Exercise-induced left bundle branch block – A case report with stress-echocardiographic assessment

We report the case of a 51-year-old male who presented with exertional chest discomfort and dyspnea concurring with an exercise-induced left bundle branch block (EI-LBBB). Possible underlying causes and treatment options are presented and discussed. The case represents the first stress-echocardiographic assessment of a case with EI-LBBB, performed in order to document a possible left ventricular dyssynchrony during the EI-LBBB and thereby the possible treatment option of biventricular pacemaker implantation.     

Is there an association between left bundle branch block and coronary slow flow in patients with normal coronary arteries?

Slow flow in angiographically normal coronary arteries is not a rarely seen problem. It is unknown whether it is related with conduction disorders. In this study we investigated the frequency of conduction disorders in patients with normal coronary artery and slow flow. The study included 36 (22 female; mean age 63 +/-11 years) patients who have normal coronary arteries and slow flow in coronary angiography. Patients' 12-lead electrocardiograms were analyzed for the presence of bundle branch block. Twenty-two of 36 patients (61%) demonstrated left bundle branch block. Twelve patients (33%) had normal intraventricular conduction. Only 2 of 36 patients (6%) had right bundle branch block. Microvascular disease has been implicated in coronary slow flow. However, according to the results of this study there is a close association between especially left bundle branch block and coronary slow flow. A causal relation should be sought between them with future studies.     

Detection of left anterior descending coronary artery stenosis in patients with left bundle branch block: exercise,adenosine or dobutamine imaging?

Objectives. This study sought to assess the diagnostic value of myocardial perfusion imaging during exercise and pharmacologic stress in patients with left bundle branch block.Backgroud. Patients with left bundle branch block often have septal perfusion defects during exercise perfusion tomography that mimic defects caused by coronary artery disease. These defects appear to be less frequent during pharmacologic stress using adenosine or dipyridamole. Data are scanty on the value of dobutamine tomography in these patients.Methods. We studied 383 consecutive patients with left bundle branch block referred for perfusion scintigraphy over a 5-year span. Perfusion tomography was performed in conjunction with exercise in 206 patients, adenosine in 127 and dobutamine in 50. Coronary angiography was performed within 1 month of the nuclear study in 77, 50 and 27 patients, respectively.Results. Exercise, adenosine and dobutamine tomography had similar sensitivity and specificity for the detection of >50% stenosis in the left circumflex (74% and 96%; 50% and 100%; 63% and 91%, respectively) and right coronary arteries (96% and 86%; 82% and 91%; 79% and 100%, respectively) and similar sensitivity for left anterior descending coronary artery stenosis (88%, 79% and 100%, respectively). However, the false-positive rate for septal defects was higher by exercise tomography (26 [46%] of 57) than by pharmacologic methods (5 [10%] of 48, p < 0.001), and there was no significant difference between adenosine (4 [11%] of 35) and dobutamine (1 [8%] of 13, p = 0.7). The specificity and predictive value of a positive test response for left anterior descending coronary artery stenosis were 36% and 51% for exercise compared with 81% and 85% for adenosine (p ≤ 0.001) and 80% and 90% for dobutamine (p < 0.05), respectively.Conclusions. In patients with left bundle branch block, pharmacologic stress is more specific than exercise tomography in the diagnosis of left anterior descending coronary artery stenosis. Dobutamine and adenosine tomography appear to be equally specific in these patients.     

Do we overestimate left ventricular ejection fraction by two‐dimensional echocardiography in patients with left bundle branch block?

Aims

Left bundle branch block (LBBB) causes a dyssynchronized contraction of left ventricle. This is a kind of regional wall‐motion abnormality and measuring left ventricular ejection fraction (LVEF) by two‐dimensional (2D) echocardiography could be less reliable in this particular condition. Our aim was to evaluate the role of dyssynchrony index (SDI), measured by three‐dimensional (3D) echocardiography, in assessment of LVEF and left ventricular volumes accurately in patients with LBBB.

Methods and Results

In this case–control study, we included 52 of 64 enrolled participants (twelve participants with poor image quality were excluded) with LBBB and normal LVEF or nonischemic cardiomyopathy. Left ventricular ejection fraction (LVEF) and left ventricular volumes were assessed by 2D (modified Simpson's rule) and 3D (four beats full volume analysis) echocardiography and the impact of SDI on results were evaluated. In patients with SDI ≥6%, LVEF measurements were significantly different (46.00% [29.50–52.50] vs 37.60% [24.70–45.15], P < .001) between 2D and 3D echocardiography, respectively. In patients with SDI < 6%, there were no significant differences between two modalities in terms of LVEF measurements (54.50% [49.00–59.00] vs 54.25% [40.00–58.25], P = .193). LV diastolic volumes were not significantly different while systolic volumes were underestimated by 2D echocardiography, and this finding was more pronounced when SDI ≥ 6%.

Conclusion

In patients with LBBB and high SDI (≥6%), LVEF values were overestimated and systolic volumes were underestimated by 2D echocardiography compared to 3D echocardiography.     

Reservations about the Selvester QRS score in left bundle branch block — Experience in patients with transcatheter aortic valve implantation

Background

The Selvester QRS score (S-score) estimates myocardial scar using electrocardiographic criteria. We evaluated the S-score for left bundle branch block (LBBB).

Comparison of clinical characteristics, treatments and outcomes of patients with ST-elevation acute myocardial infarction with versus without new or presumed new left bundle branch block (from NCDR®)

Guidelines recommend urgent reperfusion for patients with new left bundle branch block (LBBB), similar to patients with ST-segment elevation myocardial infarction (STEMI). However, there are limited contemporary data comparing these 2 groups of patients. Patients presenting with acute STEMI or presumed new LBBB (nLBBB) enrolled in the Acute Coronary Treatment and Intervention Outcomes Network (ACTION) Registry-Get With the Guidelines (GWTG) from January 2007 to March 2009 were evaluated for clinical characteristics, treatment patterns, and outcomes. Logistic generalized estimating equation modeling was used to examine associated risk-adjusted mortality. Of 46,006 patients with either STEMI or nLBBB, 44,405 (96.5%) had STEMI, and 1,601 (3.5%) had nLBBB. Overall, patients with nLBBB had more baseline co-morbidities compared to those with STEMI. Compared to patients with STEMI, those with nLBBB were less likely to receive acute reperfusion (93.9% vs 48.3% p <0.0001) and were less likely to have door-to-balloon times ≤90 minutes (76.8% vs 34.5%, p <0.0001). Mortality rates were higher for patients with nLBBB compared to those with STEMI (13.3% vs 5.6%, p <0.0001). After multivariate adjustment, nLBBB was not associated with an increased risk for in-hospital mortality (odds ratio 0.91, 95% confidence interval 0.75 to 1.12, p = 0.38). In conclusion, patients with nLBBB were clinically different from those with STEMI, with significantly more co-morbidities, and were less likely to receive emergent reperfusion therapy. Despite these differences, adjusted mortality rates were similar between patients with nLBBB and those with STEMI.     

Is the left bundle branch pacing a choice to conquer the right bundle branch block?—A case report

In patients with preserved ejection fraction or right bundle branch block (RBBB) pattern requiring a high percentage of ventricular pacing, His-bundle pacing (HBP) might be an alternative to biventricular pacing, although the high threshold occasionally occurs. We provided a case of the intrinsic RBBB correction by capturing intra-Hisian left bundle branch (LBB) or distal His-bundle with different output settings. LBB pacing had the advantage of a much lower threshold while remained most synchrony as HBP. LBB pacing might be a promisingly safe and effective procedure for patients with high-grade atrioventricular (AV) block and RBBB pattern.     

Wenckebach pattern in right bundle branch block – benign or not?

A Mobitz type I block (Wenckebach phenomenon) with narrow QRS complex is almost always due to a lesion in the AV node. In a type I block with wide QRS complex (>0.12 sec), the block can be in the His-Purkinje system in 60–70% of the cases. Even though the progressive PR prolongation with every conducted beat suggests Wenckebach phenomenon, one needs to pay attention to the accompanying QRS complex. In the setting of persistent right bundle branch block, axis change of subsequent conducted beat before an unconducted p suggests alternating fascicular block, giving clue to unreliable infra-Hisian conduction; and in the setting of symptoms, a pacemaker should be implanted. Infra-Hisian Wenckebach block is rare with only sparse literature reports. The present case report adds to these, suggesting that wide QRS with Wenckebach block on surface ECG may indicate infra-Hisian conduction abnormalities.     

New formula for defining “normal” and “prolonged” QT in patients with bundle branch block

Objectives

To predict the QT interval in the presence of normal QRS for patients with left bundle branch block (LBBB).

Is the left bundle branch pacing a choice to conquer the right bundle branch block?—A case report

In patients with preserved ejection fraction or right bundle branch block (RBBB) pattern requiring a high percentage of ventricular pacing, His‐bundle pacing (HBP) might be an alternative to biventricular pacing, although the high threshold occasionally occurs. We provided a case of the intrinsic RBBB correction by capturing intra‐Hisian left bundle branch (LBB) or distal His‐bundle with different output settings. LBB pacing had the advantage of a much lower threshold while remained most synchrony as HBP. LBB pacing might be a promisingly safe and effective procedure for patients with high‐grade atrioventricular (AV) block and RBBB pattern.     

A case of ‘Masquerading’ bundle branch block: A forgotten concept

‘Masquerading’ bundle branch block (right bundle branch block in the precordial leads with left bundle branch block in frontal leads and left axis deviation) is seen most commonly with coronary artery disease and hypertension. No definite explanation is available so far for these changes. We are presenting a case of rare congenital intranuclear inclusion myopathy with congestive heart failure and ‘Masquerading’ bundle branch block in ECG.