title: Reclassification of cardiovascular risk in patients with normal myocardial perfusion imaging using heart rate response to vasodilator stress.
abstract: Previous studies have shown that patients with normal vasodilator myocardial perfusion imaging (MPI) findings remain at a greater risk of future cardiac events than patients with normal exercise MPI findings. The aim was to assess improvement in risk classification provided by the heart rate response (HRR) in patients with normal vasodilator MPI findings when added to traditional risk stratification. We retrospectively studied 2,000 patients with normal regadenoson or adenosine MPI findings. Risk stratification was performed using Adult Treatment Panel III framework. Patients were stratified by HRR (percentage of increase from baseline) into tertiles specific to each vasodilator. All-cause mortality and cardiac death/nonfatal myocardial infarction (MI) ≤2 years from the index MPI were recorded. During follow-up, 11.8% patients died and 2.7% patients experienced cardiac death/nonfatal MI in the adenosine and regadenoson groups, respectively. The patients who died had a greater Framingham risk score (12 ± 4 vs 11 ± 4, p = 0.009) and lower HRR (22 ± 16 vs 32 ± 21, p <0.0001). In an adjusted Cox model, the lowest tertile HRR was associated with an increased risk of mortality (hazard ratio 2.1) and cardiac death/nonfatal MI (hazard ratio 2.9; p <0.01). Patients in the highest HRR tertile, irrespective of the Adult Treatment Panel III category, were at low risk. When added to the Adult Treatment Panel III categories, the HRR resulted in net reclassification improvement in mortality of 18% and cardiac death/nonfatal MI of 22%. In conclusion, a blunted HRR to vasodilator stress was independently associated with an increased risk of cardiac events and overall mortality in patients with normal vasodilator MPI findings. The HRR correctly reclassified a substantial proportion of these patients in addition to the traditional risk classification models and identified patients with normal vasodilator MPI findings, who had a truly low risk of events.
authors.affiliation: Tulane University Heart and Vascular Institute, Tulane University, New Orleans, Louisiana, USA. fiqbal1@tulane.edu
authors.forename: Fahad M
authors.initials: FM
authors.lastname: Iqbal
authors.forename: Wael
authors.initials: W
authors.lastname: Al Jaroudi
authors.forename: Kumar
authors.initials: K
authors.lastname: Sanam
authors.forename: Aaron
authors.initials: A
authors.lastname: Sweeney
authors.forename: Jaekyeong
authors.initials: J
authors.lastname: Heo
authors.forename: Ami E
authors.initials: AE
authors.lastname: Iskandrian
authors.forename: Fadi G
authors.initials: FG
authors.lastname: Hage
mesh_terms: D000241:Adenosine; D000407:Alabama / Q000453:epidemiology; D002318:Cardiovascular Diseases / Q000145:classification* / Q000175:diagnosis* / Q000453:epidemiology; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D014665:Vasodilator Agents
chemical_list: D014665:Vasodilator Agents; D000241:Adenosine