What is the clinical evidence from this study?

Study design: Case-Control. Population: Myocardial Infarction (n=68). Intervention: Myocardial infarction (exposure) vs. Healthy controls. Primary outcome: Average left ventricular blood flow kinetic energy indexed to end-diastolic volume (LV KEiEDV) (p=0.02).

February 1, 2018Open Access

Left ventricular blood flow kinetic energy after myocardial infarction - insights from 4D flow cardiovascular magnetic resonance

Key Result

Myocardial infarction patients demonstrated significantly lower average left ventricular blood flow kinetic energy compared to healthy controls (6.5 vs 8.5 μJ/ml, P=0.02).

Study Design

Type

Case-Control (n=68)

Multicenter

Yes

Structured PICO

Does 4D flow CMR detect altered left ventricular blood flow kinetic energy in patients with myocardial infarction compared to healthy controls?

Population

68 subjects: 48 patients with myocardial infarction (22 acute STEMI treated by primary PCI within 12 hours, 26 chronic MI with ischemic scar on LGE) and 20 age/gender-matched healthy controls. Mean age 57 in MI group, 52 in controls. Exclusions: non-ischemic cardiomyopathy, severe valvular heart disease, eGFR < 30 ml/min/1.73m2, hemodynamic instability (Killip class III/IV requiring IV diuretics), and contraindications to CMR.

Intervention

Four-dimensional (4D) flow cardiovascular magnetic resonance (CMR) imaging

Comparator

Healthy controls with no history or symptoms of cardiovascular disease and normal LV ejection fraction

Outcome

Left ventricular (LV) blood flow kinetic energy (KE) parameters indexed to LV end-diastolic volume (KEiEDV), including averaged LV, minimal, systolic, diastolic, peak E-wave, and peak A-wave KEiEDV, as well as in-plane proportion of LV KE and time difference to peak E-wave KE propagationsurrogate

4D flow CMR demonstrates that myocardial infarction is associated with significant reductions in left ventricular systolic blood flow kinetic energy, which correlates with infarct size and the degree of LV impairment.

Main Result

Absolute Event Rate: 6.5% vs 8.5%

p-value: p=0.02

Limitations

Respiratory navigation was omitted for the 4D flow acquisition.
Temporal resolution of the 4D flow was 40 ms, which may affect the quality of KE and TD assessment.
MI patients received contrast whereas healthy controls did not, potentially introducing bias.
Scanner's electrocardiogram used to calculate time differences may result in less precise estimates.
Differences in physiological conditions between breath-hold cine and free-breathing 4D flow.
Results cannot be applied to patients with significant valvulopathy, cardiomyopathies and congenital heart disease.

Abstract

Myocardial infarction (MI) leads to complex changes in left ventricular (LV) haemodynamics that are linked to clinical outcomes. We hypothesize that LV blood flow kinetic energy (KE) is altered in MI and is associated with LV function and infarct characteristics. This study aimed to investigate the intra-cavity LV blood flow KE in controls and MI patients, using cardiovascular magnetic resonance (CMR) four-dimensional (4D) flow assessment. Forty-eight patients with MI (acute-22; chronic-26) and 20 age/gender-matched healthy controls underwent CMR which included cines and whole-heart 4D flow. Patients also received late gadolinium enhancement imaging for infarct assessment. LV blood flow KE parameters were indexed to LV end-diastolic volume and include: averaged LV, minimal, systolic, diastolic, peak E-wave and peak A-wave KEiEDV. In addition, we investigated the in-plane proportion of LV KE (%) and the time difference (TD) to peak E-wave KE propagation from base to mid-ventricle was computed. Association of LV blood flow KE parameters to LV function and infarct size were investigated in all groups. LV KEiEDV was higher in controls than in MI patients (8.5 ± 3 μJ/ml versus 6.5 ± 3 μJ/ml, P = 0.02). Additionally, systolic, minimal and diastolic peak E-wave KEiEDV were lower in MI (P < 0.05). In logistic-regression analysis, systolic KEiEDV (Beta = − 0.24, P < 0.01) demonstrated the strongest association with the presence of MI. In multiple-regression analysis, infarct size was most strongly associated with in-plane KE (r = 0.5, Beta = 1.1, P < 0.01). In patients with preserved LV ejection fraction (EF), minimal and in-plane KEiEDV were reduced (P < 0.05) and time difference to peak E-wave KE propagation during diastole increased (P < 0.05) when compared to controls with normal EF. Reduction in LV systolic function results in reduction in systolic flow KEiEDV. Infarct size is independently associated with the proportion of in-plane LV KE. Degree of LV impairment is associated with TD of peak E-wave KE. In patient with preserved EF post MI, LV blood flow KE mapping demonstrated significant changes in the in-plane KE, the minimal KEiEDV and the TD. These three blood flow KE parameters may offer novel methods to identify and describe this patient population.

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Cite This Study

Garg et al. (Thu,) conducted a case-control in Myocardial Infarction (n=68). Myocardial infarction (exposure) vs. Healthy controls was evaluated on Average left ventricular blood flow kinetic energy indexed to end-diastolic volume (LV KEiEDV) (p=0.02). Myocardial infarction patients demonstrated significantly lower average left ventricular blood flow kinetic energy compared to healthy controls (6.5 vs 8.5 μJ/ml, P=0.02).

synapsesocial.com/papers/6a0f2bf204e2b0ba896ca10f https://doi.org/https://doi.org/10.1186/s12968-018-0483-6

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