Background
: Chronic atrial stretch is an important determinant for atrial fibrillation (AF). Whether relief of stretch reverses the substrate predisposed to AF is unknown.
Methods:
Twenty one pts (31±9 years) with mitral stenosis (MS; MVA 0.89±0.1cm
2
) undergoing mitral commissurotomy (MC) were studied by electrophysiological or electroanatomical mapping of both atria before and after MC. Multipolar catheters were placed in the lateral RA, Crista (CT), coronary sinus (CS), septal RA and LA. We measured: effective refractory period (ERP) at the LA appendage, septal/lateral LA roof, posterior LA, inferior LA, proximal/distal CS, low/high LRA and SRA at 600 and 450ms; P wave duration (PWD); double potentials (DP) or fractionated signals (FS) along CT; and conduction time along CS, LRA, inferior LA and LA roof. Activation and voltage maps were created to evaluate changes in conduction and voltage. In 14 pts, RA studies were repeated ≥6 months after MC.
Results
: Following MC, there was significant increase in MVA (2.1±0.3 cm
2,
p<0.0001) with decrease in LA (23±8 to 10±4 mmHg, p<0.0001) and PA pressures (38±17 to 27±14mmHg, p<0.0001) and LA volume (75±12 to 52±13ml, p<0.0001). This was associated with no change in ERP and No. of DP/FS along the CT but with reduction in PWD (139±19 to 135±20ms, p=0.047), increase in conduction velocity (CV) in LA (1.3±0.3 to 1.7±0.2m/s, p=0.005) and RA (1.0±0.1 to 1.3±0.3 m/s, p=0.007) and increase in LA voltage (1.7±0.6 to 2.5±1.0 mV, p=0.05). Late after MC, there was a further decrease in PWD and RA ERP, with increase in RA CV (1.0±0.1 to 1.3±0.2 m/s, p=0.01) and voltage (1.7±0.7 to 2.8±0.6 mV, p=0.004) but with no change in other parameters. See table
for details of pts studied late after MC.
Conclusion:
The electrophysiologic and electroanatomic abnormalities within the atria that result from MS are reversed after MC. These observations suggest that the substrate predisposing to atrial arrhythmias may be reversed.
Results
Improved hemodynamics after surgical weight loss in patients with morbid obesity
