The World Health Organisation has predicted an increase in the worldwide prevalence of diabetes of epidemic proportions. Eighty percent of people with diabetes will die from cardiovascular complications -- stroke and/or coronary heart disease (CHD).
CHD causes narrowing of sections of one or more arteries. Diabetics are four to six times more likely to die of coronary artery disease (CAD) than non-diabetics . Treatment aims to restore restricted blood flow to the heart and avoid a heart attack.
Traditionally, the best therapeutic option for diabetics has been coronary artery bypass graft (CABG) surgery, particularly when more than one vessel is involved. Now, growing clinical evidence suggests that angioplasty using the Cypher Sirolimus-eluting Coronary Stent may offer diabetic patients the choice of a new, less invasive treatment with similar outcomes to CABG.
During angioplasty a small wire mesh tube (stent) is placed in the coronary artery via a wire inserted into the groin to open a narrowed section of a coronary artery. Diabetics tend to have smaller diameter arteries which places them at a higher risk of recurrent narrowing -- restenosis -- following angioplasty using traditional bare metal stents (BMS). In fact, as many as 30 percent of patients may have renarrowing due to an ingrowth of tissue that limits or obstructs the blood flow.
The Cypher Stent, developed by Cordis Corporation, a Johnson & Johnson company, elutes an anti-proliferative and anti-inflammatory drug called sirolimus that protects the arterial lining, allowing it to heal naturally after angioplasty. Several independent, randomized clinical trials have demonstrated strong results to support the use of this particular stent in diabetic patients, which are among the most complex patient groups with CHD.
Importantly, these trials were either specifically designed to assess clinical results of drug-eluting stents in diabetic patients alone or had pre-specified in the protocol that data would be analysed in diabetic patients, and were not conducted by the manufacturer of the stents.
The independent, multicentre, prospective randomised DIABETES trial compared the Cypher Stent with traditional bare metal stents in 160 diabetic patients. High-risk patients with among the smallest arteries treated in any clinical trial -- average vessel diameter of 2.34mm -- were included.
In this study, late lumen loss was measured after nine months as a sensitive marker for efficient healing of the arterial lining over the stent (the greater the loss, the narrower the artery becomes). In patients who had a follow-up angiogram at nine months, there was a significant reduction in late lumen loss (88 per cent) with the Cypher stent compared to the bare metal stent.
Dr. Manel Sabate of Hospital Clinico San Carlos in Madrid, principal investigator of the DIABETES trial, remarks: "Undoubtedly, the Cypher Stent patients in the study had markedly better clinical outcomes. Only 7.7 per cent had reblockage (restenosis) compared to 33 percent of patients receiving the bare metal stent. This is a challenging patient population to treat and these results are very encouraging across the board."
"With significant reductions in restenosis and in major adverse cardiac events (MACE: death, MI and additional revascularization procedure), the Cypher Stent confers a considerable benefit that justifies clinicians using drug-eluting stents rather than conventional stents in diabetic patients," he added.
Another independent study, ISAR-DIABETES, compared the Cypher Stent with Taxus -- a stent which delivers a different type of drug -- paclitaxel. Assessment of 250 diabetic patients in this trial showed that Cypher Stents are more effective than Taxus in preventing restenosis in diabetic patients, with a 58 per cent relative reduction in restenosis.
Dr. Adnan Kastrati of the Technische Universitat in Munich, Germany, says: "We set out to demonstrate in ISAR-DIABETES that Taxus was not inferior to the Cypher Stent. However, the Cypher Stent outperformed Taxus in this complex group of patients, showing consistently better results in all major parameters."
Two further trials have shown promising outcomes for diabetic patients. The independent SIRTAX trial, conducted in Switzerland, enrolled a wide variety of patients, representing a real-life situation, and compared Cypher Stent with Taxus in 1012 patients -- 201 of whom were diabetic.
SIRTAX patients receiving Taxus were 74 per cent more likely to have a serious cardiac event or undergo subsequent surgery than those treated with the Cypher Stent.. Furthermore, in follow up angiography after nine months, fewer Cypher patients suffered restenosis (3.2 per cent) than those with Taxus stents (7.6 per cent).
Dr. Angela Wilson, Director of Research at Diabetes UK said, "Heart disease is one of the major complications for people with diabetes. The risk of developing heart disease and other complications can be reduced through effective control of blood glucose levels, a healthy diet and regular physical activity. However, in patients where heart disease has developed, any procedure that offers a less invasive and safer approach to treatment is to be welcomed. We await the results of further trials with interest."
The wealth of data on the Cypher Stent reinforces its suitability for treating diabetic patients and may offer many an alternative to coronary bypass grafting. Additional data on the Cypher Stent will be presented at the EuroPCR Congress in Paris, France from May 24 - 27, 2005.