Procedural microvascular activation in long lesions treated with bioresorbable vascular scaffolds or everolimus-eluting stents: the PROACTIVE trial

AIMS

Significant platelet activation after long stented coronary segments has been associated with periprocedural microvascular impairment and myonecrosis. In long lesions treated either with an everolimus-eluting bioresorbable vascular scaffold (BVS) or an everolimus-eluting stent (EES), we aimed to investigate (a) procedure-related microvascular impairment, and (b) the relationship of platelet activation with microvascular function and related myonecrosis.

METHODS AND RESULTS

Patients (n=66) undergoing elective percutaneous coronary intervention (PCI) in long lesions were randomised 1:1 to either BVS or EES. The primary endpoint was the difference between groups in changes of pressure-derived corrected index of microvascular resistance (cIMR) after PCI. Periprocedural myonecrosis was assessed by high-sensitivity cardiac troponin T (hs-cTnT), platelet reactivity by high-sensitivity adenosine diphosphate (hs-ADP)-induced platelet reactivity with the Multiplate Analyzer. Post-dilatation was more frequent in the BVS group, with consequent longer procedure time. A significant difference was observed between the two groups in the primary endpoint of ΔcIMR (p=0.04). hs-ADP was not different between the groups at different time points. hs-cTnT significantly increased after PCI, without difference between the groups.

CONCLUSIONS

In long lesions, BVS implantation is associated with significant acute reduction in IMR as compared with EES, with no significant interaction with platelet reactivity or periprocedural myonecrosis.

3286Fractional flow reserve-guided treatment strategy for left main coronary artery stenoses. Ten-year clinical outcome

Background

Revascularization decisions regarding left main (LM) coronary stenoses are often very challenging. Non-invasive tests can yield false negative results. On the other hand, some technical aspects of fractional flow reserve (FFR) measurement, as well as the interpretation of their results, are less codified than for other coronary segments.

Purpose

To investigate the 10-year clinical outcome of patients with isolated angiographically intermediate LM coronary stenosis in whom the treatment strategy was based on Fractional Flow Reserve (FFR) measurements.

Methods

From 1999 to 2009 we included 96 patients with isolated intermediate LM coronary disease (DS% 30–70%) evaluated with FFR measurement. When FFR was >0.80, patients were deferred to medical therapy (Deferral-group, n=71). When FFR was ≤0.8, surgical revascularization therapy was proposed (Revascularization-group, n=25). Death, the occurrence of myocardial infarction (MI) and the need for target vessel revascularization (TVR) were evaluated in both groups.

Results

There were no significant differences in clinical characteristics between the 2 groups. Mean DS% was 35% in the Deferral-group and 43% in the Revascularization-group (p<0.01). Average FFR was 0.88 in the Deferral-group and 0.71 in the Revascularization-group (p<0.01). In the latter, the 10-year survival estimate was 72% while it was 77% in the Deferral group (HR [95% CI]: 1.28 [0.53–3.10]; p=NS). No difference was found between the 2 groups in terms of MI (4.5% vs. 1.6%; HR [95% CI]: 3.5 [0.22–56.0]; p=NS) or TVR (9% vs. 12%; HR [95% CI]: 0.94 [0.20–4.43]; p=NS).

Conclusions

The use of FFR to defer revascularization in patients with non-significant isolated LM stenosis is safe and is associated with favourable clinical outcome at 10 years.

Intracoronary EnalaPrilat to Reduce MICROvascular Damage During Percutaneous Coronary Intervention (ProMicro) study

OBJECTIVES

This study investigated the influence of intracoronary enalaprilat on coronary microvascular function and peri-procedural outcome measures in patients with stable angina undergoing percutaneous coronary intervention (PCI).

BACKGROUND

Intracoronary angiotensin-converting enzyme inhibitors have been shown to relieve myocardial ischemia in stable patients and to improve epicardial flow in patients with ST-segment elevation myocardial infarction. Yet, it is still unclear whether these effects are mediated by a modulation of the coronary microcirculation.

METHODS

We randomly assigned 40 patients to receive either an intracoronary bolus of enalaprilat (50 μg) or placebo before elective PCI. The index of microvascular resistance was measured at baseline, 10 minutes after study drug administration, and after PCI. High-sensitivity cardiac troponin T was measured as a marker of myocardial injury.

RESULTS

Infusion of enalaprilat resulted in a significant reduction in index of microvascular resistance (27 ± 11 at baseline vs. 19 ± 9 after drug vs. 15 ± 8 after PCI), whereas a significant post-procedural increase in index of microvascular resistance levels was observed in the placebo group (24 ± 15 at baseline vs. 24 ± 15 after drug vs. 33 ± 19 after PCI). Index of microvascular resistance levels after PCI were significantly lower in the enalaprilat group (p < 0.001). Patients pre-treated with enalaprilat also showed lower peak values (mean: 21.7 ng/ml, range: 8.2 to 34.8 ng/ml vs. mean: 32.3 ng/ml, range: 12.6 to 65.2 ng/ml, p = 0.048) and peri-procedural increases of high-sensitivity cardiac troponin T (mean: 9.9 ng/ml, range: 2.7 to 19.0 ng/ml vs. mean: 26.6 ng/ml, range: 6.3 to 60.5 ng/ml, p = 0.025).

CONCLUSIONS

Intracoronary enalaprilat improves coronary microvascular function and protects myocardium from procedure-related injury in patients with coronary artery disease undergoing PCI. Larger studies are warranted to investigate whether these effects of enalaprilat could result into a significant clinical benefit.

Effective radiation dose, time, and contrast medium to measure fractional flow reserve

OBJECTIVES

This study sought to define the additional effective radiation dose, procedural time, and contrast medium needed to obtain fractional flow reserve (FFR) measurements after a diagnostic coronary angiogram.

BACKGROUND

The FFR measurements performed at the end of a diagnostic angiogram allow the obtaining of functional information that complements the anatomic findings.

METHODS

In 200 patients (mean age 66 +/- 10 years) undergoing diagnostic coronary angiography, FFR was measured in at least 1 intermediate coronary artery stenosis. Hyperemia was achieved by intracoronary (n = 180) or intravenous (n = 20) adenosine. The radiation dose (mSv), procedural time (min), and contrast medium (ml) needed for diagnostic angiography and FFR were recorded.

RESULTS

A total of 296 stenoses (1.5 +/- 0.7 stenoses per patient) were assessed. The additional mean radiation dose, procedural time, and contrast medium needed to obtain FFR expressed as a percentage of the entire procedure were 30 +/- 16% (median 4 mSv, range 2.4 to 6.7 mSv), 26 +/- 13% (median 9 min, range 7 to 13 min), and 31 +/- 16% (median 50 ml, range 30 to 90 ml), respectively. The radiation dose and contrast medium during FFR were similar after intravenous and intracoronary adenosine, though the procedural time was slightly longer with intravenous adenosine (median 11 min, range 10 to 17 min, p = 0.04) than with intracoronary adenosine (median 9 min, range 7 to 13 min). When FFR was measured in 3 or more lesions, radiation dose, procedural time, and contrast medium increased.

CONCLUSIONS

The additional radiation dose, procedural time, and contrast medium to obtain FFR measurement are low as compared to other cardiovascular imaging modalities. Therefore, the combination of diagnostic angiography and FFR measurements is warranted to provide simultaneously anatomic and functional information in patients with coronary artery disease.

Fractional flow reserve and myocardial perfusion imaging in patients with angiographic multivessel coronary artery disease

OBJECTIVES

The aim of this study was to investigate the correlation between myocardial ischemia detected by myocardial perfusion imaging (MPI) with single-photon emission computed tomography with intracoronary pressure-derived fractional flow reserve (FFR) in patients with multivessel coronary disease at angiography.

BACKGROUND

Myocardial perfusion imaging can underestimate the number of ischemic territories in patients with multivessel disease. However, there are limited data comparing MPI and FFR, a highly accurate functional index of myocardial ischemia, in multivessel coronary disease.

METHODS

Sixty-seven patients (201 vascular territories) with angiographic 2- or 3-vessel coronary disease were prospectively scheduled to undergo within 2 weeks MPI (rest/stress adenosine) and FFR in each vessel.

RESULTS

In 42% of patients, MPI and FFR detected identical ischemic territories (mean number of territories 0.9 +/- 0.8 for both; p = 1.00). In the remaining 36% MPI underestimated (mean number of territories; MPI: 0.46 +/- 0.6, FFR: 2.0 +/- 0.6; p < 0.001) and in 22% overestimated (mean number of territories; MPI: 1.9 +/- 0.8, FFR: 0.5 +/- 0.8; p < 0.001) the number of ischemic territories in comparison with FFR. There was poor concordance between the ability of the 2 methods to detect myocardial ischemia on both a per-patient (kappa = 0.14 [95% confidence interval: -0.10 to 0.39]) and per-vessel (kappa = 0.28 [95% confidence interval: 0.15 to 0.42]) basis.

CONCLUSIONS

Myocardial perfusion imaging with single-photon emission computed tomography has poor concordance with FFR and tends to underestimate or overestimate the functional importance of coronary stenosis seen at angiography in comparison with FFR in patients with multivessel disease. These findings might have important consequences in using MPI to determine the optimal revascularization strategy in patients with multivessel coronary disease.

Quantitative assessment of coronary microvascular function in patients with and without epicardial atherosclerosis

AIMS

The influence of atherosclerosis and its risk factors on coronary microvascular function remain unclear as current methods of assessing microvascular function do not specifically test the microcirculation in isolation. We examined the influence of epicardial vessel atherosclerosis on coronary microvascular function using the index of myocardial resistance (IMR).

METHODS AND RESULTS

IMR (a measure of microvascular function) and fractional flow reserve (FFR, a measure of the epicardial compartment) were measured in 143 coronary arteries (116 patients). Fifteen patients (22 arteries, mean age 48+/-16 years) had no clinical evidence of atherosclerosis (control group). One hundred and one patients (121 arteries, mean age 63+/-11 years) had established atherosclerosis and multiple cardiovascular risk factors (atheroma group). Mean IMR in the control group (19+/-5, range 8-28) was significantly lower than in the atheroma group (25+/-13, range 6-75) (P<0.01). However, there was large overlap between IMR in both groups, with 69% of IMR values in patients with atheroma being within the control range. Mean FFR was also higher in the control group (0.96+/-0.02, range 0.93-1.00) than in the atheroma group (0.85+/-0.14, range 0.19-1.00) (P<0.01). There was no correlation between IMR and FFR (r=0.09; P=0.24), even when results in the control (r=0.02; P=0.92) and atheroma (r=0.15; P=0.10) groups were analysed in isolation. Using stepwise multiple regression analysis presence/absence of atheroma (ss=0.42; P=0.02) was the only independent determinant of IMR.

CONCLUSIONS

Mean IMR is higher in patients with epicardial atherosclerosis. However, there is a large overlap between IMR in patients with and without epicardial atherosclerosis.

Long-term clinical outcome after fractional flow reserve-guided treatment in patients with angiographically equivocal left main coronary artery stenosis

BACKGROUND

Significant left main coronary artery stenosis is an accepted indication for surgical revascularization. The potential of angiography to evaluate the hemodynamic severity of a stenosis is limited. The aims of the present study were to assess the long-term clinical outcome of patients with an angiographically equivocal left main coronary artery stenosis in whom the revascularization strategy was based on fractional flow reserve (FFR) and to determine the relationship between quantitative coronary angiography and FFR.

METHODS AND RESULTS

In 213 patients with an angiographically equivocal left main coronary artery stenosis, FFR measurements and quantitative coronary angiography were performed. When FFR was > or =0.80, patients were treated medically or another stenosis was treated by coronary angioplasty (nonsurgical group; n=138). When FFR was <0.80, coronary artery bypass grafting was performed (surgical group; n=75). The 5-year survival estimates were 89.8% in the nonsurgical group and 85.4% in the surgical group (P=0.48). The 5-year event-free survival estimates were 74.2% and 82.8% in the nonsurgical and surgical groups, respectively (P=0.50). Percent diameter stenosis at quantitative coronary angiography correlated significantly with FFR (r=-0.38, P<0.001), but a very large scatter was observed. In 23% of patients with a diameter stenosis <50%, the left main coronary artery stenosis was hemodynamically significant by FFR.

CONCLUSIONS

In patients with equivocal stenosis of the left main coronary artery, angiography alone does not allow appropriate individual decision making about the need for revascularization and often underestimates the functional significance of the stenosis. The favorable outcome of an FFR-guided strategy suggests that FFR should be assessed in such patients before a decision is made "blindly" about the need for revascularization.

Severity of coronary arterial stenoses responsible for acute coronary syndromes

Acute myocardial infarctions were generally believed to result from plaque rupture and thrombosis at the site of a "mild to moderate" coronary stenosis. To assess the severity of coronary stenoses that predisposed to acute coronary syndrome, the 317 patients prospectively included were (1) 102 patients with acute ST-elevation myocardial infarction (STEMI) referred for primary percutaneous coronary intervention (PCI), (2) 135 patients with non-STEMI or unstable angina pectoris (UAP) referred for semiurgent PCI, and (3) 80 patients with stable angina pectoris (SAP) admitted for elective PCI. Patients with STEMI were included if thrombus aspiration could restore normal antegrade coronary blood flow. After aspiration (but before PCI), a high-quality angiogram was obtained and the reference diameter, minimal luminal diameter, and percentage of diameter stenosis of the culprit lesion were quantified. In patients with non-STEMI/UAP and SAP, aspiration was not performed. Average diameter of stenosis was similar in patients with STEMI and those with SAP (66 +/- 12% vs 65 +/- 10%, respectively; p = NS), but was slightly larger in patients with non-STEMI/UAP (71 +/- 12%; p <0.05 vs both STEMI and SAP). In patients with STEMI, only 11% of culprit stenoses were found to have diameter stenosis <50% after removal of the thrombus. In conclusion, most STEMIs occurred at the site of severe coronary stenosis. Diameter stenosis severity was <50% in a minority of cases.

Relation of low response to clopidogrel assessed with point-of-care assay to periprocedural myonecrosis in patients undergoing elective coronary stenting for stable angina pectoris

Impaired responses to antiplatelet therapy assessed by laboratory tests are associated with an increased risk of recurrent ischemic events after percutaneous coronary intervention (PCI). This study was designed to determine the relation between responses to aspirin and clopidogrel as assessed by a point-of-care assay (Verify Now, Accumetrics, San Diego, California) and periprocedural myocardial infarction (PMI) in patients undergoing elective PCI for stable angina. One hundred twenty-two consecutive patients undergoing elective coronary stenting prospectively received aspirin 500 mg and clopidogrel 600 mg >or=12 hours before PCI. Clopidogrel response was measured with P2Y12 reaction units (PRUs) and percent inhibition P2Y12 from baseline (percent inhibition P2Y12) and aspirin response with aspirin reaction units (ARUs). Troponin T level was considered positive if it was >0.03 ng/ml. Responses to aspirin and clopidogrel were correlated (r=0.42, p <0.0001). PMI occurred in 27 patients (22%) who showed significantly lower percent inhibition P2Y12 (25.3+/-26 vs 38.3+/-25, p=0.01) and a trend toward higher PRU values (221+/-87 vs 193+/-94, p=0.21). We did not find any difference for aspirin response as assessed by ARUs in patients with or without PMI (460+/-82 vs 454+/-73, p = 0.82). Stratification of percent inhibition P2Y12 isolated a quartile of clopidogrel nonresponders (inhibition P2Y12 <15%) with significantly higher incidence of PMI (44% vs 15%, odds ratio 4.6, 95% confidence interval 1.9 to 11.5, p=0.001). In conclusion, point-of-care assessment of clopidogrel response reliably predicted PMI after low- to medium-risk elective PCI for stable angina.

Effects of intravenous dobutamine on coronary vasomotion in humans

OBJECTIVES

We sought to investigate the vascular mechanisms of dobutamine-induced myocardial ischemia.

BACKGROUND

Dobutamine stress is often used as a surrogate for exercise. The effects of dobutamine on the epicardial arteries are incompletely understood and possibly different from those of physical exercise.

METHODS

Intravenous (IV) dobutamine (40 microg/kg per min) was administered in 19 patients with normal, 23 patients with mildly atherosclerotic, and 12 patients with stenotic coronary arteries. In another two groups of patients with stenotic arteries, IV dobutamine was preceded by 1) an intracoronary (IC) bolus of the alpha-adrenergic blocker phentolamine (12 microg/kg, n = 12); and 2) an IC infusion of the nitric oxide substrate L-arginine (150 micromol/l per min for 20 min, n = 11). Intravenous saline instead of dobutamine was infused into eight patients with normal arteries. After dobutamine (or saline), an IC bolus of isosorbide dinitrate (ISDN, 0.2 mg) was given. Coronary vasomotion was evaluated by quantitative coronary angiography on angiograms obtained after each dose of dobutamine, saline, phentolamine, L-arginine, and ISDN.

RESULTS

Dobutamine increased the rate-pressure product and heart rate similarly in all patients except those who received saline. Dobutamine induced vasodilation in normal (change in luminal diameter [DeltaLD] vs. baseline: 19 +/- 2%) and in mildly atherosclerotic arteries (DeltaLD: 8 +/- 2%, p < 0.05 vs. normal). In stenotic arteries, dobutamine did not induce significant vasomotion (DeltaLD: -3 +/- 3%); the latter was improved by L-arginine (DeltaLD: 10 +/- 3%, p < 0.05 vs. stenotic arteries) and fully restored by phentolamine (DeltaLD: 19 +/- 3%, p < 0.05 vs. stenotic arteries).

CONCLUSIONS

Endothelial dysfunction and enhanced alpha-adrenergic tone contribute to the loss of dobutamine-induced vasodilation in coronary atherosclerosis. In contrast to physical exercise, dobutamine does not induce "paradoxical vasoconstriction" of atherosclerotic coronary arteries.