Background: Cardiac resynchronization therapy via biventricular pacing is an established therapy for patients with heart failure. However, high nonresponder rates and inability to predict response remains a challenge. Recently left bundle branch area pacing (LBBAP) has been shown to be feasible and may also improve clinical outcomes. In this article we describe the new technique (sequential LBBAP followed by left ventricular pacing, LOT-CRT) and assess the feasibility of LOT-CRT.Methods: The RV implantation site was positioned and the LBBAP lead was implanted using our methods. The QRS duration (QRSd) at baseline, during LBBAP, biventricular pacing, and LOT-CRT was measured. Results: LOT-CRT was successful in 5 patients (age 71.8 ± 5.1 years, men 3, ischemic 3). The QRSd at baseline was 158.0 ± 13.0 ms and significantly narrowed to 117.0 ± 6.7 ms during LOT-CRT (P < 0.01). During 3-month follow-up, LV ejection fraction improved from 32.8 ± 5.2 % to 45.0 ± 5.1% (P < 0.01), and New York Heart Association functional class changed from 3.25 ± 0.5 to 2.5 ± 0.6 (P < 0.05). A decrease in left ventricular end-diastolic dimension was observed, with widening from (68.2 ± 12.3) mm at baseline to (62.2 ± 11.3) mm at pacing (P < 0.05). The length of operation time was (152.0 ± 31.1) min. Conclusions: The study demonstrates that LOT-CRT is clinically feasible in patients with systolic HF and LBBB. LOT-CRT was associated with significant narrowing of QRSd and improvement in LV function, especially in patients with ischemic cardiomyopathy.

Background Hypothyroidism is known to be associated with adverse clinical outcomes in heart failure. The association between hypothyroidism and cardiac resynchronization therapy outcomes in patients with severe heart failure is not clear.Methods The study included 1,316 patients who received cardiac resynchronization therapy between 2002 and 2015. Baseline demographics and cardiac resynchronization therapy outcomes, including left ventricular ejection fraction, New York Heart Association class, appropriate implantable cardioverter-defibrillator therapy, and all-cause mortality, were collected from the electronic health record. Results Of the study cohort, 350 patients (26.6%) were classified as the hypothyroidism group. The median duration of follow-up was 3.6 years (interquartile range, 1.7-6.2). Hypothyroidism was not associated with a higher risk of all-cause mortality in patients receiving CRT for heart failure. The risk of appropriate implantable cardioverter-defibrillator therapy significantly increased in association with increased baseline thyroid-stimulating hormone level in the entire cohort (hazard ratio, 1.23 per 5mIU/L increase; 95% CI, 1.01-1.5; P=0.04) as well as in the hypothyroid group (hazard ratio, 1.44 per 5mIU/L increase; 95% CI, 1.13-1.84; P=0.004). Conclusions CRT improves cardiac function in hypothyroid patients. The ventricular arrhythmic events requiring ICD therapies are associated with baseline TSH level, which might be considered as an important biomarker to stratify the risk of sudden death for patients with heart failure and hypothyroidism.

Background Hypothyroidism is known to be associated with adverse clinical outcomes in heart failure. The association between hypothyroidism and cardiac resynchronization therapy outcomes in patients with severe heart failure is not clear. Methods The study included 1,316 patients who received cardiac resynchronization therapy between 2002 and 2015. Baseline demographics and cardiac resynchronization therapy outcomes, including left ventricular ejection fraction, New York Heart Association class, appropriate implantable cardioverter-defibrillator therapy, and all-cause mortality, were collected from the electronic health record. Results Of the study cohort, 349 patients (26.5%) were classified as the hypothyroidism group. The median duration of follow-up was 3.6 years (interquartile range, 1.7-6.2). Hypothyroidism was associated with a greater all-cause mortality than euthyroidism (hazard ratio, 1.19; 95% CI, 1.01-1.38; P=0.04). In this group, the risk of appropriate implantable cardioverter-defibrillator therapy significantly increased in association with increased baseline thyroid-stimulating hormone level (hazard ratio, 1.27 per 5 mIU/L increase, 95% CI, 1.00-1.53, P=0.04). Conclusions Cardiac resynchronization therapy improves cardiac function in hypothyroid patients. Hypothyroidism has adverse effects on cardiac resynchronization therapy outcomes with reduced survival and increased implantable cardioverter-defibrillator therapies for ventricular arrhythmic events.

Background Hypothyroidism is known to be associated with adverse clinical outcomes in heart failure. The association between hypothyroidism and cardiac resynchronization therapy outcomes in patients with severe heart failure is not clear. Methods The study included 1,316 patients who received cardiac resynchronization therapy between 2002 and 2015. Baseline demographics and cardiac resynchronization therapy outcomes, including left ventricular ejection fraction, New York Heart Association class, appropriate implantable cardioverter-defibrillator therapy, and all-cause mortality, were collected from the electronic health record. Results Of the study cohort, 350 patients (26.6%) were classified as the hypothyroidism group. The median duration of follow-up was 3.6 years (interquartile range, 1.7-6.2). Hypothyroidism was not associated with a higher risk of all-cause mortality in patients receiving CRT for heart failure. The risk of appropriate implantable cardioverter-defibrillator therapy significantly increased in association with increased baseline thyroid -stimulating hormone level in the entire cohort (hazard ratio, 1.23 per 5mIU/L increase; 95% CI, 1.01-1.5; P=0.04) as well as in the hypothyroid group (hazard ratio, 1.44 per 5mIU/L increase; 95% CI, 1.13-1.84; P=0.004). Conclusions CRT improves cardiac function in hypothyroid patients. The ventricular arrhythmic events requiring ICD therapies are associated with baseline TSH level, which might be considered as an important biomarker to stratify the risk of sudden death for patients with heart failure and hypothyroidism.