Cardiology overview invasive cardiology

STEMI

 * Revascularization in STEMI patients greater than 12 hours from symptom onset who have no symptoms of ischemia or clinical instability was deemed inappropriate. Likewise the need for immediate angiography in these patients was deemed unnecessary.
 * Revascularization of the non-culprit artery in STEMI patients who are not clinically unstable was deemed appropriate.

Stable Ischemia without Prior CABG

 * High risk findings on non invasive testing, greater symptoms, a large burden of disease in the native vessels increases the likelihood that the revascularization is appropriate.
 * In patients who have not undergone a stress test, PCI was deemed to be appropriate in the presence of 1 or 2 vessel disease with or without involvement of the proximal LAD if class III or IV anginal symptoms were present. The amount of medical therapy was not included in their consideration of appropriateness.
 * In patients who have not undergone a stress test who have an intermediate stenoses, revascularization without further documentation of the significance of the stenosis by either FFR or IVUS was deemed inappropriate.
 * In patients who have not undergone a stress test who have severe symptoms and either an abnormal FFR or IVUS, revascularization is appropriate.

Stable Ischemia with Prior CABG

 * High risk findings on non invasive testing, greater symptoms, a large burden of disease in the native vessels or bypass conduits increases the likelihood that the revascularization is appropriate.
 * Revascularization was deemed inappropriate in patients on no or minimal medications who had low risk findings on non-invasive testing.
 * There are many uncertain scenarios in this population.

PCI and CABG Among Patients with Advanced Coronary Artery Disease

 * In general revascularization was deemed necessary in this population of patients.
 * CABG was deemed to be appropriate in all the clinical scenarios.
 * PCI was deemed to be appropriate in patients with 2 vessel disease without involvement of the proximal LAD, and it was deemed uncertain in patients with 3 vessel disease.
 * Among patients with left main disase and or left main disease plus multivessel disease, CABG was deemed to be appropriate. PCI was deemed not to be a reasonable approach and "unlikely to imporve the patient's health or survival".

Results of COURAGE

 * PCI improved symptoms and quality of life over optimal medical treatment for the first 6 months and not at 3 years
 * Based upon the nuclear substudy of COURAGE, PCI should only be perfromed if > 10% of the myocardium is jeopardized.

The Outcomes of Lesions that are not Hemodynamically Significant by FFR: The DEFER Trial
The DEFER trial demonstrated that among intermediate lesions that were not hemodynamically significant (i.e. the FFR was greater than 0.75), there was no impact on clinical outcomes (Death or death / MI). Furthermore the risk of adverse events was quite low and mortality attributable to these lesions was under 1% per year.

In the DEFER trial, a total of 325 patients undergoing PCI of an intermediate lesion were randomized to deferral of the PCI if the FFR was > 0.75 (n=91) or performance of a PCI (n=90) even though the lesion was not functionally significant. In other words this trial test what would happen if lesions that are not functionally significant either are or are not dilated. If the FFR was < 0.75, the lesion was dilated.

At 5 years, the survival did not differ between those patients who had a a PCI versus those who did not have a PCI (the deferred group) of a stenosis that was not associated with ischemia. Likewise there was no difference in the risk of death or MI or the number of patients who were free of chest pain on follow-up between the two groups. The risk of cardiovascular death was less than 1% per year in vessels that were either treated or untreated and was not affected by stenting.

The Role of FFR in Selecting Which Lesions to Dilate in the Patient with Multivessel Disease: Results of the FAME Trial
The FAME trial randomized 1005 patients with multivessel disease (excluding those with left main disease or STEMI) who were undergoing intracoronary stent implantation to one of the two following strategies:
 * 1) Drug-eluting stent implantation guided by angiography alone in which case all significant lesions were stented versus
 * 2) Drug-eluting stent implantation guided by FFR measurements in addition to angiography. patients who were randomly assigned to the FFR strategy had stents implanted in those lesions with an FFR of 0.80 or less.

Patients in the FFR guided strategy had fewer stents placed than those in the strategy relying upon angiography alone (2.7±1.2 versus 1.9±1.3 stents, p<0.001). At one year, the primary end point of death, nonfatal myocardial infarction, and repeat revascularization was observed in 18.3% of patients in the angiography group versus 13.2% patients) in the angiography plus FFR group (P=0.02). there was no difference in the incidence of survival free from angina at one year: 78% of patients in the angiography group versus 81% of patients in the FFR group (P=0.20). The risk of death was 3.0% vs 1.8% (p=0.19).  The risk of death or MI was 11.1% in the angiography group versus 7.3% in the FFR group (p=0.04).  The number of patients who were event free and free of angina were 73% in the FFR group and 67.6% in the angiography group (p=0.07).  Procedure costs and the use of contrast was lower in the FFR group as well.  It should be noted that only 63% of lesions that were measured had an FFR less than 0.80.

The authors speculate that the results of COURAGE and SYNTAX might have been different had stenting been performed with FFR guidance in which case only those lesions that were ischemic would have been treated. THE FFR cutpointis 075 to 0.80 and FAME used the higher end of this range to that fewer lesions were left unrevascularized.

By not dilating and stenting lesions that appear to be severe angiographically but are not associated with ischemia, you avoid the placement of a stent which could result in a risk of thrombosis or restenosis in a lesion that was not associated with ischemia. The FAME authors concluded that "Routine measurement of FFR in patients with multivessel coronary artery disease who are undergoing PCI with drug-eluting stents significantly reduces the rate of the composite end point of death, nonfatal myocardial infarction, and repeat revascularization at 1 year."

The Role of FFR in Left Main Coronary Artery Disease (LMCA)
In a small non-randomized study, 30 patients who had a hemodynamically significant FFR of <0.75 underwent coronary artery bypass grafting, and an accompanying 24 patients who had a non-hemodynamically significant FFR > 0.75 were managed medically. There was no difference in clinical outcomes between these two groups. In this very small study no patients in the medically managed group died or had AMI.

Likewise, in a small study of 51 patients, FFR measurenet was helpful to identify patients with intermediate left main disease in whom deferral of surgical revascularization was associated with excellent survival and low event rates.

The Role of FFR in Acute Coronary Syndromes
The utility of FFR during the course of an acute coronary syndrome is unclear.

In patients with previous myocardial infarction (defined as > 6 days before FFR is performed), FFR has been closely related to abnormalities on SPECT imaging (sensitivity of 82%, specificity of 87%). Patients with a higher LVEF had higher FFRs independent of the lumen diameters. FFR may be helpful in identifying those patients who may benefit from revascularization > 6 days after an MI.

The Role of FFR in Serial Lesions
Serial lesions may limit the maximal hyperemia achievable in each of the stenoses. The interaction and significance of serial stenoses depends upon their sequence, the distance between them, their severity, the length of the stenoses, and the flow down the artery. A pullback can be performed, and the lesion with the greatest gradient can be dilated first. The gradient can then be checked again to determine if any of the remaining lesions need to be dilated as well.