was the only predictor of in-
hospital mortality. Regardless the presenting symptoms, CHF was the final diagnosis in most cases with LBBB.
Keywords
left bundle branch block, myocardial infarction, heart failure, Qatar
Introduction
Left bundle branch block (LBBB) is uncommon in healthy
populations (<1%).
1-3
However, its prevalence is significantly
higher among patients with hypertension, heart failure, coronary
artery disease (CAD), or structural heart disease.
4-8
Left bundle
branch block is associated with high short- and long-term mor-
bidity and mortality in patients with cardiac disease.
9-11
This has
been partly attributed to the challenge of diagnosing acute cor-
onary syndrome (ACS) in patients with LBBB by electrocar-
diogram (ECG) as well as to LBBB-associated risk factors
such as old age, diabetes, and hypertension.
12-14
Many criteria have been proposed to assess the diagnosis of
ACS in patients with LBBB; therefore, it is possible to miss a
diagnosis of ST-segment elevation myocardial infarction
(STEMI) in LBBB.
12-14
Current guidelines state that sympto-
matic patients with new or presumably new LBBB should be
treated as STEMI equivalents. However, the true prevalence
of myocardial infarction (MI) in symptomatic patients with
LBBB is not well established. Recent data suggested that
some of those patients with LBBB are incorrectly diagnosed
with STEMI and subsequently exposed to unnecessary comp-
lications of fibrinolysis therapy as well as angiography.
8,15,16
Notably, a proportion of these patients in fact have congestive
heart failure (CHF) rather than ACS as the primary cause of
admission.
Left bundle branch block data mostly involved caucasians,
and little is known about populations in the Middle East.
17
Therefore, we studied the demographics, clinical presenta-
tion, and final diagnosis of patients who presented with acute
cardiac event and LBBB based on a 23-year registry.
Materials and Methods
Study Setting
The cardiology and cardiovascular (CV) surgery database of
the cardiology department, Hamad General Hospital (HGH)
1
Department of Cardiology and Cardiovascular Surgery, Heart Hospital,
HMC, Doha, Qatar
2
Department of Clinical Medicine, Weill Cornell Medical School, Ar-Rayyan,
Qatar
3
Clinical Research, Trauma Section, Hamad Medical Corporation, Doha, Qatar
4
Internal Medicine, Cardiology Section, Ahmed Maher Teaching Hospital,
Cairo, Egypt
5
Cardiovascular Research, Heart Hospital, Hamad Medical Corporation,
Doha, Qatar
Corresponding Author:
Abdulrahman Arabi, Heart Hospital, Hamad Medical Corporation, PO Box
3050, Doha, Qatar.
Email: abdarabi@yahoo.com
Angiology
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ªThe Author(s) 2014
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in Qatar, was used for this study. We analyzed these registry
data from 1991 to 2013. Qatar is a Middle-Eastern country with
population of only 1.6 million.
18
This registry includes >95%
of patients with cardiac disease admitted to the HGH during
that period. The present analysis focused on those who were
admitted with provisional diagnosis of ACS, heart failure,
arrhythmias, and valvular heart diseases. Being the only ter-
tiary hospital in Qatar, the vast majority of patients with cardiac
disease are admitted to the HGH cardiology department. This
qualifies it as an ideal center for population-based studies.
Data were collected from the clinical record written at
patient discharge according to predefined criteria for each data
point and maintained electronically in our department. Before
analysis, data were screened randomly by a senior physician
in-charge to rule out data duplication and ensure data accuracy.
The study was approved by Research Committee, Hamad Med-
ical Corporation, prior to data analysis.
Definitions
Left bundle branch blockwas defined as a QRS durationof
0.120 seconds in the presence of sinus rhythm, dominant
S wave or rS in V1, broad monophasic R wave in I, aVL, and
V5-V6 associated with the absence of a Q wave in the same
lead.
13,16,19
Congestive heart failure. The simultaneous presence of at least
2 major criteria or 1 major criterion in conjunction with 2
minor criteria was required to establish a diagnosis of CHF.
Major criteria included paroxysmal nocturnal dyspnea or
orthopnea, jugular venous distension, pulmonary rales, radio-
graphic cardiomegaly, acute pulmonary edema, a third heart
sound, central venous pressure >16 cm of water, hepatojugu-
lar reflux, and weight loss of at least 4.5 kg in 5 days in
response to treatment of CHF. Minor criteria included bilat-
eral ankle edema, nocturnal cough, dyspnea on ordinary exer-
tion, hepatomegaly, pleural effusion, and a heart rate of at
least 120 beats/min and were acceptable only if they could not
be attributed to any other medical condition (such as chronic
lung disease, cirrhosis, ascites, or nephrotic syndrome).
20
Acute MI was defined according to the World Heart Orga-
nization criteria.
21
Adjunct therapy during hospitalization
was recorded. The presence of hyperlipidemia was defined
as a fasting cholesterol >5.2 mmol/L in the patient records
or treatment of hyperlipidemia. Chronic kidney failure (CKF)
is defined as creatinine >1.5 the upper limit of the reference
range.
22
Presence of hypertension or diabetes mellitus was deter-
mined by documentation in the medical records or treatment.
Patients were divided into current cigarette smokers, past
smokers defined as >6 months abstinence from smoking, and
those who never smoked from smoking history.
22
The diagno-
sis of ACS was based on the final decision of the assigned
consultants using the clinical, electrocardiographic, labora-
tory, and echocardiographic data collectively.
Statistical Analysis
Patient characteristics are presented as percentages for cate-
gorical variables and mean +standard deviation for contin-
uous variables. The frequencies of categorical variables in
the 2 populations (LBBB and non-LBBB) were compared
using the chi-square test, and continuous variables were
compared using the Student ttest for normal distributed
continuous variables. The Mann-Whitney Utest was used
for nonnormal continuous variables. Variables influencing
in-hospital mortality were assessed by multiple logistic
regression analysis. Adjusted odds ratios (ORs), 95%con-
fidence interval (CI), and Pvalues were reported for signifi-
cant predictors. A 2-tailed P< .05 was considered significant.
Patients with incomplete data on admission and during
hospitalization were excluded from the study analysis. All
data analyses were carried out using the SPSS version 19.0
(SPSS Inc, Armonk, NY, USA).
Results
A total of 50 992 consecutive patients were hospitalized with
acute cardiac event at the cardiology department at HGH from
1991 to 2013; 768 (1.5%) patients had LBBB.
Baseline Clinical Characteristics
Compared to patients without LBBB, those with LBBB were
older (63 +12 vs 54 +13 years; P¼.001), more likely to
be female (31.9%vs 23.1%;P¼.001), and of Arab Middle-
Eastern origin (77.6%vs 57.3%;P¼.001). Also, patients with
LBBB were more likely to have hypertension (59%vs 42.8%;
P¼.001), diabetes mellitus (54.3%vs 40.2%;P¼.001), CKF
(10.9%vs 4.3%;P¼.001), old MI (23.2%vs 17.3%;P¼
.001), dyslipidemia (10.7%vs 7.6%;P¼.001), coronary artery
bypass grafting (10%vs 5.1%;P¼.001), and history of previ-
ous CHF (36.5%vs 15.5%,P¼.001) compared to non-LBBB
patients. In contrast, previous angina (49.1%vs 33.1%;P¼
.001), percutaneous transluminal coronary angioplasty (4.9%
vs 2.1%;P¼.001), and family history of CAD (2%vs
0.9%;P¼.03), and smoking (23.3%vs 15.9%;P¼.001) were
more frequently observed in the non-LBBB group (Table 1).
Shortness of breath (53.1%vs 22.7%;P¼.001) and dizzi-
ness (5.5%vs 4%;P¼.03) were more often observed in
patients with LBBB. Within the ACS patients (n=21406), the
frequency of STEMI was less observed in the LBBB group in
comparison to non-LBBB; however, this difference was not
statistically significant (47 vs 54.5%, P<0.08).
Figure 1 shows the distribution of CHF, STEMI, NSTEMI,
unstable angina, and valvular heart disease among LBBB
patients.
Overall, acute MI (n ¼16070) was diagnosed in 32%of
non-LBBB (n ¼15911/50224) vs 21%of LBBB (n ¼159/
768) cases (P¼0.001). The most frequent cause of admission
with LBBB was CHF (54.2%), followed by STEMI (13.3%),
valvular heart disease (9.4%), UA (8.3%) and NSTEMI
(7.7%) and others (7.1%).
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Laboratory Findings
Patients with LBBB had significantly lower median levels of
creatine kinase (CK)-MB isoenzyme 12 (range, 1-22 890) ver-
sus 6 ng/mL (range, 1-1664; P¼.001), serum triglycerides
1.74 (range, 1-4.99) versus 1.57 mmol/L (range, 1-4.90; P¼
.002), low-density lipoprotein-cholesterol 2.74 (range, 1-6.99)
versus 2.42 mmol/L (1.6.18; P¼.003), high-density
lipoprotein-cholesterol 0.97 (range, 0.30-2.97) versus 1.07
mmol/L (range, 0.30-2.90; P¼.001), total cholesterol 4.77
(range, 2-10.8) versus 4.4 mmol/L (range, 2.0-9.0; P¼.001)
but had higher serum creatinine levels 85 (range, 10-10 839)
versus 97 mmol/L (range, 30-820; P¼.012; Table 2).
Medication
On admission, both groups were treated equally with antiplate-
let medications (aspirin and clopidogrel). However, patients
Table 1. Baseline Clinical Characteristics and Presentation of Patients
With LBBB Versus Non-LBBB.
Characteristics
Non-LBBB
(n ¼50 224)
LBBB
(n ¼768) P
Age, mean +SD 54 +13 63 +12 .001
Gender female, n (%) 11 582 (23.1) 245 (31.9) .001
Race, n (%)
Middle Eastern Arabs 28 797 (57.3) 596 (77.6) .001
South Asian 19 719 (39.3) 158 (20.6) .001
Others 1708 (3.4) 14 (1.8) .001
Medical history, n (%)
Previous myocardial infarction,
n (%)
8697 (17.3) 178 (23.2) .001
Previous angina, n (%) 24 683 (49.1) 254 (33.1) .001
PTCA, n (%) 2442 (4.9) 16 (2.1) .001
CABG, n (%) 2565 (5.1) 77 (10) .001
Hypertension, n (%) 21 493 (42.8) 453 (59) .001
Diabetes mellitus, n (%) 20 179 (40.2) 417 (54.3) .001
Current smoker, n (%) 11 716 (23.3) 122 (15.9) .001
Stroke, n (%) 131 (0.3) 3 (0.4) .486
Family history, n (%) 981 (2.0) 7 (0.9) .038
Dyslipidemia, n (%) 3811 (7.6) 82 (10.7) .001
Body mass index 28.1 +6 28.3 +6 .697
Chronic renal failure, n (%) 2160 (4.3) 84 (10.9) .001
Congestive heart failure, n (%) 7786 (15.5) 280 (36.5) .001
Clinical presentation, n (%)
Chest pain 2699 (5.4) 40 (5.2) .84
Shortness of breath 11 413 (22.7) 408 (53.1) .001
Palpitation 4270 (8.5) 71 (9.2) .464
Dizziness 1999 (4.0) 42 (5.5) .037
Other symptoms 29 843 (59.4) 207 (27)
Final diagnosis within acute coronary syndrome
STEMI 11 536 (54.5) 105 (47.1) .089
NSTEMI 4375 (20.7) 54 (24.2) .089
Unstable angina 5272 (24.9) 64 (28.7) .089
Abbreviations: LBBB, left bundle branch block; PTCA, percutaneous coronary
angioplasty; CABG, coronary artery bypass surgery; STEMI, ST-segment eleva-
tion myocardial infarction; NSTEMI, non-ST-segment elevation myocardial
infarction; SD, standard deviation.
54.20%
13.30% 9.40% 8.30% 7.70% 7.10%
Congestive heart
failure
STEMI Valvular heart
disease
Unstable angina NSTEMI Others
LBBB
Figure 1. Distribution of congestive heart failure, ST-segment elevation myocardial infarction (STEMI), non-ST-segment elevation myocardial
infarction (NSTEMI), unstable angina, and valvular heart disease, among patients with left bundle branch block (LBBB) and non-left bundle branch
block (LBBB) patients.
Table 2. Comparison of Laboratory Findings Among Patients With
LBBB Versus Non-LBBB.
Non-LBBB
(n ¼50 224)
LBBB
(n ¼768) P
Creatine kinase-MB, ng/mL
a
11.5 (1-22 890) 6 (1-1664) .001
Creatine kinase, m/L
a
153 (1-150 200) 129 (3-45 190) .02
Triglyceride, mmol/L
a
1.74 (1-4.99) 1.57 (1-4.9) .002
LDL-C, mmol/L
a
2.74 (1-6.99) 2.42 (1-6.18) .003
HDL-C, mmol/L
a
0.97 (0.3-2.97) 1.07 (0.3-2.9) .001
Total cholesterol, mmol/L
a
4.77 (2-10.8) 4.4 (2-9) .001
Hemoglobin, g/L
b
13 +512+2 .001
FBS, mmol/L
a
7 (3-3206) 7 (3-58) .66
Creatinine, mmol/L
a
86 (10-10 839) 99 (30-820) .012
BNP, ng/L
a
12 (1-111 456) 35 (1-3500) .45
Abbreviations: LDL-C, low-density lipoprotein cholesterol; HDL-C, high-
density lipoprotein cholesterol; FBS, fasting blood sugar; BNP, B-type natriure-
tic peptide; LBBB, left bundle branch block.
a
Values are given as (median and range).
b
Values are given as mean and standard deviation.
Alkindi et al 3
by guest on December 6, 2014ang.sagepub.comDownloaded from
with LBBB were less likely to be prescribed heparin (19.5%vs
28%;P¼.001), b-blockers (30.2%vs 41.1%;P¼.001), and
calcium channel blockers (9.6%vs 12.7%;P¼.01) but more
likely to be treated with angiotensin-converting enzyme inhibi-
tors (ACEIs; 47.4%vs 33.9%;P¼.001) and diuretics (56.8%
vs 26.2%;P¼.001; Table 3).
At discharge, patients with LBBB were more likely to be pre-
scribed an ACEI (53.3%vs 38.8%;P¼.001) and diuretics (62%
vs 28.5%;P¼.001). However, prescription of aspirin (72.5%vs
76.4%;P¼.01), b-blockers (35.3 vs 54%;P¼.001), and clo-
pidogrel (26.1%vs 20.7%;P¼.001) was significantly lower in
patients with LBBB compared to non-LBBB patients.
Table 4 compares serum CK-MB levels in patients with
STEMI and NSTEMI based on the conduction status. Patients
with LBBB had significantly lower levels of CK-MB among
patients with STEMI (P< .04).
Complications and Outcome
Patients with LBBB were more likely to have malignant
arrhythmias (ventricular tachycardia/ventricular fibrillation;
4.4%vs 2.2%;P¼.001) and CHF (10.7%vs 3.2%;P¼
.001; Table 5). Moreover, patients with LBBB had lower ejec-
tion fraction (32%+14%vs 47%+71%;P¼.001) and
shorter length of stay (7 +20 vs 9 +22 days; P¼.04) but
had higher incidence of cardiogenic shock (3.8%vs 1.7%;
P¼.001) and mortality (13.6%vs 6.1%;P¼.001).
Table 3. Treatment According to the Presence of LBBB.
Non-LBBB LBBB P
Admission drugs, n (%)
Aspirin 39 162 (78) 293 (77.2) .614
b-Blockers 20 646 (41.1) 232 (30.2) .001
Clopidogrel 13 632 (27.1) 199 (25.9) .446
CCB 3690 (12.7) 74 (9.6) .011
ACEI/ARB 17 007 (33.9) 364 (47.4) .001
Diuretics 13 164 (26.2) 436 (56.8) .001
Heparin 14 039 (28) 150 (19.5) .001
Thrombolytics 11.6% 4.6% .001
Coronary angiography 9.5% 3.5% .001
PTCA 4.9% 2.1% .001
Treatment on discharge, n (%)
Aspirin 38 388 (76.4) 557 (72.5) .011
Clopidogrel 13 105 (26.1) 159 (20.7) .001
b-Blockers 27 096 (54) 271 (35.3) .001
Statin
a
20 207 (40.2) 328 (42.7) .165
ACEI/ARB 19 474 (38.8) 409 (53.3) .001
Diuretics 14 322 (28.5) 476 (62) .001
CCB 50 224 (100) 768 (100) .002
Abbreviations: CCB, calcium channel blocker; ACEI/ARB, angiotensin convert-
ing enzyme inhibitor/angiotensin receptor blockers; PTCA, percutaneous cor-
onary angioplasty; LBBB, left bundle branch block.
a
Data for statin on admission were lacking.
Table 4. Cardiac Biomarkers.
Patients With
LBBB
Non-LBBB
Patients P
ST-segment elevation myocardial infarction
CK-MB, mean +SD, unit/
L Median and range
182 +325
72 (3-1664)
621 +1894
125 (3-13 872)
.04
Non-ST-segment elevation myocardial infarction
CK-MB, mean +SD, unit/
L Median and range
21 +42
6 (1-263)
96.6 +446
7 (2-2801)
.30
Abbreviations: CK-MB, creatine kinase-MB; SD, standard deviation; LBBB, left
bundle branch block.
Table 5. Complications and Outcome in Patients With LBBB Versus
Non-LBBB Patients.
Non-LBBB LBBB P
Arrhythmias (VT/VF), n (%) 1102 (2.2) 34 (4.4) .001
Congestive heart failure, n (%) 1594 (3.2) 82 (10.7) .001
Ejection fraction, mean +SD, % 47 +71 32 +14 .001
Cardiogenic shock, n (%) 870 (1.7) 29 (3.8) .001
Length of stay, mean +SD, days 9 +22 7 +20 .04
Mortality, n (%) 3063 (6.1) 70 (13.6) .001
Abbreviations: VT, ventricular tachycardia; VF, ventricular fibrillation; LBBB,
left bundle branch block; SD, standard deviation.
Table 6. Predictors of In-Hospital Mortality Using Multivariate Logis-
tic Regression Analysis.
Variable OR 95% CI P
Age 1.01 0.99-1.03 .20
Gender male 1.12 0.71-1.7 .64
Diabetes mellitus 0.91 0.60-1.38 .66
Smoking 1.22 0.77-1.95 .40
Hypertension 0.67 0.43-1.03 .07
Dyslipidemia 0.50 0.06-4.2 .53
Chronic kidney failure 2.02 1.09-3.7 .02
Old myocardial infarction 1.22 0.75-1.95 .41
Atrial fibrillation 1.30 0.72-2.33 .38
Congestive heart failure 1.15 0.74-1.75 .50
Left bundle branch block 2.96 2.0-4.4 .001
Abbreviations: CI, confidence interval; OR, odds ratio.
Table 7. Predictors of In-Hospital Mortality Using Multivariate Logis-
tic Regression Analysis in Left Bundle Branch Block Cases.
Variable OR 95% CI P
Age 0.99 0.97-1.02 .74
Gender male 1.05 0.60-1.94 .87
Diabetes mellitus 0.76 0.40-1.4 .35
Smoking 1.80 0.90-3.5 .08
Hypertension 0.75 0.40-1.40 .33
Chronic kidney failure 2.93 1.40-6.12 .004
Old myocardial infarction 1.14 0.60-2.11 .67
Atrial fibrillation 1.21 0.50-2.70 .64
Congestive heart failure 1.09 0.60-1.91 .77
Abbreviations: CI, confidence interval; OR, odds ratio.
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Predictor of In-Hospital Mortality
On multivariate analysis, CKF (OR: 2.02, 95%CI: 1.09-3.7;
P¼.02) and LBBB (OR: 2.96, 95%CI: 2.0-4.4; P¼.001)
were significant predictors of overall in-hospital mortality in
the entire study population (Table 6). Further analysis after
adjusting for all confounding variables showed that CKF
(OR: 2.93, 95%CI: 1.40-6.12; P¼.004) was the only predictor
of in-hospital mortality among patients with LBBB (Table 7).
Discussion
This study describes the clinical presentation, implication,
and outcome of LBBB among patients presenting with acute
cardiac events in a Middle-Eastern country. Consistent with
previous data, patients with LBBB in our study were more
likely to be older, female, and have a history of hypertension
andCHFthanthosewhohadnoLBBB.
7,23
Theprevalenceof
LBBB among ACS patients is estimated at around 2%, which
is similar to the prevalence of LBBB among the Heart Hospi-
tal admissions in Qatar (1.5%).
24
However, age distribution in
Qatar may be relevant since the elderly patients represent a
minority of the population (<10%).
25
Moreover, our finding
showed that LBBB is associated with higher CKF in univari-
ate and multivariate analyses.
The current guidelines suggest that symptomatic patients
with new, or presumably new, LBBB should be considered
as STEMI equivalents.
24
However, the proportion of MI in
our analysis was significantly lower among patients with
LBBB (21%) compared to 32% in those without LBBB.
Previous data showed no difference in the prevalence of acute
MI between patients with LBBB (whether old or new).
12,15,26
As the minority of patients with LBBB are ultimately diag-
nosed with acute MI, false-positive cardiac catheterization
laboratory activation is frequently reported.
24,27,28
This false
activation is known as an activation in which the coronary
angiography does not recognize a culprit artery that could
explain the initial impression of STEMI diagnosis.
24
Larson
et al
27
and Lopes et al
28
reported a high rate of this false activa-
tion (44%and 39%, respectively) among those who presented
with LBBB and considered to have STEMI equivalent. This
finding suggests that LBBB as a true reflection of acute MI is not
common.
24,27-29
Other studies demonstrated that less than half
of all patients with ACS having LBBB will accurately have
acute MI as final diagnosis and a great number of those who
have LBBB plus acute MI will not show an occluded culprit
vessel on coronary angiography.
24
It is presumed that MI may
present with LBBB secondary to proximal left anterior des-
cending coronary artery occlusion which will result in a larger
MI than those without LBBB; however, the level of CK-MB
was statistically lower in patients with LBBB indicating that
the main cause of LBBB was not necessarily ischemic.
24
In-Hospital Treatment
Both groups received equal antiplatelet treatment; however,
patients with LBBB received less b-blockers, heparin, and
fibrinolytic treatment because only a minority of patients with
LBBB ultimately were finally diagnosed as having acute MI.
Patients with LBBB may have been exposed to unnecessary
coronary angiogram that can lead to increased risk of compli-
cations (including contrast induced nephropathy and kidney
damage).
24,30
Given these findings, the concern of increased
morbidity and mortality due to delay in diagnosis of true acute
MI in patients with LBBB (due to diagnostic complexity) is
less likely compared with the risk of complication of fibrino-
lytic therapy and angiography, which might be magnified in
such patients with high-risk profile like hypertension and old
age. In our study, patients with LBBB underwent significantly
less often coronary intervention in comparison to non-LBBB;
however, in each group, therapeutic intervention was
performed in nearly half of those who underwent diagnostic
angiography.
Level of CK-MB was significantly higher in STEMI in the
non-LBBB group compared to the LBBB group, which prob-
ably indicates that the size of MI could be larger in the non-
LBBB group. Moreover, serum B-type natriuretic peptide was
higher in the LBBB group compared with the non-LBBB group;
however, this difference was not statistically significant.
Similar to previous studies,
24
in-hospital mortality in
patients with LBBB in our study was significantly higher than
those without LBBB. This may be explained by the older age
and the higher prevalence of CV risk factors, in addition to the
potential delay in the diagnosis and treatment of ACS in
patients with LBBB.
Patients presenting with LBBB in our analysis were also
more likely to have major adverse CV events like arrhythmias,
heart failure, and cardiogenic shock. This high-risk profile in
these patients plays a role in the significant increase in mortality.
One of the main questions in patients with LBBB is whether the
increase in mortality is acute MI-associated or as a result of other
reasons. The in-hospital mortality for patients with heart failure
was 8%and was not statistically different between the LBBB
and no LBBB groups. This is similar to the finding of Huvelle
and his group who found no significant short-term mortality
difference in 403 patients admitted with acute heart failure,
despite 2-fold increase in mortality at 1 year.
31
Left bundle branch block is associated with significant
increase in the in-hospital mortality compared to patients with-
out LBBB; this was observed in patients with NSTEMI and
STEMI. Concurrent recommendations need to be reviewed in
a sense that new diagnostic strategies are required to guide a
more appropriate selection of patients with suspected acute MI
and LBBB. Serial ECG and echocardiography in a hemodynami-
cally stable patient with suspected acute MI and LBBB could
prevent unnecessary exposure to the bleeding risk of fibrinolysis
therapy and complications of an invasive procedure.
24
\In patients presenting with acute cardiac events, logistic
regression analysis showed that CKF increased mortality
2-fold, whereas LBBB was associated with 3-fold increase in
the mortality. In further analysis of those who had LBBB at
presentation, CKF was associated with 2-fold increase in the
mortality in patients presented with acute cardiac event.
Alkindi et al 5
by guest on December 6, 2014ang.sagepub.comDownloaded from
Limitations
The data of this study were collected retrospectively. There
were no angiographic data for all patients. Door-to-treatment
and stages of CKF were also lacking. The reasons of admis-
sions in this study were limited to ACS (MI and UA), CHF,
arrhythmias, and valvular heart diseases. There is a need for
new algorithm for the appropriate diagnosis and management
of LBBB in the acute cardiac settings.
29
Conclusions
Although LBBB presents in the minority of acute cardiac
cases, it has particular comorbidities and mortality patterns.
Dyspnea was the main clinical presentation and CHF was the
final diagnosis in majority of the cases. They were less likely
to have acute MI regardless of the presenting symptoms com-
pared to patients without LBBB. Further studies are needed to
address the implications of CKF in patients with LBBB.
Acknowledgments
We thank the registry database team in the cardiology department.
Authors’ Note
FA, AE, and AA contributed to data analysis, interpretation, and writ-
ing the article. HA, AP, and JA contributed to data analysis, interpre-
tation, and reviewing the article. RS contributed to statistical analysis
and reviewing the article. AAG contributed to data interpretation,
reviewed and approved the article. All authors read the article and
approved it. The Medical Research Center at Hamad Medical Corpo-
ration, Qatar, approved the study.
Declaration of Conflicting Interests
The author(s) declared no potential conflicts of interest with respect to
the research, authorship, and/or publication of this article.
Funding
The author(s) received no financial support for the research, author-
ship, and/or publication of this article.
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... A new or presumably new-onset BBB in an appropriate setting is pathological with management similar to an STelevation myocardial infarction (STEMI). [2] In a recent registry, the prevalence of left BBB (LBBB) was around 2%. [3] Acute coronary syndrome (ACS) associated with a BBB has a higher risk of adverse cardiac events and mortality, especially with right BBB (RBBB). [4,5] The evidence or guidance on the management approach to transient BBB during the perioperative period is lacking. ...
... Left bundle branch block (LBBB) is a pattern seen on the surface ECG, which results when there is alteration of normal electrical activity in the His-Purkinje fibres. 1 Most often, LBBB occurs from chronic conditions that progressively damage the conduction system (eg, coronary artery disease, hypertension, cardiomyopathy) or more acutely from myocardial ischaemia or myocarditis, among others. [2][3][4] Infrequently does it manifest in patients with structurally normal hearts without coronary disease and even less commonly does the LBBB appear intermittently. 5 6 We present the case of a 70-year-old woman with HER2+/ER+ breast cancer on adjuvant trastuzumab therapy who presented with respiratory failure from influenza and was found to have intermittent LBBB with new onset systolic heart failure in the setting of chemotherapy-induced cardiotoxicity. ...
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A 70-year-old woman with HER2+/ER+ breast cancer on adjuvant trastuzumab therapy without a history of cardiovascular disease presented with respiratory failure from influenza and was found to have intermittent left bundle branch block (LBBB) with new onset systolic heart failure. Her course was complicated by polymorphic ventricular tachycardia and recurrent chest pain. Significant investigations included a normal cardiac MRI and cardiac catheterisation with unobstructed coronaries. It was determined that the aetiology of her heart failure was trastuzumab-induced cardiotoxicity after comprehensive workup. This case highlights an uncommon presentation of LBBB and the steps taken to diagnose a rare cardiomyopathy.
... 1,4 Left bundle branch block (LBBB) was defined as a QRS duration of >0.120 seconds in the presence of sinus rhythm, dominant S wave or rS in V1, broad monophasic R wave in I, aVL, and V5 to V6 associated with the absence of a Q wave in the same lead. [7][8][9][10] On-admission acute cardiac events included acute heart failure or AMI. The simultaneous presence of at least 2 major criteria or 1 major criterion in conjunction with 2 minor criteria was required to establish a diagnosis of CHF. ...
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We conducted a retrospective analysis of 50 974 patients admitted with acute cardiac events with and without right bundle branch block (RBBB) over 23 years. Compared to non-RBBB, patients with RBBB (n = 386; 0.8%) were 3 years older ( P = .001), more likely to present with breathlessness rather than chest pain ( P = .001), and had more diabetes mellitus ( P = .001). Patients with RBBB had significantly higher cardiac enzymes ( P = .001); however, there were no significant differences in the presentation with ST-segment elevation myocardial infarction (24.6% vs 22.2%), non-ST-segment elevation myocardial infarction (23.7% vs 22.4%), and unstable angina (51.7% vs 55.4%). Patients with RBBB were more likely to have congestive heart failure (CHF; 9.6% vs 3.2%, P = .001), cardiogenic shock (10.6% vs 1.7%, P = .001), and ventricular tachyarrhythmias (7.3% vs 2.2%, P = .001). Left ventricular ejection fraction and hospital length of stay were comparable between the groups. All-cause mortality was 5 times greater in patients with RBBB (21% vs 4.2%, P = .001). Right bundle branch block was independent predictor of mortality (adjusted odd ratio 5.14; 95% confidence interval: 3.90-6.70). Subanalysis comparing normal QRS, RBBB, and left BBB showed that RBBB was associated with the worst outcomes except for CHF. Although RBBB presents in only about 1% of patients with cardiac disease, it was found to be an independent predictor of hospital mortality.
... 3 Although it has been proposed that symptomatic patients with new or presumably new left bundle branch block (LBBB) and anginal pain should be treated as STEMI equivalents, in a recent registry the proportion of myocardial infarction was significantly lower among patients with LBBB (21%) compared to those without LBBB (32%). 4 Apart from coronary artery disease (CAD), other causes of LBBB include valve disease, dilated cardiomyopathy, infiltrative cardiomyopathy, hypertensive cardiomyopathy, congenital heart disease, degenerative conduction heart disease (Lenegre and Lev diseases), myocarditis, infective endocarditis, heart trauma/surgery, hyperkalemia, myxedema, and systemic sclerosis. 5 Our review provides a comprehensive overview of transient or intermittent LBBB cases described in the literature and discusses its clinical impact. ...
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