Background: The endothelins are peptides with vasoconstricting and growth-promoting properties. Endothelin-1 (ET-1) is known for its direct positive inotropic and chronotropic effects on isolated heart, and for growth effects. The aim of this pilot study was to investigate the frequency distribution of a common polymorphism of the endothelin (ET-1) gene and its possible relation to the hemodynamic consequences of malignant ventricular arrhythmia in patients with structural heart disease.
Material/methods: We studied 26 consecutive patients with malignant ventricular arrhythmia and implantable cardioverter defibrillators (ICD), mean age 62.7 +/- 12.2 years, mean LVEF 0.37 +/- 11. The Taq polymorphism of ET-1 was detected using our original PCR method. The PCR product with a length of 358 bp in its non-mutated form contains a target sequence for the TaqI restrictive enzyme, while the mutated product loses this cleavage site.
Results: Out of the 26 patients, 9 (34%) had recurrent palpitations and 8 (30.8%) had syncopes during their malignant arrhythmic episodes. 19 of the patients were receiving amiodarone after ICD implantation, 7 were not. 15 patients had the (++) and 11 had the (+ -) ET-1 genotype; none had the (- -) genotype. The risk of syncopes was associated with the (++) genotype (p=0.01). Patients with amiodarone had a significantly higher frequency of the (++) genotype (p=0.011).
Conclusions: All our results suggested that the presence of the (++)ET-1 genotype in patients with structural heart disease, severe left ventricular dysfunction, and malignant ventricular arrhythmia put these patients at a higher risk of hemodynamic collapse during arrhythmic episodes.