Intracardiac Delineation of Septal Conduction in Left Bundle-Branch Block Patterns.

BACKGROUND: Septal activation in patients with left bundle-branch block (LBBB) patterns has not been described previously. We performed detailed intracardiac mapping of left septal conduction to assess for the presence and level of complete conduction block (CCB) in the His-Purkinje system. Response to His bundle pacing was assessed in patients with and without CCB in the left bundle. METHODS: Left septal mapping was performed with a linear multielectrode catheter in consecutive patients with LBBB pattern referred for device implantation (n=38) or substrate mapping (n=47). QRS width, His duration, His-ventricular (HV) intervals, and septal conduction patterns were analyzed. The site of CCB was localized to the level of the left-sided His fibers (left intrahisian) or left bundle branch. Patients with ventricular activation preceded by Purkinje potentials were categorized as having intact Purkinje activation. RESULTS: A total of 88 left septal conduction recordings were analyzed in 85 patients: 72 LBBB block pattern and 16 controls (narrow QRS, n=11; right bundle-branch block, n=5). Among patients with LBB block pattern, CCB within the proximal left conduction system was observed in 64% (n=46) and intact Purkinje activation in the remaining 36% (n=26). Intact Purkinje activation was observed in all controls. The site of block in patients with CCB was at the level of the left His bundle in 72% and in the proximal left bundle branch in 28%. His bundle pacing corrected wide QRS in 54% of all patients with LBBB pattern and 85% of those with CCB (94% left intrahisian, 62% proximal left bundle-branch). No patients with intact Purkinje activation demonstrated correction of QRS with His bundle pacing. CCB showed better predictive value (positive predictive value 85%, negative predictive value 100%, sensitivity 100%) than surface ECG criteria for correction with His bundle pacing. CONCLUSIONS: Heterogeneous septal conduction was observed in patients with surface LBBB pattern, ranging from no discrete block to CCB. When block was present, we observed pathology localized within the left-sided His fibers (left intrahisian block), which was most amenable to corrective His bundle pacing by recruitment of latent Purkinje fibers. ECG criteria for LBBB incompletely predicted CCB, and intracardiac data might be useful in refining patient selection for resynchronization therapy.

Brief Report: IRF5 systemic lupus erythematosus risk haplotype is associated with asymptomatic serologic autoimmunity and progression to clinical autoimmunity in mothers of children with neonatal lupus.

OBJECTIVE: Variation in the interferon regulatory factor 5 (IRF5) gene has been associated with risk of developing systemic lupus erythematosus (SLE), and this association is largely dependent upon anti-Ro autoantibodies. This study was undertaken to determine if the IRF5 genotype is associated with maternal diagnosis or progression of autoimmunity. METHODS: Genotyping of haplotype-tagging polymorphisms in IRF5 was performed in 93 subjects of European ancestry who were recruited to the Research Registry for Neonatal Lupus. All subjects had high-titer anti-Ro autoantibodies and had a child with neonatal lupus (NL); allele frequencies were compared to those in nonautoimmune controls. The mothers had SLE, Sjögren's syndrome (SS), or undifferentiated autoimmune syndrome (UAS), or were asymptomatic. RESULTS: The SLE risk haplotype of IRF5 was enriched in all anti-Ro-positive subjects except in those with SS (odds ratio [OR] 2.55, P = 8.8 × 10(-4) ). The SLE risk haplotype was even enriched in asymptomatic individuals with anti-Ro antibodies (OR 2.69, P = 0.019). The same haplotype was more prevalent in subjects who were initially asymptomatic but developed symptomatic SLE during followup (OR 5.83, P = 0.0024). Interestingly, SS was associated with 2 minor IRF5 haplotypes, and these same haplotypes were decreased in frequency in mothers with SLE and those with UAS. CONCLUSION: The IRF5 SLE risk haplotype was associated with anti-Ro antibody positivity in asymptomatic individuals, as well as with progression to SLE in asymptomatic anti-Ro-positive individuals. SS in mothers of children with NL was associated with different IRF5 haplotypes. These data suggest that IRF5 polymorphisms play a role in serologic autoimmunity in humans and may promote the progression to clinical autoimmunity.

Lateralization of face processing in the human brain.

Are visual face processing mechanisms the same in the left and right cerebral hemispheres? The possibility of such 'duplicated processing' seems puzzling in terms of neural resource usage, and we currently lack a precise characterization of the lateral differences in face processing. To address this need, we have undertaken a three-pronged approach. Using functional magnetic resonance imaging, we assessed cortical sensitivity to facial semblance, the modulatory effects of context and temporal response dynamics. Results on all three fronts revealed systematic hemispheric differences. We found that: (i) activation patterns in the left fusiform gyrus correlate with image-level face-semblance, while those in the right correlate with categorical face/non-face judgements. (ii) Context exerts significant excitatory/inhibitory influence in the left, but has limited effect on the right. (iii) Face-selectivity persists in the right even after activity on the left has returned to baseline. These results provide important clues regarding the functional architecture of face processing, suggesting that the left hemisphere is involved in processing 'low-level' face semblance, and perhaps is a precursor to categorical 'deep' analyses on the right.

Complications of Cardiac Resynchronization Therapy: Comparison of Safety Outcomes from Real-world Studies and Clinical Trials.

Cardiac resynchronization therapy (CRT) is an important intervention in heart failure. Whether real-world complication rates mirror those reported in randomized clinical trials (RCTs) is unknown. We sought to compare rates of procedural complications between major RCTs of CRT with "real-world" complication rates reported in registries and administrative claims database studies. We conducted a PubMed search to identify all relevant publications on CRT and classified them into RCTs and registry studies. Pooled procedural complication rates were analyzed. Differences between groups were compared using the chi-squared test. We identified a total of 6 RCTs, 2 administrative claims database studies, and 4 CRT registry studies. RCTs included a total of 4,442 patients and "real-world" studies included a total of 72,554 patients. The overall rates of procedural complications with CRT were significantly higher in RCTs compared to the real world (8.1% vs. 6.9%, P = .002). Lead-related complications were higher in the real-world studies compared to RCTs (11.3% vs. 6.5%, P = .0001). This could represent a follow-up bias with patients in registries being followed up for longer durations that would compound lead complication rates. Interestingly, RCTs had a higher incidence of pocket hematomas (2.1% vs. 0.4%, P = .001). In conclusion, real-world procedural complication rates of CRT appear to be significantly lower than those reported in RCTs.

Subcutaneous Implantable Cardioverter-defibrillator Explantation-A Single Tertiary Center Experience.

The subcutaneous implantable cardioverter-defibrillator (S-ICD) is an appealing alternative to transvenous ICD systems. However, data on indications for S-ICD explantations are sparse. The objective of this study was to assess the incidence and indications for S-ICD explantation at a large tertiary referral center. We conducted a retrospective study of all S-ICD explantations performed from 2014-2020. Data on demographics, comorbidities, implantation characteristics, and indications for explantation were collected. A total of 64 patients underwent S-ICD explantation during the study period. During that time, there were 410 S-ICD implantations at our institution, of which 53 (12.9%) were explanted with a mean duration from implant to explant of 19.7 ± 20.1 months. The mean age of the patients at explantation was 44.8 ± 15.3 years, and 42% (n = 27) were women. The indication for S-ICD implantation was primary prevention in 58% and secondary prevention in 42% of patients, respectively. The most common reason for explantation was infection (32.8%), followed by abnormal sensing (25%) and the need for pacing (18.8%). Those who underwent S-ICD explantation for pacing indications were significantly older (55.7 ± 13.6 vs. 42.3 ± 14.6 years, P = 0.005) with a wider QRS duration (111 ± 19 vs. 98 ± 19 ms, P = 0.03) at device implantation compared to patients who underwent explantation for other indications. The incidence of S-ICD explantation in a large tertiary practice was 12.9%. While infection was the indication for one-third of the explantations, a significant number of explantations were due to sensing abnormalities and the need for pacing. These data may have implications for patient selection for S-ICD implantation.

Recurrent Atrial Fibrillation After Radiofrequency Ablation: What to Expect.

Recurrent atrial fibrillation after radiofrequency ablation is observed in up to 50% of patients within 3 months. Early and multiple recurrences predict late recurrences within 1 year, which occurs in 20% to 50% of patients. Although no consensus exists regarding patient selection and timing of redo ablation, we refer symptomatic patients with multiple recurrences and persistent atrial fibrillation for ablation. Reisolation of reconnected pulmonary veins and ablation of nonpulmonary vein triggers is the primary ablation strategy. In addition to repeat ablation, we recommend weight loss, treatment of sleep-disordered breathing, and management of comorbid conditions for durable maintenance of sinus rhythm.

Right Ventricular Pacing and Cardiac Resynchronization Devices.

Long-term right ventricular pacing is associated with electrical and mechanical dyssynchrony and ultimately development of pacing-induced cardiomyopathy (PICM) in a subset of patients. Patients with a high degree of pacing burden and reduced left ventricular (LV) function prior to pacemaker implantation are at the greatest risk for developing PICM. Cardiac resynchronization therapy (CRT) has an established role in the treatment of patients with LV systolic heart failure and intraventricular delay and has been used to successfully treat PICM. This review evaluates predictors for PICM, as well as highlights the role for CRT in prevention and treatment in high risk patients.

Narrow Complex Tachycardia.

This case report presents the electrocardiogram findings of a patient in their 50s with sudden onset, severe palpitations lasting for 2 hours.

Effect of Atrial Fibrillation on Mortality, Stroke Risk, and Quality-of-Life Scores in Patients With Heart Failure (from the Outcomes Registry for Better Informed Treatment of Atrial Fibrillation [ORBIT-AF]).

The degree to which clinical outcomes are worsened in patients with atrial fibrillation (AF) with heart failure (HF) compared with those without HF is not well described. This study aimed to determine the impact of HF on clinical outcomes in patients with AF. We analyzed data from Outcomes Registry for Better Informed Treatment of Atrial Fibrillation, a national registry of 10,135 patients with AF to determine associations between HF and left ventricular ejection fraction (LVEF) and outcomes, including stroke, mortality, and hospitalization using Cox multivariable modeling. Atrial Fibrillation Effect on Quality-of-Life Questionnaire (AFEQT) scores between groups were also compared. Overall, 33% (n = 3,203) of patients had HF; of these 33% (n = 985) had LVEF ≤40%. Oral anticoagulation was prescribed more commonly in patients with HF (81% vs 74%). Compared with patients without HF, those with HF had similar rate of stroke (1.28 vs 0.88 per 100-patient years, hazard ratio [HR] 1.11, confidence interval [CI] 0.83 to 1.48, p = 0.47) but higher mortality (HR 1.69, CI 1.49 to 1.92, p <0.001) and hospitalization (HR 1.31, CI 1.23 to 1.39, p <0.0001). Patients with LVEF ≤40% had similar stroke risk (HR 1.06, CI 0.67 to 1.67) but higher mortality (HR 2.06, CI 1.74 to 2.44) and hospitalization (HR 1.38, CI 1.25 to 1.51). AFEQT overall score was significantly lower (76.9 vs 83.3, p <0.0001) in patients with HF. In conclusion, HF was associated with increased risk of death and hospitalization and worse quality of life, but similar rates of thromboembolism regardless of LVEF among patients with AF. These findings highlight the need to develop therapeutic strategies targeting functional status and survival for patients with HF and AF.