Fractional flow reserve after previous myocardial infarction

Marques and colleagues have conducted an interesting study on microvascular resistance of viable tissue within an infarcted area. 1 This study is important, not only from a conceptual point of view, but also because it has several relevant implications for the applicability of MIBI spect and fractional flow reserve (FFR) measurement in patients with previous myocardial infarction and a residual or recurrent stenosis in the infarct-related coronary artery. The use of these methods, one non-invasive and the other invasive, has been supported by theoretical and empirical data, but the present study corroborates their usefulness in patients with previous myocardial infarctions. To understand the clinical implications of the study by Marques et al., it is paramount to understand microvascular resistance, which so far has been hard to assess in conscious humans. Microvascular resistance equals the ratio of distal coronary pressure divided by myocardial blood flow. As surrogates for the numerator and denominator of that ratio, sometimes aortic pressure and coronary blood flow or flow velocity, respectively, have been used, which might be correct in healthy persons. However, in patients with coronary artery disease, the first number overestimates distal coronary pressure and the second one underestimates myocardial blood flow, and therefore use of these surrogates leads to progressive overestimation of myocardial resistance in the case of a stenotic coronary artery. 2– 4 As a consequence, our knowledge about microvascular resistance in patients with coronary disease, and especially after previous myocardial infarction, has remained questionable. Furthermore, from a clinical point of view, i.e. the question of whether inducible ischaemia is still present or present again, the interesting index to study is hyperaemic blood flow, corresponding to minimal resistance of the viable myocardium within the infarcted zone, not the resistance of the scar tissue

The crux of maximum hyperemia:the last remaining barrier for routine use of fractional flow reserve

In the decision-making process of revascularization of coronary artery stenoses by percutaneous coronary intervention (PCI) or coronary artery bypass graft surgery (CABG), the presence and extent of reversible ischemia associated with such particular stenoses is of paramount importance (1, 2, 3). A stenosis associated with reversible ischemia (also called functionally significant or hemodynamically significant stenosis) causes symptoms of angina pectoris and has a negative influence on outcome (1, 2). Therefore, the general feeling is that such lesions should be revascularized if technically feasible. On the contrary, functionally nonsignificant stenoses do not cause symptoms by definition and have an excellent outcome with medical therapy (3, 4, 5). Therefore, revascularization of such lesions is generally not indicated

From research to clinical practice:current role of intracoronary physiologically based decision making in the cardiac catheterization laboratory

\u3cp\u3eDecisions regarding coronary interventions should be combined with objective evidence of myocardial ischemia. The most common physiologic approach utilizes hospital facilities outside the catheterization laboratory, requiring additional time and cost. With the introduction of sensor-tipped angioplasty guide wires, distal coronary flow velocity and pressure can be obtained in the cardiac catheterization laboratory, facilitating physiologically based decisions regarding the need for intervention. In the catheterization laboratory, physiologically significant stenoses can be characterized as having impaired post-stenotic coronary flow reserve <2.0 and pressure-derived fractional flow reserve <0.75, both variables related strongly to positive ischemic perfusion imaging or stress testing results. Deferring coronary interventions on the basis of normal translesional physiology is safe and is associated with a low rate (<10%) of lesion progression over a 10-month follow-up period. Preliminary data indicate that excellent physiologic and anatomic end points after balloon angioplasty are associated with low (<20%) restenosis rates at 6-month follow-up. Clinically relevant relations of in-laboratory physiology support the insight that physiologic, as much as or more than anatomic variables, ultimately determine the functional status of a patient. Current data suggest that an intracoronary physiologic approach complements coronary lumenology and appears to have important clinical and economic implications for patients undergoing invasive evaluation and treatment of coronary artery disease.\u3c/p\u3

False-negative myocardial scintigraphy in balanced three-vessel disease, revealed by coronary pressure measurement

\u3cp\u3eIn nuclear perfusion imaging of the myocardium, a false-negative test result in patients with balanced three-vessel disease is a well-known pitfall. This paper describes a patient with typical chest pain and a negative myocardial perfusion scintigram. At coronary angiography, intermediate stenoses in the left anterior descending (LAD), left circumflex (LCX), and right coronary (RCA) arteries were present. Fractional flow reserve, measured by coronary pressure measurement, was 0.54, 0.56, and 0.66 respectively for the LAD, LCX, and RCA, unequivocally demonstrating the presence of balanced three-vessel disease. The patient underwent successful bypass surgery and remained event-free thereafter.\u3c/p\u3

Noninvasive assessment of right gastroepiploic artery graft patency using transcutaneous color Doppler echocardiography

\u3cp\u3eBackground. Because the right gastroepiploic artery graft (GEA), when routed antegastrically, is situated just behind the abdominal wall, we investigated the possibility of evaluating graft patency and flow characteristics using transabdominal color Doppler echocardiography. Methods. The right GEA graft was evaluated in 71 patients who underwent complete arterial revascularization, 4 months (range, 2 to 17 months) postoperatively. Selective angiography of the right GEA was performed in the patients in whom the graft could not be visualized using color Doppler echocardiography. Results. Flow in the right GEA graft was detected in 65 (91.5%) of 71 patients using color Doppler echocardiography. In all visualized right GEAs, a biphasic flow pattern was observed, with higher peak velocity during systole. Mean (± standard deviation) peak systolic velocity was 76 ± 16 cm/s. Mean (± standard deviation) velocity was 41 ± 14 cm/s. Selective angiography of the right GEA in 5 patients in whom the graft could not be visualized using echocardiography showed four patent and functional grafts and one graft that was open but not functional ('slender sign'). One patient died before angiography could be performed. The sensitivity of noninvasive ultrasound assessment of the patency of the right GEA graft was 94% (65 of 69 patients). In this group of patients, an overall right GEA graft patency rate of 97% (69 of 71 patients) was found at mean follow-up of 4 months (range, 2 to 17 months). Conclusions. The right GEA graft is an adequate coronary artery graft with a good short-term patency rate, and transcutaneous color Doppler echocardiography is a useful tool for evaluating its patency and flow characteristics. Selective angiography of the right GEA can be avoided in most cases and is indicated only when the graft cannot be detected using Doppler echocardiography.\u3c/p\u3