Cytomegalovirus replication is not a cause of instability in unstable angina

Unstable angina is most frequently caused by coronary thrombosis, with or without plaque fissure, but the mechanisms underlying these events are still speculative. Since cytomegalovirus (CMV) antigens and DNA encoding CMV major immediate-early (MIE) gene have been detected in atherosclerotic arterial walls, the active replication of CMV may be responsible for plaque instability. Therefore the expression of CMV MIE gene mRNA, an early marker of viral replication, was assessed in coronary atherectomy specimens from patients with stable or unstable angina.

Twenty patients with unstable angina (12 men and 8 women; mean age, 62 years; range, 44 to 89 years) and 20 patients with stable angina (16 men and 4 women; mean age, 62 years; range, 43 to 81 years) who underwent successful directional coronary atherectomy were enrolled in the study. The efficiency of mRNA extraction, transcription, and amplification from each coronary atherectomy specimen was assessed by performance of reverse transcription and thermal cycling amplification of a 548-bp human beta-actin cDNA segment. After Southern blotting and hybridization with a specific probe, all specimens but one showed a positive hybridization signal. The negative sample was excluded from the study. Reverse transcription and thermal cycling amplification of a 145-bp CMV cDNA segment of the MIE gene were then carried out. After Southern blotting and hybridization with a specific probe, none of the specimens showed a positive hybridization signal. Plasmid pACYC 184 containing the Xba I-inserted MIE gene cDNA was used as a positive control: as few as 10 molecules of the plasmid per reaction were detectable after amplification.

Our results do not support the hypothesis that, in patients with unstable angina, replication of CMV in coronary atherosclerotic plaques is a major cause of plaque instability. These findings suggest that the research for the causes of unstable angina should be directed toward processes other than CMV replication.