Читать книгу Practical Cardiovascular Medicine - Elias B. Hanna - Страница 190

 High pre-test probability:Coronary angiography is directly performed if typical exertional angina is severe and requires revascularization.CTA is preferred if typical angina is not severe. It excludes left main disease and allows conservative CAD management, as per ISCHEMIA trial.¹⁹As an alternative to CTA in typical angina that is not severe, stress testing may be performed, especially in CKD. Here, stress testing is less useful for diagnostic purposes, as the likelihood of CAD remains high even with a negative test. It is, however, useful for risk stratification: a low-risk result allows conservative management.²⁰

 Intermediate pre-test probability: stress testing or CTA is performed for diagnosis and prognosis. CTA is also indicated after a high- or intermediate-risk stress test or a negative stress test yet persistent symptoms. SCOT-Heart trial showed that routine CTA on top of functional testing reduces the 5-year MI risk in patients with chest pain, typical or atypical, compared to functional testing alone, not via more revascularizations but via assessing plaque burden and dictating aggressive risk factor control.²¹

 Low pre-test probability (young patient with atypical angina): stress testing may not need to be performed. Even if the stress test is positive, the probability of CAD increases from <10% up to 20%, i.e., the stress test is likely falsely positive. However, if judged necessary, ECG or echo stress testing may be performed (class IIa). Avoid nuclear stress testing in low-probability patients, as it has a high false-positive rate in this population and a radiation hazard.

Table 3.1 Indications for stress imaging, as opposed to plain treadmill stress ECG.

Treadmill stress imaging (nuclear or echo) >Treadmill stress ECGBaseline ST depression >1 mmaHigh pre-test probability of CADPrior coronary revascularization (stress imaging allows localization of ischemia and has a higher sensitivity in detecting single-vessel ischemia)Prior stress ECG with intermediate result Pharmacological stress imaging (nuclear or echo)Unable to walkAble to walk but baseline ECG has LBBB or ventricular paced rhythm (classically, pharmacological nuclear imaging is performed)b

^a LVH without ST depression is appropriately tested with stress ECG.

^b Exercise and dobutamine may exaggerate the septal motion abnormality and septal defect present in LBBB, falsely suggesting ischemia, but have shown an appropriate yield when the apical motion or perfusion is analyzed, rather than the septum.²⁵

Table 3.2 Risk stratification with stress testing.

High risk: yearly cardiac mortality >3%, yearly cardiac events >5%DTS ≤–11aReversible, large or severe perfusion defect (summed stress score >+8, corresponding to ischemia involving >10% of the myocardium)Fixed, large or severe perfusion defect with LV dilatation/low EFRest- or stress-induced LV dysfunction with EF ≤35%, even if the defect is mild or moderateOn stress echo: ischemia of ≥3 segments (out of 17), or >one coronary distribution, especially if it occurs at a low rate <120 bpm or a low dose of dobutamine (≤10 mcg/kg/min) Intermediate risk: yearly cardiac mortality 1–3%, cardiac events 1–5%DTS –10 to +4Summed stress score 4–8 Low risk: yearly cardiac mortality and cardiac events <1% (~0.5% with stress imaging)DTS ≥+5 (≥ +8 is very low risk)No perfusion defect or small perfusion defect with a summed stress score <4

^a Duke Treadmill Score (DTS) = prognostic score for treadmill stress testing

= Exercise time on Bruce protocol – 5 × (the deepest ST depression on ECG) – 4 × (angina score) (Angina score: 0 = no angina, 1 = non-limiting angina, 2 = exercise-limiting angina)