If drugs don't work to relieve pain from narrowed arteries, doctors may recommend procedures to restore blood flow. For diabetes patients undergoing one of these procedures, outcomes seem to have improved.

Diabetes can boost the risk of many heart problems, including narrowed arteries that slow blood flow. Percutaneous coronary intervention (PCI) is a procedure to restore blood flow in patients with heart disease.

According to a recent study, patients undergoing PCI today may have better outcomes than they did over the past three decades, whether or not they had diabetes. In addition, the risk of heart attack and stroke associated with diabetes may be smaller in recent years than in past decades.

Mandeep Singh, MD, MPH, of Mayo Clinic, and colleagues set out to describe the in-hospital and long-term outcomes of diabetes patients who underwent PCI.

Patients who underwent PCIs were grouped by era into four categories:

• Group 1 underwent PCI between 1979 – 1989 (408 with diabetes and 2,684 without diabetes)
• Group 2 underwent PCI between 1990 – 1996 (1,170 with diabetes and 4,664 without diabetes)
• Group 3 underwent PCI between 1997 – 2003 (2,032 with diabetes and 6,584 without diabetes)
• Group 4 underwent PCI between 2004 – 2008 (1,412 with diabetes and 4,141 without diabetes)

• In-hospital deaths
• Major heart-related events, such as heart attack
• Death rates over the long-term
• Composites of mortality with revascularization (PCI is a revascularization procedure)
• Ischemic events, or events involving restricted blood flow

Results showed that patients with diabetes had fewer negative outcomes in the hospital over time. This decline in negative outcomes was similar to that in patients without diabetes.

Throughout the course of the studied decades, there was no significant change in the link between diabetes and in-hospital deaths or heart-related events.

Over time, more patients started using medications that prevent narrowed arteries and other cardiovascular problems, which may partly account for the improved outcomes.

The effect of diabetes on long-term survival without revascularization did not change much between group 2 and group 4. However, the effect of diabetes on survival free of heart attack and stroke was significantly lower in group 4 than in group 2.

In other words, diabetes patients today may have a lower risk of heart attack and stroke after PCI than they did a couple decades ago. Compared to patients without diabetes, diabetes patients in group 2 had a hazard ratio of 1.71 for heart attack and stroke while diabetes patients in group 4 had a hazard ratio of 1.39.

A hazard ratio explains how much an event happens in one group versus another. A hazard ratio of more than 1.0 means the event happens more in the first group than in the second. In this case, the comparison was between those with diabetes and those without diabetes during different time periods.

According to the study's authors, "Over 30 years, the improving outcomes in patients with diabetes who underwent PCIs have been similar to improvements in patients without diabetes. However, the risk-adjusted association of diabetes with long-term death, heart attack, and stroke has decreased in the current era (group 4) compared with the bailout stent era (group 2)."

Mayo Clinic Proceedings, Jan 2013

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