PT  - JOURNAL ARTICLE
AU  - Shuai Yang
AU  - Zhifang Wu
AU  - Bin Huang
AU  - Bingbing Li
AU  - Yongxin Wan
AU  - Xiaomeng Li
AU  - Yi Hu
AU  - Doudou Lyv
TI  - Diagnostic and prognostic value of chronotropic incompetence on exercise gated 99mTc-MIBI SPECT in patients with suspected CAD
DP  - 2021 May 01
TA  - Journal of Nuclear Medicine
PG  - 1664--1664
VI  - 62
IP  - supplement 1
4099  - http://jnm.snmjournals.org/content/62/supplement_1/1664.short
4100  - http://jnm.snmjournals.org/content/62/supplement_1/1664.full
SO  - J Nucl Med2021 May 01; 62
AB  - 1664Objectives: The aims of this study were to evaluate the relationship between chronotropic incompetence (CI) on exercise treadmill testing in patients with suspected CAD and the perfusion and functional parameters of gated 99mTc-MIBI SPECT, and to determine whether CI can predict future cardiac events. Methods: All patients were studied by means of an ergometric exercise test using a standard Bruce protocol and Gated SPECT with Methoxyisobutyl Isonitrile-99mTechnetium (99mTC-MIBI). Exclusion criteria included history of coronary angiography or invasive procedures, cardiac surgery, congestive heart failure, valvular heart disease, pre excitation syndrome, or congenital heart disease and taking drugs with negative chronotropic properties. The criteria for judging CI include failure to reach 85% of the age-predicted maximum HR, a low chronotropic response index (CRI<0.8), low Heart rate recovery at 1 minutes after exercise (HRR1<18 beats/min) and low heart rate reserve (HR reserve<0.8). The perfusion and functional parameters include ejection fraction (EF), end-diastolic volume (EDV), end-systolic volume (ESV), the anomalous range of ventricular wall motion and its percentage of myocardial surface area in the middle segment (Mot Ext), summed motion score (SMS), summed thickening score (STS), End-diastolic shaped index (SI ED), end-systolic shaped index (SI ES), Eccentricity (Ecc), peak emptying rate (PER) and peak filling rate (PFR), time to peak filling from end-systole (TTPF). Endpoint events were cardiac death, nonfatal myocardial infarction and myocardial revascularization treatment. Based on heart rate reached in treadmill testing, patients were divided into two groups: with CI (30 patients who did not reach 85% of maximum heart rate recommended for age) and without CI (73 patients who achieved 85% of the maximum age-predicted heart rate). In secondary analyses, patients were divided into 4 groups according to perfusion defects (absent or present) and chronotropic response (normal or abnormal). Results: A total of 125 consecutive patients with suspected CAD who underwent exercise Tc-99m gated myocardial perfusion SPECT (MPS), 103(82.4%) cases were successfully followed for a mean of 57 ± 15 months. 30 patients (29.1%) did not achieve 85% of the maximal predicted heart rate, 6 (5.8%) had chronotropic response index (CRI<0.8), and 50 (48.5%) had perfusion defects, 17 (16.5%) happened heart events. On stepwise forward Cox regression, after adjustment for age, sex, perfusion defects, and other confounders, CRI (adjusted relative risk [RR], 5.3; 95% confidence interval [CI], 1.6-17.2; P= 0.005), HRR1 (adjusted RR, 2.8; 95% CI, 1.02-7.82; P<0.05) and number of segments with perfusion defects (adjusted RR, 1.6; 95% CI, 1.02-2.61; P<0.05) were associated with increased risk of death. On logistic regression, ESV<30ml (adjusted RR, 0.29; 95%CI, 0.11-0.77; P<0.05) and TTPF (adjusted RR, 1.2; 95%CI, 1.12-1.54; P=0.002) were found to be independent impact factors of CI. Patients who had reached 85% of the age-predicted maximum heart rate and normal perfusion imaging were at low risk for cardiac events (7%) during the follow-up period, when patients have both CI and positive perfusion defects the risk for cardiac events is the highest (40%). There was significant difference among these groups (X2=11.94, P<0.01). Conclusions: Low chronotropic response index (CRI<0.8) and low Heart rate recovery at 1 minutes after exercise (HRR1<18 beats/min) are independently predictive of cardiac events and combining number of segments with perfusion defects may improve the accuracy of risk stratification of exercise gated 99mTc-MIBI SPECT. Except for ESV<30ml and TTPF, CI did not affect other perfusion and functional parameters of gated 99mTc-MIBI SPECT. The risk for cardiac events is the highest with patients have both CI and positive perfusion defects, but it is the lowest when both are normal.