Semiquantitative SPECT myocardial perfusion with dipyridamole in patients unable to exercise. Event rate during 4 years of follow up

The increasingly numbers of patients (P) that can't reach an adequate level of exercise in order to evaluate CAD, lead us to use pharmacological and technical tools available for this subgroup of P. Aim: evaluate the prognostic significance of myocardial perfusion SPECT imaging with pharmacological stress in P without LBBB, unable to exercise. Material and Methods: 209 P were included. Mean age: 65 years old (39-88), male 66%. Clinical: Pre test likelihood <= 20%: 36.4 %, 21-75%: 15.8%, 76-99%: 8.1%, known CAD: 39.7%; Risk Factors: High blood pressure (BP): 70%, diabetes: 23%, cholesterol: 49%, smokers: 39%; EKG: scar 18%. Stress test: dipyridamole: 0.56 mg/kg/4 min.; analyzed variables: D heart rate (HR), D BP, cardiac and non cardiac side effects. Myocardial Perfusion SPECT: semiquantitative analysis to evaluate perfusion defects with a 20-segment model and 5-point scoring system for uptake reduction. Scintigraphic indices SSS (sum of stress scores), SRS (sum of rest scores) and SDS (SSS-SRS). Follow up: soft cardiac events (SCE): need for PTCA or CABG, unstable angina, heart failure; hard cardiac events (HCE): non-fatal acute myocardial infarction and cardiac death. Results: I) Pharmacologic stress test: D HR 27%; D systolic BP 3%; D diastolic BP 1%; non cardiac side effect: headache 13%, dyspnea 9%, nausea 0.5%; cardiac side effect: angina 21%, ST download 6%, atrial fibrillation 3%, severe ventricular arrhythmia 1.5%. II) Image analysis: SSS 0-3: 54.3%, SSS 4-8: 17.7%, SSS >8: 28%; SDS 0 and SRS 0: 31.7%; SDS 0 + SRS >=1: 21%; SDS >=1: 47.3%. III) Follow up: 13 patients were early re-vascularized induced by SPECT study results, 10 patients get lost and 186 were follow up by a mean 1086 days. Cumulative events rate: 1st year SCE 9.7%, HCE 1.6%; 2nd year SCE 14%, HCE 4.3%; 3rd year SCE 17.7%, HCE 5.4%; 4th year SCE 21%, HCE 5,4%. Scintigraphic indices and events rate relationship are presented. Conclusion: There was a relationship between scintigraphic indices and hard cardiac events. The semiquantitative myocardial perfusion with dipyridamole stress was a safe test and useful to discriminate groups of P with different risk of events