Summary

Abdominal aortic aneurysm is a condition where the aorta, which is the main artery that leaves the heart
and travels down towards the legs, starts to bulge and expand at a section just below the diaphragm, level
with the navel. If the bulge continues to expand, it can rupture and this can lead to an emergency operation
and often results in death.

Studies have shown that if the aneurysm increases to a certain size the risk of rupture, which is generally low,
starts to increase and a planned operation can be performed to repair the bulging section of aorta. There are
two ways of repairing this section and doctors are unsure which method is better. The open repair method is
the tried and trusted method as it has been around for about 50 years and is known to be durable and last for
the rest of most patients lives. However, it is quite a serious operation which generally involves a longer stay in
hospital and a slightly higher chance of dying within 30 days of the operation when compared to a new method
called EndoVascular Aneurysm Repair (EVAR). This new method is less of a strain on the patients body which
results in a shorter recovery time and a better chance of surviving within the first 30-days after the procedure.
The downside of this new procedure is that it is more common for there to be problems following the operation that may require further small procedures to correct them. In some cases, patients are not considered fit enough for the open repair operation as it may be too much of a strain on their body and always requires a general anaesthetic. For these patients, doctors are not sure whether repairing the aneurysm using an EVAR would be best for these patients or whether they would be better treated with regular scans of the aneurysm and given medication to try and improve their fitness. Thus, two experimental clinical trials have been set up to test the new endovascular method in two clinical situations, 1) when the patient is considered fit for an open repair and 2) when the patient is considered unfit for an open repair.

EVAR Trial 1 is for patients considered fit for an open repair and once the patient is happy to participate in the trial a computer randomly allocates them to receive either an open repair or the new EVAR procedure and these two groups are then compared to see how they get on.

EVAR Trial 2 is for patients considered unfit for an open repair and once they have indicated that they are happy to participate in the trial a computer randomly allocates them to receive either an EVAR with standard medical treatment or medical treatment alone and these two groups are then compared to see how they get on.

Early and mid-term results have been published for EVAR Trial 1 and these have shown that the EVAR group of patients do very well early on after their operation compared to the open repair group, however, they experience a greater number of problems later on after the operation, many of which require further small procedures to correct them but these operations tend to be quite minor and do not appear to have an effect on survival. In fact, there is no difference between the groups in terms of overall survival or quality of life and the doctor and patient need to discuss the pros and cons of each treatment before deciding which might be better for the patient.

Mid-term results have been published in EVAR Trial 2 and these have shown that patients considered unfit for open repair do not do very well just after they have had an EVAR and later on they tend to die from causes other than their aneurysm. In this situation it is better that the doctor concentrates on improving the patient fitness and monitoring the aneurysm with scans. There was no improvement in survival or quality of life by performing an EVAR in this group of patients and for those who did receive an EVAR, they needed to be monitored regularly and tended to have problems with the EVAR that required further operations.

It is now important that we continue to monitor all the patients in these two trials for another 5 years to see if there are any changes in the conclusions that have been drawn from the early and mid-term results published in June 2005. Long-term results are due to be released in 2010.