The Stent or Surgery (SoS) Trial

This study compared two different methods of restoring blood flow to the heart when there has been a narrowing or blockage in the blood vessels that supply the heart. Currently there are two different ways of restoring blood flow. One is heart surgery where a surgeon operates directly on the heart, through an incision in the breast bone (sternum) and takes segments of the patient’s (non-essential) veins or arteries and then uses these to bypass blocked or narrowed segments in the coronary arteries. This way additional blood can be “piped” into the heart muscle wall. The second method is coronary angioplasty with stent implantation. Coronary angioplasty is a non-surgical method performed under a local anaesthetic. During angioplasty a special balloon is advanced to the site of a coronary narrowing, then inflated to make it expand and this action removes the narrowing. This is a more simple and less invasive than surgery but its value has been limited by a tendency for narrowings to reoccur(restenosis) in the six months following the treatment. When this happens a repeat procedure is often performed. To reduce the incidence of restenosis coronary stents are implanted. These are tubular metal scaffold devices that are placed inside a coronary artery at the site of a previous narrowing to help keep the artery open. These devices are usually delivered on an angioplasty balloon and expanded into place.

Both treatments are equally effective at preventing death and subsequent myocardial infarction and most doctors are happy to recommend either option. Angioplasty offers a more simple initial procedure but with a chance of needing a repeat performance. Bypass surgery represents a more significant initial undertaking with a longer recovery and convalescent period but in most cases, provides good relief of symptoms. Patient preference plays an important part in the decision process.

Bypass grafting is currently the therapy most frequently performed world-wide. Angioplasty has a number of important advantages but the need for repeat procedures currently limits its appeal.

Since these trials were performed there have been important advances in angioplasty techniques. Prominent amongst these has been the development and use of Coronary Stents which has been shown (in clinical trials) to reduce the need for repeat procedures after an initial angioplasty. Consequently stent implantation is now in routine use world wide.

If angioplasty is performed with coronary stent implantation then this may reduce the need for repeat procedures and address the principal factor currently limiting the value of this approach. If the results were found to be as good as with bypass grafting then patients could benefit from a shorter hospital stay, a less traumatic operation and a shorter recovery period. We therefore wish to compare the outcomes in patients treated with a) bypass grafting or b) angioplasty with coronary stent implantation.