Prognostic significance of bundle-branch block in acute myocardial infarction: the importance of location and time of appearance

In-Hospital Prognostic Value of Electrocardiographic Parameters Other Than ST-Segment Changes in Acute Myocardial Infarction: Literature Review and Future Perspectives

Electrocardiography (ECG) remains an irreplaceable tool in the management of the patients with myocardial infarction, with evaluation of the QRS and ST segment being the present major focus. Several ECG parameters have already been proposed to have prognostic value with regard to both in-hospital and long-term follow-up of patients. In this review, we discuss various ECG parameters other than ST segment changes, particularly with regard to their in-hospital prognostic importance. Our review not only evaluates the prognostic segments and parts of ECG, but also highlights the need for an integrative approach in big data to re-assess the parameters reported to predict in-hospital prognosis. The evolving importance of artificial intelligence in evaluation of ECG, particularly with regard to predicting prognosis, and the potential integration with other patient characteristics to predict prognosis, are discussed.

Prevalence, Temporal Evolution, and Impact on Survival of Ventricular Conduction Blocks in Patients With Acute Coronary Syndrome and Cardiogenic Shock

Changes in QRS duration and pattern are regarded to reflect severe ischemia in acute coronary syndromes (ACS), and ventricular conduction blocks (VCBs) are recognized high-risk markers in both ACS and acute heart failure. Our aim was to evaluate the prevalence, temporal evolution, association with clinical and angiographic parameters, and impact on mortality of VCBs in ACS-related cardiogenic shock (CS). Data of 199 patients with ACS-related CS from a prospective multinational cohort were evaluated with electrocardiogram data from baseline and day 3. VCBs including left or right bundle branch block, right bundle branch block and hemiblock, isolated hemiblocks, and unspecified intraventricular conduction delay were assessed. Fifty percent of patients had a VCB at baseline; these patients were older, had poorer left ventricular function and had more often left main disease compared with those without VCB. One-year mortality was over 2-fold in patients with VCB compared with those without VCB (68% vs 32%, p<0.001). All types of VCBs at baseline were associated with increased mortality, and the predictive value of a VCB was independent of baseline variables and coronary angiography findings. Interestingly, 37% of the VCBs were transient, i.e., disappeared before day 3. However, 1-year mortality was much higher in these patients (69%) compared to patients with persistent (38%) or no VCB (15%, p<0.001). Indeed, a transient VCB was a strong independent predictor of 1-year mortality. In conclusion, our findings propose that any VCB in baseline electrocardiogram, even if transient, identifies very early patients at particularly high mortality risk in ACS-related CS.

Prognostic Significance of Right Bundle Branch Block for Patients with Acute Myocardial Infarction: A Systematic Review and Meta-Analysis

Background

The aim of the current meta-analysis was to assess the effect of right bundle branch block (RBBB) on mortality outcome in patients with acute myocardial infarction (AMI).

Material/Methods

Embase, PubMed, and Cochrane databases were searched through January 2015 using the keywords “RBBB”, “mortality”, “AMI”, “Coronary Heart Disease”, and “cardiovascular”. An odds ratio (OR) of RBBB on mortality endpoints was calculated using random-effects models.

Results

RBBB was associated with significantly increased overall mortality in patients with AMI. The OR of RBBB for deaths was 1.56 [95% confidence interval (CI), 1.44 to 1.68, p<0.001]. Moreover, RBBB showed a considerable effect on both in-hospital mortality (OR: 1.94, 95% CI: 1.60 to 2.37, p=0.002) and long-term mortality (OR: 1.49, 95% CI: 1.37 to 1.62, p<0.001).

Conclusions

RBBB is associated with an increased risk of all-cause mortality and indicates a poorer prognosis in patients with AMI.

Relation of New Permanent Right or Left Bundle Branch Block on Short- and Long-Term Mortality in Acute Myocardial Infarction Bundle Branch Block and Myocardial Infarction

The aim of this study was to investigate the prognosis associated with bundle branch block (BBB) depending on location, time of appearance, and duration in patients with myocardial infarction (MI). From January 1998 to January 2008, we recruited 5,570 patients with acute MI. Thirty-day and 7-year all-cause mortality, according to BBB location, time of appearance, and duration were analyzed by multivariable analyses. BBB was present in 964 patients (17.3%); right BBB (RBBB) 10.6% and left BBB (LBBB) 6.7%. Overall mortality rate at 30 days was 13.2% (n = 738) and 7 years was 6.34 deaths per 100 patient-year. Both RBBB and LBBB were more frequently previous, 42.9% and 58.8%. Compared with non-BBB, all BBB groups showed higher prevalence of co-morbidities, especially rates of diabetes (49.0% vs 34.3%, p <0.001) and more often heart failure during hospitalization (54.5% vs 26.6%, p <0.001). Compared with RBBB, patients with LBBB had a higher prevalence of co-morbidities and a higher mortality, especially the new BBB, 30 days: 52.5% versus 31.6% and 7 years (incident rate): 27.2 versus 13.3 per 100 patient-year. New transient BBB had lower heart failure on admission (42.6% vs 58.3%, p = 0.008) and 30-day mortality (20.3% vs 69.6%, p <0.001) compared with permanent in both locations. New permanent RBBB was independently associated with 30-day (hazard ratio [HR] 2.01, 95% confidence interval [CI] 1.45 to 2.79) and 7-year mortality (HR 3.12, 95% CI 2.38 to 4.09). New-permanent LBBB was independently associated with 30-day (HR 2.15, 95% CI 1.47 to 3.15) and 7-year mortality (HR 2.91, 95% CI 2.08 to 4.08). In conclusion, in patients with acute MI, the appearance of a new BBB was independently associated with a higher 30-day and 7-year all-cause mortality.

Left atrial and left atrial appendage systolic function in patients with post-myocardial distal blocks

INTRODUCTION

The study aimed to evaluate function of the left atrium (LA) and of the left atrial appendage (LAA) after myocardial infarction (MI) complicated by intracardiac conduction disturbances.

MATERIAL AND METHODS

The study comprised 59 patients with persistent post-myocardial distal blocks, who were allocated to one of the three following subgroups: study group I - 20 patients with left bundle branch block (LBBB); study group II - 20 patients with right bundle branch block (RBBB), and study group III -19 pts with left anterior hemiblock (LAHB). The control groups included patients with MI in their history and no BBBs (19 pts - group IV) and clinically healthy people (16 patients - group V). The parameters of LA and LAA systolic function were determined by means of transthoracic (TTE) and transoesophageal echocardiography (TOE).

RESULTS

We showed that patients who experienced myocardial infarction not complicated with conduction disturbances expressed compensatory LA systolic function enhancement. In patients with post-myocardial RBBB and LAHB significant enhancement of LA systolic function was observed as well but it was expressed to a lesser degree. There was also a tendency towards deterioration of LA systolic function in patients with post-myocardial LBBB. LBBB did not affect LAA systolic function negatively.

CONCLUSIONS

Parameters of LAA systolic function showed its enhancement in all patients after myocardial infarction irrespective of whether it was complicated by conduction disturbances.

QRS prolongation in patients with acute coronary syndromes

BACKGROUND

QRS prolongation with or without bundle branch block (BBB) has been associated with adverse outcome in myocardial infarction; we examined the relationship between QRS duration and outcome in a broad spectrum of patients with acute coronary syndrome (ACS).

METHOD AND RESULTS

Core laboratory evaluation of the presenting electrocardiogram in Canadian ACS Registry patients (n = 5,003) showed 4,289 (85.7%) had QRS <120 milliseconds, 202 (4.0%) patients had QRS > or =120 milliseconds without BBB, 262 (5.2%) had left BBB (LBBB), and 250 (5.0%) had right BBB. Compared to patients with QRS <120 milliseconds, patients with QRS > or =120 milliseconds without BBB had higher in-hospital (3.5% vs 1.9%, odds ratio [OR] 1.87, 95% CI 0.85-4.09, P = .12) and 1-year mortality (14.9% vs 7.7%, OR 2.10, 95% CI 1.38-3.18, P = .001). In-hospital and 1-year mortality was significantly higher in patients with BBB (eg, LBBB compared with QRS <120 milliseconds) (5.0% vs 1.9%, OR 2.71, 95% CI 1.49-4.94, P = .001, and 23.8% vs 7.7%, OR 3.74, 95% CI 2.72-5.13, P < .001). Analyzed as a continuous variable and after adjustment for validated prognosticators, QRS duration was an independent predictor of 1-year death (OR 1.11, 95% CI 1.06-1.16, P < .001) and death/myocardial infarction (OR 1.06, 95% CI 1.02-1.11, P = .003). However, when using clinically applicable QRS duration evaluation, only LBBB was an independent predictor of 1-year mortality (OR 1.93, 95% CI 1.28-2.90, P = .002).

CONCLUSIONS

In patients presenting with a broad spectrum of suspected ACS, QRS prolongation-particularly in the setting of LBBB-is an independent predictor of in-hospital and 1-year mortality.

Comparison of the prognostic effect of left versus right versus no bundle branch block on presenting electrocardiogram in acute myocardial infarction patients treated with primary angioplasty in the primary angioplasty in myocardial infarction trials

The presence of bundle branch block (BBB) has been associated with poor outcomes in patients who have acute myocardial infarction. Whether this is true in the angioplasty era is not known. We sought to evaluate the outcome of patients with acute myocardial infarction and BBB who were treated with primary angioplasty. We evaluated 3,053 patients who underwent emergency catheterization in the PAMI trials. Patients who had left BBB (n = 48, 1.6%) on presenting electrocardiogram were compared with patients who had right BBB (n = 95, 3.1%) or no BBB (n = 2,910, 95.3%). Patients who had BBB were older and more frequently had diabetes mellitus, peripheral vascular disease, and previous coronary artery bypass grafting. They had lower ejection fraction and more multivessel disease. There were no significant differences in door-to-balloon time, final Thrombolysis In Myocardial Infarction flow grade or stent use. In-hospital major adverse cardiac events (death, ischemic target vessel revascularization, and reinfarction) were higher in patients who had BBB due primarily to increased in-hospital death (left BBB 14.6%, right BBB 7.4%, no BBB 2.8%, p < 0.0001). In multivariate logistic regression analysis, left BBB was an independent predictor of in-hospital death (odds ratio 5.53, 95% confidence interval 1.89 to 16.1, p = 0.002). In conclusion, patients who have acute myocardial infarction and BBB have increased co-morbidities and higher mortality rates despite treatment with primary angioplasty. Despite early identification of multivessel disease with triage to angioplasty or coronary artery bypass grafting, if necessary, similar treatment times, and final Thrombolysis In Myocardial Infarction grade 3 flow, the presence of left BBB on admission electrocardiogram in patients who have acute myocardial infarction is an independent predictor of in-hospital mortality. Because 85% of deaths in patients who have left BBB occur within the first week, these patients should be recognized early and receive prompt and aggressive treatment.

Posterior myocardial infarction and complete right bundle- branch block

We describe two patients with posterior myocardial infarction (PMI) with unusually atypical clinical presentations and cardiac enzymatic profiles, but with the abrupt development of complete AV block in patient 1, and Mobitz II second-degree AV block with paroxysmal phases of higher degrees of AV block in patient 2, and mitral regurgitation leading to symptomatic pulmonary congestion. Also, both patients had complete right bundle-branch block (RBBB) [old in patient 1, new in patient 2], the pattern of which was altered due to the associated PMI. The alteration included tall R waves involving the early part of the QRS complex, and tall T waves, both noted in the right precordial leads. The mechanism of these ECG modulations of the RBBB pattern was believed to be a superimposition of the early depolarization and repolarization consequences of the PMI. The significance of this observation lies in the ECG detection of PMI, frequently underdiagnosed particularly in patients with an atypical presentation, and with the RBBB adding further to the complexity. Thus, it is gratifying to note the contribution of the ECG to diagnostics, the only modality that provided a pathophysiologic insight in these two patients who appeared to be abruptly deteriorating clinically without an apparent reason.