LOS ANGELES — Specific findings on adenosine stress myocardial perfusion imaging can be combined with other risk factors to offer precise guidance about whether a patient would obtain a significant survival advantage with early revascularization, Rory Hachamovitch, M.D., said at a meeting sponsored by the American College of Cardiology.
Dr. Hachamovitch outlined the simplest of three new prognostic adenosine scores he validated in a group of 5,873 consecutive patients who underwent adenosine stress, dual-isotope single-photon emission computed tomography (SPECT) scanning, and were followed for a mean 2.2 years.
The simple score uses a patient's age, percent of ischemic myocardium, percent of fixed myocardium, presence or absence of dyspnea, resting ECG results, resting and peak stress heart rates, and scan results following early revascularization to predict a patient's 2-year mortality from cardiac causes.
Because revascularization can be plugged into the equation or left out, the formula can offer specific guidance as to the clinical management of an individual patient, said Dr. Hachamovitch of the clinical cardiovascular medicine unit at the University of Southern California, Los Angeles.
He offered the specific example of an 80-year-old man with atypical angina, assessing points to account for his age, the fact that 30% of his myocardium is ischemic, and other clinical characteristics and scan findings.
His final score was plotted on the x-axis of a graph against the 2-year Kaplan Meier Survival Curve on the y-axis.
The hypothetical patient received a total of 150 points if he underwent medical therapy, for a survival score of 91%, meaning he had a 9% chance of dying of cardiac causes in the ensuing 2 years.
When revascularization was factored into the formula, the patient's score dropped to 85 points, and his 2-year survival estimate rose to 97%.
The derivation of such a formula has been dependent on years of research into risk stratification for cardiac patients based on nuclear scan findings, said Dr. Hachamovitch at the meeting, which was cosponsored by the American Society of Nuclear Cardiology and Cedars-Sinai Medical Center.
This research has determined predictors of both relative and absolute risk reduction based on nuclear perfusion study results. Following Dr. Hachamovitch's talk, his findings were published (J. Am. Coll. Cardiol. 2005;45:722–9).
In general, the relative benefit of revascularization over medical therapy after nuclear imaging depends on the extent and severity of the myocardium at risk.