Inflammatory cardiac conditions, such as myocarditis and pericarditis, have been associated with live-virus vaccinations. Years ago, a fraction of children receiving other types of live- virus vaccinations developed such conditions. Cardiac inflammation also can occur with viral infection. The new cases are noteworthy, panelists said, because all occurred within four to 17 days of smallpox inoculation.

Federal health officials insist the deaths, and possibly the other cases, may be unrelated to the vaccine, which has never been associated with heart attacks. In the two deaths - one in Maryland and the other in Florida - both women had histories of underlying heart conditions. Both women were in their 50s. Medical investigators are trying to determine if vaccinia, the virus in the vaccine, might have exacerbated underlying cardiac disorders.