Differentiation between left bundle branch block and left ventricular hypertrophy: Implications for cardiac resynchronization therapy

LBBB and heart failure-Relationships among QRS amplitude, duration, height, LV mass, and sex

BACKGROUND

Height, left ventricular (LV) size, and sex were proposed as additional criteria for patient selection for cardiac resynchronization therapy (CRT) but their connections with the QRS complex in left bundle branch block (LBBB) are little investigated. We evaluated these.

METHODS

Among patients with "true" LBBB, QRS duration (QRSd) and amplitude, and LV hypertrophy indices, were correlated with patient's height and LV mass, and compared between sexes.

RESULTS

In this study cohort (n = 220; 60 ± 12 years; left ventricular ejection fraction [LVEF] 21 ± 7%; mostly New York Heart Association II-III, QRSd 165 ± 19 ms; 57% female; 70% responders [LVEF increased ≥5%]), LV mass was increased in all patients. QRS amplitude did not correlate with LV mass or height in any individual lead or with Sokolow-Lyon or Cornell-Lyon indices. QRSd did not correlate with height. In contrast, QRSd correlated strongly with LV mass (r = .51). CRT response rate was greater in women versus men (84% vs. 58%, p < .001) despite shorter QRSd [7% shorter (p < .0001)]. QRSd normalized for height resulted in a 2.7% and for LV mass 24% greater index in women.

CONCLUSION

True LBBB criteria do not exclude HF patients with increased LV mass. QRS amplitudes do not correlate with height or LV mass. Height does not affect QRSd. However, QRSd correlates with LV size. QRSd normalized for LV mass results in 24% greater value in women in the direction of sex-specific responses. LV mass may be a significant nonelectrical modifier of QRSd for CRT.

ISE/ISHNE expert consensus statement on the ECG diagnosis of left ventricular hypertrophy: The change of the paradigm

The ECG diagnosis of LVH is predominantly based on the QRS voltage criteria. The classical paradigm postulates that the increased left ventricular mass generates a stronger electrical field, increasing the leftward and posterior QRS forces, reflected in the augmented QRS amplitude. However, the low sensitivity of voltage criteria has been repeatedly documented. We discuss possible reasons for this shortcoming and proposal of a new paradigm. The theoretical background for voltage measured at the body surface is defined by the solid angle theorem, which relates the measured voltage to spatial and non-spatial determinants. The spatial determinants are represented by the extent of the activation front and the distance of the recording electrodes. The non-spatial determinants comprise electrical characteristics of the myocardium, which are comparatively neglected in the interpretation of the QRS patterns. Various clinical conditions are associated with LVH. These conditions produce considerable diversity of electrical properties alterations thereby modifying the resultant QRS patterns. The spectrum of QRS patterns observed in LVH patients is quite broad, including also left axis deviation, left anterior fascicular block, incomplete and complete left bundle branch blocks, Q waves, and fragmented QRS. Importantly, the QRS complex can be within normal limits. The new paradigm stresses the electrophysiological background in interpreting QRS changes, i.e., the effect of the non-spatial determinants. This postulates that the role of ECG is not to estimate LV size in LVH, but to understand and decode the underlying electrical processes, which are crucial in relation to cardiovascular risk assessment.

ISE/ISHNE Expert Consensus Statement on ECG Diagnosis of Left Ventricular Hypertrophy: The Change of the Paradigm. The joint paper of the International Society of Electrocardiology and the International Society for Holter Monitoring and Noninvasive Electrocardiology

The ECG diagnosis of LVH is predominantly based on the QRS voltage criteria, i.e. the increased QRS complex amplitude in defined leads. The classical ECG diagnostic paradigm postulates that the increased left ventricular mass generates a stronger electrical field, increasing the leftward and posterior QRS forces. These increased forces are reflected in the augmented QRS amplitude in the corresponding leads. However, the clinical observations document increased QRS amplitude only in the minority of patients with LVH. The low sensitivity of voltage criteria has been repeatedly documented. We discuss possible reasons for this shortcoming and proposal of a new paradigm.

Electrocardiographic predictors of echocardiographic response in cardiac resynchronization therapy: Update of an old story

BACKGROUND

A better selection of patients with left bundle branch block (LBBB) might increase the response to cardiac resynchronization therapy (CRT). The aim of the study was to investigate the association between the Strauss criteria, absence of S wave in V₅-V_6, the Selvester score and response to CRT.

METHODS AND RESULTS

The retrospective analysis included all consecutive patients having undergone implantation of biventricular defibrillators in primary prevention between 2018 and 2020. The final analysis included 236 patients (mean age 69.7 ± 9.9; 77.5% of males). The Strauss criteria were significantly associated with CRT response (p < 0.01) with a sensitivity of 71.3% and specificity of 64.1%. The Strauss criteria along with the absence of S wave in V₅ and V₆ showed a sensitivity of 56.7%, a specificity of 82.6% and a positive predictive value of 90.5%. The Selvester score was significantly and inversely associated with CRT response (OR 0.818, 95% CI 0.75-0.89; p < 0.001). The multivariable model showed that left ventricular ejection fraction (LVEF) and QRS duration (≥140 ms in males and ≥ 130 ms in females) were independently associated with CRT response (respectively OR 0.92, CI 95% 0.86-0.98, p = 0.01 and OR 3.70, CI 95% 1.12-12.21, p = 0.03).

CONCLUSIONS

Strauss criteria, especially in association with absence of S wave in V₅ and V₆, were able to increase specificity and positive predictive value for predicting CRT response. The Selvester score was inversely associated with CRT response. Finally, LVEF and QRS duration were independently associated with echocardiographic response to CRT.

Cardiac Implantable Electronic Devices in the Fontan Patient

As a result of remarkable progress in operative techniques and cardiology care during childhood, Fontan patients continue to age and require team-based multidisciplinary expertise to manage complications encountered in adulthood. They face particular challenges in terms of altered hemodynamic stressors, cardiac and hepatic failure, and arrhythmias. Arrhythmias in Fontan patients are highly prevalent and associated with underlying anatomy, surgical technique, and postoperative sequelae. Diagnostic tools, treatments, and device strategies for arrhythmias in Fontan patients should be adapted to the specific anatomy, type of surgical repair, and clinical status. Great strides in our understanding of arrhythmia mechanisms, options and techniques to obtain access to relevant cardiac structures, and application of both old and new technologies have contributed to improving cardiac implantable electronic device (CIED) therapies for this unique population. In this state-of-the-art review, we discuss the various arrhythmias encountered in Fontan patients, their diagnosis, and options for treatment and prevention, with a focus on CIEDs. Throughout, access challenges particular to the Fontan circulation are considered. Recently developed technologies, such as the sub-cutaneous implantable cardioverter defibrillator carry the potential to be transformative but require awareness of Fontan-specific issues. Moreover, new leadless pacing technology represents a promising strategy that may soon become applicable to Fontan patients with sinus node dysfunction. CIEDs are essential tools in managing Fontan patients but the complex clinical scenarios that arise in this patient population are among the most challenging for the congenital electrophysiologist.

Novel electrocardiographic dyssynchrony criteria that may improve patient selection for cardiac resynchronization therapy

Cardiac resynchronization therapy (CRT) is an evidence-based effective therapy of symptomatic heart failure with reduced ejection fraction refractory to optimal medical treatment associated with intraventricular conduction disturbance, that results in electrical dyssynchrony and further deterioration of systolic ventricular function. However, the non-response rate to CRT is still 20%-40%, which can be decreased by better patient selection. The main determinant of CRT outcome is the presence or absence of significant ventricular dyssynchrony and the ability of the applied CRT technique to eliminate it. The current guidelines recommend the determination of QRS morphology and QRS duration and the measurement of left ventricular ejection fraction for patient selection for CRT. However, QRS morphology and QRS duration are not perfect indicators of electrical dyssynchrony, which is the cause of the not negligible non-response rate to CRT and the missed CRT implantation in a significant number of patients who have the appropriate substrate for CRT. Using imaging modalities, many ventricular dyssynchrony criteria were devised for the detection of mechanical dyssynchrony, but their utility in patient selection for CRT is not yet proven, therefore their use is not recommended for this purpose. Moreover, CRT can eliminate only mechanical dyssynchrony due to underlying electrical dyssynchrony, for this reason ECG has a greater role in the detection of ventricular dyssynchrony than imaging modalities. To improve assessment of electrical dyssynchrony, we devised two novel ECG dyssynchrony criteria, which can estimate interventricular and left ventricular intraventricular dyssynchrony in order to improve patient selection for CRT. Here we discuss the results achieved by the application of these new ECG dyssynchrony criteria, which proved to be useful in predicting the CRT response in patients with nonspecific intraventricular conduction disturbance pattern (the second greatest group of CRT candidates), and the significance of other new ECG dyssynchrony criteria in the potential improvement of CRT outcome.

Conduction disorders after aortic valve replacement with rapid-deployment bioprostheses: early occurrence and one-year evolution

Background

Rapid-deployment bioprostheses represent one of the newest aortic valve substitutes introduced into clinical practice. The aim of this retrospective single-center study was to evaluate the occurrence of conduction disorders (CDs) after rapid-deployment aortic valve implantation at discharge and at 1-year follow-up, and to identify risk factors for CDs and permanent pacemaker implantation (PPI).

Methods

All patients who reached 1-year follow-up after isolated or combined aortic valve replacement (AVR) with rapid-deployment bioprostheses (Intuity Elite, Edwards Lifesciences, Irvine, CA) at our institution were included in this study. Standard 12-lead electrocardiograms (ECGs) were recorded before the procedure (within 24 hours), after the procedure as soon as the patient was moved to the intensive care unit (ICU), every day during in-hospital stay and at 1-year follow-up. The primary endpoint was the incidence of postoperative CDs at discharge and at 1-year follow up. Patients were divided in two groups: those who developed the primary endpoint (Group CD) and those who didn't (Group Non-CD).

Results

A total of 98 consecutive patients were included in the study. At discharge, the primary endpoint occurred in 40 patients (40.8%). In particular, new CDs and PPI occurred in 33 (33.7%) and in 7 (7.1%) patients, respectively. Valve size was the only independent predictor of primary endpoint at discharge. At 1-year, 30 patients (31.3%) presented with CDs or pacemaker-induced rhythm. In particular, in 25 patients of Group CD (64.1%), 1-year follow-up ECG revealed the persistence of the same CD as at discharge or pacemaker-induced rhythm, while 14 patients (35.9%) showed recovery of their CD. Age and prosthesis size were identified as independent predictors of CDs/pacemaker-induced rhythm at 1-year follow-up.

Conclusions

According to our data, nearly 40% of patients develop a new CD after rapid-deployment aortic valve implantation. Of these, one third recover after one year. Bioprosthesis size and age were identified as independent risk factors for occurrence of CD after surgery.

Detection of strict left bundle branch block by neural network and a method to test detection consistency

OBJECTIVE

To develop an automatic algorithm to detect strict left bundle branch block (LBBB) on electrocardiograms (ECG) and propose a procedure to test the consistency of neural network detections.

APPROACH

The database for the classification of strict LBBB was provided by Telemetric and Holter ECG Warehouse. It contained 10 s ECGs taken from the MADIT-CRT clinical trial. The database was divided into a training dataset (N  =  300, strict LBBB  =  174, non-strict LBBB  =  126) and a test dataset (N  =  302, strict LBBB  =  156, non-strict LBBB  =  146). LBBB-related features were extracted by Philips DXL^™ algorithm, selected by a random forest classifier, and fed into a 5-layer neural network (NN) for the classification of strict LBBB on the training dataset. The performance of NN on the test dataset was compared to two random forest classifiers, an algorithm applying strict LBBB criteria, a wavelet-based approach, and a support-vector-machine approach. The consistency of NN's detection was tested on 549 2 min recordings of the PTB diagnostic ECG database. LBBB annotations are not required to measure consistency.

MAIN RESULTS

The performance of NN on the test dataset were sensitivity  =  91. 7%, specificity  =  85.6% and accuracy  =  88.7% (PPV  =  87.2%, NPV  =  90.6%). The consistency score of strict-LBBB and non-strict-LBBB detection was 0.9341 and 0.9973 respectively.

CONCLUSION

NN achieved the highest specificity, accuracy, and PPV. Using random forest for feature selection and NN for classification increased interpretability and reduced computational cost. The consistency test showed that NN achieved high consistency scores in the detection of strict LBBB.

SIGNIFICANCE

This work proposed an approach for selecting features and training NN for the detection of strict LBBB as well as a consistency test for black-box algorithms.

Typical BBB morphology and implantation depth of 3830 electrode predict QRS correction by left bundle branch area pacing

AIM

Strict criteria of typical left bundle branch block (LBBB) can help with the prediction for cardiac resynchronization therapy response. The aim of this study is to determine whether the use of strict criteria for both LBBB and right bundle branch block (RBBB) predicts successful QRS correction (≤130 ms) by left bundle branch area pacing (LBBAP).

METHODS

Consecutive patients with pacemaker indications according to the present guideline who also underwent LBBAP implantation were retrospectively assessed. Inclusion criteria were patients with BBB and the baseline QRSd > 130 ms. Baseline characteristics and pacing parameters were compared between typical and atypical BBB groups. Multivariate logistic regression was used to adjust for covariates that were found in univariate analyses for successful QRS correction by LBBAP.

RESULTS

Seventy-three patients were enrolled. Among them, 10 (13.6%) had atypical BBB (5 LBBB and 5 RBBB) and 63 (86.4%) had typical BBB (30 LBBB and 33 RBBB). The rate of successful QRS correction was higher in typical-BBB patients (52/63; 82.5%) than that in atypical-BBB patients (3/10; 30%), P < .001. Paced QRSd was obviously narrower in patients with typical BBB than that in patients with atypical-BBB (118 ± 14 vs 133 ± 14 ms, P = .003). In multivariate logistic regression, only typical BBB morphology and the implantation depth of 3830 pacing electrode in the ventricular septum were independent predictors for successful QRS correction.

CONCLUSION

This study demonstrates that patients with typical-BBB morphology benefit more from LBBAP for QRS correction. Typical BBB morphology together with deep penetration of 3830 ventricular electrode in the interventricular septum predicts the success of QRS correction by LBBAP.

Electrocardiographic left ventricular hypertrophy and mortality in an oldest-old hypertensive Chinese population

Purpose

Previous studies have identified that electrocardiographic pattern of left ventricular hypertrophy (ECG LVH) is associated with mortality, but studies of its correlation in the oldest-old hypertensive population is extremely limited. We investigated the correlation between ECG LVH and mortality in a hypertensive Chinese population aged 80 years and older.

Patients and methods

In this study, we included 284 Chinese participants older than 80 years. All included participants with hypertension (sitting systolic blood pressure [BP] 160 to 200 mmHg; sitting diastolic BP <110 mmHg) were ascertained at the baseline. ECG LVH was defined as a Sokolow-Lyon voltage calculated as the amplitude of SV1+ (max RV5 or RV6) greater than 3.5 mV. We categorized participants into two groups by the status of baseline ECG LVH. We used Cox regression models to calculate hazard ratio (HRs) for mortality due to ECG LVH, including cardiovascular mortality and all-cause mortality.

Results

In this study, with a 28-month median follow-up, a total of 35 (12.3%) patients died; 21 of those died due to cardiovascular causes. Compared with participants without ECG LVH, there was an increased risk of cardiovascular mortality in participants with ECG LVH (adjusted HR 4.25 [95% confidence interval [CI], 1.50–12.06]) but ECG LVH did not predict all-cause mortality (adjusted HR 2.31 [95% CI, 0.93–5.72]).

Conclusion

Our study shows that ECG LVH predicts the risk of cardiovascular mortality in an oldest-old hypertensive Chinese population.

Relationships between electrical and mechanical dyssynchrony in patients with left bundle branch block and healthy controls

BACKGROUND

Abnormal electrical activation may cause dyssynchronous left ventricular (LV) contraction. In this study, we characterized and analyzed electrical and mechanical dyssynchrony in patient with left bundle branch block (LBBB) and healthy controls.

METHODS

Myocardial perfusion imaging (MPI) data from 994 patients were analyzed. Forty-three patient fulfilled criteria for LBBB and 24 for controls. Electrical activation was characterized with vector electrocardiography (VECG) and LV function including mechanical dyssynchrony with ECG-gated MPI phase analysis.

RESULTS

QRS duration (QRSd; r = 0.69, P < .001) and a few other VECG parameters correlated significantly with phase bandwidth (phaseBW) representing mechanical dyssynchrony. End-diastolic volume (EDV; r = 0.59, P < .001), ejection fraction and end-systolic volume correlated also with phaseBW. QRSd (β = 0.47, P < .001) and EDV (β = 0.36, P = .001) were independently associated with phaseBW explaining 55% of its variation. Sixty percent of patients with LBBB had significant mechanical dyssynchrony. Those patients had wider QRSd (159 vs 147 ms, P = .013) and larger EDV (144 vs 94 mL, P = .008) than those with synchronous LV contraction. Cut-off values for mechanical dyssynchrony seen in patients with LBBB were QRSd ≥ 165 ms and EDV ≥ 109 mL.

CONCLUSIONS

Despite obvious conduction abnormality, LBBB is not always accompanied by mechanical dyssynchrony. QRSd and EDV explained 55% of variation seen in phaseBW. These two parameters were statistically different between LBBB cases with and without mechanical dyssynchrony.

True complete left bundle branch block reveals dyssynchrony evaluated by semiconductor single-photon emission computed tomography

BACKGROUND

Conventional complete left bundle branch block (CLBBB) criteria sometimes result in a false-positive diagnosis that does not represent dyssynchrony. Recently, true CLBBB criteria have been proposed to detect responders to cardiac resynchronization therapy (CRT), although their correlation with severity of dyssynchrony or natural prognosis is unclear.

METHODS

Ninety-four consecutive patients (74 ± 9 years, 63 men) with conventional CLBBB during sinus rhythm underwent semiconductor SPECT. They were divided into two groups: patients with true CLBBB and others. True CLBBB was characterized by the mid-QRS notching/slurring and wide QRS duration (male, ≥140 milliseconds; female, ≥130 milliseconds). Multivariate analysis was performed to detect left ventricular dyssynchrony (LVD), defined as bandwidth ≥145° and/or phase standard deviation (SD) ≥43°. Primary endpoints (hospitalization for heart failure or cardiac death) were evaluated.

RESULTS

True CLBBB had wider bandwidth (145 ± 83° vs 110 ± 64°, P = 0.024) and higher phase SD (48 ± 26° vs 35 ± 19°, P = 0.007). Ejection fraction (EF), end-diastolic volume (EDV), summed rest score (SRS), and the presence of ischemic heart disease (IHD) showed no differences between groups (P = 0.401, 0.591, 0.165, and 0.212, respectively). Multivariate analysis revealed that true CLBBB, EF, and EDV were significant predictors of LVD (odds ratio, 12.6, 0.90, 1.03; P = 0.003, 0.002, 0.022, respectively). At 3-year follow-up (median 667 days), primary endpoints were comparable in both groups (log-rank, P = 0.92).

CONCLUSIONS

Patients with true CLBBB had more severe dyssynchrony on single-photon emission computed tomography than patients with nontrue CLBBB. On the other hand, the two groups showed no differences in EF, EDV, the presence of IHD, hospitalization for heart failure, and cardiac death.

Stricter criteria for left bundle branch block diagnosis do not improve response to CRT

BACKGROUND

Cardiac resynchronization therapy (CRT) has proved to be effective in patients with heart failure and left bundle branch block (LBBB). Recently, new electrocardiography criteria have been proposed for the diagnosis of LBBB. These criteria are stricter than the current American Heart Association (AHA) criteria. We assessed the rate of echocardiographic response to CRT in patients with traditional LBBB versus patients who met the new criteria (strict LBBB).

METHODS

Consecutive patients undergoing CRT were enrolled in the CRT MORE registry. Patients with no-LBBB QRS morphology according to AHA criteria, atrial fibrillation, right bundle branch block, and right ventricular pacing were excluded. Strict LBBB was defined as: QRS ≥ 140 ms for men and ≥130 ms for women, QS or rS in V1-V2, mid-QRS notching or slurring in ≥2 contiguous leads. Patients showing a relative decrease of ≥15% in left ventricular end-systolic volume (LVESV) at 12 months were defined as responders.

RESULTS

Among 335 patients with LBBB, 131 (39%) had strict LBBB. Patients with and without strict LBBB showed comparable baseline characteristics, except for QRS duration (166 ± 20 ms vs 152 ± 25 ms, P < 0.001). On 12-month evaluation, 205 patients (61%) were responders; 85 of 131 (65%) had strict LBBB and 120 of 204 (59%) had traditional LBBB (P = 0.267). On multivariate analysis, a history of atrial fibrillation, larger LVESV, and the presence of mid-QRS notching in ≥1 lead (odds ratio 2.099; 95% confidence interval 1.061-4.152, P = 0.033) were independently associated with echocardiographic response.

CONCLUSION

Stricter definition of LBBB did not improve response to CRT in comparison to the current AHA definition.

Prevalence and clinical significance of left bundle branch block according to classical or strict definition criteria in permanent pacemaker patients

BACKGROUND

Previous studies have shown that the presence of left bundle branch block (LBBB) is associated with an increased risk of cardiac mortality and heart failure (HF). Recently, new criteria to define strict LBBB have been proposed: QRS duration ≥140 ms for men and ≥130 ms for women, along with mid-QRS notching or slurring in ≥2 contiguous leads.

HYPOTHESIS

We assessed the prevalence and prognostic significance of LBBB according to classical (QRS duration ≥120ms) and strict criteria in permanent pacemaker patients.

METHODS

We retrospectively enrolled 723 consecutive patients who had undergone single- or dual-chamber pacemaker implantation at the study center from July 2002 to December 2014. Patients with a left ventricular ejection fraction ≤35% or a prior diagnosis of HF were excluded.

RESULTS

LBBB was reported in 54 (7%) patients, and strict-LBBB in 15 (2%) patients. During a median follow-up of 48 months (range, 18-92 months), 147 (20%) patients reached the combined endpoint of death or HF hospitalization. Patients with LBBB and those with strict-LBBB displayed significantly higher rates of death or HF hospitalization (log-rank test, all P < 0.0001). In particular, strict-LBBB was associated with the worst outcome. The presence of LBBB according to classical definition criteria (hazard ratio [HR] = 1.98, confidence interval [CI]: 1.23-3.19, P = 0.005) and to strict criteria (HR = 2.20; CI: 1.04-4.65; P = 0.039) were both confirmed as independent predictors of death or HF hospitalization after adjustment for relevant clinical covariates.

CONCLUSIONS

Among patients who had undergone standard pacemaker implantation, the prevalence of LBBB was 7% according to classical definition criteria and 2% according to strict criteria. The presence of LBBB, and particularly of strict-LBBB, at the baseline predicted a poor outcome in terms of death or HF hospitalization.

Coronary sinus activation patterns in patients with and without left bundle branch block undergoing electroanatomic mapping system-guided cardiac resynchronization therapy device implantation

BACKGROUND

Implantation of the left ventricular (LV) lead in segments with delayed electrical activation may improve response to cardiac resynchronization therapy (CRT).

OBJECTIVE

The purpose of this study was to evaluate the amount and regional distribution of LV electrical delay (LVED) in patients with or without left bundle branch block (LBBB).

METHODS

We enrolled 60 patients who underwent electroanatomic mapping system-guided CRT device implantation. Activation mapping of the coronary sinus (CS) branches was performed using an insulated guidewire. LVED was defined as the interval between the beginning of the QRS complex on the surface electrocardiogram (ECG) and the local electrogram and expressed in milliseconds or as percentage of the total QRS duration (LVED%).

RESULTS

Forty-three patients showed a LBBB and 17 a non-LBBB electrocardiographic pattern. A total of 148 CS branches (mean 2.5 per patient; range 2-4 per patient) were mapped. Patients with LBBB showed higher maximum LVED (135 ms [108-150 ms] vs 100 ms [103-110 ms]; P < .001) and LVED% (86% [79%-89%] vs 72% [54%-80%]; P < .001) than did patients without LBBB. The maximum LVED was recorded in mid-basal anterolateral or inferolateral LV segments (traditional CRT targets), significantly more often in patients with LBBB than in patients without LBBB (85% vs 59%; P = .02). The number of CS branches showing LVED >50% of the total QRS duration, >75% of the total QRS duration, and >85 ms was significantly higher in patients with LBBB than in patients without LBBB.

CONCLUSION

Patients without LBBB showed lower LVED and more heterogeneous electrical activation of the CS than did patients with LBBB. This finding may contribute to a lower rate of response to CRT of patients without LBBB and suggests the use of activation mapping to guide LV lead placement.

Incidence of strict versus nonstrict left bundle branch block after transcatheter aortic valve replacement

BACKGROUND

Up to one-third of patients diagnosed with left bundle branch block (LBBB) by conventional electrocardiographic (ECG) criteria are misdiagnosed. Strict LBBB shows decreased left ventricular pumping efficiency compared with nonstrict LBBB. However, no previous study has evaluated the frequency of strict LBBB after transcatheter aortic valve replacement (TAVR). The aim of this study was to determine the incidence of developing strict versus nonstrict LBBB after TAVR and test the hypothesis that preprocedure QRS duration does not predict strict LBBB but predicts development of nonstrict LBBB.

METHODS

All patients receiving TAVR between 4/2011 and 2/2013 (n = 71) with no preexisting bundle branch block or permanent pacemaker were included. Twelve-lead ECGs were acquired preprocedure and both 1-day and 1-month postprocedure. All ECGs were classified as strict LBBB, nonstrict LBBB, or no LBBB.

RESULTS

Sixty-eight patients had ECGs eligible for final analysis. On postprocedure day 1, 25 (37%) of 68 patients developed strict LBBB, and 2 patients (3%) developed nonstrict LBBB. At 1-month follow-up, the 2 patients diagnosed with nonstrict LBBB had resolved to normal, and 5 (20%) of 25 patients with strict LBBB had resolved to normal. Preprocedure QRS duration did not predict strict LBBB (P = .51). Because of the low incidence of nonstrict LBBB, QRS duration as a predictor of nonstrict LBBB could not be tested.

CONCLUSIONS

Almost all patients who developed evidence of LBBB after TAVR met the new strict criteria, indicating probable procedural injury to the left bundle branch. Preprocedural QRS duration did not predict the development of strict LBBB.

Current algorithms for the diagnosis of wide QRS complex tachycardias

The differential diagnosis of a regular, monomorphic wide QRS complex tachycardia (WCT) mechanism represents a great diagnostic dilemma commonly encountered by the practicing physician, which has important implications for acute arrhythmia management, further work-up, prognosis and chronic management as well. This comprehensive review discusses the causes and differential diagnosis of WCT, and since the ECG remains the cornerstone of WCT differential diagnosis, focuses on the application and diagnostic value of different ECG criteria and algorithms in this setting and also provides a practical clinical approach to patients with WCTs.

Transcatheter aortic valve implantation-induced left bundle branch block: causes and consequences

Transcatheter aortic valve implantation (TAVI) is an alternative treatment option for patients with severe aortic valve stenosis who do not qualify for surgical aortic valve replacement (AVR). Besides its proven clinical benefits, one of the complications of TAVI is the creation of conduction abnormalities, like left bundle branch block (LBBB). New LBBB occurs between 7 and 65% of cases, numbers that differ considerably between devices. In this review, we discuss the possible causes and the clinical significance of TAVI-induced LBBB. Several device- and procedural-related factors seem responsible for the development of LBBB, of which depth of implantation and balloon-annulus diameter ratio are the most important ones. TAVI-induced LBBB negatively affects cardiac function and hospitalization, but its impact on mortality is subject of debate. Future research and registries should implement strict diagnostic criteria for LBBB together with recording of its timing and persistence.