Upgrade to his bundle pacing in pacing-dependent patients referred for pulse generator change: Feasibility and intermediate term follow up.

BACKGROUND: Right ventricular pacing (RVP) is associated with an increased incidence of heart failure and may impair cardiac function. Permanent His bundle pacing (HBP) has the potential to physiologically preserve and prevent cardiac dysfunction. This study was to evaluate the feasibility and intermediate follow-up results of upgrade to HBP implantation in patients referred for pulse generator change with long term RVP. METHODS: Twelve of 14 pacing dependent patients who were referred for pulse generator exchange underwent upgrade into HBP successfully in our center. QRS duration, New York Heart Association (NYHA) functional class, echocardiography, use of diuretics and lead parameters were measured at baseline and during the follow-up. RESULTS: Among the 12 patients attempted (mean age, 70.8 ±â€¯8.9 years, 75% males) successfully, the average ejection fraction (EF) was 52.2 ±â€¯11.2%. Nine of 12 patients underwent upgrade to HBP, and three patients with EF < 40% underwent HBP and biventricular pacing (BVP) as well. A significant reduction in mean QRS duration was observed compared with pre-implantation, from 157.8 ±â€¯13.3 ms to 109.3 ±â€¯16.9 ms (p < 0.001). After 6 months follow-up period, median NYHA functional class was improved from 2.7 ±â€¯0.6 to 1.8 ±â€¯0.6 (p = 0.007) and left ventricular internal diastolic diameter (LVIDd) was reduced from 5.5 ±â€¯0.4 cm to 5.3 ±â€¯0.3 cm (p = 0.03). CONCLUSIONS: HBP improves heart failure symptoms with preserved EF by long term RVP. Permanent HBP is feasible and safe for upgrade in patients with long term RVP irrespective of LVEF.

Clinical verification of Lou type warfarin pharmacokinetic dosing algorithms equation.

Warfarin is the most commonly used oral anti-coagulant in clinic practice. However, it is difficult to recommend the correct dosage due to its narrow therapeutic window. The aim of the present study was to verify the clinical value of the Lou type equation, using pharmacogenetics­based warfarin dosing algorithms to appropriately predict the actual maintenance dose. A total of 87 Chinese Han patients who required treatment with warfarin were enrolled and randomly divided into the experimental and control groups. In the experimental group, the first 3 doses of warfarin were calculated according to the Lou type equation. While in the control group, these 3 treatments were performed following the doctors' recommendations. Then the dose of warfarin was gradually adjusted to the stable dose according to the changes in the international standardized ratio. At the end of the 50 day experimental period, there were a greater number of patients in the experimental group who exhibited a stable blood concentration of warfarin than those in the control group (83.35 and 64.4%, respectively). In addition, the mean and median times for patients to obtain a stable dose in the experimental group were significantly shorter than those in the control group (mean, 18.2±1.7 and 27.3±2.0 days; and median, 11.7±1.1 and 20.5±1.8 days, respectively). The adverse reaction rate of the experimental group (9.5%) was markedly lower than that of the control group (26.7%). The occurrence of adverse reactions in the experimental group was also significantly later when compared with the control group (43.9±1.6 and 38.6±1.5 days, respectively). Furthermore, there was no significant difference between the average predicted dose (3.4±1.1 mg/day) and the average actual dose (3.5±1.4 mg/day; P=0.313). In conclusion, using the Lou type warfarin pharmacokinetic dosing algorithm equation to administer warfarin markedly shortened the adjustment time of warfarin to reach a stable dose and reduced the adverse reactions rate, thus supporting clinical feasibility.