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Published on: June 28, 2019
Prognostic implication of Doppler echocardiographic derived coronary flow reserve in patients with left bundle branch
Lauro Cortigiani1, Fausto Rigo, Sonia Gherardi
1Cardiology Division, Campo di Marte Hospital, Lucca, Italy.
Insights
Coronary flow reserve (CFR) assessed by Doppler during stress echocardiography is a strong predictor of mortality and myocardial infarction in patients with left bundle branch block (LBBB). An abnormal CFR (≤2.0) independently identifies high-risk individuals, including those with non-ischemic stress echo findings.
Area of Science:
- Cardiology
- Echocardiography
- Vascular Physiology
Background:
- Pharmacological stress echocardiography is crucial for prognostication in patients with left bundle branch block (LBBB).
- The prognostic value of Doppler-derived coronary flow reserve (CFR) in this specific patient group remains under investigation.
Purpose of the Study:
- To evaluate the additive prognostic value of CFR assessment using Doppler during dipyridamole stress echocardiography in patients with LBBB.
- To determine if CFR provides independent prognostic information beyond traditional markers in LBBB patients.
Main Methods:
- 324 patients with LBBB and known or suspected coronary artery disease underwent dipyridamole stress echocardiography.
- Coronary flow reserve (CFR) of the left anterior descending artery was assessed by Doppler; CFR ≤ 2.0 was considered abnormal.
- Patients were followed for mortality and myocardial infarction (MI); multivariate analysis identified independent predictors of events.
Main Results:
- 16% of patients had stress echo-detected ischemia, and 43% had an abnormal CFR (≤2.0).
- An abnormal CFR (≤2.0) was an independent predictor of mortality (HR 4.69) and death or MI (HR 3.91).
- Patients with CFR ≤ 2.0 had significantly higher 4-year mortality (49% vs. 6%) and hard event rates (56% vs. 8%) compared to those with CFR >2.0.
Conclusions:
- Doppler-derived CFR is a strong and independent prognostic indicator in LBBB patients.
- Abnormal CFR identifies high-risk individuals, even those with negative stress echo findings while on therapy.
- CFR assessment adds significant prognostic value to clinical findings and stress echo results in LBBB patients.
Aims:
Myocardial ischaemia during pharmacological stress echocardiography is a strong prognostic predictor in patients with a left bundle branch block (LBBB). However, the additive value of Doppler-derived coronary flow reserve (CFR) during pharmacological stress testing remains to be investigated in this subset of patients.
Methods And Results:
The study group consisted of 324 LBBB patients (187 men; age 68 ± 10 years) with known (n = 74) or suspected (n = 250) coronary artery disease who had undergone dipyridamole (up to 0.84 mg/kg over 6') stress echocardiography with CFR assessment of left anterior descending (LAD) by Doppler. A value of CFR ≤ 2.0 was considered abnormal. The median duration of follow-up was 15 months (first to third quartile: 8-34 months). Of the 324 patients, 52 (16%) had ischaemia at stress echo by wall motion criteria, and 139 (43%) had a CFR ≤ 2. During follow-up, 51 (16%) events occurred: 37 deaths and 14 myocardial infarctions (MIs). Age (HR: 1.09, 95% CI: 1.04-1.15, P < 0.0001), resting wall motion score index (HR: 5.29, 95% CI: 2.36-11.89, P < 0.0001), smoking habit (HR: 4.38, 95% CI: 1.93-9.91, P < 0.0001), and CFR ≤ 2 (4.69, 95% CI: 1.96-11.19, P = 0.001) were independently correlated with mortality, while CFR ≤ 2 (HR: 3.91, 95% CI: 1.90-8.04, P < 0.0001), age (HR: 1.06, 95% CI: 1.02-1.10, P = 0.001), smoking habit (HR: 2.25, 95% CI: 1.18-4.30, P = 0.01), ischaemia at stress echo (HR: 2.30, 95% CI: 1.11-4.77, P = 0.02), and resting wall motion score index (HR: 2.17, 95% CI: 1.11-4.25, P = 0.02) were independently correlated with death or MI. Four-year mortality and 4-year hard event rate were markedly higher in patients with CFR ≤ 2 than in those with CFR >2 (49 vs. 6% and 56 vs. 8%, respectively; P < 0.0001 for both). A CFR of ≤ 2 was associated with a significantly higher annual hard event rate independently of age, sex, ejection fraction, history of coronary artery disease, diabetes, and hypertension. Moreover, it was correlated with an increased (P < 0.0001) yearly mortality and event rate in patients with non-ischaemic stress echo conducted on therapy. At incremental analysis, a CFR of ≤ 2 added prognostic value to clinical findings, resting wall motion score index, ongoing anti-ischaemic therapy, and ischaemia at stress echo when both death and death or MI were the clinical endpoints.
Conclusions:
Abnormal CFR on LAD is a strong and independent indicator of mortality and death or MI in patients with LBBB, and is associated with markedly increased risk also in the subset of patients with stress echo negative for ischaemia on therapy.
