Arrhythmic risk in single or recurrent episodes of unexplained syncope with complete bundle branch block

INTRODUCTION AND OBJECTIVES

Patients with a single syncopal episode (SSE) and complete bundle branch block (cBBB) are frequently managed more conservatively than patients with recurrent episodes (RSE). The objective of this study was to analyze if there are differences between patients with single or recurrent unexplained syncope and cBBB in arrhythmic risk, the diagnostic yield of tests, and clinical outcomes.

METHODS

Cohort study of consecutive patients with unexplained syncope and cBBB with a median follow-up time of 3 years. The patients were evaluated via a stepwise workup protocol based on electrophysiological study (EPS) and long-term follow-up with an implantable cardiac monitor.

RESULTS

Of the 503 patients included in the study, 238 (47.3%) had had only 1 syncopal episode. The risk of an arrhythmic syncope was similar in both groups (58.8% in SSE vs 57.0% in RSE; P=.68), also after adjustment for possible confounding variables (HR, 1.06; 95%CI, 0.81-1.38; P=.674). No significant differences between the groups were found in the EPS results and implantable cardiac monitor diagnostic yield. A total of 141 (59.2%) patients with SSE and 154 (58.1%) patients with RSE required cardiac device implantation (P=.797). After appropriate treatment, 35 (7%) patients had recurrence of syncope. The recurrence rate and mortality were also similar in both groups.

CONCLUSIONS

Patients with cBBB and unexplained syncope are at high risk of an arrhythmic etiology, even after the first syncopal episode. Patients with SSE and RSE have a similar arrhythmic risk and similar outcomes, and therefore there is no clinical justification for not managing them in the same manner.

Sex-Related Differences in Patients With Unexplained Syncope and Bundle Branch Block: Lower Risk of AV Block and Lesser Need for Cardiac Pacing in Women

Objective

To analyze if there are sex-related differences in patients with unexplained syncope and bundle branch block (BBB).

Background

Despite increasing awareness that sex is a major determinant of the incidence, etiology, and the outcomes of different arrhythmias, no studies have examined differences in presentation and outcomes between men and women with syncope and BBB.

Methods

Cohort study of consecutive patients with unexplained syncope and BBB was included from January 2010 to January 2021 with a median follow-up time of 3.4 years [interquartile range (IQR) 1.7–6.0 years]. They were evaluated by a stepwise workup protocol based on electrophysiological study (EPS) and long-term follow-up with an implantable cardiac monitor (ICM).

Results

Of the 443 patients included in the study, 165 (37.2%) were women. Compared with men, women had less diabetes (25.5 vs. 39.9%, p = 0.002) and less history of ischemic heart disease (IHD; 13.3 vs. 25.9%, p = 0.002). Left bundle branch block (LBBB) was more frequent in women (55.2 vs. 27.7%, p < 0.001) while right bundle branch block (RBBB) was more frequent in men (41.5 vs. 67.7%, p < 0.001). His to ventricle (HV) interval in the EPS was shorter in women (58 ms [IQR 52–71] vs. 60 ms [IQR 52–73], p = 0.035) and less women had an HV interval longer than 70 ms (28.5 vs. 38.1%, p = 0.039), however, EPS and ICM offered a similar diagnostic yield in both sexes (40.6 vs. 48.9% and 48.4% vs. 51.1%, respectively). Women had a lower risk of developing atrioventricular block (AVB) (adjusted odds ratio [OR] 0.44–95% CI 0.26–0.74, p = 0.002) and of requiring permanent pacemaker implantation (adjusted hazard ratio [HR] 0.72–95% CI: 0.52–0.99, p = 0.046). The mortality rate was lower in women (4.5 per 100 person-years [95% CI 3.1–6.4 per 100 person-years] vs. 7.3 per 100 person-years [95% CI 5.9–9.1 per 100 person-years]).

Conclusions

Compared to men, women with unexplained syncope and BBB have a lower risk of AVB and of requiring cardiac pacing. A stepwise diagnostic approach has a similar diagnostic yield in both sexes, and it seems appropriate to guide the treatment and avoid unnecessary pacemaker implantation, especially in women.

Etiology and prognosis of patients with unexplained syncope and mid-range left ventricular dysfunction

BACKGROUND

Syncope in patients with mid-range left ventricular ejection fraction (LVEF) can be due to potentially serious arrhythmic causes. However, there is no clear consensus on the best way to manage these patients.

OBJECTIVES

The objectives of this study were to determine the causes of syncope and assess the diagnostic yield and safety of a stepwise workup protocol in this population.

METHODS

This was a prospective observational study. A stepwise workup protocol was applied to patients with LVEF 35%-50% and unexplained syncope after the initial assessment (step 1).

RESULTS

One hundred four patients were included {median age 75.6 years; (interquartile range [IQR] 67.6-81.2 years); median LVEF 45% (IQR 40%-48%); median follow-up 2.0 years (IQR 0.7-3.3 years). In 71 patients (68.3%), a diagnosis was reached: 55 (77.5%) in step 2 (hospital admission and electrophysiology study) and 16 (36.5%) in step 3 (implantable cardiac monitor). Arrhythmic causes were the most common etiology (45.2% auriculoventricular block and 9.6% ventricular tachycardia). Sixty patients (57.7%) required the implantation of a cardiac device and 11 had a defibrillation function. Patients diagnosed in step 3 had a higher global risk of recurrence of syncope (hazard ratio 6.5; 95% confidence interval 2.3-18.0). The mortality rate was 8.1 per 100 person-years, and the sudden or unknown death rate was 0.9 per 100 person-years.

CONCLUSION

In patients with mid-range left ventricular dysfunction and syncope of unknown cause, a systematic diagnostic strategy based on electrophysiology study and/or implantable cardiac monitor implantation allows a diagnosis to be reached in a high proportion of cases and guides the treatment. Arrhythmia is the most common cause of syncope in this population, particularly auriculoventricular block.

Cardiac resynchronization therapy is associated with a reduction in ICD therapies as it improves ventricular function

BACKGROUND

Repeated implantable cardioverter-defibrillator (ICD) therapies cause myocardial damage and, thus, an increased risk of arrhythmias and mortality.

HYPOTHESIS

Cardiac resynchronization therapy-defibrillator (CRT-D) reduces the number of appropriate therapies in patients with left ventricular dysfunction (left ventricular ejection fraction [LVEF] <50%).

METHODS

The retrospective study involved 175 consecutive patients (mean age, 64.6 ±10.4 years; 86.9% males) with reduced LVEF of 27.9% ±7.6% treated with an ICD (56.6%) or CRT-D (43.4%), according to standard indications, between January 2009 and July 2014. Devices were placed for either primary (54.3%) or secondary prevention (45.7%). Mean follow-up was 2.5 ±1.5 years. Predictors of first appropriate therapy were assessed using Cox regression analysis.

RESULTS

Forty-four (25.1%) patients received ≥1 appropriate therapy. Although patients treated with CRT-D had lower LVEF and poorer New York Heart Association class, CRT-D patients with LVEF improvement >35% at the end of follow-up had a significantly lower risk of receiving a first appropriate therapy relative to those with an ICD (adjusted hazard ratio: 0.24, 95% confidence interval: 0.07-0.83, P = 0.025), independently of ischemic cardiomyopathy, baseline LVEF, and secondary prevention. There were no differences in mortality between the ICD and the CRT-D groups.

CONCLUSIONS

Although patients receiving CRT-D had a worse clinical profile, they received fewer device therapies in comparison with those receiving an ICD. This reduction is associated with a significant improvement in LVEF.