Measurement of myocardial fractional flow reserve during coronary angioplasty in patients with old myocardial infarction

Coronary pressure measurements in post-myocardial infarction patients

The development of pressure monitoring guide-wires has facilitated the measurements of coronary pressures distal to a stenosis. The ratio of the distal coronary and aortic pressures (P(d)/P(a)) measured during maximal hyperaemia is a useful index for diagnosis and monitoring the treatment of patients with coronary artery disease and for guiding percutaneous coronary intervention. However, the role of coronary pressure measurements in post- myocardial infarction (MI) patients is not well established. Coronary pressure measurements should be used with caution during the acute phase of MI due to serious micro-vascular impairment. The hyperaemic pressure P(d)/P(a) ratio can identify ischaemic myocardial territories in patients with recent MI. Theoretically, coronary pressure measurements may be of value in predicting myocardial recovery after revascularization in post-MI patients with a moderate stenosis of the infarct-related artery and without angiographically evident collaterals.

Use of fractional flow reserve versus stress perfusion scintigraphy after unstable angina. Effect on duration of hospitalization, cost, procedural characteristics, and clinical outcome

OBJECTIVES

The present study sought to determine the value of fractional flow reserve (FFR) compared with stress perfusion scintigraphy (SPS) in patients with recent unstable angina/non-ST-segment elevation myocardial infarction (UA/NSTEMI).

BACKGROUND

Fractional flow reserve, an invasive index of stenosis severity, is a reliable surrogate for SPS in patients with normal left ventricular function. An FFR > or = 0.75 can distinguish patients after myocardial infarction (MI) with a positive SPS from those with a negative SPS. However, the use of FFR has not been investigated after UA/NSTEMI.

METHODS

Seventy patients who had recent UA/NSTEMI and an intermediate single-vessel stenosis were randomized to either SPS (n = 35) or FFR (n = 35). Patients in the SPS group were discharged if the SPS revealed no ischemia, whereas those in the FFR group were discharged if the FFR was > or = 0.75. Patients with a positive SPS and those with an FFR <0.75 underwent percutaneous transluminal coronary angioplasty. The use of FFR markedly reduced the duration and cost of hospitalization compared with SPS (11 +/- 2 h vs. 49 +/- 5 h [-77%], p < 0.001; and 1,329 US dollars +/- 44 US dollars vs. 2,113 US dollars +/- 120 US dollars, respectively, p < 0.05). There were no significant differences in procedure time, radiation exposure time, or event rates during follow-up, including death, MI, or revascularization.

CONCLUSIONS

These data indicate that: 1) the use of FFR in patients with recent UA/NSTEMI markedly reduces the duration and cost of hospitalization compared with SPS; and 2) these benefits are not associated with an increase in procedure time, radiation exposure time, or clinical event rates.

Relationship between extent of residual myocardial viability and coronary flow reserve in patients with recent myocardial infarction

BACKGROUND

The presence of viability in an infarct zone implies an intact microvasculature. We hypothesized that coronary flow reserve (CFR), which assesses the microcirculation, would correlate with the extent of viability in infarction zones.

METHODS

CFR was measured after stenting in 17 patients with single vessel disease >48 hours from infarction. Viability was determined with use of single-photon emission computed tomography sestamibi imaging.

RESULTS

Sestamibi uptake in the infarct zone correlated with CFR in the infarct artery (r = 0.62, P =.008) and sestamibi uptake in the infarct zone was greater in patients with normal CFR than in patients with abnormal CFR (61.9 +/- 9.1% vs 46.3 +/- 9.6%, P =.004). In addition, CFR was greater in patients with viability compared with patients without viability (2.4 +/- 1.3 vs 1.4 +/- 0.4, P =.015).

CONCLUSIONS

CFR correlates with the extent of viability after infarction. Preserved CFR in an infarct-related artery implies preserved viability.