Summary

It has long been assumed that the outcomes from heart bypass surgery are better in so-called high volume hospitals, where such complex procedures are almost routine. But a new survey of patients in United States hospitals shows that death rates have declined from 1988 to 2003, despite the fact that the proportion of higher volume hospitals involved in heart surgery has gone down. This suggests that improvement in clinical practice may have disseminated throughout all hospitals.

Introduction

There are two main ways of dealing with coronary artery disease - coronary artery bypass grafting (CABG) and percutaneous transluminal coronary intervention (PTCI). Both improve the blood flow to the heart which is otherwise impaired because the coronary arteries are blocked. Bypass surgery is somewhat more invasive, as it involves removing a blood vessel from elsewhere in the body and attaching it to the heart, bypassing the blocked vessel. In PTCI, the blocked artery is opened up and kept open by the insertion of a wire device called a stent.

Previous research has shown that hospitals which do a lot of CABG procedures have lower mortality rates. This has led some experts to suggest that bypass surgery should be confined to hospitals that specialize in it, while those with little experience should not carry it out, in the interests of patient safety. This is an important health policy issue, so Rocco Ricciardi, formerly of the University of Minnesota (and now at Tufts University) and colleagues carried out a survey of heart patients over the period 1988 and 2003 to see how they fared after bypass surgery and what impact the widespread introduction of PTCI has had.

What was done

The researchers studied data on over 108 million hospital discharges across the United States. They recorded what heart procedures had been carried out, what type of hospital was attended, and what the outcome was, including mortality.

What was found

The number of patients having CABG was 1,082,218 and the number having PTCI was 1,589,942. Meanwhile, 186,483 underwent heart valve replacement and repair. Over time there was a distinct trend. The rate of CABG went up from 7.2 cases per 1,000 discharges in 1988 to 12.2 percent in 1997. But then it went down to 9.1 cases per 1,000 in 2003. Over this time, the rate of PTCI actually tripled - probably as surgeons got more experienced with it.

They also found that CABG became more widespread. In 1997, the proportion of high volume hospitals carrying out CABG was 32.5 percent while in 2003 it was 15.5 percent. With more inexperienced hospitals carrying out the procedure, you might think death rates went up. In fact, the in-hospital death rate decreased from 5.4 percent in 1988 to 3.3 percent in 2003. The hospitals performing the fewest CABG actually had the largest decreases in death rates.

What this study means

This new research is good news for heart patients. First, you are more likely than ever before to survive and benefit from heart bypass surgery. It looks as if better clinical practice is disseminating throughout the whole hospital system and CABG is no longer seen as a specialist procedure. And, second, the less invasive option of PTCI is now becoming more widely available. The research team concludes that hospital volume should not longer be considered a mark of quality when it comes to selecting a facility for heart surgery.