Chufan Luo

Thermodilution-Derived Coronary Microvascular Resistance and Flow Reserve in Patients With Cardiac Syndrome X

Background—Although increased coronary microvascular resistance (CMR), resulting in coronary microvascular dysfunction, is speculated to be responsible for myocardial ischemia in patients with cardiac syndrome X (CSX), it has never been directly demonstrated, and the correlation between CMR and severity of myocardial ischemia has not been elucidated in this setting. This study aimed to ascertain the increased CMR directly and to explore the relationship between CMR and severity of ischemia in patients with CSX. Methods and Results—We studied 18 patients with CSX and 18 age- and sex-matched control subjects. Thermodilution-derived coronary flow reserve and index of microvascular resistance were measured using a pressure–temperature sensor-tipped coronary wire. Exercise treadmill test was performed by the Bruce protocol for calculating Duke treadmill score. Coronary flow reserve was significantly lower (2.37±0.81 versus 3.68±0.72; P<0.001) and index of microvascular resistance was higher (33.1±7.9 versus 18.8±5.6 U; P<0.001) in patients with CSX compared with those in control subjects. The Duke treadmill score was correlated positively to coronary flow reserve (r=0.539; P=0.021) and negatively to index of microvascular resistance (r=−0.742; P<0.001) in patients with CSX. Conclusions—Using an intracoronary thermodilution method, we for the first time directly demonstrated an increased microvascular resistance in patients with CSX. Furthermore, severity of ischemia was found to be intimately associated with CMR in this setting.

Pregnancy-associated plasma protein predicts outcomes of percutaneous coronary intervention in patients with non'ST-elevation acute coronary syndrome

OBJECTIVE Pregnancy-associated plasma protein A (PAPP-A) may play an important role in the development of acute coronary syndrome. This study aimed to investigate the relationship between the levels of circulating PAPP-A and the mid-term outcomes of percutaneous coronary intervention (PCI) in patients with non-ST-elevation acute coronary syndrome. METHODS The circulating PAPP-A levels and high-sensitivity C-reactive protein before PCI were measured in 129 patients with single coronary artery stenosis. The end point of clinical follow-up was cardiac death, nonfatal myocardial infarction, target vessel revascularization, and rehospitalization for angina. RESULTS During the follow-up of an average of 20.3 ± 5.2 months, a cardiac event was recorded in 25 patients (19.4%). The levels of PAPP-A (29.85 ± 19.51 mIu/L vs 20.47 ± 14.33 mIu/L, P = .007) and high-sensitivity C-reactive protein (5.63 ± 2.13 mg/L vs 4.11 ± 1.28 mg/L, P = .014) in patients with cardiac events were higher than in those without cardiac events. PAPP-A ≥ 11.33 mIu/L has a strong predictive value for a combined end point (risk ratio = 4.1; 95% confidence interval, 1.0-16.2; P = .037). Patients with lower PAPP-A levels (<11.33 mIu/L) had higher event-free survivals than patients with higher PAPP-A levels (log rank = 9.334, P = .025). CONCLUSION Circulating PAPP-A levels predict the mid-term outcomes of PCI in patients with non-ST-elevation acute coronary syndrome and single-vessel stenosis.

Documentation of impaired coronary blood flow by TIMI frame count method in patients with atrial fibrillation

BACKGROUND Atrial fibrillation (AF) is associated with impaired coronary flow and diminished myocardial perfusion. In the present study we aimed to evaluate coronary blood flow by means of Thrombolysis in Myocardial Infarction (TIMI) frame count (TFC) in patients with AF in the absence of obstructive coronary artery disease (CAD). METHODS This prospective study initially enrolled 166 patients with AF and 332 age- and gender-matched control subjects without AF. After diagnostic coronary angiography, TFC was assessed in the participants without obstructive CAD, with 146 in the AF group and 150 in the control group. RESULTS The TFC for three major coronary arteries and the mean TFC were found to be significantly higher in AF patients compared to control subjects (34.1 ± 10.4 vs. 25.0 ± 10.4, 31.8 ± 9.7 vs. 23.7 ± 9.1, and 32.3 ± 9.5 vs. 24.1 ± 8.4 for each artery and 32.8 ± 9.2 vs. 24.3 ± 8.9 for mean TFC, p<0.001 for all comparisons). The mean TFC was 28.8 ± 7.9 in patients with paroxysmal AF, 33.7 ± 8.7 in those with persistent AF, and 39.0 ± 8.8 in those with long-standing or permanent AF (p<0.01 for all comparisons). After multivariate analysis, we found that the presence of AF remains to be independently associated with mean TFC. In AF group, baseline heart rate, left ventricular ejection fraction, AF duration and left atrium diameter were found to be independently associated with mean TFC. CONCLUSIONS Patients with atrial fibrillation in the absence of obstructive coronary artery disease have significantly higher TIMI frame counts for all three coronary vessels, indicating impaired coronary blood flow, compared to the control subjects without atrial fibrillation.

Thermodilutional Confirmation of Coronary Microvascular Dysfunction in Patients With Recurrent Angina After Successful Percutaneous Coronary Intervention

BACKGROUND Recurrent angina (RA) after percutaneous coronary intervention (PCI) remains a challenging problem that confronts cardiologists in routine clinical practice. In patients without epicardial coronary causes, RA is commonly speculated as resulting from coronary microvascular dysfunction. The aim of this study was to investigate the coronary microvascular function in patients with RA late after successful PCI and without epicardial stenosis at the time of repeat angiography. METHODS We studied 39 consecutive patients with RA in whom PCI was successfully performed 6 to 12 months previously because of angina and single-vessel disease and without restenosis and disease progression at the time of repeat angiography. Twelve subjects without RA were recruited as the control group. Thermodilution-derived coronary flow reserve (CFR) and index of microvascular resistance (IMR) were measured using a pressure-temperature sensor-tipped coronary wire. The exercise treadmill test was performed according to the Bruce protocol. RESULTS Patients with RA showed significantly higher IMR and lower CFR than control subjects, in the target arteries and in the reference vessels (P < 0.05). The hyperemic IMR was more remarkably increased in the target arteries than in the reference vessels (29.3 ± 11.7 vs 24.4 ± 9.7; P = 0.008). The hyperemic IMR was increased and the CFR was impaired more significantly in patients with a positive exercise treadmill test (P < 0.05). CONCLUSIONS Using an intracoronary thermodilution method, to our knowledge, we have for the first time confirmed that, in patients who underwent successful coronary stenting and without epicardial stenosis at repeat angiography late after PCI, coronary microvascular dysfunction was responsible for the RA.

Relationship Between Mean Platelet Volume and Coronary Blood Flow in Patients with Atrial Fibrillation

INTRODUCTION Atrial fibrillation (AF) is associated with impaired coronary flow by means of Thrombolysis in Myocardial Infarction (TIMI) frame count (TFC). Mean platelet volume (MPV) is elevated in patients with AF. In the present study we aimed to investigate the relationship between MPV and TFC in patients with AF in the absence of obstructive coronary artery disease (CAD). METHODS This observational study enrolled 185 AF patients and 189 control subjects, all with angiographically documented normal coronary arteries. MPV was measured at baseline and mean TFC was assessed after diagnostic coronary angiography. RESULTS The MPV was 9.95±1.32 in the AF group and 9.02±1.16 in the control group (p<0.001). In AF patients, MPV was significantly correlated with mean TFC (r=0.419, p<0.001), AF duration (r=0.407, p<0.001), AF classification (r=0.378, p<0.001), systemic hypertension (r=0.165, p=0.024), diabetes mellitus (r=0.233, p=0.001), left ventricular ejection fraction (r=-0.347, p<0.001), and baseline use of diuretics (r=0.177, p=0.016). In linear regression analysis, mean TFC, left ventricular ejection fraction and diabetes mellitus were found to be independently associated with MPV (p<0.001, p=0.028 and p=0.045 respectively). CONCLUSION Mean platelet volume seems to be independently associated with coronary blood flow in patients with atrial fibrillation in the absence of obstructive coronary artery disease.

Short-term effects of enhanced external counterpulsation on transthoracic coronary flow velocity and reserve in patients with coronary slow flow ☆

flow velocity and reserve in patients with coronary slow flow☆ Chufan Luo , Donghong Liu , Zhimin Du , Gregory W. Barsness , Xing Wu , Chengheng Hu , Yi Li , Xun Hu , Yan Zhang , Guifu Wu a,d,⁎ a Division of Cardiology, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China b Department of Ultrasound, First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China c Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minn 55905, USA d Key Laboratory on Assisted Circulation, Ministry of Health, Guangzhou, China

Effect of enhanced external counterpulsation on coronary slow flow and its relation with endothelial function and inflammation: a mid-term follow-up study.

Background: Although enhanced external counterpulsation (EECP) showed short-term effects in improving coronary flow in patients with coronary slow flow (CSF), whether such improvement is durable remains uncertain, and the relationships between such improvement and changes in endothelial function as well as inflammatory markers have not been elucidated. Objectives: The aim of the present study was to investigate the effects of EECP on transthoracic coronary flow, flow-mediated dilatation (FMD), and high-sensitivity C-reactive protein (hsCRP) in patients with CSF. Methods: Forty-five patients with documented CSF underwent transthoracic Doppler echocardiography (TTDE) for the assessment of coronary diastolic peak flow velocity (DPFV) and coronary flow reserve (CFR), and measurements of FMD and hsCRP; they were then nonrandomly assigned to two groups. Subjects in the control group (n = 24) received only medical therapy, and those in the EECP group (n = 21) were additionally treated with the 36 one-hour sessions of EECP. After 8 weeks of medical/EECP therapy, TTDE, FMD, and hsCRP examinations were repeated, and TTDE was additionally repeated after the 6-month clinical follow-up. Results: In the EECP group, resting DPFV, hyperemic DPFV, and CFR were significantly increased shortly after therapy (p < 0.001) and the improvement was maintained up to the 6-month follow-up, whereas in the control group those variables were not statistically increased. Meanwhile, hsCRP significantly decreased and FMD increased after therapy in the EECP group (p < 0.001). In all subjects, CFR improvement was negatively correlated with hsCRP change and positively correlated with FMD increase (p < 0.001). Conclusions: EECP may have a durable effect in improving coronary flow in patients with CSF. Such improvement is related to the favorable effects of EECP on vascular inflammation and endothelial function.

Vessel heterogeneity of TIMI frame count and its relation to P-wave dispersion in patients with coronary slow flow.

BACKGROUND The vessel heterogeneity of thrombolysis in myocardial infarction (TIMI) frame count (TFC) in patients with coronary slow flow (CSF) remains to be further evaluated, and the correlation between TFC heterogeneity and P-wave dispersion (PWD) has not been elucidated. We aim to investigate the vessel heterogeneity of TFC in coronary arteries, and its relation to PWD in patients with CSF and otherwise normal coronary arteries. METHODS We studied 72 patients with angiographically documented CSF and 66 age- and gender-matched control subjects. The coefficient of variation (CV) and mean TFC of the three vessels were calculated. P-wave duration and PWD were measured on the standard electrocardiograms (ECGs). RESULTS The mean TFC and CV were both significantly higher in CSF patients than in controls (P<0.001 for both comparisons). The maximum P-wave duration (Pmax) and PWD were found to be significantly higher in CSF patients than in controls (P<0.001 for both comparisons). In patients with CSF, both Pmax and PWD were mildly correlated to mean TFC (r=0.318, P=0.009; and r=0.307, P=0.010), and were more significantly correlated to CV (r=0.506, P<0.001; and r=0.579, P<0.001). CONCLUSIONS These data demonstrate that variability of TFC in three coronary arteries is increased in CSF patients, and that the vessel heterogeneity in coronary flow might be intimately associated with PWD.

Association of Inflammation and Endothelial Dysfunction with Coronary Microvascular Resistance in Patients with Cardiac Syndrome X

Background Although a proportion of CSX patients have impaired brachial artery flow-mediated dilatation (FMD) in response to hyperemia, suggesting that endothelial dysfunction in these patients may be systemic and not just confined to the coronary circulation; the underlying mechanisms triggering endothelial dysfunction in these patients are still incompletely understood. Objectives To assess the association of the index of Microcirculatory Resistance (IMR) with endothelial dysfunction and inflammation in patients with CSX. Methods We studied 20 CSX patients and 20 age and gender-matched control subjects. Thermodilution-derived coronary flow reserve (CFR) and IMR were measured using a pressure-temperature sensor-tipped guidewire. Brachial artery FMD was measured using high-resolution, two-dimensional ultrasound images obtained with a Doppler ultrasound device (HDI-ATL 5000, USA) with a 5 MHz to 12 MHz linear-array transducer. Results Compared with in control subjects, CFR was significantly lower (2.42 ± 0.78 vs. 3.59 ± 0.79, p < 0.001); IMR was higher (32.2 ± 8.0 vs. 19.5 ± 5.5, p < 0.001); the concentration of hs-CRP and FMD was higher (4.75 ± 1.62 vs. 2.75 ± 1.50; 5.24 ± 2.41 vs. 8.57 ± 2.46, p < 0.001) in CSX patients. The Duke treadmill score (DTS) was correlated positively to CFR and FMD (0.489 and 0.661, p < 0.001), it was negative to IMR and hsCRP (-0.761 and -0.087, p < 0.001) in CSX patients. Conclusions The main finding in this study is that the DTS measured in patients with CSX was associated to hsCRP and FMD. Moreover, the independent effects of exercise tolerance can significantly impair FMD and hsCRP in CSX patients; especially it is particularly important to whom where FMD was associated negatively with IMR.