A large-scale multicentre study of patient skin doses in interventional cardiology: dose-area product action levels and dose reference levels.

For 318 patients in 8 different Belgian hospitals, the entire skin-dose distribution was mapped using a grid of 70 thermoluminescence dosimeters per patient, allowing an accurate determination of the maximum skin dose (MSD). Dose-area product (DAP) values, exposure parameters and geometry, together with procedure, patient and cardiologist characteristics, were also registered. Procedures were divided into two groups: diagnostic procedures (coronary angiography) and therapeutic procedures (dilatation, stent, combined procedures (e.g. coronary angiography + dilatation + stent)). The mean value of the MSD was 0.310 Gy for diagnostic and 0.699 Gy for therapeutic procedures. The most critical projection for receiving the MSD is the LAO90 (left anterior oblique) geometry. In 3% of cases, the MSD exceeded the 2 Gy dose threshold for deterministic effects. Action levels in terms of DAP values as the basis for a strategy for follow-up of patients for deterministic radiation skin effects were derived from measured MSD and cumulative DAP values. Two DAP action levels are proposed. A first DAP action level of 125 Gy cm(2) corresponding to the dose threshold of 2 Gy would imply an optional radiopathological follow-up depending on the cardiologist's decision. A second DAP action level of 250 Gy cm(2) corresponding to the 3 Gy skin dose would imply a systematic follow-up. Dose reference levels - 71.3 Gy cm(2) for diagnostic and 106.0 Gy cm(2) for therapeutic procedures - were derived from the 75 percentile of the DAP distributions. As a conclusion, we propose that total DAP is registered in patient's record file, as it can serve to improve the follow-up of patients for radiation-induced skin injuries.

Complementary saphenous grafting: long-term follow-up.

OBJECTIVE: Recently we reviewed the 10-year clinical and angiographic outcomes of sequential internal thoracic artery grafting. Most of the patients also received complementary saphenous grafts, and their overall long-term patency rates were surprisingly high. Therefore, we decided to analyze these results in more detail. METHODS: The first consecutive 500 patients having received at least one sequential internal thoracic artery graft between October 1985 and August 1991 were restudied retrospectively. The saphenous grafts were only used to achieve complete revascularization in addition to complex arterial grafting on less significant or remote coronary vessels. A total of 161 patients consented to a late angiographic restudy at a mean postoperative interval of 7.5 years (1-12.2 years). RESULTS: At 5 and 10 years postoperatively, freedom from angina was 96% and 82%, and freedom from any cardiac event was 92.8% and 69%, respectively. Only 15 (3.1%) patients needed additional revascularization (0.3% per patient-year): 4 coronary artery bypass grafting (0.8%) and 11 percutaneous transluminal coronary angioplasty (2.3%). The overall patency and intactness rates of saphenous anastomoses were 72.5% and 60.2%, respectively. There was a significant difference between the patency and intactness of sequential versus single anastomoses: 76% versus 60% and 64.5% versus 44.4%, respectively. There was no significant difference in either patency or intactness between right internal thoracic and sequential saphenous grafts anastomosed to the right coronary artery: 83.4% versus 75.2% and 77.8% versus 62.4%, respectively. The same was true for the anastomoses to the "remote area" (distal circumflex, distal right coronary artery). CONCLUSIONS: Complementary sequential saphenous grafting still deserves consideration in some patients below 70 years of age, particularly for those with disease in the "remote area": the distal circumflex and right coronary branches.

The influence of stent length on clinical and angiographic outcome in patients undergoing elective stenting for native coronary artery lesions; final results of the Magic 5L Study.

AIMS: To prospectively evaluate the influence of stent length on 6 month clinical and angiographic outcome, in patients with native coronary lesions up to 45 mm in length, undergoing elective Magic Wallstent implantation. METHODS AND RESULTS: On the basis of pre-procedural angiography, 276 patients (aged 61.3+/-10.2 years; 78.6% male; 41.7% unstable angina) with a total of 302 lesions were prospectively assigned to one of five different length categories of Magic Wallstent. Angiography in multiple matched projections before and after implantation and at 6 months follow-up was analysed at the core laboratory. Primary end-points for the efficacy analysis were cumulative incidence of major adverse cardiac events and quantitative coronary angiography analysis 6 months after stent implantation. Magic Wallstent implantation was successful in 301 of 302 lesions and in 98.6% a residual stenosis <20% by online quantitative coronary angiography was achieved. At 30 days, 6.2% (1.8% subacute occlusion) of patients had experienced major adverse cardiac events, 27.5% at 6 months and 30.4% at 9 months. Angiographic restenosis occurred in 37%. Restenosis rates for the mini, extra-short, short, medium and long Wallstent groups were 25.9%, 25%, 22.6%, 36.2% and 67.5%, respectively. Multivariate analysis revealed stent length to be independently associated with greater angiographic restenosis and major adverse cardiac events. CONCLUSIONS: While shorter Magic Wallstents provided late outcomes comparable with short balloon-expandable stents, excessive restenosis with longer Wallstents should obviate their use in elective percutaneous intervention. Long coronary lesions provide a challenging substrate for emerging antirestenosis therapies, such as stent coatings and brachytherapy.

The immediate and long-term effect of optimal balloon angioplasty on the absolute coronary blood flow velocity reserve. A subanalysis of the DEBATE study. Doppler Endpoints Balloon Angioplasty Trial Europe.

BACKGROUND: There are limited data regarding the immediate and long-term effect of balloon angioplasty on the coronary flow reserve evaluated in a multicentre setting. METHODS AND RESULTS: A total of 86 patients with one-vessel disease and normal left ventricular function were analysed before and after optimal balloon angioplasty (diameter stenosis <35%) and at 6-month follow-up. Coronary flow reserve was assessed with a Doppler guide wire. A low coronary flow reserve (2.5 (46% vs 23% and 36% vs 16%, respectively; P<0.05) due to a trend towards restenosis (29% vs 16%; P=0.15) or a low coronary flow reserve at follow-up due to persistent elevated baseline blood flow velocity. Patients without restenosis showed a decrease or increase of coronary flow reserve during follow-up, determined by alterations of hyperaemic blood flow velocity. CONCLUSIONS: Patients with an impaired coronary flow reserve directly after optimal balloon angioplasty showed a higher target lesion revascularization rate compared to patients with a coronary flow reserve >2.5. This patient group consists of patients prone to develop restenosis, while other patients are characterized by a persistently low coronary flow reserve, probably secondary to disturbed autoregulation and/or diffuse mild coronary atherosclerosis. Coronary flow reserve alterations in patients without restenosis were related to changes in hyperaemic blood flow velocity, suggesting that this phenomenon relates to epicardial remodelling.

Long-term clinical and angiographic follow-up of sequential internal thoracic artery grafting.

OBJECTIVE: Sequential internal thoracic artery (ITA) grafting allows a more complete arterial revascularization of the myocardium. We wanted to verify whether the excellent clinical and angiographic short term results reported by us before where maintained over 10 years and more. METHODS: the first consecutive 500 patients having received at least one sequential ITA graft between October 1985 and August 1991 were reviewed. Age averaged 61 years. Fifty-three patients had a left ventricular ejection fraction less than 40%, 117 were not elective, 35 (7%) were reoperations, 56 (11%) had diabetes. In total 2156 anastomoses were constructed (4.3/patient), among them 1367 arterial anastomoses (2.7/patient) and 1150 sequential ITA anastomoses (2.3/patient). The clinical follow-up was 97.4% complete and averaged 9.6 (range 8.6-13.6) years. One hundred and sixty-one patients consented to a late angiographic restudy after a mean interval of 7.4 (range 1-12.2) years. RESULTS: At 5 and 10 years, 89 and 72% of the patients were still alive. At 10 years 82% are still asymptomatic and 71% free of any type of ischaemia. Only four patients (0.8%) needed a repeat surgical revascularization, and 11 (2.3%) a percutaneous coronary angioplasty. At 5 and 10 years, 92.8 and 69% of the patients remained free of any cardiac event. Overall, 95.5% of the arterial anastomoses were patent and 96.1% of the sequential ITA were patent. There was a significant difference between the patency rate of pedicled ITA and free ITA anastomoses: 96.3 vs. 86.5% (P=0.02). There was no difference in patency between left ITA and right ITA anastomoses for the LAD and Cx areas. Sequential ITA anastomoses showed excellent patency rates to all coronary vessels but the very distal circumflex and the distal branches of right coronary artery (85%). There was no significant difference between the patency of the proximal and the distal sequential ITA anastomoses. The sequential anastomoses constructed in the length tend to remain more patent than the diamond-shaped ones: 97.2 vs. 91.5% (P=0.004). CONCLUSIONS: Sequential ITA grafting optimizes arterial revascularization. The long-term patency is excellent, is identical to that of single ITA grafting, and appears not much different from postoperative patency. The need for repeat surgical and interventional revascularization has been extremely low: 3.1% over the whole follow-up.

Angiographical and Doppler flow-derived parameters for assessment of coronary lesion severity and its relation to the result of exercise electrocardiography. DEBATE study group. Doppler Endpoints Balloon Angioplasty Trial Europe.

AIMS: Evaluation of angiographical and intracoronary Doppler-derived parameters of coronary stenosis severity. METHODS AND RESULTS: A total of 225 patients with one-vessel disease were studied before PTCA and at 6 months follow-up. Exercise electrocardiography was performed to document presence (n = 157) or absence (n = 138) of an ST segment shift (> or =0.1 mV). Intracoronary blood flow velocity analysis was performed to determine the proximal/distal flow velocity ratio, the distal diastolic/systolic flow velocity ratio and coronary flow velocity reserve. Receiver operator characteristic curves were calculated to assess the predictive value of these variables compared with the exercise test. The distal coronary flow velocity reserve demonstrated the best linear correlation for both percentage diameter stenosis and minimum lumen diameter (r = 0.67 and r = 0.66; P<0.01), compared to the diastolic/systolic flow velocity ratio (r = 0.19 and r = 0.14; P<0.01) and the proximal/distal flow velocity ratio (r = 0.03 and r = 0.07; not significant). The areas under the curve were 0. 84+/-0.02; 0.82+/-0.03 and 0.83+/-0.03 for diameter stenosis, minimum lumen diameter and coronary flow velocity reserve, respectively. Logistic regression analysis revealed that the percentage diameter stenosis or minimum lumen diameter and coronary flow velocity reserve were independent predictors for the result of stress testing. CONCLUSIONS: The distal coronary flow velocity reserve is the best intracoronary Doppler parameter for evaluation of coronary narrowings. Angiographical estimates of coronary lesion severity and distal coronary flow velocity reserve are good and independent predictors for the assessment of functional severity of coronary stenosis, emphasizing the complementary role of these parameters for clinical decision making.

Multicenter evaluation of the phosphorylcholine-coated biodivYsio stent in short de novo coronary lesions: The SOPHOS study.

AIMS: The BiodivYsio trade mark stent (Biocompatibles Ltd, Farnham, UK) is coated with a phosphorylcholine (PC)-containing copolymer to confer biocompatibility. The SOPHOS (Study Of PHosphorylcholine coating On Stents) study was designed to assess the safety and efficacy of this novel coronary stent and by indirect comparison to indicate equivalence with other formal stent studies. METHODS AND RESULTS: Patients with angina and a single short (#x2A7F;12 mm) de novo lesion in a native coronary artery of >/=2.75 mm diameter were included. A total of 425 patients were allocated in 24 centers. Clinical data were collected at one-, six- and nine-month follow-up. Angiography was performed before and after the stent implantation. In addition, in the first 200 patients (SOPHOS A) angiography was routinely performed at six months. The following 225 patients (SOPHOS B) were merely followed up clinically. The primary end-point of the study, the six-month MACE-rate (MACE = Major Adverse Cardiac Events) was 13.4% (two cardiac death; five Q-wave/nine non-Q-wave myocardial infarctions (MI); nine CABG and 32 target lesion revascularization (TLR), which is similar to the calculated 15% MACE-rate in comparable reference studies. Secondary end-points included among others restenosis at six months in the SOPHOS A population. The target vessel diameter was 2.98 +/- 0.48 mm. Minimal lumen diameter pre/post procedure and at follow-up was 1.00 +/- 0.32, 2.69 +/- 0.37, 1.91 +/- 0.71 mm, respectively. The binary restenosis rate (>/=50% diameter stenosis at follow-up) was 17.7%. CONCLUSION: The coronary BiodivYsio stent is safe and effective as a primary device for the treatment of native coronary artery lesions in patients with stable or unstable angina pectoris. Clinical and angiographic results are in the statistical range of equivalence with comparable studies with other current stents.

Does angiography six months after coronary intervention influence management and outcome? Benestent II Investigators.

OBJECTIVES: This study was performed to assess whether angiography six months after coronary balloon angioplasty or stent implantation has an influence on clinical management and one-year outcome. BACKGROUND: The Benestent II study randomized 827 patients to balloon angioplasty or stent implantation. A subrandomization was undertaken allocating patients to six-month clinical follow-up (CF) or clinical and angiographic follow-up (AF). METHODS: Seven hundred and six patients (349 CF and 357 AF) had no intercurrent angiography, so that restenosis and disease progression elsewhere remained unknown until the time of six-month follow-up. These two groups, which were well matched at enrolment, were compared with respect to symptoms, medication and major cardiac events defined as death, myocardial infarction and need for revascularization at six and 12 months. RESULTS: At six-month follow-up, 53 (15%) of the CF and 76 (21%) of the AF patients had stable angina (p = 0.041), while 5 (1%) and 4 (1%) had symptoms of unstable angina. At 12-month follow-up, 44 (13%) patients in both groups had stable angina, and only 1 patient in the CF group had unstable angina. Seventy-seven patients (27 CF and 50 AF; p < 0.01) had major cardiac events between 6 and 12 months. Of the 349 patients in the CF group, 21 underwent repeat percutaneous transluminal coronary angioplasty or coronary artery bypass graft surgery between 6 and 12 months, compared with 44 of the 357 patients in the AF group (relative risk 2.05 [1.24 to 3.37], p = 0.003). CONCLUSIONS: Patients who had AF six months after balloon angioplasty or stent implantation experienced more repeat revascularization procedures than those who had CF. They also had significantly more angina at six-month follow-up but this may be due to bias.

Prognostic value of intracoronary flow velocity and diameter stenosis in assessing the short- and long-term outcomes of coronary balloon angioplasty: the DEBATE Study (Doppler Endpoints Balloon Angioplasty Trial Europe).

BACKGROUND: The aim of this prospective, multicenter study was the identification of Doppler flow velocity measurements predictive of clinical outcome of patients undergoing single-vessel balloon angioplasty with no previous Q-wave myocardial infarction. METHODS AND RESULTS: In 297 patients, a Doppler guidewire was used to measure basal and maximal hyperemic flow velocities proximal and distal to the stenosis before and after angioplasty. In 225 patients with an angiographically successful percutaneous transluminal coronary angioplasty (PTCA), postprocedural distal coronary flow reserve (CFR) and percent diameter stenosis (DS%) were correlated with symptoms and/or ischemia at 1 and 6 months, with the need for target lesion revascularization, and with angiographic restenosis (defined as DS > or = 50% at follow-up). Logistic regression and receiver operator characteristic curve analyses were applied to determine the prognostic cutoff value of CFR and DS separately and in combination. Optimal cutoff criteria for predictors of these clinical events were DS, 35%; CFR, 2.5. A distal CFR after angioplasty > 2.5 with a residual DS < or = 35% identified lesions with a low incidence of recurrence of symptoms at 1 month (10% versus 19%, P=.149) and at 6 months (23% versus 47%, P=.005), a low need for reintervention (16% versus 34%, P=.024), and a low restenosis rate (16% versus 41%, P=.002) compared with patients who did not meet these criteria. CONCLUSIONS: Measurements of distal CFR after PTCA, in combination with DS%, have a predictive value, albeit modest for the short- and long-term outcomes after PTCA, and thus may be used to identify patients who will or will not benefit from additional therapy such as stent implantation.

Surgical angioplasty of the left main coronary artery.

OBJECTIVE: The conventional surgical treatment of isolated critical stenosis of the left main coronary artery (LMCA) leads to the definitive occlusion of LMCA, restores only a retrograde perfusion to a rather extensive myocardial area and consumes bypass material. Direct surgical angioplasty avoids these inconveniences. METHODS: Between June 1985 and August 1996, 49 surgical angioplasties have been performed in 47 patients. LMCA was approached posteriorly in the first 11 procedures, and an anterior approach was preferred in the last 38 because of better exposure. The onlay patch consisted of saphenous vein in 37 cases; pericardium was used in 12 cases, and only for ostial stenosis. RESULTS: No technical failure occurred in the last 28 cases. 44 procedures, (90%), succeeded, but 1 patient (2.3%) died later of a massive air embolism, and 2 patients needed conventional CABG after 3 and 5 months, respectively. The 35 survivors still benefiting from a successful LMCA angioplasty on the long term are free of ischemia after a mean follow-up of 75 months (2-136). Angiographic restudy was obtained in 30 patients (70%) at an average of 38 months and revealed an excellent result in 26 (87%). In 10 patients, a late angiographic restudy at an average of 71 months (32-119) still revealed a perfect result. CONCLUSION: Provided that well-defined contra-indications (involvement of the distal bifurcation, heavy calcification) are respected, LMCA surgical angioplasty deserves a place in the array of surgical strategies.

Is acoustic shadowing at intracoronary ultrasound always the marker of intramural calcium accumulation?

Intracoronary ultrasound (ICUS) is increasingly used at catheterization to assess more precisely the severity of luminal narrowing, to delineate the composition of the atherosclerotic plaque, and to select the optimal therapeutic strategy. With this technique, a drop in signal intensity, known as acoustic shadowing, is usually equated with the presence of calcium in the plaque. We report the study of an atherosclerotic coronary artery showing intense acoustic shadowing at ICUS, but in which no calcium deposition could be evidenced at postmortem pathological analysis. This observation suggests a word of caution with regard to considering acoustic shadowing at ICUS as the reflection of superficial calcium deposition within a vessel wall.

Use of exercise electrocardiography, technetium-99m-MIBI perfusion tomography, and two-dimensional echocardiography for coronary disease surveillance in a low-prevalence population of heart transplant recipients.

BACKGROUND: Coronary artery disease has been reported to be a significant cause of long-term morbidity and mortality after heart transplantation. However, the diagnosis of coronary disease by means of noninvasive procedures has shown disappointing accuracy, and many centers currently recommend an annual surveillance coronary angiogram. METHODS: We prospectively studied the accuracy and feasibility of a symptom-limited upright bicycle exercise, combined with computerized electrocardiogram analysis, echocardiography, and perfusion scintigraphy in 37 consecutive heart transplant recipients at 2.8 +/- 1.4 years after transplantation for routine follow-up coronary angiography. RESULTS: No patient had any hemodynamically significant (> 50% diameter) coronary stenosis, but luminal irregularities were detectable in four patients. The exercise electrocardiogram was interpretable in only 22 patients (59%), and two of the remaining patients (9%) had false-positive results. The feasibility of perfusion tomography (100%) and two-dimensional echocardiography (97%) were greater than for stress electrocardiogram (p < 0.001 and p < 0.01 respectively). False-positive results were obtained at stress echocardiography in one patient (3%), and at scintigraphy in six patients (16%, p = not significant). None of these methods detected coronary artery stenoses of less than 50% diameter. CONCLUSIONS: Both exercise perfusion tomography and two-dimensional echocardiography are feasible and can be used with adequate specificity for the noninvasive diagnosis of coronary artery disease in heart transplant recipients. However further studies are needed to determine their respective sensitivity.

Noninvasive estimation of pulmonary arterial wedge pressure with Doppler transmitral flow velocity pattern in patients with known heart disease.

Pulmonary arterial wedge pressure (PAWP) is an important marker of cardiac function. Regrettably, it requires catheterization, which can occasionally result in serious complications. A noninvasive method of estimating PAWP would thus be helpful. Recent studies have indicated that the Doppler transmitral flow velocity pattern was strongly dependent on preload and could provide an estimate of PAWP. This study was therefore designed to evaluate the relation between doppler transmitral flow velocity indexes and measured PAWP in 91 patients (learning group: 73 men, mean age 57 +/- 13 years) with ischemic heart disease (n = 41), dilated (n = 29) or hypertrophic cardiomyopathy (n = 4), or aortic stenosis (n = 17). Multiple regression analysis was used to derive an equation for estimation of PAWP, which was subsequently tested in a separate group of 33 patients (testing group: 28 men, mean age 58 +/- 12 years) with similar cardiac conditions. PAWP ranged from 4 to 48 mm Hg in the learning group and from 7 to 40 mm Hg in the testing group. In the learning group, PAWP correlated with the E/A ratio (r = 0.95), atrial filling fraction (r = -0.80), peak E velocity (r = 0.79), isovolumic relaxation period (r = -0.75), and deceleration time (r = -0.61). In the learning group, PAWP was best predicted as PAWP = 18.4 + [17.1.In(E/A ratio)]. This equation allowed prediction of PAWP within 3 mm Hg of the measured value in 24 of 33 patients (73%) in the testing group. In 8 additional patients, the equation also accurately predicted the changes in PAWP induced by volume loading or intravenous nitrates (r = 0.98).(ABSTRACT TRUNCATED AT 250 WORDS)

Differences in vasoreactivity between gastroepiploic artery grafts late after bypass surgery and grafted coronary arteries.

BACKGROUND: The gastroepiploic artery is increasingly used as an alternative arterial coronary bypass conduit. In vitro studies have reported differences in vasoreactivity among various types of coronary graft conduits, susceptible to influencing the adaptation of myocardial blood flow and long-term patency rate. METHODS AND RESULTS: To evaluate in vivo the vasoreactivity of gastroepiploic artery grafts implanted long-term, nine angiographically smooth grafts implanted to the distal right or to the left circumflex coronary artery were studied with quantitative angiography 6 to 36 months after surgery. Angiograms were obtained on 35mm cinefilms in basal conditions, after injection of methylergometrine (0.4 mg IV), and after intragraft injection of 1 mg isosorbide dinitrate. In basal conditions, there was no difference in luminal diameter between gastroepiploic and coronary arteries (1.64 +/- 0.32 versus 1.51 +/- 0.31 mm; P = NS). After methylergometrine, a constriction was observed in all gastroepiploic artery grafts (-14 +/- 6% of basal diameter) and in all but one grafted coronary artery (-6 +/- 5%). After isosorbide dinitrate, a dilation was consistently observed in all gastroepiploic artery grafts (+26 +/- 9%) and grafted coronary arteries (+14 +/- 7% of basal). Changes in lumen diameter in response to these constrictor and dilator stimuli, either expressed in absolute values or in percentage of control were significantly greater (P < .001) in gastroepiploic artery grafts than in grafted coronary arteries. CONCLUSIONS: Gastroepiploic artery grafts implanted long-term are more reactive than grafted coronary arteries to ergometrine and nitrates. This response differs from that previously reported of internal mammary artery grafts to the same pharmacological vasoactive stimuli. This suggests that the concept of a more efficient endothelium-dependent control of vasomotor tone contributing to better long-term functional results of internal mammary artery grafts cannot be directly extrapolated to gastroepiploic artery grafts.

Effects of endothelin-1 at pathophysiologic concentrations on coronary perfusion and mechanical function of normal and postischemic myocardium.

We assess hemodynamic, vascular, and hormonal effects of endothelin-1 (ET-1) at pathophysiologic levels on normal and ischemic myocardium. Thirty conscious chronically instrumented dogs were studied before, during, and after a 10-min coronary artery occlusion (CAO) performed either during ET-1 infusion (2.5 ng/kg.min, n = 15) or during placebo infusion (n = 15). ET-1 infusion produced an increase in plasma ET-1 (from 1.3 +/- 0.1 to 11.5 +/- 1.1 pM, p < 0.0001) during CAO (pathophysiologic value). Left anterior descending artery (LAD) blood flow (measured by Doppler flow probe) decreased similarly during CAO with ET-1 or placebo (p = 0.0001, NS, ET-1 vs. placebo). Both endocardial and epicardial blood flows in ischemic regions also decreased (p = 0.0001) during CAO but were threefold greater with ET-1 than with placebo (endocardium 42 +/- 7 vs. 14 +/- 2 ml/min/100 g, p = 0.003). No significant difference in myocardial blood flows between groups was observed in control regions. CAO produced increases (p < 0.005) in heart rate (HR), mean aortic pressure (AOP), and ventricular pressures but no change in atrial pressures. The changes in these parameters were comparable in the ET-1 and placebo groups. Despite the greater residual flow during CAO, however, ET-1 decreased the function of the ischemic zone during reperfusion as assessed by systolic shortening (p < 0.05). Atrial natriuretic factor (ANF), unchanged during CAO with placebo, increased from 38.3 +/- 6.1 to 53.3 +/- 10 pM with ET-1 (p = 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Flow-mediated vasodilator response to tachycardia of epicardial coronary arteries is preserved in heart transplant recipients.

BACKGROUND: Increasing blood flow through conduit arteries induces vasodilation through endothelium-dependent mechanisms. In humans, flow-mediated dilation of angiographically normal epicardial coronary arteries has been observed during tachycardia, this response being impaired in the presence of atherosclerosis. METHODS AND RESULTS: To evaluate whether the endothelium-dependent physiological vasodilatory response of epicardial coronary arteries to tachycardia is preserved in heart transplant recipients, 22 patients with angiographically smooth coronary arteries were studied with quantitative angiography. A total of 14 patients had undergone cardiac transplantation more than 1 year (mean, 28 +/- 18 months) before the study, and 8 patients were nontransplant patients with atypical chest pain and normal exercise tests (control group). Angiograms of the left coronary artery were obtained on 35-mm cinefilms at 3-minute intervals in basal conditions, during pacing-induced tachycardia (150 beats per minute), and after intracoronary injection of 1.5 mg of isosorbide dinitrate. During tachycardia, the mean luminal diameter of the midsegment of the left anterior descending coronary artery increased by 8.9 +/- 6.1% from 2.64 +/- 0.56 to 2.88 +/- 0.62 mm (P < .001) in transplant recipients and by 7.5 +/- 5.0% from 2.37 +/- 0.54 to 2.53 +/- 0.50 mm (P < .025) in the control group (transplant vs control patients, NS). A further coronary dilation was observed in all patients after isosorbide dinitrate, up to 124.8 +/- 8.1% of basal lumen diameter in transplant recipients and up to 129.1 +/- 16.1% of basal diameter in the control group. CONCLUSIONS: The vasodilator response of epicardial coronary arteries to tachycardia is preserved in heart transplant recipients. This suggests that the functional response of the endothelium to an increase in coronary blood flow remains normal in these patients.