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Changes in phasic coronary blood flow velocity profile and relative coronary flow reserve in patients with
M K Kyriakidis1, J M Dernellis, A E Androulakis
1Department of Cardiology, Hippokration Hospital, University of Athens, Greece.
Insights
Hypertrophic obstructive cardiomyopathy (HOCM) can cause regional coronary flow impairment due to uneven hypertrophy. Relative coronary flow reserve (CFR) effectively identifies these disturbances, aiding in selecting patients for therapeutic interventions.
Area of Science:
- Cardiology
- Cardiovascular Physiology
Background:
- Hypertrophic obstructive cardiomyopathy (HOCM) is characterized by abnormal thickening of the heart muscle.
- Nonuniform myocardial hypertrophy can affect coronary artery function.
Purpose of the Study:
- To investigate coronary flow velocity in HOCM patients.
- To test the hypothesis of differing coronary flow reserve (CFR) in coronary arteries supplying regions with nonuniform myocardial hypertrophy.
Main Methods:
- Assessed coronary flow velocity in the left anterior descending (LAD) and left circumflex (LCX) arteries in HOCM, hypertrophic cardiomyopathy (HCM), and normal subjects.
- Measured relative CFR (LAD/LCX ratio) at rest, during rapid atrial pacing, and dobutamine stress.
Main Results:
- Relative CFR was reversed in HOCM patients during stress (LAD/LCX(CF) decreased from 1.25 to 0.82), unlike controls.
- HOCM patients showed significantly lower relative CFR (0.62) compared to normal subjects (1.05).
- A strong inverse correlation was found between relative CFR and peak systolic outflow tract gradient (r²=0.74).
Conclusions:
- Regional hypertrophy in HOCM can lead to impaired regional coronary flow.
- Relative CFR is a valuable tool for estimating regional coronary flow disturbances.
- Relative CFR may assist in patient selection for novel interventional therapies.
Background:
In this study, we both investigated coronary flow velocity in hypertrophic obstructive cardiomyopathy (HOCM) and tested the hypothesis of differing coronary flow reserve (CFR) of coronary arteries perfusing left ventricular regions with nonuniform myocardial hypertrophy by measuring the relative CFR.
Methods And Results:
Coronary flow velocity was assessed in left anterior descending coronary (LAD) and left circumflex (LCX) arteries in 18 patients with HOCM and marked hypertrophy only in the ventricular septum, in 13 patients without obstruction (HCM), and in 9 age- and sex-matched normal subjects at rest, during rapid atrial pacing, and after dobutamine infusion (5 to 30 microg/kg per minute). Relative CFR was estimated as the ratio between absolute CFR of the LAD and absolute CFR of the LCX (LAD/LCX(CF)). At the peak of rapid atrial pacing and during dobutamine stress, LAD/LCX(CF) was reversed in HOCM patients (from 1.25+/-0.11 to 0.82+/-0.07 and 0.79+/-0.06, respectively), whereas it remained unchanged in control subjects (from 1.0+/-0.1 to 1.0+/-0.05 and 1.0+/-0.05, respectively; P<.001). In HCM patients, LAD/LCX(CF) at rest was 1.10+/-0.11, whereas during rapid atrial pacing and dobutamine stress, it was 0.92+/-0.08 and 0.90+/-0.09, respectively. Relative CFR was 0.62+/-0.05 in HOCM patients and 1.05+/-0.05 (P<.001) in normal subjects. There was an inverse correlation between relative CFR and peak systolic outflow tract gradient (r2=.74, P<.001).
Conclusions:
Regional distribution of hypertrophy in some patients with HOCM resulted in regional impairment of coronary flow. Relative CFR can be used to estimate regional disturbances of coronary flow and may help in patient selection for new interventional therapeutic techniques.