Implications of Left Bundle Branch Block in AcuteMyocardial Infarction Treated With

Primary Angioplasty

Raul Moreno, MD, Eulogio Garcıa, MD, Esteban Lopez de Sa, MD,Manuel Abeytua, MD, Javier Soriano, MD, Ana Ortega, MD, Rafael Rubio, MD, and

Jose-Luis Lopez-Sendon, MD

The presence of left bundle branch block (LBBB) isassociated with higher mortality in acute myocar-

dial infarction (AMI), not only in patients managedconservatively, but also in those treated with throm-bolysis.1–4 Primary percutaneous coronary interven-tion (PCI) is the most effective treatment for AMI.5–8

Patients with LBBB have been excluded from moststudies of primary PCI,9–14 and because of this, theoutcome of these patients when treated with PCI ispoorly known. The aim of our study was to evaluatethe implications of LBBB among patients with AMIundergoing primary PCI.

• • •We studied 945 patients with AMI who underwent

PCI within 12 hours of symptom onset at our institu-tion from August 1991 to December 1999. All patientshad chest pain lasting�30 minutes, as well as either�1 mm of ST-segment elevation in�2 adjacent leadson the electrocardiogram, or LBBB. Of the 945 pa-tients, 17 (1.8%) had LBBB.

Cardiac catheterization was performed by the fem-oral approach with 6Fr to 8Fr guiding catheters. Inpatients with multivessel disease, only the culprit ves-sel was treated in the absence of hemodynamic insta-bility or persistent ischemia.15 A femoral sheath wasremoved 6 to 8 hours after the procedure. Coronarystents were used according to the physician’s prefer-ence, except in patients included in the Primary An-gioplasty in Myocardial Infarction-3 (PAMI) andControlled Abciximab and Device Investigation toLower Late Angioplasty Complications (CADILLAC)trials, in which patients were randomly assigned tostent or balloon-alone angioplasty.16,17

Patients received aspirin 200 to 500 mg intrave-nously on admission if they had no contraindications.At the beginning of the procedure, patients receivedheparin 10,000 IU (5,000 IU when receiving IIb/IIIainhibitors) and additional boluses when necessary tomaintain an activating clotting time of�300 seconds(200 to 250 seconds in those receiving IIb/IIIa inhib-itors). No routine anticoagulation was administeredafter the procedure.

The decision to administser IIb/IIIa inhibitors (ab-

ciximab) was according to the physician’s preference,except in patients included in the CADILLAC trialwhere patients were randomly assigned to receiveabciximab or placebo.

The following criteria were used for the diagnosisof LBBB: (1) QRS complex�0.12 second in dura-tion; (2) monophasic R wave in leads I, V5, and V6;(3) absence of Q waves in leads I, V5, and V6; (4)intrinsicoid deflection delay in V5 and V6; and (5)repolarization abnormalitites (ST-segment andT-wave displacement opposite the QRS complex).18

An angiographically successful result was defined asthe presence of Thrombolysis In Myocardial Infarc-tion (TIMI) 2 to 3 flow and residual stenosis�50%after the procedure, although the frequency of TIMI 3flow after the procedure was also evaluated. Cardio-genic shock was defined as the presence of systolicblood pressure�90 mm Hg despite intravenous fluidadministration or the inability to maintain a systolicblood pressure�90 mm Hg in the absence of inotro-pic drugs.19 Patients in whom hypotension was sec-ondary to mechanical complications, especially leftventricular free wall rupture, were not considered ashaving cardiogenic shock.20 The status on differentrisk factors was coded according to the history of thepatient. Major bleeding included intra- and extracra-nial bleeding requiring blood transfusion.

Continuous variables are expressed as mean� SD,and qualitative variables as percentages (proportions).The comparison between 2 media was studied withStudent’st test, and the comparison of proportions bythe chi-square test. A step-by-step logistic regressionmultivariate analysis was performed to identify theindependent predictors of death. Associations wereconsidered statistically significant when the p valuewas�0.05.

Of the 945 patients, 17 (1.8%) had LBBB at ad-mission. The electrocardiogram on admission showedinfarct locations in 8 patients (47%, inferior in 4 andanterior in 4), whereas infarct locations were undeter-mined in the remaining 9 patients (53%).

Clinical characteristics of patients with and withoutLBBB are listed in Table 1. Importantly, patients withLBBB were older (73� 6 vs 64� 13 years, p�0.005), had hypercholesterolemia less often (12% vs38%, p� 0.017), and higher frequency of heart failure(65% vs 26%, p� 0.009), and cardiogenic shock atthe beginning of the procedure (35% vs 10%, p�0.004). There was a tendency toward a longer timefrom the onset of symptoms in patients with LBBB

From the Coronary Unit and Division of Interventional Cardiology,Hospital Gregorio Maranon, Madrid, Spain. Dr. Moreno’s address is:Instituto Cardiovascular, University Hospital Clınico San Carlos,Martın Lagos, s/n, 28040 Madrid, Spain. E-mail: raulmorenog@terra.es. Manuscript received February 27, 2002; revised manuscriptreceived and accepted April 17, 2002.

401©2002 by Excerpta Medica, Inc. All rights reserved. 0002-9149/02/$–see front matterThe American Journal of Cardiology Vol. 90 August 15, 2002 PII S0002-9149(02)02497-9

(312 � 243 vs 191 � 215 minutes, p � 0.065). Therewere no other significant differences between bothgroups regarding other clinical characteristics. Infarctsize, defined as peak creatine phosphokinase plasmavalue, was greater in patients with LBBB (488 � 365vs 319 � 242 IU, p � 0.030).

Patients with LBBB had more extensive coronaryartery disease (2.4 � 0.8 vs 1.7 � 0.8 vessels dis-

eased, p �0.001), as well as a higherfrequency of the left main artery asthe infarct vessel (18% vs 2%, p �0.003). Multivessel disease waspresent in 82% of patients with ver-sus 47% patients without LBBB (p� 0.004) (Table 2). Of the 17 pa-tients with LBBB, 8 (47%) had3-vessel disease, 3 (18%) left maindisease, and 3 (18%) 2-vessel dis-ease. The remaining 3 patients had a1-vessel disease. Three-vessel dis-ease was also present in 1 patientwith left main disease, whereas theremaining 2 patients with left maindisease also had right coronary andleft circumflex disease, respectively.

The infarct-related artery was theleft anterior descending coronary ar-tery in 7 patients (41%), the rightcoronary artery in 5 (29%), the leftmain in 3 (18%), and the left circum-flex artery in 2 (12%). In the patientwho had previously undergone coro-nary artery bypass grafting (saphe-nous vein graft to a marginal branchof the left circumflex artery), the in-farct-related artery was the nativeright coronary artery.

Table 3 lists procedural resultsand in-hospital outcomes of patientswith versus without LBBB. An an-giographic successful result (71% vs94%, p � 0.003) and a final TIMI 3flow (59% vs 85%, p � 0.011) wereachieved less often in patients withLBBB. Coronary stents (88% vs54%, p � 0.003) and aortic counter-pulsation balloon pumps (29% vs11%, p � 0.040) were used morefrequently in patients with LBBB,but there were no significant differ-ences in the use of abciximab (6% vs11%, p � 0.710). Mortality was sig-nificantly higher in patients withLBBB (41% vs 11%, p � 0.002).

Although LBBB was associatedwith an increased mortality rate, itwas not an independent predictor ofmortality in the multivariate analysis.In contrast, cardiogenic shock, ante-rior location, age �70 years, angio-graphic failure, female gender, andmultivessel disease were indepen-

dently associated with a higher mortality rate in themultivariate analysis (Table 4).

The mortality rate was higher in patients with thanwithout LBBB when heart failure was present (25% vs17% in patients with Killip class II or III, and 100% vs69% in those in Killip class IV, respectively). How-ever, mortality was not significantly lower in patientswith LBBB when no heart failure was present at the

TABLE 1 Comparison Between Patients With and Without LBBB

Characteristics

LBBB

p Value� (n � 17) � (n � 928)

Age (yrs) 73 � 6 64 � 13 0.005Women 2 (12%) 210 (23%) 0.255Diabetes mellitus 4 (24%) 214 (23%) 0.964Hypertension 11 (65%) 457 (49%) 0.262Smoking 8 (47%) 630 (68%) 0.246Hypercholesterolemia 3 (14%) 417 (45%) 0.015Previous coronary bypass 1 (6%) 10 (1%) 0.182Previous infarction 3 (18%) 135 (15%) 0.720Previous PCI 1 (6%) 40 (4%) 0.753Time from symptoms onset (min) 312 � 243 191 � 215 0.065Rescue PCI 0 (0%) 49 (5%) 0.205Peak MB creatine phosphokinase (IU) 488 � 366 319 � 242 0.030Cardiac failure 11 (65%) 241 (26%) 0.009Cardiogenic shock 6 (35%) 93 (10%) 0.004

TABLE 2 Angiographic Data in Patients With and Without LBBB.

LBBB

p Value� (n � 17) � (n � 928)

No. of narrowed coronary arteries 2.4 � 0.8 1.7 � 0.8 0.001Multivessel disease 14 (82%) 436 (47%) 0.004Infarct-related artery

Left main 3 (18%) 15 (2%) 0.003Left anterior descending 7 (41%) 551 (59%) 0.131Right coronary 5 (29%) 273 (29%) 1.000Left circumflex 2 (12%) 103 (11%) 0.932

Initial TIMI 2–3 flow 3 (18%) 112 (12%) 0.167Proximal occlusion 8 (47%) 433 (47%) 0.809Left ventricular ejection fraction 0.37 � 0.13 0.46 � 0.13 0.046

TABLE 3 Comparison of In-hospital Outcomes in Patients With Versus WithoutLBBB

LBBB

p Value� (n � 17) � (n � 928)

Overall mortality 7 (41%) 104 (11%) 0.002Mortality after excluding cardiogenic shock 1/11 (9%) 50/835 (6%) 0.722Reinfarction 0 (0%) 21 (2%) 0.380Postinfarction angina 0 (0%) 44 (5%) 0.441Documented reocclusion 0 (0%) 40 (4%) 0.378Left ventricular free wall rupture 0 (0%) 17 (2%) 0.719New target vessel revascularization 0 (0%) 27 (3%) 0.608Coronary artery bypass grafting 0 (0%) 11 (1%) 0.818Repeat PCI 0 (0%) 16 (2%) 0.746Cardiac transplantation 0 (0%) 8 (1%) 0.864Atrioventricular blockade (second to third degree) 2 (12%) 53 (6%) 0.260Ischemic stroke 2 (12%) 8 (1%) 0.013Intracranial bleeding 0 (0%) 3 (0.3%) 0.947Major bleeding 3 (18%) 35 (3%) 0.022Angiographic success 12 (71%) 873 (94%) 0.003Final TIMI 3 flow 10 (59%) 784 (85%) 0.011

402 THE AMERICAN JOURNAL OF CARDIOLOGY� VOL. 90 AUGUST 15, 2002

beginning of the procedure (0% vs 4% in patients withand without LBBB, respectively).

No significant differences were observed in theincidence of reinfarction or postinfarction angina be-tween groups.

No patient with LBBB underwent coronary arterybypass grafting or a new target vessel PCI duringhospitalization. Three patients underwent PCI of anonrelated infarct-related artery during a second pro-cedure. In 1 patient with LBBB and cardiogenicshock, a ventricular assist system was implanted as abridge to cardiac transplantation, but the patient dieddue to sepsis and renal failure.

Finally, major bleeding occurred more frequentlyin patients with LBBB (18% vs 3%, p � 0.019). Nosignificant differences were observed in other out-comes that were evaluated.

• • •In our study, the mortality rate in patients with

LBBB was 3.7-fold compared with patients withoutLBBB. The higher mortality in these patients seemedto be due to several reasons. First, patients with LBBBhad a worse clinical profile, especially more advancedage and worse Killip class; they were in cardiogenicshock more often at the beginning of the procedure.Second, AMI was larger in size (a higher creatinephosphokinase peak value) in patients with LBBB;this fact explains the more impaired left ventricularejection fraction in these patients. Additionally, pa-tients with LBBB also had a higher risk angiographicprofile. Patients with LBBB had more extensive cor-onary artery disease (multivessel disease was presentin 82% of these patients compared with 47% in pa-tients without LBBB). Also of note, the left mainartery was the infarct vessel in 18% of patients withLBBB compared with 2% in patients without LBBB.The left anterior descending coronary artery was theinfarct-related artery in 41% of patients; this finding isconsistent with the study of Newby et al,7 in whichthis vessel was the infarct artery in 43% of patients.Other angiographic data that could potentially haveprognostic implications were the levels of occlusionand the initial TIMI grade flow. These were not sig-nificantly different between the 2 groups.

Thus, among patients with AMI, those present-ing with LBBB are also at high risk when beingtreated with primary PCI. This is mainly due to the

higher risk angiographic profile and those present-ing more often with severe heart failure.

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TABLE 4 Independent Predictors of In-hospital Mortality in theMultivariate Analysis

OR 95% CI p Value

Cardiogenic shock 25.66 14.44–46.83 �0.001Angiographic failure 6.27 2.98–14.32 �0.001Anterior location 2.78 1.51–5.33 0.036Age �70 yrs 1.90 1.08–3.34 0.027Women 2.00 1.09–3.63 0.043Multivessel coronary disease 2.89 1.63–5.28 0.007

CI � confidence interval; OR � odds ratio.

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