Time course of functional recovery after coronary artery bypass grafting surgery according to the preoperative reversibility of perfusion impairment on myocardial SPECT

Abstract

PURPOSE: Ischaemic myocardial dysfunction shows different time courses of functional recovery according to the pathophysiological characteristics of the dysfunction. In this study, we investigated the time course of functional recovery according to the preoperative reversibility of perfusion impairment on myocardial single-photon emission computed tomography (SPECT) after revascularisation surgery. METHODS: Forty-eight patients (42 men and 6 women; mean age 59+/-9 years) who underwent revascularisation surgery were included in the study. 201Tl rest/dipyridamole stress (99m)Tc-sestamibi gated SPECT was performed 10+/-8 days before (preoperative), 105+/-13 days after (early follow-up) and 497+/-66 days after (late follow-up) surgery. Using a 20-segment model, segmental perfusion and thickening were quantified with automatic software. As an indicator of the reversibility of perfusion impairment, a reversibility score (RevS) was defined as a measure of rest minus stress perfusion values. Segmental dysfunction and functional recovery were defined from quantified thickening values. Function-recovered segments were divided into early recovery and late recovery groups, and preoperative perfusion status was compared in these groups. Function-recovered segments were also re-classified into high-RevS and low-RevS groups according to the preoperative RevS, and the time courses of functional recovery were investigated in each group. RESULTS: A total of 502 segments were included in the analysis and 263 were finally classified as function-recovered segments. Of these, 172 were in the early recovery and 91 in the late recovery group. In terms of preoperative perfusion status, RevS was 8.9+/-10.8 in the early recovery group and 5.4+/-11.0 in the late recovery group (P=0.01). When all 502 segments were classified by RevS, no difference in the proportion of final function recovery was observed between the high-RevS and the low-RevS group (54% vs 51%). However, the proportion of early recovery was higher in the high-RevS group (73%) than in the low-RevS group (57%) (P=0.01). CONCLUSION: Ischaemic dysfunctional myocardium with reversible perfusion impairment tends to recover function earlier after revascularisation surgery than myocardium with a persistent decrease in perfusion.