Physiologic assessment of coronary artery stenoses

Percutaneous Mechanical Reperfusion During Acute Myocardial Infarction

The treatment of acute myocardial infarction has progressed from bedrest to mechanical, catheter-based reperfusion. The authors review the use of percutaneous coronary intervention (PCI) as a primary treatment for acute myocardial infarction and the use of adjunctive agents. The most recent American College of Cardiology/ American Heart Association (ACC/AHA) guidelines for the use of PCI in ST segment elevation myocardial infarction (MI) advocate the use of PCI as primary therapy at those centers in which the procedure can be performed within accepted standards. Because a majority of hospitals (80%) do not have the capability of performing primary PCI, most patients are treated with thrombolytic therapy. PCI should be considered in those patients treated with thrombolytic therapy who have persistent or recurrent ischemia and/or cardiogenic shock. For patients with non-ST elevation MI, the use of an invasive strategy (early angiography and PCI if needed) has recently shown to be beneficial. Although revascularization is the basis of the acute therapy of MI, additional pharmacologic therapy in the acute setting is now recognized as a key to favorable long-term outcome.

Outcome of patients with acute coronary syndromes and moderate coronary lesions undergoing deferral of revascularization based on fractional flow reserve assessment

OBJECTIVES

To determine the outcome of consecutive patients with and without acute coronary syndromes (ACS) in whom revascularization was deferred on the basis of fractional flow reserve (FFR).

BACKGROUND

FFR < 0.75 correlates with ischemia on noninvasive tests and deferral of treatment on the basis of FFR is associated with low event rates in selected populations. Whether these low event rates apply to patients undergoing assessment of moderate stenoses in association with an ACS is not known and is an important clinical question.

METHODS

Retrospective analysis and 12 month follow-up of consecutive, moderate (50-70%) de novo coronary lesions assessed with FFR.

RESULTS

Revascularization was deferred in 120 lesions (111 patients) with FFR > or = 0.75. ACS was present in 35 patients (40 lesions). The clinical, angiographic and coronary hemodynamic characteristics of patients with and without ACS were similar. Among the 35 patients with ACS, there were 3 deaths, 1 MI, and 6 target vessel revascularizations (TVRs) (15% of lesions). Among the 76 patients without ACS, there were 5 deaths, 1 MI, and 7 TVR's (9% of lesions).

CONCLUSIONS

Deferral of revascularization based on FFR in patients with ACS and moderate coronary stenoses is associated with acceptable and low event rates at 1 year.

How to prevent unnecessary coronary interventions: identifying lesions responsible for ischemia in the cath lab

PURPOSE OF REVIEW

Coronary angiography is limited by the inability to identify intermediate coronary lesions responsible for ischemia. In the catheterization laboratory three techniques can be used for the evaluation of the physiologic significance of intermediate or borderline significant coronary stenoses: (1) pressure wire-derived coronary fractional flow reserve (FFR), (2) Doppler wire-derived measurement of coronary flow reserve (CFR), and (3) intravascular ultrasound (IVUS).

RECENT FINDINGS

All of these techniques have been validated for assessing the functional significance of intermediate stenoses, but also have inherent limitations.

SUMMARY

Overall, measurement of FFR appears to be the best method for interrogating intermediate coronary lesions. This review discusses the strengths and limitations of each of these techniques.