Is There an Age When Myocardial Perfusion Imaging May No Longer Be Prognostically Useful?

BACKGROUND: Heart disease continues to be the leading cause of death, and the prevalence of coronary artery disease is expected to increase as the population ages. It is important to understand the clinical utility of medical tests, or its lack thereof, in the aging population. The objective of this study was to understand the incremental prognostic value of positron emission tomographic (PET) myocardial perfusion imaging in the elderly (≥85 years of age). METHODS AND RESULTS: A total of 3343 patients enrolled in a multicenter observational PET registry were analyzed. Participants were initially divided into 3 age categories: 65 to 74.9, 75 to 84.9, and ≥85 years of age and followed for all-cause death. Median follow-up time was 3 years. Of the total patient population, 248 patients (49% men) were ≥85 years old. When compared with younger patients, individuals ≥85 years had a higher prevalence of hypertension (79%) and a lower incidence of dyslipidemia (54%) and diabetes mellitus (24%). On multivariable analysis, %left ventricular stress defect and %left ventricular ischemia were predictors of patient outcome for those \u3c85 years of age but was not statistically significant in those ≥85 years of age. The prognostic value of PET (%left ventricular stress defect and %left ventricular ischemia) appeared to decrease with advancing age. CONCLUSIONS: The elderly is a high-risk population irrespective of PET myocardial perfusion imaging results, and incremental prognostic value of PET myocardial perfusion imaging appears to wane in those ≥85 years of age. Although PET myocardial perfusion imaging may be diagnostically useful in the elderly, its prognostic value in this population requires further evaluation

Prognostic value of vasodilator response using rubidium-82 positron emission tomography myocardial perfusion imaging in patients with coronary artery disease

Prognostic value of positron emission tomography (PET) myocardial perfusion imaging (MPI) is well established. There is paucity of data on how the prognostic value of PET relates to the hemodynamic response to vasodilator stress. We hypothesize that inadequate hemodynamic response will affect the prognostic value of PET MPI.Using a multicenter rubidium (Rb)-82 PET registry, 3406 patients who underwent a clinically indicated rest/stress PET MPI with a vasodilator agent were analyzed. Patients were categorized as, responders [increase in heart rate ≥ 10 beats per minute (bpm) and decrease in systolic blood pressure (SBP) ≥10 mmHg], partial responders (either a change in HR or SBP), and non-responders (no change in HR or SBP). Primary outcome was all-cause death (ACD), and secondary outcome was cardiac death (CD). Ischemic burden was measured using summed stress score (SSS) and % left ventricular (LV) ischemia. After a median follow-up of 1.68 years (interquartile range = 1.17- 2.55), there were 7.9% (n = 270) ACD and 2.6% (n = 54) CD. Responders with a normal PET MPI had an annualized event rate (AER) of 1.22% (SSS of 0-3) and 1.58% (% LV ischemia = 0). Partial and non-responders had higher AER with worsening levels of ischemic burden. In the presence of severe SSS ≥12 and LV ischemia of ≥10%, partial responders had an AER of 10.79% and 10.36%, compared to non-responders with an AER of 19.4% and 12.43%, respectively. Patient classification was improved when SSS was added to a model containing clinical variables (NRI: 42%, p \u3c 0.001) and responder category was added (NRI: 61%, p \u3c 0.001). The model including clinical variables, SSS and hemodynamic response has good discrimination ability (Harrell C statistics: 0.77 [0.74-0.80]).Hemodynamic response during a vasodilator Rb-82 PET MPI is predictive of ACD. Partial and non-responders may require additional risk stratification leading to altered patient management

Standardising the elimination of unnecessary data from interview transcripts for the purposes of knowledge-based systems - A case study

Although knowledge elicitation, the process of extracting knowledge from human experts to be incorporated into a knowledge-based system, has been the subject of some notable studies, less attention has been paid to the methods of analysing the raw data once it has been extracted from the expert. When knowledge elicitation sessions are interview-based, the resultant form of raw data is usually a transcript of the interviewee's utterances. This paper describes an investigation into the preliminary stage of analysing such transcripts. It outlines the development of an approach to eliminate unnecessary detail from interview transcripts, thus enabling attention to be focused upon the remaining, more relevant data via a simple technique based upon cheap and readily available technology. The paper then outlines a rapid-prototyping approach for evaluating this method, the results of which were felt to be very encouraging