1. Ontario Cardiac Rehabilitation Pilot Project
Risk Stratification
Ontario Cardiac Rehabilitation Pilot Project

2. Recommendation: CACR
“ …programs consistently use some form of risk stratification for all their patients entering cardiac rehabilitation…”

3. Why risk stratify? Ensure safety of the patient
Identify patient’s prognosis and progression variables – direct intervention
Assess long term outcomes
Assist in allocation of resources

4. Risk Stratification Guidelines
AACVPR
ACC
ACP
AHA
CACR
Duke treadmill score
Currently, risk stratification in Canada follows the format and guidelines laid out by these various associations.
The format of these risk stratification schemes (1-4) is broad based and reflects both good clinical judgement and some of the available prognostic information/variables from the literature.
Disadvantages:
These other formats do not take into account the patient’s risk for disease progression based on the number and severity of heart hazards.
Poorly predictive of complications observed in a cardiac rehab program (JCR article)
Can be stratified in more than one category with some algorithms (AHA), or be clustered in only two groups (Class B or C)
Advantages:
They do highlight patient safety concerns, wrt exercise
The algorithm can still be used if data is missing.
The Duke treadmill score determines an individual’s prognosis form their TMT based on functional capacity, degree of ST depression, presence or absence of angina.

5. AACVPR Guidelines
Three categories: Low, moderate, high
Based on the following variables:
Functional capacity, LV function, history, signs and symptoms of ischemia, arrhythmias, hemodynamic response to exercise, presence of clinical depression.
Highest category assumed with the presence of any one of the risk factors in that category. Missing data not accounted for in the process.
Guidelines for Cardiac Rehabilitation and Secondary Prevention Programs, AACVPR,
Human Kinetics, 1999

6. CACR Guidelines Prognosis score (short-term absolute risk)
GXT: functional capacity
Ischemia, CCS class or max ST depression
LVEF
Dysrhythmias
Heart hazard score (long-term absolute risk)
Smoking
Lipids BP
Diabetes
Psychological distress
The CACR tool is relatively new, first appearing n the CACR Guidelines of It is UNVALIDATED, however, the variables on which the scores are based have been shown to be highly predictive of risk. The composite score has yet to be shown to be predictive of outcome, of complication rate in rehab, or of outcome in rehab. Studies are currently using the model (Lynette, UOHI) and further information on the valididty and predictive power of this meodel wil be forthcoming. Furthermoe, the MoH pilot project will also provide further experience with the model and short term outcome data.
It is the only tool that includes both the risk for recurrent event (prognosis score, short term absolute risk) and risk for cardiovascular disease progression (heart hazard score or long term absolute risk).
ST: In general, an individual’s risk of future CVD events is dependent on both the number and severity of their risk factors and their susceptibility to those risk factors.
LT: represents the 10 year absolute risk for CVD development or progression.
Epidemiological data from the last 50 years, particularly the Framingham study, has clearly shown that the risk of CVD rises as the magnitude of risk the heart hazard abnormality increases.
Evidence from clinical trials has also demonstrated that the benefits of heart hazard modification are greatest in those with the most abnormal baseline values.

7. Absolute vs. relative risk
Absolute: probability of suffering an acute CVD related event within a finite time period
Short-term (<5-10yrs)
Long-term (>10 yrs)
Relative: ratio between two levels of absolute risk
Individual’s absolute risk
Absolute risk of low-risk reference population
By definition, all our patients with documented cardiovascular disease are at high long-term absolute risk for subsequent cardiovascular events as opposed to those populations where the symptoms and signs of CVD are not yet manifest.
- Yet, within the CVD population, these individuals can be risk stratified further into those at moderate, high or very high risk for future cardiovascular events.

8. Short-term Absolute Risk
< 5 yr risk of future cardiac event
Linked to prognostic variables
Assist in:
optimizing safety of exercise
allocating resources
The short-term absolute risk of future cardiac events, although linked to the progression of atherosclerotic CVD, is most often determined by factors such as functional capacity, ventricular function, ischemic burden, and the presence or absence of significant cardiac dysrhythmias.
Therefore, an individuals ST absolute risk is linked to prognostic variables, while their long term risk is related to risk of atherosclerotic progression which is linked to risk factor load.

9. Short Term Absolute Risk
Functional Capacity (METs)
Score
Pt’s Score
> 12
> 10 1
> 9 2
> 8 3
> 7 5
> 6 7
< 6 10
Poor functional capacity, usually defined as <5 METs on GXT, can predict poor cardiac function and poor cardiac prognosis, severe deconditioning of skeletal muscles may prevent individuals form reaching their exercise potential. In these circumstances, poor FC cannot be used as a surrogate for poor cardiac systolic function.
FC should be determined by a standardized GXT. CPX vs. regular GXT, different protocols.
8 METs low risk
6-8 METs moderate risk
< 6 METs high – very high risk, unless restricted by other medical conditions
GXT should be performed on MEDs (BB) as this is the state that the patient will be exercising in and the original trials that looked at the implication of <5 MET capacity plus ST depression comprised 50% of patients on BB (McNeer et al, Circ, 57: 64-70, 1977

10. Short Term Absolute Risk
LVEF (%)
Score
Pt’s Score
> 55 3 7
< 35 15
Traditionally, LV systolic function has been viewed as one of the most powerful predictors of future cardiac events.
However, the relationship between LVEF and functional capacity is relatively poor, and LVEF cannot be used to predict FC.
NYHA functional class is sometimes used tp predict the presence of LV dysfunction, the scale is far frm reliable in many settings. Particularly, many deconditioned individuals will have lower NYHA class than their objective LVEF may suggest.
Consequently, wherever possible, objective determination of LVEF should be made:
May have more than one measure of LVEF:
Cath (best)
Nuclear (MUGA) or echo next best
Use most recent.
? Pre-event?

11. Short Term Absolute Risk
Ischemic Burden: use one of following
Score
Pt’s Score
History
CCS Class I
CCS class II 3
CCS class III 5
CCS class IV 7
ST MaxHR
None
1 mm
1- 2 mm
> 2 mm 10
Myocardial Perfusion
Mild-mod, 1 vessel
Mod, multivessel
Severe, single-multi 15
- Ischemic burden refers to the severity and extent of inducible myocardial ischemia in CAD pts with CAD.
- The magnitude of ST depression and workload achieved can provide some information on ischemic burden, the most sensitive and specific information is obtained through myocardial perfusion and/or cardiac imaging studies. (thallium, PET, Cardiolite, myoview, stress echo).
- Patients with evidence of multivessel disease on imaging, have the worst prognosis and the highest rate of subsequent CVD events of all patients with documented CVD.
- If on intake GXT, substantial ischemic burden is still present, the patient should be referred back to their cardilogist for further investigation before beginning exercise training.
- Pts with severe inducible ischemia, evidence of multivessel CVD but not suitable for revascularization, may still be referred. These patients are at very high risk for future events, and should participate in supervised, closely monitored exercise: telemetry monitoring, conservative exercise prescription, thorough teaching re: S&S. Flagging of GXT results to cardiologist.
- Likewise, if there is a change in ischemic burden from entry to exit GXT, the referring MD and cardiologist must be notified and further f/u arranged.
Conversely, pts with single vessel CAD, minimal symptoms, and only mild to moderate inducible ischemia may be considered to be at reduced risk for future cardiac events.
GXT on or off meds: Diagnostic GXT pre-d/c off meds to predict prognosis, and on meds for ExRx ideal.
However, in the absence of symptoms to suggest myocardial ischemia, pts tested with anti-ischemic meds present are likely at low risk for future cardiac events.
See data dictionary for explanations of CCS class 1-4 (0=assymp.; 1=no angina with ordinary activity, angina with strenuous, rapid or prolonged activity,; 2=slight limitation of ordinary activity, walking or climbing stairs rapidly, walk uphill, walk in cold or after meals, under emotional distress or in few hrs after awakening, walk>2 blocks on level, climb>1 flight stairs; 3= marked limitation of ordinary activity, walk 1-2 blocks climb 1 flight of stairs at normal pace; 4=symptoms with any physical activity.

12. Short Term Absolute Risk
Dysrhythmias
Score
Pt’s Score
None
Atrial 2
Isolated PVC, <10/hr 3
Isolated PVC, >10/hr 6
Nonsustained VT 8
Recurrent VT 15
Hx VF MI < 6hr
MI > 6hr
No MI with ischemia
No MI no ischemia 12
Cardiac dysrhythmias are common in patients with CHD.
The presence of atrial and/or ventricular dysrhythmias is frequently dependent on left ventricular systolic function and ischemic burden.
Patients with symptomatic dysrhythmias, regardless of etiology, should be immediately and expediently referred back to the attending physician.
In asymptomatic individuals, high risk dysrhythmias include non-sustained or sustained VT and arial fib with a rapid, uncontrolled ventricular response rate. These should precipitate immediate referral to the the attending physician.
The most common scenario you will encounter is patients with frequent PVCs. Unfortunately the suppression of PVCs in some patients with CVD results in an increased not decreased mortality (CAST trial). Action: consider contirbuting variables such as ischemic burden, LV dysfunction, biochemical and/or haematological abnormalities. Monitor in exercise for any symptoms.

13. Short Term Absolute Risk
Sum of:
Functional capacity score
LVEF score
Ischemic burden score
Dysrhythmia score

14. Long Term Absolute Risk
Risk of disease progression
Increasing number of points reflects increasing ‘exposure’ of heart hazard
10 year absolute risk of CVD development/progression
Only traditional risk factors
It is important to emphasize that the risk of CVD progression refers specifically to the ongoing process of atherosclerosis as it applies to the formation of new atherosclerotic plaques and to the progressive narrowing of existing plaques . Disease progression risk is not meant to reflect the risk of future cardiac events per se. However, the risk of future cardiac events in any one individual must take into account both disease progression risk and risk of an acute event.
Assessment of risk for disease progression should be beneficial for helping establish length and intensity of therapy for secondary prevention interventions.
The total risk score is determined from scales based on Framingham data.
Thus these scores apply best to white suburban populations.
The increased number of points assigned to progressively abnormal heart hazards reflects the element of exposure.
The level of disease progression risk scores reflects the ten-year absolute risk of CVD development.
Only so-called traditinal risk factors included, and not newly emergong risk factors such as homocysteune, Lp(a), PAI-1, c-reactive protein or even physical activity level.

15. Disease Progression Risk
Heart Hazard
Women
Men
Pt’s score
Age, yrs
< 34
- 9
- 1
35 – 39
- 4
40 – 44 1
45 – 49 3 2
50 – 54 6
55 – 59 7 4
60 – 64 8 5
65 – 69 9
70 – 74 10
> 75 15

16. Disease Progression Risk
Heart Hazard: Cholesterol
Women
Men
Pt’s score
Total: <4.14 mmol/L -3 -2 1 2
>7.25 3
LDL: <2.59 mmol/L -1
>4.93 5
HDL: <0.9 mmol/L
>1.56

17. Disease Progression Risk
Heart Hazard: BP (mmHg)
Women
Men
Pt’s score
Systolic
<120 -3 1 2
>160 3
Diastolic
<80
80-84
85-89
90-99
>100

18. Disease Progression Risk
Heart Hazard
Women
Men
Pt’s score
Diabetes
Yes 6 4 No
Psychological distress
Smoking
Diabetes: Defined as diagnosed diabetes.
If intake glucose is above target (>7), then it should be repeated and patient referred back to primary care physician or be assessed for diabetes. If diabetes is diagnosed after intake, based on intake glucose, then you must change this field in the database, so a positive diagnosis for diabetes is used for RS score calculation.
Psychological distress: For purposes of this pilot, this will be defined by HADS score. >8 on depression, >10 on anxiety, or >14 overall would indicate psychological distress.
Smoking: Yes indicates a current smoker or a former smoker who has quit less than 1 year from intake date. Therefore important to record the quit date if smoker quit within the past year.

19. Long Term Absolute Risk
Sum of:
Age score
Lipid (TC, LDL, HDL) score
BP score
Diabetes score
Psychosocial distress score
Smoking score
Women = sum of scores x 1.5
Men = sum of scores x 1.4
The number of options for each heart hazard is added up and the point total determines the absolute risk of CVD development or progression.
In the secondary prevention setting, the risk scores are adjusted to reflect the increased risk of subsequent events in this population. The risk adjustments are based on data form the lipid lowering trials and unstable angina trials and are based on the incidence of recurrent CV events in patients form the placebo groups of these trials.
The higher risk adjustment score for women reflects their increased risk of CV events, compared to males, once they have developed CVD.

20. CACR Guidelines: Overall Risk
A risk category is then assigned according to the point totals.
Overall risk is determined by adding the two subscales.
?? Also suggests in CACR guidelines, that in the interest of patient safety and to maximize opportunities for heart hazard intervention, if the risk of disease progression and the risk of acute cardiac event falls within a different risk category, then the variable with the highest risk level should be used to determine overall risk.??
A moderate level of risk is equivalent to approximately a 10% risk or less of disease progression and recurrent CVD events over a ten year period (<1%/year)
High level is equivalent to approx 10-50% risk over 10 years (1-5%/year)
Very high level is approx equivalent to >50% risk or >5% per year.
Canadian Guidelines for Cardiac Rehabilitation & CVD Prevention, CACR, 1999

21. Use of Risk Stratification Scores
Low S/T & L/T risk
Minimal or no intervention
Low S/T, high L/T risk
Home or unsupervised programs & heart hazard modification
High S/T & L/T risk
Supervised exercise & structured heart hazard modification

22. Clinical Application High or very high long term risk:
Structured approach to heart hazard modification
Educational tool for patients
High or very high short term risk:
Supervised exercise
Consider ECG monitoring
Higher degree of supervision
May need to hold exercise until further investigation
Satellite sites: refer to coordinating centre
Non-invasive evidence of LM or 3VD with poor LV function, I.e. poor short term risk, should be aggressively investigated for treatable coronary lesions.

23. Case Study #1 Medical History Heart Hazards IWMI May 2000
Cath: LM, LAD, Cx normal; RCA 100% distally; LVEF 76%
PTCA/stent RCA, 100% to 0
GXT: 8.3 METs, no angina, no ST changes, no arrhythmias
Heart Hazards
63 yrs., male
BP: 130/78
BMI: 28.2
Girth: 98 cm
Physical activity: 75 min/week
TC 4.8, LDL 2.7, HDL 1.12, Tg 2.25, FBG 4.8
D/c smoking x 25 yrs
8.3 METs 108% predicted
Physical activity: walk 25 min, 3x/wk at moderately brisk pace

24. Case Study #1: S/T Risk Variable Pt’s Results Range Pt’s Score
FC (METs)
8.3
>8 3
LVEF
76%
>55
Ischemic Burden
No ST depression
Dysrhythmias
None
Total
3 = low-mod
8.3 METs, 108% predicted

25. Case Study #1: L/T Risk Heart Hazard Pt’s value Range Pt’s score (M)
Age 63 5
T-Chol
4.8
4.15 – 5.17
LDL-C
2.7
2.60 – 3.36
HDL-C
1.12
0.91 – 1.16 1
SBP
130
130 –139
DBP 78
<80
Diabetes No
Psychological distress
HADS n/a, none o
Smoking
D/C 25 yrs
Total
7 X 1.4=9.8 = high

26. Case Study # 1 Low-Mod S/T risk High L/T risk
Total = 12.8, low-mod overall risk
Cardiac rehab program:
Home exercise program: min/wk, resistance training
Nutrition counselling: weight control, dyslipidemia
Pharmacotherapeutic intervention: Baycol
Home program with structured approach to risk factor modification:
Physical activity to address increasing physical activity level to target, promote weight loss, optimize blood pressure. Monitored with log books and three visits to UOHI.
Nutrition counselling to address weight loss and dietary changes to improve LDL. (Food score was 76, target >81).
Physician evaluation, Baycol started 0.2 mg, monitored at 12 weeks and 20 wks.

27. Case Study #1: Outcomes Clinical variable Intake score Exit score
Smoking No BP
130/78
120/72
Physical activity
75 min/wk
305 min/wk
BMI
28.2
27.6
Waist, girth 98 92
T-chol
4.8
3.5
LDL-C
2.7
1.8
HDL-C
1.12
1.17
Triglycerides
2.25
1.26
Glucose
4.1
FC (METs)
8.3
8.8
CACR Risk score
12.1-low-mod
5.6 – low-moderate
ST risk: Unchanged at 3
LT risk improved at 2x1.3=2.6 (low-moderate)
Total risk at 5.6 (low-moderate)

28. Case Study #2 Medical History Heart Hazards IWMI 1992, PTCA RCA
PTCA RCA x
Recurrent angina 2000, cath: LAD 70%, Cx 100%, RCA 95/90%, LVEF 34%
PTCA/stent RCA mid and distal
GXT: 6.1 METs, ST depression to 3 mm, assymptomatic, frequent PVCs & couplets
Heart Hazards
71 yr old male
D/C smoking x 35 yrs
BP 168/68
No regular exercise
BMI 27.5, girth 103 cm
TC 4.3, LDL 1.7, HDL 1.3, Tg 2.77, FBG 5.6
Strongly positive ECG response for ischemia, starting at 2’55” into the test. (achieved 8’59”)
6.1 METs 95% predicted
MEDs: Novasen, novahydrazide, lipitor, metoprolol, accupril, diltiazem
On lipitor

29. Case Study #2: S/T Risk Variable Pt’s Results Range Pt’s Score
FC (METs)
6.1
>6 7
LVEF
34%
<35 15
Ischemic Burden
3 mm ST depression
>2mm 10
Dysrhythmias
Freq PVC
PVC>10/hr 6
Total
38 = very high

30. Case Study #2: L/T Risk Heart Hazard Pt’s value Range Pt’s score (M)
Age 71
70 – 74 7
T-Chol
4.3
4.15 – 5.17
LDL-C
1.7
<2.59 -1
HDL-C
1.3
1.30 – 1.55
SBP
168
>160 3
DBP 68
<80
Diabetes No
Psychological distress
HADS n/a, none o
Smoking
D/C 35 yrs
Total
8 X 1.4=11.2 = high

31. Case Study #2: Very high S/T risk High L/T risk
Total = 49.2, very high overall risk
Cardiac rehab program:
Referred back to cardiologist, exercise initially on hold, now returned to supervised exercise, ExRx below ischemia, telemetry monitoring, booked for CABG July 2001.
BP monitored, multiple therapy