Reserve pulse pressure useful prognostic factor in patients with suspected CAD
medwireNews: Reserve pulse pressure (PP) can be used to identify those patients with suspected coronary artery disease (CAD) but normal exercise myocardial perfusion imaging (MPI) who are at increased risk for death, a study shows.
Patients with normal MPI have an excellent prognosis; however, the majority of patients evaluated for CAD fall into this group, and the absolute number of adverse events is higher in those with normal MPI than in those with abnormal results, point out Sharmila Dorbala (Brigham and Women's Hospital, Boston, Massachusetts, USA) and team.
Thus, "conventional tests of ischaemia such as exercise treadmill testing and MPI may underestimate a significant proportion of future clinical events."
After using a multivariable model to adjust for known risk factors in CAD such as age and gender, and for Duke treadmill score (DTS) - a standard test used to predict CAD - the researchers found that each 10 mmHg lower reserve-PP was associated with a 20.6% increase in risk-adjusted mortality.
"In patients with suspected CAD and normal MPI, suboptimal reserve-PP is a simple and useful marker of risk that provides incremental prognostic value by appropriately reclassifying a significant proportion of subjects with normal MPI into higher or lower risk of mortality," comment Dorbala and colleagues.
The study cohort consisted of 4269 patients referred for evaluation to the Brigham and Women's Hospital with symptoms suggestive of CAD but who were found to have normal exercise MPI.
In addition to exercise MPI, all patients were given a structured interview and chart review, and underwent a maximum symptom-limited treadmill exercise test. Heart rate, blood pressure, and an electrocardiogram were obtained before exercise, at the beginning of each stage of the test, and during recovery. From this, DTS scores and pulse pressure were calculated.
After a mean follow-up period of 5.2 years, there were 202 (4.7%) deaths from any cause, with about two-thirds of those occurring in patients who had abnormal reserve-PP values.
The researchers also found that, when any one of abnormal DTS score, heart rate recovery, or reserve-PP were considered, only 6.8% of the deaths were unaccounted for.
Writing in the European Heart Journal, the authors admit that "the precise mechanistic links between lower reserve-PP and mortality cannot be determined from this study."
However, they go on to suggest that "reserve-PP likely represents a functional measure of overall cardiac and vascular health obtained during routine treadmill testing."
medwireNews (www.medwirenews.com) is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2013
By Afsaneh Gray, medwireNews Reporter