Clinical data and histological features of transmyocardial revascularization with CO2-laser

TMR is a modern therapeutic approach in the treatment of patients with severe chronic ischemic cardiac disease. Clinical data from world-wide over 1800 TMR-treated patients shows that TMR can improve cardiac status in cases without preoperative congestive heart failure. The mechanisms underlying beneficial TMR-effects are not well understood.

The 61 patients of the Hamburg University TMR-trial were treated with a CO2-laser. Clinically, both a 6 and a 12 months follow-up were performed. Pathologically, hearts from four patients who died 3 (2 persons), 16 and 150 days after TMR, respectively, were examined by trichrom-and immunostaining (anti-collagen types I and III).

In a 6 months follow-up clinical data indicates that TMR was able to improve clinical status in 50 of 61 laser-treated patients (82%), whereas 5 (8.2%) did not show any benefit evaluated by CCS grading and six (9.8%) died. CCS grade reduction was found in 22 patients with a 12 months follow-up (28 patients still in evaluation). Days 30, mortality amounted to 6.5%; late mortality (over 30 days) was 3.3%. Histopathological investigations revealed tissue remodeling comparable with different stages of wound healing. The cicatricial tissue in the original laser-created channels displayed a stronger immunostaining for collagen type III than for type I.

Clinically, TMR improves cardiac function in some patients with severe ischemic cardiac disease, but pathophysiological data as well as morphological features from human myocardium could not explain this phenomenon. Therefore, TMR treatment should be used only as 'the last chance' in patients with severe angina pectoris.