Diagnosis by icy hand

Diabetics respond quite differently to the cold pressor test.
Arterial constrictions point to heart trouble to come

By Raymond Reese

An inexpensive, easy-to-do test has been shown to be a good predictor of cardiovascular difficulties in people with type II diabetes, even in those with no overt cardiovascular symptoms.

"Our results confirm that [the] cold pressor test (which assesses heart condition by dipping one hand of the patient in ice-cold water for several minutes) is a reliable method for testing endothelial function and may reveal endothelial dysfunction," said the researchers from the University Hospital Jean Verdier, Paris, in the January issue of Diabetes Care. The research revealed that people with diabetes react very differently from normal subjects to this standard test.

The study looked at the efficacy and reliability of the test in determining endothelial health. Because the endothelium is a key player in the vascular system, the researchers reasoned that any abnormality in this tissue could be a harbinger of cardiovascular problems. Given that the epicardial coronary artery is inhibited in diabetic patients, a malfunctioning endothelium might precede atherosclerosis.

In healthy people, the test causes the arteries of the heart to dilate and increases blood pressure, which returns to normal within minutes after removing the hand. But in people with diabetes, the test triggers the arteries to constrict instead, and blood pressure increases after the hand is removed from the ice water.

The test holds the potential to be used as "an easy means to evaluate the efficiency of therapy in high-risk patients," said Dr Alain Nitenberg, lead author of the study.

The study looked at 72 patients who, aside from type II diabetes, had no other risk factors for heart trouble. Fifty-six control participants were also included. In 51 of the control subjects, the average increase in the diameter of the coronary artery after the cold pressor test was 17.2%, with no change observed in five people (8.9%). But none of the patients with diabetes displayed an increased arterial diameter. Instead 53 of the 72 diabetic patients displayed an average 14.4% constriction. No change was evident in 19 of those with diabetes (26.4%).

In the intervening follow-up period, which averaged 45 months, a single cardiovascular event occurred in the control group. In contrast, 26 events occurred in 18 of those with diabetes. Twenty-three of the 26 heart events occurred in 16 of the 53 diabetics who had obstructed coronary arteries. The remaining three events occurred in two of the 19 diabetes patients who had no change in the diameter of their coronary arteries.

While these results for a small-scale study are impressive, confirmation awaits a larger trial.