evaluation of suspected cad in 2011march 4, 2011 . disclosure of relevant financial ... the cme...
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RWC Physicians’ Conference
Evaluation of Suspected CAD in 2011
Nader M. (Nader) Banki, MD
Xiushui (Mike) Ren, MD March 4, 2011
Disclosure of Relevant Financial Relationships
Under the ACCME Standards for Commercial Support, everyone who is in a position to control the content of an education activity must disclose all relevant financial relationships with any commercial interest. A “commercial interest” includes any proprietary entity producing health care goods or services, with the exemption of non-profit or government organizations and non-health care related companies. A financial relationship is relevant if it pertains to the activity’s content matter including any related health care products or services to be discussed or presented.
Drs. Banki and Ren have disclosed that they have no relevant relationships with commercial or industry organizations. The CME Department has reviewed their disclosure information for the planner(s) and/or committee/faculty for this program and they do not have relationships that present a relevant conflict of interest.
Outline
Indications for
“stress testing”
Contraindications
Testing modalities
Including CTA
Test selection
Cases
Indications
Suspected CAD Pre-operative
Pulmonary hypertension
DOE
Valvular heart disease
Viability
Risk stratification
Indications: Suspected CA
Bayes’ Theorem
Indications: Suspected CA
Indications: Suspected CA
Contraindications
Evaluation of Suspected CAD
(symptomatic)
Treadmill ECG
Stress Echo Exercise
Dobutamine
Myocardial perfusion (nuclear) Exercise
Persantine
CTA
Coronary angiography (invasive)
Evaluation of Suspected CAD
Functional: Treadmill ECG
Stress Echo
Myocardial perfusion
Anatomic CTA
Coronary angiography
Treadmill ECG
Exercise: preferred if possible Treadmill
Good for detecting ischemia and arrhythmia
Cheap
Readily available
Treadmill ECG
Stress Echo and Outcomes
Stress Echo
MPI and Outcomes
MPI
MPI
Test Performance
Stress echo: Sensitivity = 85%
Specificity = 77%
Stress MPI: Sensitivity = 87%
Specificity = 64%
Bayes’ Theorem
The probability of a patient having the
disease after a test is performed depends
on pretest probability and the test
characteristics
Bayes’ Theorem
Bayes’ Theorem
Bayes’ Theorem
Bayes’ Theorem
Use Clinical Judgment!
RWC Case #1
56 year old female with a history of hypertension, dyslipidemia, fibromyalgia and chronic L-sided upper chest pain who reports 3 months mid-chest burning with exertion.
What is her pre-test probability of obstructive CAD?
Bayes’ Theorem
RWC Case #1
Treadmill Test:
6:55 Bruce Protocol
chest burning at peak exercise
1mm horizontal ST depression
Invasive Coronary Angiography
Invasive Coronary Angiography
RWC Case #2
43 y.o. woman without CAD risk factors
presents with 2 week history of sharp
chest pain lasting 1-2 min
ECG is normal
What is the pre-test probability?
Bayes’ Theorem
RWC Case #2
Treadmill test: 8 min on Bruce protocol
Borderline ST depressions
Equivocal test
Stress thallium was (-) for ischemia
RWC Case #3
43 year old male smoker with h/o dyslipidemia presents to ED with 1-2 week history of chest pain with and without exertion
Ruled out for MI in ED, EKG normal
What is his pre-test probability of obstructive CAD?
Bayes’ Theorem
RWC Case #3
Same-day treadmill test
4:20 seconds Bruce Protocol (7.0 METs)
118 bpm (66% of MPHR)
Normal blood pressure response
Chest pain after 2 minutes
No ischemic ST-T changes were noted
Referred for CT angiogram
Coronary CT Angiography
LV
RV
LAD
Invasive Coronary Angiography
Cardiac CT Invasive Angiography
RWC Case #3
PCI of the LAD
Coronary CT Angiography
Non-invasive diagnostic imaging test using CT technology and contrast to diagnose the presence and severity of coronary artery disease
Significant improvement in diagnostic accuracy because of increase in detector rows from 4 to 16 to 64
High negative predictive value (NPV)
Coronary CT Angiography
28 studies (>2,400 patients) evaluating the sensitivity and specificity coronary artery disease (>50% stenosis) in CTA when compared with coronary angiography
Sensitivity: 99%
Specificity: 89%
PPV: 93%
NPV: 100%
Mowatt G., Heart 2008 94; 1386-1393
Coronary CT Angiography
Indications:
Equivocal stress test
Symptomatic patients with an intermediate probability of obstructive CAD
Young patient prior to valve surgery
Anomalous coronary artery
Avoid when:
No symptoms
CKD (GFR<60)
Atrial fibrillation or frequent PAC’s/PVC’s
Pregnant
Dye hypersensitivity
Coronary CT Angiography
Experience at Kaiser RWC
64 slice CT scanner
First CTA in 2007
>200 CTA’s performed
Preparation:
Renal Function <30 days prior to scan
Hold Metformin 48 hours prior
Metoprolol 25mg the night before and 50mg morning of scan
Prior to Scan
18 gauge iv started in antecubital vein of L arm
+/- iv metoprolol at time of scan
SL NTG
90 cc of contrast
Coronary CT Angiography
>9,000 patients who underwent coronary CTA Followed for 20 months
Endpoints
Major adverse cardiac events
Death
MI Revascularization
Coronary CTA- Prognosis
Radiation Exposure
Experimental and epidemiologic evidence show strong link between low-dose ionizing radiation and solid cancers and leukemia
Medical uses of radiation are the largest source exposure to public
Measured in sieverts (Sv)
Unit of ionizing radiation absorbed
Attempts to reflect the biological effect rather than the physical aspects
Background radiation in one year (3mSv)
Radiation
Retrospective study of >950,000 patients enrolled in United Health Care
Utilization data were used to estimated:
cumulative effective dose
3 year study period
NEJM 2009;361:849-57
Radiation
Background Radiation:
3 mSv/year
Radiation
Radiation Exposure
Shuman, W,Radiology 248;2:431-37
RWC Case #4
76 year old male with known CAD with a history of NSTEMI in July 2009 -> stent placement to the LAD and LCx who reports:
3 months of non-exertional L shoulder and upper arm discomfort
What is his pre-test probability of obstructive CAD?
Bayes’ Theorem
RWC Case #4
Referred for treadmill EKG test
Bruce Protocol
6 minutes
L arm pain and diaphoresis
130/90 mmHg (rest) 96/70 mmHg at peak exercise
1 mm ST segment elevation in the inferior leads
Invasive Coronary Angiography
Safety of Stress Echo
Exercise > dipyridamole > DSE
1/6,574 1/557
N=85,997
1/1,294
RWC Case #5
92 year old active female with a h/o CAD, s/p CABG x 3 in 1980 who lives alone presented to the ED with 12 hours of chest pressure. No improvement with sl ntg or asa.
Ruled out for MI in ED, EKG normal; cxr normal
What is her pre-test probability of obstructive CAD?
Bayes’ Theorem
90-99
RWC Case #5
Same-day treadmill test
9:30 seconds on modified Bruce Protocol (4.6 METs)
128 bpm (100% of MPHR)
Normal blood pressure response
Pt did not report cp or dyspnea with exercise
Non-specific st-t changes that did not meet criteria for ischemia
RWC Case #5
She presented to the RWC ED about two weeks later with recurrent chest pain and nausea
EKG showed changes consistent with acute posterior ST segment elevation MI
Heart Alert activated; patient taken urgently to RWC cath lab
Invasive Coronary Angiography
Invasive Coronary Angiography
Case Discussion
Why was this patient’s treadmill test negative?
Non-obstructive disease (true negative)
Obstructive disease (false negative)
Stress Testing in CABG patients
Exercise echo and coronary angiography performed in 182 CABG patients
JACC 1995;25:1019-23
Stress Testing in CABG Patients
“The exercise ECG has a number of limitations after
coronary bypass surgery. Resting ECG abnormalities are
frequent, and if an imaging test is not incorporated in the
study, more reliance must be placed on symptom status,
hemodynamic response, and exercise capacity. Because of
these considerations, together with the need to document
the site of ischemia, stress imaging tests are more favored
in this group, although there are insufficient data to justify
recommending a particular frequency of testing.”
ACC/AHA 2002 Guideline Update for Exercise Testing
Plaque Rupture
Circulation. 1995 Aug 1;92(3):657-71.
86%
Plaque Rupture
Subclinical Coronary Atherosclerosis
How do we identify patients who may have subclinical (non-obstructive) coronary artery disease?
Framingham Risk Score (FRS)
Age
HTN
Sex
Dyslipidemia
Smoker
Diabetic
FRS calculates a 10 year risk of death of MI
Low <10%
Intermediate 10-20%
High >20%
Wilson PW. Prediction of coronary heart disease using risk factor categories. Circulation. 1998; 97 : 1837-47
Coronary Calcium Score
Limited CT scan to assess calcification of coronary arteries
Coronary calcification is marker of atherosclerosis
1-2 mSv (plain film lumbar spine)
Coronary Calcium Score
High sensitivity for CAD but low specificity for obstructive CAD
Incremental predictive value over Framingham risk score
Indication:
Asymptomatic
Intermediate FRS (10-20% 10 year risk)
60 year old non-smoking male with:
Hypertension
Total cholesterol 190
HDL 40 LDL 125
FRS: 11% (10 years) or 1.1 % in 1 year
Coronary Calcium Score
ACCF/AHA 2007 Clinical Expert Consensus on Coronary Artery Calcium Scoring
Conclusions
Functional versus anatomic
Obstructive CAD versus the presence of CAD
Bayes’ theorem and intermediate risk
Treadmill test is safe and effective and should be first-line
in appropriate patients
Conclusions
CT Coronary Angiography
Radiation
CABG patients consider stress testing with imaging
Framingham Score
Intermediate risk population consider coronary calcium score
Bonus Clinical Case
51 year old asymptomatic obese female with DM II referred for persantine SPECT (stress test) for “pre-op evaluation for bariatric surgery.”
Is pre-operative cardiac stress test indicated?
Results
A mildly abnormal study with:
1) small reversible area (ischemia) over the anteroseptal wall
2) a fixed area (infarct) over the inferolateral wall
3) normal left ventricular (LV) systolic function
Referred for cardiac CT because of abnormal SPECT
1) Normal coronary arteries