Red Light Therapy for Coronary Artery Disease: Scientific Evidence

This 2003 observational study described 2 pilot procedures using laser light inside the heart artery during treatment to open a narrowed vessel. A diode laser at 808 nm was fed through a special diffuser to light the treated stretch evenly, with follow-up at 3 and 6 months and an X-ray scan of the arteries at 6 months. Neither patient showed the artery narrowing again, and both appeared to tolerate the procedure well with no side effects. They noted the group was far too small for any statistical analysis.

81.8% of patients showed a good response in a 2002 observational study of infrared laser therapy for CAD alongside type 2 diabetes. The light fell between 780 and 1400 nm and was pulsed at 300 Hz, combined with mineral-water bath treatment and patient education at a health resort, and set against standard rehabilitation there. Upper blood pressure fell by an average of 18 mmHg and lower blood pressure by 10 mmHg, with fewer chest pain attacks and lower doses of anti-angina drugs. The authors concluded that the combined program improved clotting, sugar and fat handling, and that the effect on blood flow to the heart held for 24 weeks.

Whether infrared laser light could match a standard heart drug was tested in a 2001 clinical trial of 115 people with CAD. The light fell in the near-infrared band between 780 and 1400 nm and was compared against carvedilol, a beta-blocker. The trial found a similar positive effect from both on the heart's squeezing strength and on its filling function. That similarity was taken as grounds for using light to limit structural change in the heart muscle and head off heart failure.

22 patients with chest pain took part in a 1998 observational study of red light delivered inside the artery straight after a small mesh tube was placed to hold it open. A diode laser at 650 nm was passed through a balloon catheter carrying the light fibre, in a single treatment during the procedure. 4 of the 22 later showed the artery narrowing again on X-ray imaging, and according to the report, 91% went without a serious heart event across roughly 11 months. The procedure went to plan in every patient, with no complications during it or in hospital afterward.

Comparing 10 patients who had CAD against 5 healthy volunteers, a 1998 observational study examined a type of white blood cell before and after laser treatment. Red light at 632.8 nm from a helium-neon laser was delivered into the blood. Before treatment, the patients' cells showed swelling, extra granules, a thinner internal support layer, and an altered shape. After treatment the study found those measures had moved closer to the values seen in the healthy volunteers.

When 101 patients were followed for a year after treatment to open a heart artery, a 2010 randomized controlled trial compared light delivered inside the vessel against no light. 52 received 808 nm light at 100 mW/cm² and 9 J/cm², and 49 formed the control group, with the 2 groups matched on the type and severity of the narrowing. Re-narrowing was 15.0% in the laser group against 32.4% in the control group at 6 months, a gap that did not reach significance. The treated arteries were significantly wider at that point, averaging 2.18 mm across their narrowest stretch against 1.76 mm, and had lost less width since the procedure. The authors concluded the treatment seemed effective and safe, resting that judgment on the artery measurements rather than the re-narrowing rate.

Among 39 people with advanced disease in several heart arteries, a 2007 observational study tested laser light applied to the skin of the chest. The group averaged 64.8 years, 64% were men, 69% had already had a heart attack, and their hearts pumped out 46% of their blood with each beat. Red light at 632.8 nm from helium-neon lasers was given for 15 minutes, 6 days a week for a month, in 2 blocks separated by a month off. Distance walked in 6 minutes rose from an average of 341 to 405 and then 450 metres, while chest pain during a treadmill test appeared in 65% of patients at the start, 44% after the first block and 38% after the second. No side effects were noted, and the heart's pumping strength did not change.

9 of 61 patients who returned for imaging showed the artery narrowing again in a 2001 clinical trial of red light delivered inside the vessel during stenting for CAD. 68 consecutive patients were treated, receiving 650 nm light at 10 mW for 60 seconds, delivering 1.8 J and 0.95 J/cm² at the treated stretch of artery. Re-narrowing appeared to depend heavily on vessel size, running at 0% in arteries wider than 3 mm, 14.2% between 2.5 and 3 mm, and 41.6% below 2.5 mm. No complications occurred during the procedure or in hospital afterward.

Published in 1992, this observational study looked at whether laser light delivered into a vein could reduce chemical damage to the fats in cells in people with CAD. Red light at 632.8 nm from a helium-neon laser was given to patients with stable chest pain brought on by exertion. Markers of that chemical damage appeared to fall, most clearly in patients with milder disease and normal circulation. The researchers recommended using those patient features to judge who is likely to benefit.