New Minimally Invasive and Tailor-Made Strategy for Cryoballoon Ablation in Patients With Paroxysmal Atrial Fibrillation

BACKGROUND

The optimal dosage for cryoballoon ablation (CBA) of atrial fibrillation (AF) is still unknown.

OBJECTIVE

This study aimed to evaluate the clinical implications of a reduction in the freezing duration to <180 seconds during CBA guided by the time to the target temperature.

METHODS

This study enrolled 325 consecutive paroxysmal AF patients who underwent CBA. It was a retrospective observational study in a single centre. It compared 164 patients who underwent a tailor-made CBA procedure (group T) with 161 who had a standard CBA procedure (group S). In group T, the freezing duration was reduced to 150 seconds when the temperature reached ≤ -40 °C within 40 seconds. Furthermore, it was reduced to 120 seconds when it reached ≤ -50 °C within 60 seconds. In the other patients, the freezing duration was 180 seconds, except for excessive freezing of ≤ -60 °C and/or emergent situations while monitoring the oesophageal temperature, and for phrenic nerve injury, as in group S.

RESULTS

In group T, 89 patients (83%) underwent CBA with a reduction in the freezing duration. The total freezing time for each pulmonary vein was significantly shorter in group T than group S, and the total procedure time in group T decreased by an average of 4 minutes compared with group S. The rate of requiring additional radio frequency ablation following the CBA was significantly lower in group T than group S. The AF-free survival rate during the follow-up period (median, 366 days) was similar between the two groups.

CONCLUSION

The safety and efficacy of the new CBA strategy were non-inferior to the standard procedure.

Cold fluids for induction of targeted temperature management: A sub-study of the TTH48 trial

BACKGROUND

Pre-intensive care unit (ICU) induction of targeted temperature management (TTM) with cold intravenous (i.v.) fluids does not appear to improve outcomes after in out-of-hospital cardiac arrest (OHCA). We hypothesized that this may be due to ineffective cooling and side effects.

METHODS

A post hoc analysis of a sub-group of patients (n = 352) in the TTH48 trial (NCT01689077) who received or did not receive pre-ICU cooling using cold i.v. fluids. Data collection included patient characteristics, cardiac arrest factors, cooling methods, side effects and continuous core temperature measurements. The primary endpoint was the time to target temperature (TTT, <34 °C), and the secondary endpoints included the incidence of circulatory side effects, abnormal electrolyte levels and hypoxia within the first 24 h of ICU care. A difference of 1 h in the TTT was determined as clinically significant a priori.

RESULTS

Of 352 patients included in the present analysis, 110 received pre-ICU cold fluids. The median time to the return of spontaneous circulation (ROSC) and TTT in the pre-ICU cold fluids group was longer than that of the group that did not receive pre-ICU cold fluids (318 vs. 281 min, p < 0.01). In a linear regression model including the treatment centre, body mass index (BMI), chronic heart failure, diabetes mellitus and time to ROSC, the use of pre-ICU cold i.v. fluids was not associated with a shorter time to the target temperature (standardized beta coefficient: 0.06, 95% CI for B -49 and 16, p  =  0.32). According to the receipt or not of pre-ICU cold i.v. fluids, there was no difference in the proportion of patients with hypoxia on ICU admission (1.8% vs. 3.3%, p =  0.43) or the proportion of patients with electrolyte abnormalities (hyponatremia: 1.8% vs. 2.9% p = 0.54; hypokalaemia: 1.8% vs. 4.5%, p =  0.20). Furthermore, there was no difference in hospital mortality between the groups.

CONCLUSIONS

The initiation of TTM with cold i.v. fluids before ICU arrival did not decrease the TTT. We detected no significant between-group difference in mortality or the incidence of side effects according to the administration or not of pre-ICU cold i.v fluids.