Development Of Left Bundle Branch Block Research Articles

Development of QT interval evaluation methods in the presence of left bundle branch block

The relevance of this development is due to the fact that prolongation or shortening of the QT interval is associated with an increased risk of sudden cardiac death and there is no validated and recognized method to calculate corrected QT interval (QTc) in left bundle branch block (LBBB). The aim of the study is to develop a method for evaluating the duration of corrected QT interval in patients with LBBB. Electrocardiogams (ECGs) of 43 patients, including 31 women and 12 men, were analyzed. Patients were included in the study if they had ECGs before and after the manifestation of LBBB. At the same time the heart rate (HR) on ECGs should have been 50–90 bpm and the difference in heart rate on ECGs with and without LBBB was no more than 10 bpm. Patients who have suffered myocardial infarction were excluded from the study. Based on the analysis of ECGs before and after the manifestation of LBBB, two methods to calculate QTc have been developed. These methods make it possible to compensate for prolongation of the QT interval caused by enlargement of QRS and demonstrated high accuracy in the calculation of QTc by different formulas, comparing the calculated values for LBBB and values of QTc before the development of LBBB. 1. Linear regression method Bazett QTc linB = 120,5692 + 0,6315 x QT c B b Fridericia QTc linF = 130,4425 + 0,6024 x QT c F b Sagie QTc linS = 125,4726 + 0,6182 x QT c S b QT c B b . QT c F b . QT c S b – the duration of the corrected values of QT in LBBB according to the formulas of Bazett, Fridericia, Sage, respectively. 2. Method of QT interval compensation for enlargement of QRS in LBBB QTк = QTb – (QRSb – 100 ms) and the subsequent calculation of QTc by the formulas of Bazett, Fridericia, Sage based on the values of QTк.

Usefulness of membranous septum length in the prediction of major conduction disturbances in patients undergoing transcatheter aortic valve replacement with different devices.

Conduction disturbances (CD) are one of the most common adverse events after transcatheter aortic valve replacement (TAVR), and seem to be dependent on the device used as well as anatomical factors. The aim of this study was to evaluate whether the length of the membranous septum (MS) could provide useful information about the risk of CD and to examine the impact of the MS on CD after TAVR using different devices. This study included 140 patients undergoing TAVR with a balloon‑expandable valve or self‑‑expanding valve. The length of the MS was assessed by preoperative computed tomography. ΔMSID was calculated as the length of the MS minus implantation depth. A total of 24 patients (17%) received a permanent pacemaker (PPM), 53 (38%) developed new‑‑onset left bundle‑branch block (LBBB) following TAVR. The MS length was shown to be the strongest independent predictor of new‑onset LBBB (odds ratio [OR], 3.05; 95% CI, 1.96-4.77; P <0.001) and PPM implantation (OR, 3.76; 95% CI, 2.01-7.06; P <0.001). ΔMSID was also inversely associated with the development of LBBB and the need for PPM. In a head‑to‑head comparison, ΔMSID values were found to be statistically lower in the self‑expanding valve group (-0.8 mm vs 0.7 mm; P <0.001). A short MS and ΔMSID with a negative value increase the risk of CD. Assessment of the MS length prior to TAVR might serve as an additional tool to guide clinical decision‑making and appropriate device selection to reduce the the risk of CD.

New-Onset Left bundle branch block after TAVI has a deleterious impact on left ventricular systolic function

Transcatheter aortic valve implantation (TAVI) has revolutionized the management of severe aortic stenosis. The development of new-onset complete left bundle branch block (LBBB) is, however, a frequent complication. The objective of the present study was to assess the impact of new-onset LBBB after TAVI on the evolution of left ventricular ejection fraction (LVEF). Forty consecutive patients were included following the development of new-onset LBBB after TAVI implantation and were matched for age and LVEF with 40 patients implanted during the same period who did not develop LBBB. The primary endpoint was evolution of the LVEF measured by echocardiography prior to implantation and between 6-12 months after TAVI. The development of a LBBB was associated with a 5-point decrease in LVEF [− 12.5–2.5], contrary to the non-LBBB group (1.5 [− 6.5–9.5], P = 0.007) at 8 months, with the persistence of the LBBB ( n = 23) exacerbating this decrease (− 7 [− 13; 2], P = 0.009). When left ventricular dysfunction (LVEF <50%) was present prior to TAVI, the appearance of LBBB was associated with a reduction in LVEF (− 2 [− 8 – 2]) contrary to the non-LBBB group (20 [9–22]), P = 0.02. The appearance of new-onset LBBB after TAVI has a pejorative impact on left ventricular systolic function, particularly in patients with an initial LVEF < 50%, due to a lack of recovery of the latter, thereby potentially affecting their prognosis.

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

ObjectivesTo predict the QT interval in the presence of normal QRS for patients with left bundle branch block (LBBB). BackgroundThere is no acceptable method for simple and reliable QT correction for patients with bundle branch block (BBB). MethodsWe measured the QT interval in patients with new onset LBBB who had a recent electrocardiogram with narrow QRS for comparison. 48 patients who developed in-hospital LBBB were studied. Patients who had similar heart rate before and after LBBB were included. We used linear regression, the Bogossian method, and our new fixed QRS replacement method to evaluate the most reliable correction method. ResultsJTc (QTc-QRS) interval was preserved before and after LBBB (328.9 ± 25.4 ms before LBBB vs. 327.3 ms post LBBB (p = 0.550). Mean predicted preLBBB QTc difference was 1.3 ms, −21.3 ms and 1.6 ms for the three methods respectively (p < 0.001 for Bogossian comparison with the other methods). Coefficients of correlation (R) between actual preLBBB QTc with predicted preLBBB QTc were 0.707, 0.683 and 0.665 respectively (p > 0.3 for R comparisons between all methods). The average absolute difference in preLBBB QTc was 15.5 ms and 16.7 ms for the regression and fixed-gender methods (p value between the two = 0.321) and 25.5 ms for the Bogossian method, which was found to be significantly underperforming. ConclusionsIn patients with LBBB, replacing of the QRS duration after deriving the QTc interval with a fixed value of 88 ms for female and 95 ms for male provides a simple and reliable method for predicting the QTc before the development of LBBB.

Circulation: Clinical Summaries

<i>Circulation:</i> Clinical Summaries

Echocardiographic evidence of hemodynamic and clinical improvement in patients paced for heart failure

Dilated cardiomyopathy is frequently associated with electrical conduction disturbances. Development of left bundle-branch block with discoordinated ventricular contraction pattern further contributes to impaired hemodynamic performance. Biventricular pacing has evolved as a new treatment option for patients with dilated cardiomyopathy and conduction disturbances. The “electrical” approach aims to normalize the disturbed contraction pattern, thereby improving hemodynamic function by simultaneous stimulation at different ventricular sites. Acute hemodynamic improvement with biventricular pacing has been demonstrated in patients with depressed left ventricular function and delayed intraventricular conduction. Due to the variations in optimal pacing site and atrioventricular delay, individual optimization to achieve optimal hemodynamic benefit is necessary. Echocardiography has the potential to provide hemodynamic data by Doppler techniques and combine these with geometric information about ventricular volumes, ejection fraction, and contraction patterns. This article focuses on the use of echocardiographic techniques for noninvasive optimization in cardiac pacing and presents preliminary experience from the initial trials on multisite pacing in heart failure.

Myocardial infarction-induced ventricular aneurysm in the presence of complete left bundle branch block: A case report suggesting a new electrocardiographic diagnostic criterion

A 65-year-old man who had suffered an anterior myocardial infarction (MI) 10 years ago, complicated by a ventricular aneurysm (VA), and subsequently many years later developed complete left bundle branch block (LBBB), is described, with main emphasis on the feasibility of the electrocardiographic (ECG) diagnosis of VA in the presence of this conduction abnormality. Ventricular aneurysm in our patient was repeatedly confirmed by echocardiography over the intervening years. During the time the patient maintained normal intraventricular conduction, the ECG showed persisting ST-segment elevations in the precordial leads. After the development of LBBB, the ECG displayed accentuated ST-segment elevations in the precordial leads with predominantly negative QRS complexes, and ST elevation in V5, despite its primarily positive QRS complex. The authors extend the findings from the previous literature on the diagnosis of acute MI in patients with LBBB or right intraventricular pacing, and the concept of primary and secondary repolarization changes, to the diagnosis of VA in the presence of LBBB.

Natural history of left bundle-branch block.

The purpose of this study was to examine factors associated with the development of complete left bundle-branch block and the prognosis in a group of people not in hospital, who had no clinical evidence of ischaemic or valvular heart disease. Twenty-nine cases of left bundle-branch block without clinical evidence of ischaemic heart disease were noted in the Manitoba cohort of 3983 men under observation since 1948. The most frequent electrocardiographic finding before development of left bundle-branch block was a normal electrocardiogram; left ventricular hypertrophy though infrequent, was the only abnormality significantly more common than in the rest of the group. The development of left bundle-branch block was associated with distinct leftward shift of the frontal plane mean QRS axis. The most frequent clinical cardiovascular event observed after development of the block was sudden death without previous clinical evidence of ischaemic heart disease. The five-year incidence of sudden death as the first manifestation of heart disease was 10 times greater in men with left bundle-branch block than in those without it.