Patients with idiopathic dilated cardiomyopathy (IDC) may benefit from future treatment to boost vascular endothelial growth factor (VEGF)₁₂₁ and thereby development of capillaries in the myocardium. A molecular study has shown for the first time that, of all three isomers of VEGF, VEGF₁₂₁ is downregulated the most in IDC.

VEGF₁₂₁ mRNA was expressed less than VEGF₁₈₉ and VEGF₁₆₅ isomers in ventricular endomyocardium from patients, whereas the glyceraldehyde-3-phosphate dehydrogenase (GAPDH) housekeeping gene was expressed equally in patients and controls. The ratio of cDNA for VEGF to cDNA for GAPDH was significantly less in samples from patients than controls and least for VEGF₁₂₁ (40% v VEGF₁₆₅ 82% and VEGF₁₈₉ 83%). The mean protein ratio of VEGF to GAPDH for patients was significantly below that of the controls. The results were unaffected by the severity of disease.

The study was based on 28 patients with IDC and 10 brain dead controls without heart disease, all of whom had endomyocardial biopsy of the right ventricle. Total RNA was isolated from the tissue, then first strand cDNA subjected to reverse transcriptase (RT) PCR. cDNA for each VEGF isomer and the GADPH housekeeping gene was amplified by semiquanitative PCR. The method was validated by correlating the changes in ratios for each isomer with the amount of input template.

Recent evidence suggests that VEGF₁₆₅ and VEGF₁₈₉ isomers are downregulated in IDC, but previous work seems to have overlooked VEGF₁₂₁ despite its strong stimulation of capillary growth.