Bleeding and thrombotic risk in pregnant women with Fontan physiology.

BACKGROUND/OBJECTIVES: Pregnancy may potentiate the inherent hypercoagulability of the Fontan circulation, thereby amplifying adverse events. This study sought to evaluate thrombosis and bleeding risk in pregnant women with a Fontan. METHODS: We performed a retrospective observational cohort study across 13 international centres and recorded data on thrombotic and bleeding events, antithrombotic therapies and pre-pregnancy thrombotic risk factors. RESULTS: We analysed 84 women with Fontan physiology undergoing 108 pregnancies, average gestation 33±5 weeks. The most common antithrombotic therapy in pregnancy was aspirin (ASA, 47 pregnancies (43.5%)). Heparin (unfractionated (UFH) or low molecular weight (LMWH)) was prescribed in 32 pregnancies (30%) and vitamin K antagonist (VKA) in 10 pregnancies (9%). Three pregnancies were complicated by thrombotic events (2.8%). Thirty-eight pregnancies (35%) were complicated by bleeding, of which 5 (13%) were severe. Most bleeds were obstetric, occurring antepartum (45%) and postpartum (42%). The use of therapeutic heparin (OR 15.6, 95% CI 1.88 to 129, p=0.006), VKA (OR 11.7, 95% CI 1.06 to 130, p=0.032) or any combination of anticoagulation medication (OR 13.0, 95% CI 1.13 to 150, p=0.032) were significantly associated with bleeding events, while ASA (OR 5.41, 95% CI 0.73 to 40.4, p=0.067) and prophylactic heparin were not (OR 4.68, 95% CI 0.488 to 44.9, p=0.096). CONCLUSIONS: Current antithrombotic strategies appear effective at attenuating thrombotic risk in pregnant women with a Fontan. However, this comes with high (>30%) bleeding risk, of which 13% are life threatening. Achieving haemostatic balance is challenging in pregnant women with a Fontan, necessitating individualised risk-adjusted counselling and therapeutic approaches that are monitored during the course of pregnancy.

Utility of 6-Minute Walk Test to Predict Response to Cardiac Resynchronization Therapy in Patients With Mild Heart Failure.

Clinical studies of heart failure (HF) generally utilize the 6-minute walk test (6MWT) for functional capacity (FC) assessment. However, data on the impact of cardiac resynchronization therapy (CRT) on 6MWT and its role to predict long-term outcomes in mild HF patients with CRT are lacking. We studied 1,381 subjects with mild HF enrolled in Multicenter Automatic Defibrillator Implantation Trial - Cardiac Resynchronization Therapy with 6MWT data at baseline and 1 year. We assessed the effects of CRT-D on percent change in 6MWT at 1 year by left bundle branch block (LBBB) status, identified independent predictors of 6MWT at 1 year, and evaluated the association between changes in 6MWT and risk for HF or death. Treatment with CRT-D versus implantable cardiac defibrillator (ICD) was not associated with a significant improvement in 6MWT at 1-year in LBBB subjects (2.2 % vs 0.0%, p = 0.428, but it was associated with a deterioration in 6MWT in non-LBBB subjects (4.1% vs 0.0%, p = 0.308). Multivariate analysis showed that each 5% reduction in 6MWT was independently associated with a corresponding 3% increase in the risk of subsequent HF or death (p = 0.014). In conclusion, our findings suggest that 6MWT has limited utility to identify CRT response in mild HF subjects with LBBB. However, 6MWT showed a signal toward deterioration in mild HF subjects with non-LBBB, and this was predictive of subsequent increased risk of HF or death.