Transmyocardial revascularization (TMR) is an approved surgical procedure to treat patients with ischemic heart disease. With laser transmyocardial revascularization (TMR), 1 mm transmural laser channels are created in ischemic myocardium that cannot be conventionally revascularized due to diffuse CAD.
In prospective randomized trials, stand-alone TMR has demonstrated a significant improvement in chronic stable angina, longer event free survival, and a reduction in cardiac related hospitalizations compared with patients randomized to maximum medical therapy alone.2-4,9,11 Long-term follow-up of TMR as a primary therapy shows an enduring benefit over time, and 5-year follow-up of one prospective randomized trial involving the most severe Canadian cardiovascular class IV patients has shown improved survival in the TMR-treated patients.17,26
Guidelines for Use
Specific guidelines for patient selection include the following criteria:
- Refractory but stable severe angina despite maximum medical management
- Ejection fraction >25%
- Objectively demonstrated diffuse CAD
- Region of myocardium with reversible ischemia not amenable to CABG or PCTA
During clinical studies, investigators had a higher rate of post-operative success when they strictly adhered to these precautions and recommendations during TMR:
- Avoid fluid loading immediately prior to or during TMR procedure.
- Pause 1/ 2 – 2 minutes after creating 2 – 5 channels to reduce possibility of ventricular arrhythmias when done on a beating heart.
- Space laser channels approximately one centimeter apart on the distal 2/3 of the left ventricle.
- Avoid obviously scarred tissue.
- Limit TMR channels to 50 or fewer.
- Change patients from less reversible anti-coagulant therapy to heparin prior to TMR.
- Administer post-operative diuresis.
TMR is reimbursed when performed as a stand-alone procedure in patients with medically refractory angina who are not candidates for further conventional revascularization procedures or in conjunction with CABG in patients who would be incompletely revascularized by CABG alone.