Abstract 10173: Single-Photon Emission Computed Tomography Myocardial Perfusion Imaging-Assessed Ischemia Severity is Associated with Mortality Independent of Asian Ethnicity: A Singapore Single-Centre Experience
Ischemic heart disease is growing by epidemic proportions in Asia thus making appropriate risk stratification paramount. Among patients in Western populations with similar ischemia severity on SPECT MPI, ethnicity is reportedly independently associated with mortality. It is unknown if this relationship applies in Asians.
Methods From 17,773 consecutive patients having SPECT MPI performed between 2006 and 2008, we used the summed stress score (SSS) to define 4 groups of increasing ischemia severity, minimal (SSS < 3), mild (SSS 4-7), moderate (SSS 8-13), and severe (SSS > 13), among 3 major Asian ethnic groups: Chinese, Indian, and Malay. The national death registry was used to determine mortality. After adjusting for baseline differences including age, sex, risk factors for IHD, prior MI, and LVEF, we examined the association of ethnicity with mortality within the different ischemia groups.
Results Chinese patients (n=14,065) were older than Indians (n=1,987) or Malays (n=1,721) (median age 61, 57, and 57 years respectively), with the Chinese less likely to have diabetes or a prior MI, but more likely to have normal LVEF. Annual all-cause death rates increased with increasing ischemia severity in all 3 ethnicities; being higher for Malays and lower for Indians, when compared to Chinese, across ischemia groups. (Fig A) However, after adjustment, ethnicity was not independently associated with death at 2 years. (Fig B) With Chinese as the reference group, adjusted odds ratio (AOR) for Malays and Indians with minimal ischemia was 1.2 (p = 0.3) and 1.1 (p = 0.6) respectively. Similarly, in the mild, moderate, and severe ischemia groups, AOR for Malays and Indians was 1.1 and 0.4, 1.7 and 0.9, and 1.3 and 0.7 respectively (all p not significant).
Conclusion Mortality risk is related to ischemia severity; and, unlike the Western experience, is independent of ethnicity in Asians. This emphasizes the continued utility of SPECT MPI in guiding risk stratification in Asia.
- © 2011 by American Heart Association, Inc.