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INVESTIGATING STABLE IHD TREADMILL, DOBUTAMINE STRESS ECHO OR STRESS THALLIUM??Dr Robin PintoHoly Family Hospital, Glenmark Cardiac Centre

FACTORS DECIDING CHOICEAbility to exerciseBaseline ECG abnormalitiesPrior CABGS / PTCA / MIPortabilityCostRadiationPhysician PreferenceSensitivity And Specificity

PROBABILITY OF CAD

VERIFICATION BIASDescribes the impact of reporting sensitivity and specificity when calculated primarily using patients with positive stress test results

Sensitivity = TP / TP + FN

Specificity = TN / TN + FP

VERIFICATION BIAS

ROLE OF ETT AS A DIAGNOSTIC TESTTEST OF CHOICE IN THOSE WITH

WITH INTERMEDIATE TEST PROBABILITY NORMAL BASLINE ECG ABLE TO EXERCISENO PRIOR REVASCULARISATION

INCREASING SENSITIVITY OF ETTEXISTING: ST deviation and slopeST / HR slope > 2.4 V / bpmST / HR index > 1.6 V / bpm

NEW:ST / HR Hysteresis integrates difference in ST segment depression between exercise and 3 min of recovery . Chronotropic incompetence

DST - ADVANTAGESTotally non invasive, safe , repeatable

No radiation

Relatively short procedure time

Simple instrumentation, portable

Can identify other structural abnormalities

Disadvantages of DSTImages difficult to acquire because of marked cardiac excursion

RWMA may be transient

Highly operator dependent

Inability to image all segments in 15%

Detection of residual ischemia in infarct zone difficult

WHATS NEW IN DST

Use of LV opacification

MCI - microvascular perfusion, viability, improving sensitivity of DST

Use of Speckle tracking / Strain imaging

32 yr/ M, IGT, Non smoker, Atypical chest painIntermediate pretest probability

49 yr old marathon runner, CT Calcium Score = 1095.03

Microvascular re-perfusion Acute MI

No microvascular reflow

MPI Myocardial Perfusion ImagingCan evaluate Ventricular function

Most sensitive for diagnosis of CAD

Identifies region of ischemia

Can assess myocardial viability

DISADV OF MPI

Attenuation artifacts

In severe disease, balanced ischemia can lead to a false negative test

PROGNOSTIC INDICATORS FROM ETTDuration of exercise < 6 METSFailure to increase syst BP > 120 mm Hg, sustained decrease > 10 mm hg below restST depression > 2.0 mmsExercise induced ST elevationAngina at low workloadsSustained (> 30 secs) / symptomatic VT

NEWER PROGNOSTIC INDICATORS FROM ETTMORTALITYFunctional Capacity (METS, DTS)Heart Rate Recovery - < 12 bpm in first min Chronotropic Incompetence < 80% THR

SUDDEN CARDIAC DEATH (SCD)TWA (T-wave alternans) > 65 V is high riskFrequent PVCs in recovery > 7 / min

ADVERSE PROGNOSTIC MARKERS IN DST & MPI

Amt of myocardium - > 3 segments in DST, > 10% myocardium in jeopardy

More than one territory

LV dysfunction LV dilatation on DST, Fall in EF by > 5%, Global EF < 45% , Transient ischemic dilatation ratio > 1.2, Lung uptake, RV uptake / dilatation

CONCLUSIONPerforming these tests routinely in the general population is probably not indicated

ETT Test of choice for the majority of patients with a baseline normal ECG and the ability to walk on the treadmill

DST / MPI Those with a non diagnostic ETT and intermediate test probability.

CONCLUSIONDST Increasing use, especially useful in those with LBBB / bronchoconstriction

MPI especially to assess residual ischemia in infarct territory, assess viability, post CABGS, assess significance of non critical lesions

Prognostic information gleaned from each of these tests extremely important in making clinical decisions

LAD lesion

70 yr /F LAD/RCA CT calcified, Calcium score = 1175

60 yr old man police officerEx smokerHypercholesterolemiaHigh stress job in Anti-terrorist squadChest discomfort during morning exercise

(high pre-test probability)

ISCHEMIC CASCADE

Comparative Definition of Moderate-Severe IschemiaLeslee J. Shaw,J Am Coll Cardiol Img 2014;7:593604

Cardiac death / MI 4-6 % per year

ETT Dukes Treadmill score < -10

Stress Echo > = 3 /16 new akinetic segment

Nuclear stress > 10% Ischemic myocardium

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MYOCARDIAL VIABILITYWith Thallium Redistribution. If no redistribution at 4 hrs further injection and delayed imaging even at 24 hours

Using Technetium 99m Labeled agents - > 50% of maximal tracer activity in a dysfunctional segment