Heart Boost Can Improve Outcome for Sickest Heart Attack Patients
NEW ORLEANS, LA -- Based on the results of a small clinical trial, Duke University Medical Center researchers have found that artificially intensifying the heart's pumping action can improve the outcome of heart attack patients who have gone into shock, a condition that is responsible for 60 percent of heart attack deaths in hospital.
This technique, called aortic counterpulsation, is achieved by means an intra-aortic balloon pump (IABP), and when used in conjunction with clot-busting drugs, showed modest but significant benefits for the sickest heart attack patients, according to the Duke researchers.
"IABP technology has been around for more than 20 years, and it is definitely an underutilized procedure," said Dr. Magnus Ohman, cardiologist at the Duke Clinical Research Institute (DCRI). "This procedure can help many of these extremely ill patients without additional risks."
Ohman prepared the results of his study for presentation Tuesday at the 73rd annual scientific sessions of the American Heart Association. The study was funded by Datascope Corp., Montvale, NJ.
Shock is a potentially life-threatening condition that occurs when blood pressure becomes too low to sustain normal bodily functions. While shock has many different causes, in heart attack patients it occurs when the heart is starved of its supply of oxygen-rich blood and is therefore unable to pump enough blood throughout the body.
Typically, when acute heart attack patients come to an emergency room, initial treatment is with so-called clot-busting drugs - also known as thrombolytics - which dissolve blood clots in coronary arteries and restore normal blood flow to the heart muscle.
IABP is simply a long balloon that is threaded from an insertion point in the groin through the heart and into the aorta. The balloon is then inflated and deflated in conjunction with the contraction and relaxation rhythms of the heart, intensifying its pumping action.
The researchers wanted to know if adding IABP to the standard thrombolytic therapy would improve outcomes for this difficult-to-treat patient population.
Thus was born the Thrombolytic And Counterpulsation To Improve Cardiogenic shock Survival (TACTICS) trial, which prospectively enrolled 57 patients from 1996-1999 at 17 hospitals in the United States, Australia and Europe. Patients were randomized to either thrombolytic therapy alone or thrombolytic therapy followed by IABP.
"The six-month mortality rate for patients with the combined therapy was 39 percent, compared to 43 percent for thrombolytic therapy alone," Ohman said. "While the difference appears small, the patients receiving the combined therapy tended to be much sicker, and those with the most to gain.
"We routinely use IABP at Duke for these types of very ill patients, and recommend that community hospitals do the same," Ohman said.
The combined therapy patients tended to be older (68 vs. 67), have more diabetes (30 percent vs. 11 percent), have had previous heart attacks (40 percent vs. 19 percent), and have more severe heart disease (60 percent vs. 48 percent).
The original design of the trial called for an assessment of the therapies after the first 100 patients; however, the trial was halted after 57 patients had been enrolled and treated.
"Since these are the very sickest of heart attack patients, it was very difficult to enroll enough patients," Ohman continued. "But based on the safety data, and the positive results from the patients who did receive IABP, we believe that this is an effective approach for acute heart patients who go into shock."
Patients remained on the IABP for more than three days on average.
Joining Ohman in the study were Dr. John Nannas, Alexandra Hospital, Athens, Greece; Dr. Robert J. Stomel, Botsford General Hospital, Farmington Hill, MI; Dr. Massoud A. Leesar, University of Louisville Hospital, Louisville, KY.; Dr. Dennis Nielsen, Central Hospital in Rogaland, Bergen, Norway; Dr. Michael P. Hudson, DCRI; Beth Fraulo, DCRI; Linda K. Shaw, DCRI; Kerry L. Lee, Duke; Dr. Daniel O'Dea, Hudson Valley Heart Center, Poughkeepsie, NY; Dr. Felix J. Rogers, Riverside Osteopathic Hospital, Trenton, MI; and Dr. Daniel Harber, Garden City Hospital, Garden City, MI.