What is the clinical evidence from this study?

Study design: Cross-Sectional. Population: Hypertrophic Cardiomyopathy (n=53). Intervention: Hypertrophic cardiomyopathy vs. Control subjects with structurally normal hearts. Primary outcome: Coronary flow reserve (p=0.01).

What question did this study set out to answer?

To characterize the hemodynamic mechanisms and physical wave dynamics underlying myocardial perfusion abnormalities and ischemia in patients with hypertrophic cardiomyopathy.

October 1, 2016Journal of the American College of CardiologyOpen Access

Mechanisms of Myocardial Ischemia in Hypertrophic Cardiomyopathy

Q: What are the key findings of this study?

Patients with hypertrophic cardiomyopathy had a significantly lower coronary flow reserve (1.9 vs 2.7) and a larger backward compression wave during systole (38% vs 21%) compared to control subjects.

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Key result

HCM is linked to ~30% lower coronary flow reserve and larger systolic backward compression waves.

P=0.01
n=53

Why the study?

What are the mechanisms underlying perfusion abnormalities in patients with hypertrophic cardiomyopathy compared to controls?

Population

33 patients with hypertrophic cardiomyopathy (HCM) and 20 control patients

Comparison

Simultaneous pressure and flow measurement in… vs Control patients

Design

Cross-sectional

Authors

CRClaire E. RaphaelInterventional Cardiology RCRobert CooperKaiser Permanente KPKim H. ParkerVascular Medicine

Discussion

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Implication

Supports systolic microvascular compression as a driver of perfusion deficits in HCM; hypothesis-generating for targeted interventions pending prospective validation.

Key Points

To characterize the hemodynamic mechanisms and physical wave dynamics underlying myocardial perfusion abnormalities and ischemia in patients with hypertrophic cardiomyopathy.
Assessed 33 patients with hypertrophic cardiomyopathy and 20 control subjects.
Measured simultaneous pressure and flow in the proximal left anterior descending artery at rest and during hyperemia to perform wave intensity analysis.
Quantified myocardial perfusion reserve using first-pass perfusion cardiac magnetic resonance.
Coronary flow reserve was significantly lower in patients with hypertrophic cardiomyopathy compared to control subjects (1.9 ± 0.8 vs. 2.7 ± 0.9; p = 0.01).
Hypertrophic cardiomyopathy hemodynamics exhibited a significantly larger systolic backward compression wave (38 ± 11% vs. 21 ± 6%; p < 0.001) and a smaller backward expansion wave (27% ± 8% vs. 33 ± 6%; p = 0.006) versus controls.
Severe left ventricular outflow tract obstruction induced an additional systolic deceleration wave, while the increase in flow-accelerating waves during hyperemia correlated directly with myocardial perfusion reserve (rho = 0.53; p < 0.01).

Study Design

Type

Cross-Sectional (n=53)

Multicenter

Yes

Structured PICO

What are the mechanisms underlying perfusion abnormalities in patients with hypertrophic cardiomyopathy compared to controls?

Population

33 patients with hypertrophic cardiomyopathy (HCM) and 20 control patients

Intervention

Simultaneous pressure and flow measurement in the proximal left anterior descending artery at rest and during hyperemia (wave intensity analysis) and quantitative first-pass perfusion cardiac magnetic resonance

Comparator

Control patients

Outcome

Coronary flow reserve and wave intensity parameters (backward compression wave, backward expansion wave)surrogate

Main Result

Absolute Event Rate: 1.9% vs 2.7%

p-value: p=0.01

In patients with HCM, perfusion abnormalities are driven by dynamic interactions including a large backward compression wave during systole due to compressive deformation of intramyocardial blood vessels.

Limitations

Recruited patients were symptomatic with a clinical indication for angiography, limiting generalizability to asymptomatic patients
Control subjects had risk factors for coronary disease and potential mild microvascular disease
Differences in medication use (beta-blockers, ACE inhibitors) between groups were not adjusted for
Findings cannot be generalized to pediatric or adolescent populations
Use of sum-of-squares estimate for wave speed introduces uncertainty into separated wave intensity calculations

Cite This Study

Raphael et al. (2016) conducted a cross-sectional in Hypertrophic Cardiomyopathy (n=53). Hypertrophic cardiomyopathy vs. Control subjects with structurally normal hearts was evaluated on Coronary flow reserve (p=0.01). Patients with hypertrophic cardiomyopathy had a significantly lower coronary flow reserve (1.9 vs 2.7) and a larger backward compression wave during systole (38% vs 21%) compared to control subjects.

synapsesocial.com/papers/6a0f89b2fa36b6e053fcbfe4 https://doi.org/10.1016/j.jacc.2016.07.751

Topics

Hypertrophic cardiomyopathy Cardiac imaging Women and heart disease

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Implication

Supports systolic microvascular compression as a driver of perfusion deficits in HCM; hypothesis-generating for targeted interventions pending prospective validation.

Mechanisms of Myocardial Ischemia in Hypertrophic Cardiomyopathy

Discussion

Member takes

Implication

Key Points

Study Design

Structured PICO

Main Result

Limitations

Cite This Study

Topics

Mechanisms of Myocardial Ischemia in Hypertrophic Cardiomyopathy

Discussion

Member takes

Implication

Key Points

Study Design

Structured PICO

Main Result

Limitations

Cite This Study

Also Consider

Topics

Also Consider