Primary angioplasty in acute myocardial infarction with right bundle branch block: should new onset right bundle branch block be added to future guidelines as an indication for reperfusion therapy?

Abstract

AimsThe current guidelines recommend reperfusion therapy in acute myocardial infarction (AMI) with ST-segment elevation or left bundle branch block (LBBB). Surprisingly, the right bundle branch block (RBBB) is not listed as an indication for reperfusion therapy. This study analysed patients with AMI presenting with RBBB [with or without left anterior hemiblock (LAH) or left posterior hemiblock (LPH)] and compared them with those presenting with LBBB or with other electrocardiographic (ECG) patterns. The aim was to describe angiographic patterns and primary angioplasty use in AMI patients with RBBB.Methods and resultsA cohort of 6742 patients with AMI admitted to eight participating hospitals was analysed. Baseline clinical characteristics, ECG patterns, coronary angiographic, and echocardiographic data were correlated with the reperfusion therapies used and with in-hospital outcomes. Right bundle branch block was present in 6.3% of AMI patients: 2.8% had RBBB alone, 3.2% had RBBB + LAH, and 0.3% had RBBB + LPH. TIMI flow 0 in the infarct-related artery was present in 51.7% of RBBB patients vs. 39.4% of LBBB patients (P = 0.023). Primary percutaneous coronary intervention (PCI) was performed in 80.1% of RBBB patients vs. 68.3% of LBBB patients (P< 0.001). In-hospital mortality of RBBB patients was similar to LBBB (14.3 vs. 13.1%, P = 0.661). Patients with new or presumably new blocks had the highest (LBBB 15.8% and RBBB 15.4%) incidence of cardiogenic shock from all ECG subgroups. Percutaneous coronary intervention was done more frequently (84.8%) in patients with new or presumably new RBBB when compared with other patients with blocks (old RBBB 66.0%, old LBBB 62.3%, new or presumably new LBBB 73.0%). In-hospital mortality was highest (18.8%) among patients presenting with new or presumably new RBBB, followed by new or presumably new LBBB (13.2%), old LBBB (10.1%), and old RBBB (6.4%). Among 35 patients with acute left main coronary artery occlusion, 26% presented with RBBB (mostly with LAH) on the admission ECG.ConclusionAcute myocardial infarction with RBBB is frequently caused by the complete occlusion of the infarct-related artery and is more frequently treated with primary PCI when compared with AMI + LBBB. In-hospital mortality of patients with AMI and RBBB is highest from all ECG presentations of AMI. Restoration of coronary flow by primary PCI may lead to resolution of the conduction delay on the discharge ECG. Right bundle branch block should strongly be considered for listing in future guidelines as a standard indication for reperfusion therapy, in the same way as LBBB.

Clinical characteristics and value in early reperfusion therapy for new onset right bundle branch block in patients with acute myocardial infarction

“…Previous reports about AMI combined with new onset RBBB showed that the incidence of new RBBB in AMI was 4-18%. The research results showed that the incidence of new RBBB in AMI patients in the first 12 h was 6.32%, slightly higher than the incidence in the reports of Wagner et al (17) and Widimsky et al (18), and also higher than the incidence of new LBBB in this research. There was no obvious difference in the peak level of CK-MB, the level of heart function, the incidence of in-hospital MACE and in-hospital mortality between RBBB group and LBBB group; but all indexes in the former two groups were higher than those in the non-BBB group.…”

Diagnosis and outcome in a prehospital cohort of patients with bundle branch block and suspected acute myocardial infarction

“…12,13 This has recently been shown to be the case also in the PCI era. 7 Current guidelines focus on the association between left BBB and anterior wall infarction. However, using GUSTO-1 and TAMI-19 data, Newby et al 14 demonstrated an even stronger association between right BBB and anterior wall infarction.…”

“…[1][2][3][4] The mortality risk also applies to patients with right bundle branch block myocardial infarction (BBBMI) since these patients often have significant coronary artery disease. [5][6][7] Only a minority of patients with BBBMI is treated with reperfusion therapy as recommended by the guidelines, 8 most likely because the diagnosis of new-onset BBB in the Diagnosis and outcome in a prehospital cohort of patients with bundle branch block and suspected acute myocardial infarction acute phase of myocardial infarction is based solely on an ECG and the clinical condition of the patients, with limited access to previous patient records. 9 The purpose of the present study was to determine the prevalence of acute myocardial infarction (AMI) with or without BBB and the associated outcome in an unselected cohort of patients with suspected AMI, diagnosed pre-hospital by Telemidical ECG transmission.…”

When should a non-STEMI be treated with primary PCI as for STEMIs?

“…Anterior STEMI associated with RBBB, particularly new RBBB, has bad prognosis and is often due to proximal left anterior descending (LAD) occlusion causing extensive infarction of the interventricular septum where the right bundle traverses [12]. In a retrospective analysis of 6742 consecutive patients with acute MI (including both STEMI and non-STEMI) undergoing angiography [13], Widimsky et al reported that even in large infarcts caused by left main or proximal LAD coronary occlusions RBBB may occur without the typical ST elevation required for diagnosing anterior STEMI. Indeed, they titled their paper as "Primary angioplasty in acute myocardial infarction with right bundle branch block: should new onset right bundle branch block be added to future guidelines as an indication for reperfusion therapy?"…”