Prognostic implications of Tc-99m sestamibi viability imaging and subsequent therapeutic strategy in patients with chronic coronary artery disease and left ventricular dysfunction.

OBJECTIVES: The aim of the study was to verify the prognostic implications of viability detection using baseline-nitrate sestamibi imaging in patients with left ventricular (LV) dysfunction due to chronic coronary artery disease (CAD) submitted to different therapeutic strategies. BACKGROUND: The prognostic meaning of preserved viability in these patients is still debated. Sestamibi is increasingly used for myocardial perfusion scintigraphy and is being accepted also as viability tracer, but no data are available about the relationship between viability in sestamibi imaging, subsequent treatment, and patient's outcome. METHODS: Follow-up data were collected in 105 CAD patients with LV dysfunction who had undergone baseline-nitrate sestamibi perfusion imaging for viability assessment and had been later treated medically (group 1), or submitted to revascularization, which was either complete (group 2A) or incomplete (group 2B). RESULTS: Eighteen hard events (cardiac death or nonfatal myocardial infarction) were registered during the follow-up. A significantly worse event-free survival curve was observed in the patients of group 1 (p < 0.0002) and group 2B (p < 0.03) compared to those of group 2A. Using a Cox proportional hazard model, the most powerful prognostic predictors of events were the number of nonrevascularized asynergic segments with viability in sestamibi imaging (p < 0.003, risk ratio [RR] = 1.4), and the severity of CAD (p < 0.02, RR = 1.28). CONCLUSIONS: Viability detection in sestamibi imaging has important prognostic implications in CAD patients with LV dysfunction. Patients with preserved viability kept on medical therapy or submitted to incomplete revascularization represent high-risk groups.

Excessive vasoconstriction after stress by the aging kidney: inadequate prostaglandin modulation of increased endothelin activity.

The adaptive capacity of the aging kidney to stimulation of the sympathetic nervous system, as induced by a 30-minute mental stress (MS), was assessed in 8 elderly healthy women (68 to 82 years of age) and compared with that of 8 younger women (24 to 40 years of age). The study encompassed 4 consecutive 30-minute periods (baseline, mental stress, recovery 1, and recovery 2). In the elderly subjects, baseline effective renal plasma flow (ERPF)(iodine 131-labeled hippurate clearance) was lower and glomerular filtration rate (GFR)(iodine 125-labeled iothalamate clearance) was proportionally less reduced than in the younger group; the filtration fraction (FF) was higher. The elderly group excreted more endothelin 1 (ET-1) (P < .05), prostaglandin E2 (PGE2), and 6-keto-prostaglandin F1alpha (6-keto PGF1alpha)(P < .001 for both)(radioimmunoassay). Mental stress induced similar increases in blood pressure, heart rate, and plasma catecholamines in the 2 age groups, limited to the stimulation period. In the elderly group, mental stress caused a prolonged decrease in ERPF that reached its maximum 60 minutes after mental stress (-33%, P < .05), while GFR remained constant during the whole experiment, so that FF increased. In the younger subjects, renal hemodynamic changes were limited to the mental stress period. ET-1 increased during mental stress and the first recovery period in the elderly group (+50% and +25%, P < .05) as it did in the younger group, but the elderly group differed from the younger in that vasodilating prostaglandins increased only during mental stress. In conclusion, the aging kidney reacts to adrenergic stimulation with more-pronounced and -prolonged vasoconstriction that is probably caused by a defect in prostaglandin modulation of endothelin activity. Autoregulation of GFR is maintained at the expense of increased intraglomerular pressure.

Prediction of post-revascularization functional recovery of asynergic myocardium using quantitative thallium-201 rest-redistribution tomography: has the reverse redistribution pattern an independent significance?

The significance of reverse redistribution on rest-redistribution thallium-201 myocardial scintigraphy is unclear. Previous studies suggested that reverse redistribution segments with normal resting activity include viable myocardium, whilst resting defects with further worsening correspond to scar. We evaluated whether reverse redistribution has an independent significance for the prediction of post-revascularization recovery, particularly as compared with the quantification of redistribution activity. We studied 26 coronary artery disease patients with left ventricular dysfunction, who underwent 201Tl rest-redistribution single-photon emission tomography (SPET) and echocardiography before revascularization. Viability was defined by the detection of wall motion improvement on follow-up echocardiography. 201Tl activity was considered normal if >/=80%, moderately reduced if <80% but >/=50%, and severely decreased if <50%. Reverse redistribution was defined as a defect in redistribution images with >/=10% decrease in relative 201Tl activity compared with the resting value. Reverse redistribution was detected in 33 segments (10%). Baseline dysfunction was equally observed in the reverse redistribution and in the non-reverse redistribution segments (64% vs 56%, P=0.40) and the rate of asynergic segments with post-revascularization recovery was not different between the two groups (33% vs 54%, P=0.11). The rate of functional recovery in redistribution defects without reverse redistribution was 53% in moderate and 30% in severe defects; the corresponding values for the reverse redistribution segments were 50% and 27% (all non-significant versus non-reverse redistribution segments). For the prediction of post-revascularization recovery in asynergic segments, the detection of reverse redistribution on rest-redistribution 201Tl SPET does not add any information to the quantitative analysis of redistribution activity.