Effect of ventricular function and volumes on exercise capacity in adults with repaired Tetralogy of Fallot

Objectives

Investigate the effects of left and right ventricular function and severity of pulmonary valve regurgitation, quantified by cardiac magnetic resonance (CMR), on exercise tolerance in adult patients who underwent ToF repair at a young age.

Methods

This is a retrospective cohort study of 52 patients after ToF surgery and 33 age- and sex-matched healthy volunteers. CMR and cardiopulmonary exercise testing (CPET) were performed on all patients; CPET was performed on control subjects.

Results

The main finding of CPET was a severe decrease in oxygen uptake at peak exercise VO_2peak in TOF patients. The patients were characterized also by lower pulse O_2peak and heart rate at peak exercise. Ejection fraction of the right and left ventricles was correlated (r = 0,32; p = 0,03). Left ventricle ejection fraction was negatively correlated with right ventricular volumes (r = −0,34; p = 0,01) and right ventricular mass (r = −046; p < 0,00). Right ventricular mass was positively correlated with left ventricular variables (left ventricle end diastolic volume, r = 0,43; p = 0,002; left ventricle end systolic volume, r = 0,54; p < 0,00) as was VO_2peak: LVEDV (r = 0,38; p = 0,01); LVESV (r = 0,33; p = 0,03) and LV mass (r = 0,42; p = 0,006).

Conclusion

Exercise intolerance in adults with repaired ToF is markedly depressed. The decreased exercise capacity is correlated with impaired RV function and may be associated also with LV dysfunction, which suggests right-to-left ventricular interaction.

CYP2C9 Polymorphism and Unstable Anticoagulation with Warfarin in Patients Within the First 3 Months Following Heart Valve Replacement

BACKGROUND

Warfarin dose requirements are partly determined by common single nucleotide polymorphisms in VKORC1 and CYP2C9 genes.

OBJECTIVES

The aim of this study was to investigate how the presence of allelic variants in CYP2C9 affects the stability of anticoagulation in patients within the first 3 months following elective heart valve replacement.

MATERIAL AND METHODS

In a case-control study we compared 18 consecutive carriers of CYP2C9*2 and/or *3 and 25 well-matched patients with the wild type CYP2C9*1/*1 genotype. The former group was randomly assigned to use coagulometers or monitor international normalized ratio (INR) in local outpatient clinics. Subjects receiving drugs potently interfering with warfarin were ineligible. Anticoagulation with the baseline warfarin regimens based on pharmacogenetic algorithm was assessed by time in the therapeutic INR range (TTR) within the first 3 months following implantation.

RESULTS

Carriers of the CYP2C9*2 and/or *3 genotypes were characterized by lower estimated warfarin dose (median, 21 [interquartile range, 21-35] vs. 35 [28-42] mg/week, p=0.02) and actual (27.8±13.2 vs. 46.3±13.9 mg/week, p<0.001), together with lower TTR values (56 [38.6-74.9] vs. 75.4 [58.1-83.6] %, p=0.03) and longer time above the therapeutic range (13.8 [4.9-34.5] vs. 4.5 [0-15.3]%, p=0.047) than patients with the CYP2C9*1/*1 genotype. There were no differences in the estimated and actual warfarin doses, TTR values and adverse events between the self-testing and standard-care subgroups.

CONCLUSIONS

The presence of CYP2C9*2 and/or *3 genotypes is associated with unstable warfarin treatment in patients after heart valve replacement, regardless of the type of INR testing.