Homocysteine and P wave dispersion in patients with heart transplantation

Background: Hyperhomocysteinemia (HHcy), a putative independent risk factor for the development of atherotrombosis in the general population, represents a very common finding in orthotopic heart transplantation (OHT) patients. Starting from previous studies suggesting a pro-arrhythmogenic activity of homocysteine (Hcy), we evaluated the possible correlation among Hcy plasma levels and P wave dispersion (PWD), corrected QT interval (QTc), and QTc dispersion (QTcD) as parameters of electric instability of the myocardium in patients undergone OHT whose hearts are therefore completely denervated, thus unresponsive to autonomic influences. Methods and results: Homocysteine plasma levels, PWD, QTc, QTcD, and QTc dynamics were measured in 32 patients, who underwent OHT, and in 20 control subjects. In OHT patients, PWD (39.5 +/- 11 vs. 34 +/- 6 ms, p = 0.04) and QTc interval (438 +/- 20 vs. 410 +/- 10 ms, p < 0.001) were significantly higher in comparison with control subjects. Moreover, OHT subjects with HHcy had higher PWD values than those with normal Hcy plasma levels (44.1 +/- 10.7 vs. 33.9 +/- 8.8 ms, p = 0.007), but no difference was found between this latter OHT group and controls. Accordingly, in OHT patients, plasma Hcy level correlated significantly with PWD (Spearman r = 0.70; p < 0.0001), whereas no correlation was found with QTc, QTcD, and QTc circadian dynamics. Conclusion: HHcy seems associated with an alteration in the electrical atrial conduction, possibly contributing, at least in part, to the increased risk of cardiac arrhythmias in the denervated hearts of OHT patients.