Korean Circ J.  2013 Aug;43(8):534-540. 10.4070/kcj.2013.43.8.534.

The Relationship between Microcirculatory Resistance and Fractional Flow Reserve in Patients with Acute Myocardial Infarction

• Oh JH
• Kim C
• Ahn J
• Kim JH
• Yang MJ
• Lee HW
• Choi JH
• Lee HC
• Cha KS
• Hong TJ

• KMID: 2224843
• DOI: http://doi.org/10.4070/kcj.2013.43.8.534

Abstract

BACKGROUND AND OBJECTIVES
It was demonstrated that the fractional flow reserve (FFR) with partial balloon obstruction may have implications for assessing viable myocardium. In a different way, the index of microcirculatory resistance (IMR) was introduced as a useful indicator for assessing microvascular function. We evaluated the relationship between the FFR0.8 and the IMR.
SUBJECTS AND METHODS
We studied 48 consecutive patients who had undergone coronary intervention for acute myocardial infarction (AMI). After revascularization using stent(s), an undersized short balloon was positioned inside the stent and inflated to create a specific normalized pressure drop of FFR (distal coronary/aortic pressure=0.80) at rest. The FFR0.8 was obtained during hyperemia with the fixed state balloon-induced partial obstruction. IMR was measured by three injections of saline. The association between the FFR0.8 and the IMR was investigated.
RESULTS
The mean age of the patients was 60+/-12 years and 36 (75%) overall presented with ST-segment elevation myocardial infarction. The mean FFR0.8 was 0.68+/-0.06. A statistically significant correlation between the FFR0.8 and the log-transformed IMR(true) (LnIMR(true)) was found through a multivariable linear regression analysis (beta=0.056, p<0.001). Both the FFR0.8 and the LnIMR(true) had a positive correlation with the log-transformed peak troponin I (TnI) with statistical significance (r2=0.119, p=0.017; r2=0.225, p=0.006, respectively).
CONCLUSION
There was a positive correlation between the LnIMR(true) and the FFR0.8. Both of the values were associated with peak TnI. Those values may be used as appropriate surrogate measures of microvascular function after AMI.

Keyword

Myocardial infarction; Fractional flow reserve, myocardial; Microcirculation; Percutaneous coronary intervention

MeSH Terms

Fractional Flow Reserve, Myocardial
Humans
Hyperemia
Linear Models
Microcirculation
Myocardial Infarction
Myocardium
Percutaneous Coronary Intervention
Stents
Troponin I
Troponin I

Figure

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  Fig. 1 Scatter plots between the FFR0.8 and the log-transformed IMR (LnIMR) (A), and the log-transformed IMRtrue (LnIMRtrue) (B). The dashed lines represent the 95% confidence intervals for the regression line (solid). FFR: fractional flow reserve, IMR: index of microcirculatory resistance.

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  Fig. 2 Scatter plots between the log-transformed peak TnI (LnpTnI) and the FFR0.8 (A), and the log-transformed IMRtrue (LnIMRtrue) (B). The dashed lines represent the 95% confidence intervals for the regression line (solid). FFR: fractional flow reserve, IMR: index of microcirculatory resistance, TnI: troponin I.

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  Fig. 3 Receiver-operator characteristic curve analysis for the IMR and the IMRtrue for the prediction of the FFR0.8 ≥0.7. FFR: fractional flow reserve, IMR: index of microcirculatory resistance, BCV: best cut-off value, AUC: area under the curve, CI: confidence interval.

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