CASE 15077 Published on 12.12.2017

Unstable angina during myocardial perfusion scintigraphy



Case Type

Clinical Cases


Ruta Kliokyte, MD, Augustinas Bielinis, MD, Donatas Vajauskas, PhD, Egle Sadauskiene, PhD

Vilnius University Hospital Santaros Klinikos, Radiology and Nuclear Medicine Department, Santariskiu g. 2, 08661 Vilnius, Lithuania

80 years, male

Area of Interest Cardiovascular system, Nuclear medicine ; Imaging Technique SPECT, Catheter arteriography
Clinical History
A 80-year-old male patient with coronary artery disease (CAD), stable angina, post 3 myocardial infarctions, percutaneous coronary intervention and stenting of left anterior descending artery (LAD) 6 and 7 segments (2009) underwent myocardial perfusion scintigraphy for risk stratification and prognosis assessment.
Imaging Findings
One-day stress, rest protocol was performed with 350 and 700 MBq 99mTc-sestamibi. Adenosine was used for stress testing. No symptoms followed. ST depression up to 1 mm in II, III, aVF was observed. After a rest injection the patient felt weakness, heart palpitation. ECG showed ST deviation in V1, V2 and 1 mm depression in V5, V6 in comparison to stress test ECG. No typical angina symptoms were observed.
The stress and rest myocardial perfusion imaging demonstrated a reversible perfusion defect in the inferior wall – moderate ischaemia; reverse perfusion in the apex and the anterior wall - unstable angina was suspected. The patient was immediately consulted by a cardiologist. The laboratory test showed elevated troponin levels (105, 4 ng/l). Coronary angiography was performed and showed diffuse changes in right coronary artery and critical stenosis in LAD‘s 8 segment and circumflex artery‘s 12 segment. The patient was assigned coronary artery bypass grafting.
Stress myocardial perfusion imaging (MPI) is important in the diagnosis and risk stratification of CAD [1]. Patients with angina have a high probability of myocardial ischaemia and are expected to have a high rate of future cardiac events. It is not known whether stress MPI can permit further classification of these patients into high and low-risk categories and thereby guide in the selection of patients who require invasive procedures [1]. Rest MPI is a useful technique for screening patients with no previous history of ischaemic heart disease presenting at the emergency department with chest pain suggestive of angina who have normal or inconclusive ECG findings [2]. It has a negative predictive value ranging between 99-100% and is useful in risk stratification and prognosis [3]. Limitations of rest MPI include the inability to distinguish ischaemia from an old infarct as recognition of ischaemia requires follow-up imaging in a pain-free state to evaluate for resolution of the defect [4].
Reverse perfusion (RP) pattern is observed when myocardial MIBI washout is increased after the sub-acute phase or after revascularisation, especially in patients with acute myocardial infarction as well as patients with coronary spastic angina; this phenomenon may reflect a salvaged myocardium [5-7]. However, RP is a poor predictor of flow limiting CAD, and does not correlate with stenosis location in those with significant lesions [8]. It was also implied that RP may be related to artifacts of various origins [9].
A review of clinical trials indicates that adenosine perfusion studies provide high sensitivity and specificity (80-90%) for identifying CAD. Adenosine stress test is a safe procedure [10]. It has a number of well-documented predictable minor side effects reflecting its mode of activity, such as arrhythmias, transient atrioventricular nodal block of differing degrees, hypotension [11]. A severe complication rate is 1.2 per 10000 tests [12]. Only one myocardial infarction during adenosine stress test has been reported [13].
Diseased arteries have reduced coronary flow reserve with limited ability to vasodilate and accordingly exhibit a reduced response to adenosine relative to healthy vessels. Most of the total increased blood to the myocardium comes from increased blood flow through healthy vessels [14]. As tracer uptake is proportional to blood flow, this results in a relative hypoperfusion in territories supplied by diseased vessels and the subsequent heterogeneous perfusion pattern on the stress images. Although ischaemia is inferred from this appearance, the incidence of true ischaemia is low [15].
Differential Diagnosis List
Unstable angina
Myocardial Infarction
MPI artifacts
Final Diagnosis
Unstable angina
Case information
DOI: 10.1594/EURORAD/CASE.15077
ISSN: 1563-4086