Impact of Abnormal Remote Stress Myocardial Blood Flow by Dynamic CT Perfusion on Clinical Outcomes

Nobuo Tomizawa,Shengpu Chou,Kanako K Kumamaru,Shinichi Inoh,Satoshi Matsuoka,Takeshi Nojo,Kodai Yamamoto,Sunao Nakamura,Yusuke Fujino,Shinichiro Fujimoto

doi:10.1038/s41598-020-66992-w

Nobuo Tomizawa, Shengpu Chou + Show 8 more

Open Access

https://doi.org/10.1038/s41598-020-66992-w

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Abstract

The objective of this study was to investigate the incremental prognostic value for adverse events of myocardial blood flow (MBF) derived from stress computed tomography perfusion (CTP) at remote myocardium over cardiac risk factors and ischemia. We prospectively analyzed 242 patients who underwent dynamic CTP and CT angiography. Adverse events were defined as a composite of all-cause mortality, non-fatal myocardial infarction, unstable angina, heart failure requiring hospitalization, peripheral artery disease, and stroke. MBF value was calculated in each myocardial segment and ischemia was defined as mild decrease in MBF in two consecutive segments or moderate decrease in a single segment accompanied with a coronary stenosis ≥50%. The mean MBF of the non-ischemic segments was defined as remote MBF. We divided the patients into two groups by median MBF value of 1.15 ml/min/g. During a median follow-up of 18 months, 18 patients had adverse events. Annual event rate showed a significant difference between patients with low (≤1.15 ml/min/g) and high (>1.15 ml/min/g) MBF (6.1% vs 1.8%, p = 0.02). Univariate analysis showed that low MBF was a significant predictor of events (hazard ratio (HR): 3.4; 95% confidence interval (CI): 1.2 to 12.0; p = 0.02). This relationship maintained significant after adjusted for the presence of ischemia and cardiac risk factors (HR: 3.0; 95%CI: 1.1 to 11.1; p = 0.04). In conclusion, MBF value ≤1.15 ml/min/g derived from dynamic CTP in remote myocardium is significantly related with poor outcome and this relationship was independent of myocardial ischemia and cardiac risk factors.

Highlights

Myocardial computed tomography perfusion (CTP) is an emerging technique to assess ischemia-causing stenosis using CT1–6
The present study showed that decreased myocardial blood flow (MBF) of the remote myocardium was a significant predictor of adverse events independent of myocardial ischemia and conventional cardiac risk factors
The annualized event rate for adverse events increased from 1.8% to 6.1% in patients with a MBF value of ≤1.15 ml/min/g than the remaining patients

Summary

Introduction

Myocardial computed tomography perfusion (CTP) is an emerging technique to assess ischemia-causing stenosis using CT1–6. Recent meta-analyses showed that myocardial CTP could improve the specificity to 80% without significantly reducing the sensitivity[1,2,3]. Previous studies using positron emission tomography (PET) showed that reduced coronary flow reserve (CFR) was associated with increased risk of cardiovascular events[7,8]. Recent studies using CTP showed that ischemia detected by CTP was related to incremental predictive value in assessing future events over clinical risk factors and coronary stenosis[9,10]. The prognostic value of MBF at the remote myocardium is not fully assessed. The purpose of the present study was to investigate the incremental prognostic value for adverse events of MBF at the remote myocardium over cardiac risk factors and ischemia

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