Role of variability in microvascular resistance on fractional flow reserve and coronary blood flow velocity reserve in intermediate coronary lesions.
BACKGROUND: Fractional flow reserve (FFR) and coronary blood flow velocity reserve (CFR) represent physiological quantities used to evaluate coronary lesion severity and to make clinical decisions. A comparison between the outcomes of both diagnostic techniques has not been performed in a large cohort of patients with intermediate coronary lesions. METHODS AND RESULTS: FFR and CFR were assessed in 126 consecutive patients with 150 intermediate coronary lesions (between 40% and 70% diameter stenosis by visual assessment). Agreement between outcomes of FFR and CFR, categorized at cut-off values of 0.75 and 2.0, respectively, was observed in 109 coronary lesions (73%), whereas discordant outcomes were present in 41 lesions (27%). In 26 of these 41 lesions, FFR was <0.75 and CFR>or=2.0 (group A); in the remaining 15 lesions, FFR was >or=0.75 and CFR<2.0 (group B). Minimum microvascular resistance, defined as the ratio of mean distal pressure to average peak blood flow velocity during maximum hyperemia, showed a large variability (overall range, 0.65 to 4.64 mm Hg x cm(-1) x s(-1)) and was significantly higher in group B than in group A (2.42+/-0.77 versus 1.91+/-0.70 mm Hg x cm(-1) x s(-1); P:=0.034). CONCLUSIONS: Our findings demonstrate the prominent role of microvascular resistance in modulating the relationship between FFR and CFR and emphasize the importance of combined pressure and flow velocity measurements to evaluate coronary lesion severity and microvascular involvement. (+info)
Serial intravascular ultrasound analysis of the impact of lesion length on the efficacy of intracoronary gamma-irradiation for preventing recurrent in-stent restenosis.
BACKGROUND: The relation between lesion length and effectiveness of brachytherapy is not well studied. METHODS AND RESULTS: We compared serial (postintervention and follow-up) intravascular ultrasound findings in 66 patients with native coronary artery in-stent restenosis (ISR) who were treated with (192)Ir (15 Gy delivered 2 mm away from the radiation source). Patients were enrolled in the Washington Radiation for In-Stent Restenosis Trial (WRIST; ISR length, 10 to 47 mm; n=36) or Long WRIST (ISR length, 36 to 80 mm; n=30). External elastic membrane, stent, lumen, and intimal hyperplasia (IH; stent minus lumen) areas and source-to-target (intravascular ultrasound catheter to external elastic membrane) distances were measured. Postintervention stent areas were larger in WRIST and smaller in Long WRIST patients (P:<0.0001). At follow-up, maximum IH area significantly increased in both WRIST and Long WRIST patients (P:<0.0001 for both), but this increase was greater in Long WRIST patients (P:=0.0006). Similarly, minimum lumen cross-sectional area significantly decreased in both WRIST and Long WRIST patients (P:<0.05 and P:<0.0001, respectively), but this decrease was more pronounced in Long WRIST patients (P:=0.0567). The maximum source-to-target distance was longer in Long WRIST than in WRIST, and it correlated directly with ISR length (r=0.547, P:<0.0001). Overall, the change in minimum lumen area and the change in maximum IH area correlated with the maximum source-to-target distance (r=0.352, P:=0.0038 and r=0.523, P:<0.0001 for WRIST and Long WRIST, respectively). The variability (maximum/minimum) in IH area at follow-up also correlated with the maximum source-to-target distance (r=0.378, P:<0.0001). CONCLUSIONS: Brachytherapy may be less effective in longer ISR lesions because of the greater variability and longer source-to-target distances in diffuse ISR. (+info)
Impact of peri-stent remodeling on restenosis: a volumetric intravascular ultrasound study.
BACKGROUND: Vessel remodeling is an important mechanism of late lumen loss after nonstent coronary interventions. However, its impact on in-stent restenosis has not been systematically investigated. METHODS AND RESULTS: Serial volumetric intravascular ultrasound analyses (poststent and follow-up) were performed in 55 lesions treated with a balloon-expandable stent (ACS MultiLink) using standard stent deployment techniques. The vessel volume (VV), lumen volume (LV), and volume bordered by the stent (SV) were measured using Simpson's method. The volume of plaque and neointima outside the stent (peri-stent volume, PSV) and volume of neointima within the stent (intrastent volume) were also measured. The change of each parameter during the follow-up period (follow-up minus poststent) was calculated and then divided by SV to normalize these values (designated as percent change [%]). As expected, %PSV directly correlated with %VV (P<0.0001, r=0.935), with no significant SV. A highly significant inverse correlation was seen between %PSV and the percent change of intrastent volume (P<0.0001, r=0.517). Consequently, %LV significantly correlated with peri-stent remodeling, as measured by %VV (P<0.0001, r=0.602). CONCLUSION: Positive remodeling of the vessel exterior to a coronary stent occurs to a variable degree after stent implantation. There is a distinct trade-off between positive remodeling and in-stent hyperplasia: in segments in which the degree of peri-stent remodeling is less, intrastent neointimal proliferation is greater and accompanied by more significant late lumen loss. (+info)
Magnesium deficiency in patients with recent myocardial infarction and provoked coronary artery spasm.
This study sought to clarify the relationship between magnesium (Mg) deficiency and coronary artery spasm provoked by pharmacologic agents in patients with a recent acute myocardial infarction (AMI). Twenty-three consecutive patients suffering from AMI were investigated with a Mg retention test (Mg: 0.1 mmol/kg for 4 h) in both the acute phase (within I week (3+/-2 days) of onset) and the subacute phase (3-4 weeks (24+/-6 days) of the onset). Early coronary arteriography was performed in all patients. Coronary stenosis in the infarct-related artery was less than 90% in all patients in the subacute phase. The spasm provocation test was performed in the subacute phase and coronary spasm was defined as transient subtotal or total occlusion in association with angina or electrocardiographic ST-segment deviation. Coronary artery spasm was provoked in only 13 of the 23 patients. Compared with the control subjects (12 patients without coronary artery disease or coronary spasm), the 24-h Mg retention was significantly higher in patients with AMI (acute phase: 78+/-27%, subacute phase: 66+/-32%, vs control: 48+/-12%, p<0.05). In the subacute phase, the 24-h Mg retention decreased in patients without coronary spasm (43+/-26%), but a high level of Mg retention was still observed in patients with coronary spasm (84+/-25%). There was no difference in the serum concentrations of Mg, calcium and phosphorus between the 2 groups on both phases. In conclusion, both Mg deficiency and provoked coronary artery spasm were noted in more than half of the Japanese patients with a recent AMI, suggesting a close association between Mg deficiency and AMI. (+info)
Seroprevalence of antibodies to microorganisms known to cause arterial and myocardial damage in patients with or without coronary stenosis.
Infections are assumed to play a role in coronary artery disease (CAD) and cardiomyopathies. It is unknown whether the seroprevalence of antibodies to these microorganisms is higher in patients with than without CAD. The seroprevalence of antibodies to Bartonella henselae, Borrelia burgdorferi, Chlamydia pneumoniae, Coxiella burnetii, Helicobacter pylori, human granulocytic Ehrlichia, Leptospira, Rickettsia conorii, and Treponema pallidum was assessed prospectively in patients with exertional dyspnea or anginal chest pain who underwent coronary angiography because of suspected CAD. Patients with normal angiograms (NA) were those in whom no more than 50% stenosis of any coronary artery was found. Patients with CAD were patients who underwent percutaneous transluminal coronary angioplasty. There were 50 patients with CAD (9 female) and 62 with NA (25 female), with a mean age of 62 years. All patients had antibodies to at least one microorganism: to B. henselae, 8% of CAD patients and 5% of NA patients; to B. burgdorferi IgG, 14% CAD and 6% NA; to B. burgdorferi IgM, 6% CAD and 3% NA; to C. pneumoniae lipopolysaccharide (LPS) IgA, 76% CAD and 77% NA; to C. pneumoniae LPS IgG, 80% CAD and 90% NA; to C. burnetii, 0% CAD and 5% NA; to H. pylori, 92% CAD and 68% NA; to human granulocytic Ehrlichia, 8% CAD and 3% NA; to Leptospira IgG, 4% CAD and 2% NA; to R. conorii, 10% in both groups; and to T. pallidum, 2% CAD and 0% NA. The seroprevalence of antibodies to micro-organisms known to induce arterial and myocardial damage does not differ between patients with CAD and NA. (+info)
Dobutamine stress echocardiography versus quantitative technetium-99m sestamibi SPECT for detecting residual stenosis and multivessel disease after myocardial infarction.
OBJECTIVE: To compare the relative accuracy of dobutamine stress echocardiography (DSE) and quantitative technetium-99m sestamibi single photon emission computed tomography (mibi SPECT) for detecting infarct related artery stenosis and multivessel disease early after acute myocardial infarction. DESIGN: Prospective study. SETTING: University hospital. METHODS: 75 patients underwent simultaneous DSE and mibi SPECT at (mean (SD)) 5 (2) days after a first acute myocardial infarct. Quantitative coronary angiography was performed in all patients after imaging studies. RESULTS: Significant stenosis (> 50%) of the infarct related artery was detected in 69 patients. Residual ischaemia was identified by DSE in 55 patients and by quantitative mibi SPECT in 49. The sensitivity of DSE and mibi SPECT for detecting significant infarct related artery stenosis was 78% and 70%, respectively, with a specificity of 83% for both tests. The combination of DSE and mibi SPECT did not change the specificity (83%) but increased the sensitivity to 94%. Mibi SPECT was more sensitive than DSE for detecting mild stenosis (73% v 9%; p = 0.008). The sensitivity of DSE for detecting moderate or severe stenosis was greater than mibi SPECT (97% v 74%; p = 0.007). Wall motion abnormalities with DSE and transient perfusion defects with mibi SPECT outside the infarction zone were sensitive (80% v 67%; NS) and highly specific (95% v 93%; NS) for multivessel disease. CONCLUSIONS: DSE and mibi SPECT have equivalent accuracy for detecting residual infarct related artery stenosis of >/= 50% and multivessel disease early after acute myocardial infarction. DSE is more predictive of moderate or severe infarct related artery stenosis. Combined imaging only improves the detection of mild stenosis. (+info)
Value of fractional flow reserve in making decisions about bypass surgery for equivocal left main coronary artery disease.
OBJECTIVE: To investigate the value of coronary pressure derived fractional flow reserve (FFR) measurements in supporting decisions about medical or surgical treatment in patients with angiographically equivocal left main coronary artery stenosis. DESIGN: A two centre prospective single cohort follow up study. INTERVENTIONS: FFR of the left main coronary artery was determined in 54 consecutive patients with angiographically equivocal left main coronary artery disease. If FFR was >/= 0.75, medical treatment was chosen; if FFR was < 0.75, surgical treatment was chosen. MAIN OUTCOME MEASURES: Freedom from death, myocardial infarction, or any coronary revascularisation procedure. RESULTS: In 24 patients (44%), FFR was >/= 0.75 and medical treatment was chosen (medical group). In the remaining 30 patients (56%), FFR was < 0.75 and bypass surgery was performed (surgical group). Mean (SD) follow up was 29 (15) months (range 12-65 months). Survival among patients at three years of follow up was 100% in the medical group and 97% in the surgical group. Event-free survival was 76% in the medical group and 83% in the surgical group. CONCLUSIONS: FFR supports decision making in equivocal left main coronary artery disease. If FFR is below 0.75, the decision for bypass surgery is supported. If FFR is above 0.75, a conservative approach is justified. (+info)
Coronary thermodilution to assess flow reserve: experimental validation.
BACKGROUND: Fractional flow reserve (FFR) and coronary flow reserve (CFR) are indices of coronary stenosis severity that provide the clinician with complementary information on the contribution of epicardial arteries and microcirculation to total resistance to myocardial blood flow. At present, FFR and CFR can only be obtained by 2 separate guidewires. The present study tested the validity of the thermodilution principle in assessing CFR with one pressure-temperature sensor-tipped guidewire. METHODS AND RESULTS: In an in vitro model, absolute flow was compared with the inverse mean transit time (1/T(mn)) of a thermodilution curve obtained after a bolus injection of 3 mL of saline at room temperature. A very close correlation (r>0.95) was found between absolute flow and 1/T(mn) when the sensor was placed >/=6 cm from the injection site. In 6 chronically instrumented dogs (60 stenoses; FFR from 0.19 to 0.98), a significant linear relation was found between flow velocity and 1/T(mn). A significant correlation was found between CFR(Doppler), which was calculated from the ratio of hyperemic to resting flow velocities, and CFR(thermo), which was calculated from the ratio of resting to hyperemic T(mn) (r=0.76; SEE=0.24; P<0.001). CONCLUSION: The present findings demonstrate the validity of the thermodilution principle to assess CFR. Because the pressure-temperature sensor was mounted in a commercially available angioplasty guidewire, this technique permits simultaneous measurements of CFR and FFR. (+info)