Injection of a beta blocker distal to the target lesion before percutaneous coronary intervention is performed significantly reduces the incidence of small infarctions during the procedure, according to an article in the June 17th issue of Circulation.

The American researchers randomized 150 patients to pre-procedural injection of propranolol or to an identically appearing placebo. In the double-blind study, drug was released from an intravascular catheter whose tip was distal to the region of intervention.

No patients involved in the study died. At 30 days, 40 percent of the placebo group had myocardial infarctions that required another revascularization procedure compared with 18 percent of the propranolol group.

Serial testing for creatine kinase-MB and troponin T showed that members of the placebo group had significantly more small infarctions within 24 hours and then 30 days of the procedures than propranolol patients (36 and 17 percent of patients and 33 and 13 percent, respectively, for the enzymes).

Previous work with animal models had shown the research group that a high intravenous dose of beta blocker significantly reduced myocardial injury associated with the procedure. An earlier study of patients had shown that injecting propranolol into the heart before percutaneous coronary intervention increased the time before the ischemic effects were seen due to obstructed inflow of arterial blood.

Senior author Barry F. Uretsky, MD, said, "We've taken a cheap, time-tested drug with a known record of safety and proven efficacy in other settings and, in our basic innovation, increased the size of the dose we can give patients by injecting it directly into the artery supplying the myocardium at risk for a heart attack." Previously, he said, cardiologists had found that they couldn't provide heart patients large enough doses of propranolol orally or intravenously to confer a protective benefit during revascularization procedures without causing serious side effects in some patients.

"Further research is required to show that preventing myocardial infarctions [after percutaneous coronary intervention] actually decreases numbers of subsequent deaths," Uretsky noted. "But if propranolol's ability to decrease damage to the myocardium actually increases survival rates, data from previous studies involving nearly 9,000 patients undergoing percutaneous coronary intervention, together with data from our study, suggest that for every 1,000 patients undergoing this procedure, an additional 20 patients will be alive in 6 months if propranolol is injected into the heart prior to the procedure."

If that survival data proves accurate in larger studies and if the beta blocker becomes routinely used on the 80 percent of patients who should qualify for it, Uretsky said, "Each year about 10,000 patients in the United States alone who would otherwise die will still be alive after 6 months." The 150 patients in the current study continue to be tracked, he said, to see how long the survival benefit continues.

The authors stressed that intracoronary "beta blocker in the dose used in this study is extremely safe and without any adverse effects" even in patients with moderate heart disease and chronic lung disease.