Upload
truongbao
View
214
Download
1
Embed Size (px)
Citation preview
Ondrej Lisy M.D. Ph.D. F.A.C.C.
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
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
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
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
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)
Testing for diagnostic purposes – avoid anti-ischemic medications (nitrates) and medications that slow heart rate (beta blockers, non-dihydropyridine 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
0.3
1.3
5.0
0
2
4
6
8
10
Low Intermediate High
Score =
Duration (min Bruce protocol) –
(5x ST-seg deviation)(mm) –
(4x angina index)(0, 1, 2)
AnnualCV
mortality(%)
Mark DB: NEJM 325:849, 1991
(<-10)(-10 to +4)(5)
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
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
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
Exercise or pharmacological
Detection of ischemia – development of new RWMAs; changes in end systolic volume, LVEF, LV cavity
Limitations: body habitus; LBBB; pacing
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)
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
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
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
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
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
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
Active bronchospastic airway disease
Hypotension
Sick sinus rhythm
High grade AV block
Unstable angina
Ventricular arrhythmia
Severe systemic hypertension
Prognostic SPECT39 Studies; 69,655 Patients
0.85
5.9
0
2
4
6
8
10
Normal PharmModerately-severely abnormal
Normallow risk
AnnualCD/MI
(%)
Shaw LJ and Iskandrian AE: JNC 11:171, 2004
AgeNonanginal pain Atypical angina Typical angina
Men Women Men Women Men Women
30 to 39 4 2 34 12 76 26
40 to 49 13 3 51 22 87 55
50 to 59 20 7 65 31 93 73
60 to 69 27 14 72 51 94 86
Values expressed as the % of patients with significant CHD on angiography. N. Engl J Med 1979
Sensitivity (%) Specificity (%)
Exercise ECG 45 to 61 70 to 90
Exercise stress echocardiography
70 to 85 77 to 89
Exercise stress SPECT 73 to 92 63 to 88
Pharmacologic stress echocardiography
72 to 90 79 to 95
Pharmacologic stress SPECT
88 to 91 75 to 90
Coronary CTA 93 to 99 64 to 90
2012 ACCF/AHA/ACP guidelines for dg. and management of stable CHD.
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