Ondrej Lisy M.D. Ph.D. F.A.C.C.

Transcription

1 Ondrej Lisy M.D. Ph.D. F.A.C.C.

2 Pts. with symptoms suggesting angina with intermediate or high pre-test likelihood of CHD Pts. with acute CP after ACS exclusion Within three months post-acs for risk assessment Known CHD and change in clinical status After five years post CABG one time in asympt. For newly dg. CHF or cardiomyopathy For valvular heart disease AS with low output For active cardiac condition prior non-cardiac surgery

3 Screening of asymptomatic pts. (except high risk occupation) Pts. with unstable symptoms Pts. with low probability of CHD and atypical sx. Pts. requiring emergency noncardiac surgery

4 For pts. who can attain an adequate level of exercise (5 min walk or 1-2 flights of stairs)- symptoms limited exercise testing is preferred For pts. who are unable to exercise to sufficient cardiac workload pharmacological stress testing Modality based on factors: - resting ECG - clinical indication for performing the test - body habitus - history of prior revascularization

5 Acute MI within 2 days Unstable angina Uncontrolled arrythmias Symptomatic severe valvular stenosis Uncontrolled symptomatic CHF Active endocarditis or myocarditis Acute aortic dissection Acute pulmonary embolism Inability to obtain consent

6 Treadmill and stationary bicycle or arm ergometry Bruce protocol extensively validated; 3 min stages with steeper grade (Bruce 2 = 7 METS) Modified Bruce adds two low-workload stages to the beginning of Bruce Naughton protocol post MI and high risk pts.(naughton 4 = 5 METS; 6 = 7 METS)

7 Testing for diagnostic purposes avoid antiischemic medications (nitrates) and medications that slow heart rate (beta blockers, nondihydropyridine Ca channel blockers) and certain antiarrhytmics (amiodarone, sotalol) Target HR: 85% of maximal HR (220 age) SBP should rise with each stage of exercise while DBP falls or remains unchanged

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10 Annual CV mortality (%) Score = Duration (min Bruce protocol) (5x ST-seg deviation)(mm) (4x angina index)(0, 1, 2) Low Intermediate High ( 5) (-10 to +4) (<-10) Mark DB: NEJM 325:849, 1991

11 Severe chest pain Near syncope; cyanosis Fall in SBP (> 10 mmhg from baseline) BP > 250/120 Marked ST segment depression or elevation Increasing frequency of ventricular ectopy High grade AV block Sustained VT or Vfib Achievement of 70% of MPHR for submaximal testing

12 Claudications, arthritis, deconditioning, pulmonary disease Failure to achieve 85% MPHR WPW pattern on ECG V paced rhythm LBBB Greater than 1 mm ST-T depression LVH with ST-T abnormalities Digoxin use with ST-T abnormalities

13 Stress echocardiography (exercise or dobutamine) Radionuclide stress myocardial perfusion imaging (SPECT or PET) Stress cardiac magnetic resonance imaging Main indications: ECG baseline abnormalities; inability to exercise; known CHD

14 Exercise or pharmacological Detection of ischemia development of new RWMAs; changes in end systolic volume, LVEF, LV cavity Limitations: body habitus; LBBB; pacing

15 Goal: assessment of relative myocardial blood flow or perfusion between the resting and stressed states Focus: intracellular myocardial extraction and retention of tracer (reversible vs. fixed defect)

16 Thalium-201 cyclotron produced; uptake involving Na-K-ATPase pump directly proportional to coronary blood flow Prolonged half life of 73 hrs limits allowable dose Redistribution continuous exchange between the myocyte and the extracellular compartment; post-stress imaging should begin within 15 min Viability assessment

17 Technetium-99m labeled perfusion agents generator produced Tc-99m sestamibi (Cardiolite) and Tc-99 tetrofosmin (Myoview) lipophilic compounds with myocardial uptake proportional to flow with higher photon energy 140keV resulting in less photon attenuation and scatter Minimal redistribution; injection during peak stress and at rest Half life 6 hrs allows larger doses while keeping lower radiation exposure; high count rates - improved image resolution

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19 PET uses radionuclides that decay by positron emission relies on the detection of two 511keV gamma photons Rubidium-82 (from strontium-82 generator) and N13-ammonia (from cyclotron) Half life of Rb-82 is only 78 sec PET imaging equivalent, if not greater, overall sensitivity (84-93% PET vs 88% SPECT), specificity (81% PET vs 61-76% SPECT), and accuracy for the detection of CHD

20 Adenosine, dipyridamole and selective A2A receptor agonists regadenoson (Lexiscan) Increase coronary blood flow through their effects on adenosine A2A receptors Presence of flow-limiting obstructive CHD leads to perfusion defects. The increase of blood flow is attenuated and there is relative reduction of radiotracer uptake. Can be combined with low level of exercise May be administered at peak exercise in pts. who fail to achieve target HR

21 Stimulates adenosine A2A receptors on vascular smooth muscle cells Rapid injection over 10 sec (onset in 30 sec) Half life of initial phase 2-4 minutes Radioisotope (Tc-99m sestamibi) usually infused 10 sec after saline flush Side effects (most resolves within 15 min): dyspnea, headache, chest pain, flushing

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23 Dobutamine synthetic catecholamine stimulates beta1-adrenergic receptors with the effect of increase HR and contractility For pts. with vasodilators contraindications; on theophylline or who had caffeine within 12 hrs Dobutamine with atropine results in hyperemia and significant increase in myocardial blood flow

24 Active bronchospastic airway disease Hypotension Sick sinus rhythm High grade AV block Unstable angina Ventricular arrhythmia Severe systemic hypertension

25 Prognostic SPECT 39 Studies; 69,655 Patients 10 Annual CD/MI (%) Normal low risk Shaw LJ and Iskandrian AE: JNC 11:171, 2004 Moderatelyseverely Pharm abnormal

26 Age Nonanginal pain Atypical angina Typical angina Men Women Men Women Men Women 30 to to to to Values expressed as the % of patients with significant CHD on angiography. N. Engl J Med 1979

27 Sensitivity (%) Specificity (%) Exercise ECG 45 to to 90 Exercise stress echocardiography 70 to to 89 Exercise stress SPECT 73 to to 88 Pharmacologic stress echocardiography Pharmacologic stress SPECT 72 to to to to 90 Coronary CTA 93 to to ACCF/AHA/ACP guidelines for dg. and management of stable CHD.

28 The estimate of pretest probability of CHD and clinical information can help to determine optimal diagnostic testing Stress testing is the most useful in pts. with an intermediate pretest probability In general, exercise ECG is preferred in pts. able to exercise Stress testing with an imaging modality is typically performed in majority of pts. who are unable to adequately exercise, have baseline ECG abnormalities or have known CHD