Triggered SPECT Usefulness and its Impact on
Evaluatingthe Prognosis of Ischemic Burden
Camilletti Jorge, Erriest Juan
Unidad de Medicina Nuclear. Hospital Italiano de La Plata.
(1900) La Plata, Buenos Aires. E-mail
Recibido 15-ENE-2014 – ACEPTADO después de revisión el 21-MARZO-2014.
The authors declare not having conflicts of interest
Rev Fed Arg Cardiol. 2014; 43(3): 161-162
Patient referred by the clinical physician for a first cardiological consultation due to presenting factors of cardiovascular risk: male, age (55 years), hypertension, dyslipidemia, obesity (BMI 33.6), smoking and sedentarism. He did not mention cardiovascular history. Symptomatic by stable chronic angina with a one-year evolution.
The physical examination did not show any pathology. The electrocardiogram presented regular sinus rhythm, 78 beats per minute, with signs of left ventricular enlargement, without other findings to mention.
Before the high pre-test probability of CAD, due to his risk factors and the clinical symptoms suggesting ischemic heart disease, myocardial perfusion stress/rest Tc-99m sestamibi gated-SPECT test was requested to stratify risk and confirm or rule out the presumed diagnosis.
In stress test, 85% of the theoretical maximal heart rate, the patient reached 1050 Kgm, 6.8 METS, with 1/10 intensity of precordial pain, which yielded in the second minute of recovery, and no changes detected in ECG. Myocardial perfusion gated SPECT images were acquired with a one-day protocol in prone position, first images in rest and then in stress.
Gated SPECT images showed moderate ischemia of infero-lateral side (mid and apical views). The semi-quantitative assessment of the perfusion defect in the stress images was 4 according to the SSS (summed stress score), and 0 according to SRS (summed rest score), and 4 according to SDS (summed difference score). The extension of the affected myocardium estimated in a semi-quantitative form was 6% of the total left ventricle (Figure 1).
Left ventricular function was preserved, with an ejection fraction of 56%, and ventricular volumes of end of systole of 64 ml, and of end of diastole of 145 ml (normal) without segmental parietal motility disorders (Figure 2).
The patient was interpreted as in low clinical risk. The medical treatment was optimized for ischemic heart disease with bisoprolol 10 mg/day, aspirin 100 mg/day, rosuvastatin 10 mg/day, losartan 100 mg/day, with cardiovascular rehabilitation being indicated and encouraging him to change life habits.
With a good adherence to the medical treatment, the patient started regular physical activity, 3 weekly stimuli of 90 minutes in a cardiovascular rehabilitation program, thus achieving a weight loss of 9 kg (8.6% of his weight), asymptomatic with functional capacity I.
At one year, with full medical treatment, a control with new myocardial perfusion Tc-99m sestamibi gated-SPECT test was conducted. Before physical challenge he developed 1200 Kgm, 7.5 METS, reached 72% of the theoretical maximal rate (probable pharmacological effect), asymptomatic, without ST segment alterations, or arrhythmias during stress.
In the analysis of the myocardial perfusion images, a homogeneous distribution of the radiopharmaceutical was observed before stress, with normal left ventricular function, and Tc-99m sestamibi gated-SPECT test reported as normal (Figure 3).
There is increasing evidence that the myocardial perfusion studies may identify therapeutic strategies that improve the evolution of patients and the result of the procedures . The reduction of myocardial ischemia detected by nuclear cardiology leads to a decrease in the rates of major cardiac events after the treatment . A worsening of left ventricular dyssynchrony induced by the stress only would present in patients with perfusion alterations .
Al-Housini MB, Hutchings F, Dalby M, et al. Does myocardial perfusion scintigraphy predict improvement in symptoms and exercise capacity, following successful elective percutaneous coronary intervention? J NuclCardiol2009; 16 (6); 869-77.
Hori Y, Yoda S, Nakanishi K, et al. Myocardialischemicreductionevidencedbygatedmyocardialperfusionimagingaftertreatmentresults in good prognosis in patientswithcoronaryarterydisease.J Cardiol2014; [Epubahead of print].
Singh H, Patel CD, Sharma P, et al. Doesperfusionpatterninfluence stress-inducedchanges in left ventricular mechanicaldyssynchronyon thallium-201-gated SPECTmyocardialperfusionimaging?.J NuclCardiol2014; [Epubahead of print].