Prognostic value of stress echocardiography assessed by the ABCDE protocol

Journal Club Nov 4, 2021 | Atul Jaidka

Background

Traditional Stress Echo

  • Identification of regional wall motion abnormalities to identify coronary artery disease
    • Qualitatively assessed

 

  • Other prognostic parameters:
    • Exercise duration, BP response, ST-T changes and LV dilation (not reliably reported)

Compared to Alternatives

  • Advantages
    • ​Inexpensive
    • No radiation
    • Portable
    • Exercise and non-exercise
  • Disadvantages
    • Functional testing thus may not pick up non-obstructive clinical atherosclerosis that can cause events
      • Compared to Coronary CT
    • WMA are later in the ischemic cascade (not capturing perfusion changes)
      • Compared to MIBI

Pelikka 2019

Pelikka 2019

Pelikka 2019

Rest

Post Exercise

LAD Ischemia

Why New Protocol?

  • Incidence of coronary disease on stress testing has significantly decreased over the years

 

  • Traditional stress testing does not capture the heterogeneity of patients

 

  • Goal of new protocol is to provide new metrics to further risk stratify patients
    • Different variables to independently and incrementally assess points of vulnerability in a patient

 

  • When functional test is "normal", can be confidently tell patients they are "low risk"

ABCDE-SE Protocol

ABCDE Stress Echo

Step A: Myocardial Ischemia

  • Assessment: Wall motion score index, 1 (normal) - 4 (dyskinetic) in a 17 segment LV model
  • Positivity: 2 adjacent segments of same vascular territory increment by at least 1 point

GrepMed

Picano 2017

Step B: B Lines

  • Assessment: 4 quadrant lung ultrasound for b lines
  • Positivity: 2 or more  

Scali 2020

Step B: B Lines

  • Assessment: 4 quadrant lung ultrasound for b lines
  • Positivity: 2 or more  

Scali 2020

Arntfield 2021

Step C: LVCR

  • Assessment: Left ventricular contractile reserve is calculated as systolic blood pressure/end-systolic volume
  • Positivity: LVCR < 2 for exercise/dobutamine or <1 for vasodilators

Picano 2020

Step D: CFVR

  • Assessment: Coronary flow velocity reserve of mid-distal LAD (low PLAX or modified A2/3/4)
  • Positivity: CFVR < 2 

 

  • Success rate of 88% in obtaining CFVR on LAD (3000/3410). Acquisition and Interpretation in < 4 minutes

Ciampi 2019

Step D: CFVR

Cardiology 4U

Step D: CFVR

Cardiology 4U

Ciampi 2019

Ciampi 2019

Step E: HRR

  • Assessment: Heart rate reserve peak/rest heart rate
  • Positivity: HRR <1.8 for exercise/dobutamine or <1.22 for vasodilator 

 

  • Previous studiers show blunted HRR is a predictor or adverse events in vasodilator stress echo independent of inducible ischemia and beta blocker therapy

Cortigiani 2019

Example: Normal

Example: Abnormal

Study

Design

  • Design: prospective, multi-centre, international, effectiveness study
  • Intervention: ABCDE stress echo protocol
  • Patients: known or suspected chronic coronary syndrome
  • Outcomes: All cause death

Inclusion/Exclusion

  • age >18 years
  • referral for known or suspected CAD
  • no severe primary valvular or congenital heart disease, or presence of prognosis-limiting comorbidities, such as advanced cancer, reducing life expectancy to <1 year
  • echocardiography of acceptable quality at rest and during stress

Results

  • Of those with normal SE who underwent coronary angiography, 30% demonstrated obstructive CAD, whereas in those with all five abnormal steps on SE, 95% had significant CAD.

Predictors of Mortality

  • Postive:
    • B-lines
    • Coronary flow velocity reserve
    • Heart rate reserve
    • ABCDE Score 3 or greater
  • Negative:
    • Regional Wall Motion Abnormalities
    • Left ventricular contractile reserve

 

  • The mortality rate was 0.4%/year for a normal SE compared with 2.7%/year when all SE steps were abnormal.

Incremental Benefit

Study Conclusions

  • Higher ABCDE score predicts less benign outcome

 

  • Regional wall motion abnormalities, most used measure, less helpful in predicting prognosis

 

  • Steps B-E are feasibly added to current stress echo protocols

 

  • Shift assessing only coronary stenosis to patient as a whole
    • Other vulnerabilities including coronary microvascular dysfunction and autonomic dysfunction

Study Conclusions

  • Consider targeting treatments towards the identified abnormal steps

 

  • Stress echo low cost/risk/environmental impact and no radiation

 

  • ABCDE protocol can be used with any stress - exercise or pharmacological (ie. in a global pandemic pharm preferred)

Proposed Tailored Therapy

  • Step A identifies inducible ischemia --> BB/CCB/nitrates or possible revasc

 

  • Step B identifies pulmonary congestion --> diuretics

 

  • Step C (LVCR) identifies LV dysfunction --> ACEi

 

  • Isolated Step D identifies microvascular dx --> statin

 

  • Step E abnormalities can be targets by neurohormonal modulation (ie. BB/ACEi/MRA/renal denervation)

 

Treatments potentially titratable to ABCDE risk score

Discussion

Discussion

  • Dedicated training required to implement protocol
    • Specifically coronary flow of LAD is most challenging

 

  • Originally planned 5000 patients and 3 year followup but achieved ~3600 and 21 month followup
    • 2020 was planned last year of study but COVID

 

  • No other end points other than mortality to assess predictive power of protocol steps
    • Ie. B-lines and HF admissions

Discussion

  • Images were not reviewed by core lab
    • Practical for effectiveness study as has real-world applicability

 

  • Parameters were binary, positive or negative, future studies plan to consider mild-mod-severe stratification

 

  • Most patients underwent dipyridamole stress, would be beneficial to compare predictive value of the steps by stress modality (could explain why physiological measures such as LVCR were not predictive)
    • High score 4-5 were mostly in exercise group

Discussion

  • RWMA may not be a strong enough tool to assess for ischemia as significant oxygen supply demand mismatch is needed
    • Future protocols could employ myocardial contrast echocardiography to assess perfusion
    • Low usage of contrast in general in the study

 

  • Functional testing may not pick up non-obstructive lesions which can still lead to to events
    • Critics recommend carotid ultrasound to pick up on clinical atherosclerosis

Future Direction

Modified ABCDE?

Stress Echo 2030

ABCDE + F (regurgitant flow) G (LVOT gradients) L (left atrial volume/function) P ( pulmonary and LV pressures) L (RV function)

Stress Echo 2030

  • 1-SE in coronary artery disease (SECAD)
  • 2-SE in diastolic heart failure (SEDIA)
  • 3-SE in hypertrophic cardiomyopathy (SEHCA)
  • 4-SE post-chest radiotherapy and chemotherapy (SERA)
  • 5-Artificial intelligence SE evaluation (AI-SEE)
  • 6-Environmental stress echocardiography and air pollution (ESTER)
  • 7-SE in repaired Tetralogy of Fallot (SETOF)
  • 8-SE in post-COVID-19 (SECOV)
  • 9: Recovery by stress echo of conventionally unfit donor good hearts (RESURGE)
  • 10-SE for mitral ischemic regurgitation (SEMIR)
  • 11-SE in valvular heart disease (SEVA)
  • 12-SE for coronary vasospasm (SESPASM)

Questions?