Revascularization with CO2 Laser in Patients With Refractory Angina Pectoris: Clinical Results From the Norwegian Randomized Trial - TMR

Description:

TMR was an open, prospective, single-center study of the clinical effects of transmyocardial revascularization (TMR) with CO2-laser in patients with refractory angina pectoris.

Hypothesis:

TMR with CO2-laser will be associated with improved exercise performance and myocardial oxygen consumption.

Study Design

Study Design:

Patients Screened: 226
Patients Enrolled: 100
Mean Follow Up: 12 months
Mean Patient Age: 41-75
Female: 7
Mean Ejection Fraction: Average 49%

Patient Populations:

Patients with angina pectoris New York Heart Association functional class III or IV despite optimal medical treatment who were not candidates for percutaneous coronary intervention or coronary artery bypass surgery because of peripheral obstructions in the coronary arteries

Exclusions:

Age >75, ejection fraction <30%, nondemonstrated reversible ischemia, overt heart failure, inability to undergo study tests, or thoracic surgery

Primary Endpoints:

Time to 1 mm ST-segment depression during exercise and MVO2 during exercise

Secondary Endpoints:

Time to chest pain, total exercise time, and accumulated work

Drug/Procedures Used:

Patients were randomized into one of two groups: a medical treatment (MT) arm or a TMR arm. The patients were followed for 12 months. Patients randomized to the TMR arm underwent surgery at the Feiring Heart Clinic in Norway by the same surgeon. Through a left anterior thoracotomy, laser treatment was performed on the beating heart. At 3 and 12 months, all patients underwent an exercise evaluation on a cycle ergometer.

Concomitant Medications:

For the MT and TMR arms at baseline, 3, and 12 months: beta-blockers (92/94/93% vs. 98/96/95%), calcium blockers (66/65/63% vs. 62/52/52%), long-acting nitrates (88/94/93% vs. 90/87/90%), aspirin (80/79/76% vs. 82/74/69%), warfarin (20/21/22% vs. 26/26/26%), angiotensin-converting enzyme inhibitors (30/31/28% vs. 24/33/36%), statins (86/83/83% vs. 82/83/79%), and diuretics (24/23/24% vs. 26/30/40%). There were no statistically significant differences between groups.

Principal Findings:

A total of 100 patients were randomized. The MT and TMR groups were well matched at baseline in terms of age (mean 64 ± 8 vs. 61 ± 8), gender (6% vs. 11%), extent of coronary disease (47% vs. 43% with three-vessel disease), prior myocardial infarction, previous revascularizations, and ejection fraction (mean 49% for all patients). The only significant baseline difference was a higher double product at maximal exercise in the TMR group (27,600 vs. 20,600, p<0.05).

Regarding the primary endpoints, maximal oxygen consumption (MVO2) and time to 1 mm ST depression did not change significantly in either arm over the course of the study. Regarding the secondary endpoints, time to chest pain improved significantly at 12 months in the TMR arm, but not in the MT arm.

Total exercise time and accumulated work did not change significantly in either arm. Mean functional class for the TMR group improved during the study from 3.3 at baseline, to 2.3 at three months, and 2.0 at 12 months (p<0.01 for all differences).

There were no significant changes in functional class for the MT group. There were no significant differences in hospitalizations over the course of the study. There were no significant differences in deaths between the arms at 3 and 12 months.

Regarding safety of the TMR procedure, four patients suffered perioperative myocardial infarction and two patients died at 4 and 14 days postoperatively.

Interpretation:

Among patients with refractory angina pectoris, TMR was not associated with significant improvement in exercise capacity. However, the procedure was associated with significant reduction in symptoms.

References:

Aaberge L, Nordstrand K, Dragsund M, et al. Transmyocardial revascularization with CO2 laser in patients with refractory angina pectoris. Clinical results from the Norwegian randomized trial. J Am Coll Cardiol 2000;35:1170-7.

Clinical Topics: Cardiac Surgery, Invasive Cardiovascular Angiography and Intervention, Aortic Surgery

Keywords: Thoracotomy, Myocardial Infarction, Oxygen Consumption, Coronary Artery Bypass, Percutaneous Coronary Intervention


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