Circulating progenitor cells in stable coronary heart disease and acute coronary syndromes: relevant reparatory mechanism?

Bone marrow-derived cells which may be involved in cardiac repair/regeneration after ischaemic injury must undergo mobilisation into peripheral blood with subsequent homing and engraftment into the target organ. Mobilisation of the heterogeneous population of stem/progenitor cells in endothelial injury or myocardial ischaemia has been described recently. The number of circulating stem/progenitor cells reflects the endothelial damage, and turnover may be a surrogate marker reflecting the burden of cardiovascular risk factors and prognostic markers in stable coronary heart disease and acute coronary syndromes. Acute coronary syndromes are associated with increased levels of inflammatory and haematopoietic cytokines which, in turn, can mobilise progenitor cells from the bone marrow. Myocardial infarction increases the number of endothelial progenitor cells and other less well-defined subpopulations, such as CD34/c-kit(+) and CD34/CXCR4(+) cells, which may take part in cardiac repair after ischaemic injury. Data on mobilisation of stem/progenitor cells in acute coronary syndromes are summarised here. Cell types, mechanisms of mobilisation, homing and engraftment are discussed and their relevance to clinical outcomes.

Prospective randomised study to evaluate effectiveness of distal embolic protection compared to abciximab administration in reduction of microembolic complications of primary coronary angioplasty

BACKGROUND

Myocardial reperfusion following primary percutaneous coronary intervention (pPCI) is limited due to, among other things, microembolic events. Abciximab and a mechanical system of distal protection both reduce their incidence during PCI.

AIM

Prospective, randomised study to compare effectiveness of abciximab and protection devices in reduction of microembolic complications during pPCI.

METHODS

One hundred and twenty consecutive patients with ST elevation acute myocardial infarction referred for pPCI after coronary angiography were randomly assigned to the following groups: Group A (n=63), treated with abciximab; and Group B (n=57), treated using the distal protection system. Primary endpoint was blood flow through the infarct-related artery (IRA) using TIMI grading after pPCI; secondary endpoints included myocardial perfusion assessment using myocardial blush grade (MBG), ST resolution and improvement of echocardiographic left ventricular ejection fraction (LVEF) after pPCI.

RESULTS

TIMI grade 3 flow after pPCI was obtained in 89% of patients in both groups, TIMI grade 2 flow in 5% (NS). Myocardial perfusion after pPCI assessed with MBG scored 3 in 66% of patients in group A and 62% of patients in group B (NS). ST resolution was present in 62% (26-84) in group A and 68% (41 - 86) in group B (NS). Logistic regression analysis showed no significant influence of selected variables on the primary endpoint. Analysis performed in the distal protection group revealed significant effects on the following factors on the final TIMI flow in IRA: presence of thrombus prior to pPCI (p=0.026), presence of residual thrombus after aspiration (p <0.001), and IRA diameter of > or =3.5 mm (p=0.01). Median LVEF in group A at sixth month of follow-up was 46% (44-50%), similar to group B - 46% (45-49%) (NS).

CONCLUSIONS

Use of the PercuSurge distal protection device during pPCI allows angiographic and electrocardiographic measures of reperfusion to be improved. It has a similar effect on left ventricular systolic function as administration of abciximab. The device seems to be useful in patients with culprit artery diameter of > or =3.0 mm, and optimally > or =3.5 mm and thrombus visible on angiography. Successful initial thrombectomy prior to deployment of stent seems particularly important when using the PercuSurge system.

Comparison of effectiveness of coronary artery bypass grafting versus percutaneous coronary intervention in patients with ischemic cardiomyopathy

The REvascularization in Ischemic HEart Failure Trial (REHEAT) is a nonrandomized, case-controlled, prospective study assessing the hypothesis that surgical and percutaneous revascularizations in patients with ischemic cardiomyopathy are associated with comparable improvement in left ventricular ejection fraction (LVEF) and functional status 12 months after myocardial revascularization. The study population consisted of 141 patients with LVEFs of <40% and angiographically confirmed coronary artery disease. The primary end point was improvement in LVEF 12 months after intervention. Secondary end points were in-hospital major adverse events, length of hospitalization, exercise tolerance of treadmill stress testing after 12 months, 1-year survival, 1-year event-free survival, angina, and heart failure severity after 12 months. The case-controlled study included 55 patients who underwent percutaneous coronary intervention (PCI) and 54 who underwent coronary artery bypass grafting (CABG). The incidence of 30-day major adverse events was higher in the CABG group (40.7% vs 9%, p = 0.0003), whereas duration of hospital stay was shorter in the PCI group (6.8 +/- 3.6 vs 9.2 +/- 2.1 days, p = 0.00001). Increase in LVEF was comparable after PCI and CABG (6.0 +/- 7.2% vs 4.4 +/- 9.0% p = 0.12). Long-term functional status based on treadmill stress testing was better after PCI (Student's t test, p = 0.0003) but, according to Canadian Cardiovascular Society and New York Heart Association classifications, was similar in the 2 treatment arms (Wilcoxon test, p <0.01). Long-term survival was significantly better for patients after PCI (Wilcoxon test, p <0.01); however, major adverse event-free survival was better after CABG (Cox-Mantel test, p = 0.0013). In conclusion, PCI and CABG are associated with comparable improvements in LVEF in patients with ischemic cardiomyopathy. PCI offers a better 1-year survival rate than CABG, but the incidence of repeat revascularization is lower with CABG.

The prognostic role of electrocardiographic left ventricular mass assessment for identifying PCI-treated patients with acute ST-elevation myocardial infarction at high risk of unfavourable outcome

BACKGROUND

In prognostic terms, evaluation of an ECG recording in acute myocardial infarction (AMI) appears to be inferior to echocardiographic (ECHO) assessment of left ventricular remodelling and the activities of cardiac enzymes and certain hormones. It was our hypothesis that, in the era of interventional treatment of AMI, some ECG parameters are still valid for the purpose of risk stratification.

METHODS

A total of 66 consecutive patients with AMI (43 male and 23 female, with a mean age of 61 +/- 11 years) were treated with primary percutaneous coronary intervention (PCI). In each patient ECG and ECHO examinations were performed within 5-7 days of admission for the detection of left ventricular hypertrophy (LVH). In further analysis the following ECG- based LVH parameters were taken into consideration: Sokolov-Lyon voltage duration (SLVd), Cornell voltage duration CVd), 12-lead QRS voltage duration (12QRSVd), their product with QRS duration and an ECG index of left ventricular mass (LVMI(ECG)). Patients were followed for 6 months. The combined end-point included death, infarction, a need for prompt coronary intervention and hospitalization for heart failure.

RESULTS

The combined end-point was observed in 16 patients (24.2%). Survival analysis revealed that the most important prognostic factors were associated with a prolongation of the QRS duration. Increased SLVd was found in 43% of the patients with events compared to 14% in those without them (p < 0.01), CVd in 43% vs. 12% (p < 0.05), 12QRSVd in 81% vs. 44% (p < 0.05) and LVMI(ECG) in 75% vs. 26%, p < 0.001). There was no evidence for a difference in Cornell voltage. Univariate logistic regression indicated a 4-fold to 8-fold increase in the risk of events associated with abnormal SLV, SLVd or LVMI(ECG). Multivariate Cox analysis showed that the LVH presence in the ECG, defined as an increased SLVd product or increased LVMI(ECG), was an independent predictor of cardiovascular events after AMI.

CONCLUSIONS

In the era of interventional treatment of AMI, the ECG features of left ventricular hypertrophy carry independent significant prognostic information. (Cardiol J 2007; 14: 347-354).

Local paclitaxel delivery as a treatment of persistent, recurrent in-stent restenosis -- safety assessment

INTRODUCTION

In-stent restenosis still remains a serious clinical problem. Local intramural drug delivery (LDD -- Local Drug Delivery) seems to be an interesting alternative to drug-eluting stents (DES).

AIM

The aim of the study was to assess the safety and effectiveness of local intramural paclitaxel administration in the treatment of recurrent in-stent restenosis (ISR).

METHODS

Five patients were enrolled in the study (3 men, mean age 50+/-7 years) with at least a second episode of ISR within the same stent. Percutaneous coronary angioplasty was performed on a total of 11 vessel segments. Remedy delivery catheters (Boston Scientific) were used for balloon angioplasty. Inflation pressure was calibrated to obtain a balloon/vessel lumen ratio of 1.1:1. Then the pressure was lowered to 3 atmospheres and 100 microg of paclitaxel diluted in 2 ml of 0.9% NaCl was given over 60 seconds under the pressure of 2-3 atmospheres. This dose was used for each 10 mm of lesions. Control coronary angiography was performed six months after the procedure.

RESULTS

In all patients effective target vessel revascularisation was achieved. No adverse events were observed in the periprocedural period or during the 6-month follow-up period. Control angiography revealed ISR in three segments (27.2%) and in-stent late lumen loss of 0.21+/-0.93 mm.

CONCLUSIONS

Local intramural paclitaxel delivery is a safe and effective method of ISR treatment. The optimal paclitaxel dose should be established in further studies.

Vibration syndrome diagnosis using a cooling test verified by computerized photoplethysmography

This study addresses the problem of vibration syndrome diagnosis by means of a cooling test verified by photoplethysmography. Measurement was taken on a small area on the fingertip plexus in which many arterio-venous anastomoses are present. In the opinion of many authors, flow disorders in this area are more typical for developing vibration syndrome than changes in the micro vessels. The study group comprised 128 subjects (58 women aged 40.9 +/- 5.4 years and 70 men aged 38.7 +/- 8.8 years) exposed to vibration. The control group consisted of 41 people (20 women aged 39.6 +/- 7.3 years and 21 men aged 39.3 +/- 6.4 years) who were not exposed to vibration. The patients were examined by a questionnaire and then a vibration perception threshold test and a cooling test were performed. The cooling test was verified both visually and using the computer method. Measurement data (S1, S2 and A) for each patient were obtained from averaging three pulse graphs. We departed from an average of 60 graphs (and more), the standard established in the literature, because of the cooling test specification, which causes huge thermodynamic parameter changeability in the plexus mass of the small finger under pulse waves coming one after another. A longer measurement time will reflect the thermal drift of the tested area in a direction to compensate for the reduced temperature. In the control group, all subjects showed an increase in planimetric indicators during the cooling test verified by computerized photoplethysmography. In the study group visual verification of the cooling test was positive in eight cases (6.2%) and the vibration perception threshold test was positive in seven cases (5.5%), but in computerized photoplethysmography the planimetric indicators decreased after cooling in 87 (67.4%) cases. Computer photoplethysmography is highly specific and shows greater sensitivity in detecting preclinical forms of vascular-type vibration syndrome when compared with palesthesiometry, the visually verified cooling test and the questionnaire. The proposed test enables the detection of vascular disorders in the prodromal period and gives time for preventive measures to be taken.

Left ventricular mass and hypertrophy assessment by means of the QRS complex voltage-independent measurements

ECG QRS-complex voltage-based criteria are relatively insensitive for detection of increased left ventricular mass (LVM). We developed and evaluate a new ECG index for LV hypertrophy (LVH) detection regardless of the QRS voltage.

METHODS

Study population consisted of 106 patients (73 m, 33 f, aged 60 +/- 10 years) with established coronary artery disease (CAD). All patients had LVM assessed echocardiographically and indexed to BSA (LVMI(ECHO)). LVH was diagnosed if LVMI(ECHO) >117 g/m2 in men and >104 g/m2 in women. LV geometry was also determined. Analysed ECG variables, obtained from 12 leads recorded simultaneously, were: the QRS complex duration (QRSd, ms), the average 12-lead time to maximal deflection (TMD, ms), the average 12-lead QRS complex voltage (12QRSV, mV), the average product of 12 lead QRS voltage and duration (12QRSVd, mV ms), Sokolow-Lyon voltage and V-d product (SLV, SLVd), Cornell voltage and V-d product (CV, CVd). A newly developed index, LVM(ECG), was calculated, as LVM(ECG) = [(2 x TMD+QRSd/pi)3-(QRSd/pi)3]*0.0001 (ms3), and indexed to BSA (LVMI(ECG), ms3/m2).

RESULTS

Means of the QRS voltage-related parameters were similar in patients with LVH and normal LVM. Greater differences existed between both groups when the QRS voltage-duration products were compared. LVMI(ECG) was most powerful in distinguishing between groups (130 +/- 33 LVH vs 91 +/- 21 normal LVM, p < 0.001). LVMI(ECG) correlated with LVMI(ECHO) better (r = 0.77, p < 0.001) than other indices (r coefficients between 0.24 for SLV and 0.49 for CVd). None of the examined indices allowed for distinction between eccentric and concentric LVH. The new index showed better statistical performance (area under ROC = 0.861) compared to the other indices (AUC range 0.545-0.697, p<0.001 vs LVMI(ECG)). At the specificity level of 92%, the value of LVMI(ECG) > 120 ms3/m2 had the sensitivity of 64% for detection of increased LVM. The sensitivities of the other parameters were significantly lower (sensitivity range 18-42%). Relative intra- and interobserver errors and correlation coefficients for LVMI(ECG) calculation were 0.4% and 1.6% and r = 0.94 and 0.98, respectively.

CONCLUSIONS

In patients with CAD an assessment of LV mass and detection of hypertrophy using the QRS complex time-dependent index is feasible. The new index correlated well with echocardiographically-determined LVM and showed better statistical performance than indices which include QRS-voltage measurements. The results are promising and warrant further studies to evaluate the utility of the new index as a risk predictor.

Stent implantation for the unprotected left main coronary artery. The long-term outcome of 62 patients

INTRODUCTION

Stent implantation for the unprotected left main coronary artery (ULMCA) is regarded as controversial and coronary heart disease with LMCA stenosis still remains a basic indication for bypass surgery. Although there is no doubt that the risk of stent implantation for LMCA lesions is low, there are still limited data on long-term outcomes. There have been no reports so far answering the question whether ULMCA stenting ensures adequate coronary blood flow in the vessel.

AIM

Assessment of the effect of LMCA flow restoration with stenting on the coronary flow reserve assessed by an exercise test, as well as on left ventricular function and angina in patients followed for 12 months after the procedure.

METHODS

The study population included 62 patients (17 women and 45 men) aged 61.4+/-11.1 (35-84 years) who underwent coronary angioplasty with elective ULMCA stenting. In all patients, serial echocardiography (before and 1, 3, 6, and 12 months after the procedure) and the exercise test according to the Bruce protocol (1, 3, 6, 12 months after the procedure) were carried out. Routine coronary angiography was performed 3 to 6 months after the procedure. Fifty-nine patients (95.2%) survived a 12-month period. In 24 (38.7%) patients major adverse cardiac events (MACE) occurred. In-stent restenosis was observed in 13 patients; in 11 of them repeated PCI was performed and 2 of them underwent CABG. One patient after repeated PCI required CABG.

RESULTS

Severity of angina, evaluated according to the CCS scale, decreased significantly in the 12-month follow-up period as compared with the preprocedural period (p <0.00001). The mean baseline left ventricular ejection fraction was 51.6+/-12.5%. It increased to 53.8+/-12.8% (p <0.02) at 6 months and remained at this level at 12 months. The mean exercise test time was 7.0+/-3.4 minutes in the first month after ULMCA stenting, and in the sixth and the twelfth month of follow-up it increased to 7.6+/-3.4 minutes (p <0.002) and 7.8+/-3.2 minutes (p <0.05), respectively. The metabolic equivalent task (MET) value did not change significantly during the observation period.

CONCLUSIONS

Restoration of the physiological blood flow in the unprotected left main coronary artery with stent implantation is associated with a significant reduction of angina, significant improvement of the left ventricular systolic function and preservation of exercise capacity in long-term follow-up.

Invasive treatment of coronary artery disease in octogenarians

INTRODUCTION

There are many patients aged over 80 years among those hospitalised for coronary artery disease (CAD). The unanswered question is whether invasive treatment of such patients is effective and safe.

AIM

To assess and compare one-year clinical outcomes after percutaneous coronary angioplasty (PTCA) and surgical coronary artery bypass grafting (CABG) in patients aged over 80 years and in younger patients.

METHOD

There were 63 patients aged over 80 years suffering from CAD who underwent either PTCA or CABG. The control group consisted of 40 patients aged 60-65 years treated in the same way. Data on medical history, cardiovascular risk factors, and angiographic findings were analysed. The potential risks of the procedures, post-procedural complications as well as the clinical status at the end of one-year follow-up were evaluated.

RESULTS

There were 24 surgical revascularisation procedures and 39 PCIs performed in the very old patients. Stable angina was found in 29 cases, unstable angina in 19 and acute myocardial infarction in 15 patients. There were three in-hospital deaths and 18 periprocedural complications were noted. During the one-year follow-up period six deaths occurred, persistent or recurrent angina was found in 11 patients after PCI and two after CABG. There were no deaths in the control group and the incidence of minor complications was similar to the senile group. In younger patients who underwent CABG, CCS class at one year was lower than in the very old ones.

CONCLUSIONS

The invasive treatment of coronary artery disease in octogenarians is feasible with satisfactory results and acceptable procedural risks.

Effect of coronary artery bypass graft in patients with unstable angina on left ventricular remodelling in medium-term follow-up

INTRODUCTION

Left ventricular remodelling is a process of change in size, shape, wall thickness and heart function, initiated by a noxious stimulus such as ischaemia. Methods of pharmacological and surgical inhibition or reversal of remodelling are being sought.

AIM

To assess the influence of coronary artery bypass grafting on echocardiographic measures of left ventricular size and shape in medium-term follow-up.

METHODS

In a group of 30 patients three echocardiographic examinations were performed: before CABG operation, 3 months after and 20 months after the operation. Left ventricular area and volumes as well as indices of sphericity, thinning and expansion were calculated.

RESULTS

After the operation, left ventricular areas measured in short axis and in apical four-chamber view increased among patients with a history of myocardial infarction. Improvement in the sphericity index occurred after the operation in patients with a history of myocardial infarction in whom the ejection fraction before the operation was less than 50%.

CONCLUSIONS

The left ventricular remodelling process progresses after coronary artery bypass grafting in patients with a history of myocardial infarction. Inhibition of remodelling may be expected in patients without myocardial infarction, with preserved left ventricular systolic function.

Mobilization of bone marrow-derived progenitor cells in acute coronary syndromes

Two hypotheses explain the role of adult progenitor cells in myocardial regeneration. Stem cell plasticity which involves mobilization of stem cells from the bone marrow and other niches, homing to the area of tissue injury and transdifferentiation into functional cardiomyocytes. Alternative hypothesis is based on the observations that bone marrow harbors a heterogenous population of cells positive for CXCR4 - receptor for chemokine SDF-1. This population of non-hematopoietic cells expresses genes specific for early muscle, myocardial and endothelial progenitor cells (EPC). These tissue-committed stem cells circulate in the peripheral blood at low numbers and can be mobilized by hematopoietic cytokines in the setting of myocardial ischemia. Endothelial precursors capable of transforming into mature, functional endothelial cells are present in the pool of peripheral mononuclear cells in circulation. Their number significantly increases in acute myocardial infarction (AMI) with subsequent decrease after 1 month, as well as in patients with unstable angina in comparison to stable coronary heart disease (CHD). There are numerous physiological and pathological stimuli which influence the number of circulating EPC such as regular physical activity, medications (statins, PPAR-gamma agonists, estrogens), as well as numerous inflammatory and hematopoietic cytokines. Mobilization of stem cells in AMI involves not only the endothelial progenitors but also hematopoietic, non-hematopoietic stem cells and most probably the mesenchymal cells. In healthy subjects and patients with stable CHD, small number of circulating CD34+, CXCR4+, CD117+, c-met+ and CD34/CD117+ stem cells can be detected. In patients with AMI, a significant increase in CD34+/CXCR4+, CD117+, c-met+ and CD34/CD117+ stem cell number the in peripheral blood was demonstrated with parallel increase in mRNA expression for early cardiac, muscle and endothelial markers in peripheral blood mononuclear cells. The maximum number of stem cells was found early in ST-segment elevation myocardial infarction (<12 hours) with subsequent decrease through the 7-day follow-up and with concomitant changes in the levels of cytokines involved in the inflammatory response and stem cell recruitment. Moreover, peak expression of cardiac muscle and endothelial markers occurred at the same time as the most significant increase in CD34/CXCR4+ stem cell number. The SDF-1/CXCR-4 axis seems particularly important in stem/muscle progenitor cell homing, chemotaxis, engraftment and retention in ischaemic myocardium. The significance of autologous stem cells mobilization in terms of cardiac salvage and regeneration needs to be proved in humans but it seems to be a reparative mechanism triggered early in the course of acute coronary syndromes.

Clinical trials using autologous bone marrow and peripheral blood-derived progenitor cells in patients with acute myocardial infarction

This paper discusses the current data concerning the results of major clinical trials using bone marrow-derived and peripheral blood-derived stem/progenitor cells in treatment of patients with acute myocardial infarction (AMI) and depressed left ventricular ejection fraction. In all major trials (TOPCARE-AMI, BOOST), the primary outcome measure was increase in left ventricular systolic function (LVEF) and left ventricle remodeling. The most consistent finding is the significant increase in LVEF. Some trials suggest also reduction of left ventricular remodeling. Although the absolute LVEF increase is small (6-9%), it may substantially contribute to the improvement of global LV contractility. None of the studies in AMI patients treated with intracoronary infusion of progenitor cells revealed excess risk of arrythmia, restenosis or other adverse effects attributable to the therapy. The exact mechanism of improved myocardial contractile function remains unknown, however, there are several possible explanations: therapeutic angiogenesis improving the blood supply to the infarct border zone, paracrine modulation of myocardial fibrosis and remodeling (e.g. inhibition of myocyte apoptosis) and transdifferentiation of stem/progenitor cells into functional cardiomyocytes. No study showed the superiority of the particular subpopulation of autologous progenitor cells in terms of left ventricular function improvement in AMI. In fact, most of the clinical trials used the whole population of mononuclear bone marrow-derived progenitor cells, peripheral blood derived progenitor cells (endothelial progenitors).

[Pathogenesis and treatment of acute coronary syndromes]

Acute coronary syndromes (ACS) include unstable angina and non-ST elevation myocardial infarction (UA/NSTEMI) and ST-segment elevation myocardial infarction (STEMI). Acute coronary syndromes lead to important epidemiological and economical problems. In polish population an estimated incidence of ACS is 250 000 cases per year. 30-day mortality in UA/NSTEMI is approximately 3.5%, and 8.4% in STEMI. The atherosclerotic plaque instability with subsequent rupture and thrombus formation is a primary mechanism of ACS. Plaque destabilization is evoked by local and systemic inflammation. The primary risk factors in ACS are: age > 65 years, diabetes, peripheral artery disease, stroke, previous myocardial infarction and elevated levels of cardiac troponins. The guidelines for treatment of ACS are based on the results of large randomized clinical trials assessing the reduction of relevant clinical end-points (death, AMI, recurrent ischaemia). The goal of treatment of UA/NSTEMI is the stabilization of the plaque, prevention and reduction of myocardial ischaemia and AMI. Inefficient medical treatment and sustained symptoms are the indication for coronary angiography and percutaneous coronary intervention (PCI). The main goal of treatment in STEMI is quick regaining of the culprit vessel patency and maintaining of sufficient myocardial perfusion. It can be done by thrombolytic therapy or primary coronary angioplasty. In comparison to fibrynolysis PCI confers the lower risk of death and recurrent AMI. New regimens of pharmacological treatment (facilitated PCI) including the half-dose of fibrynolytic and GPIIbIIIa inhibitor prior to PCI are assessed to improve the efficiency of PCI.

[Kinins--characteristics and role in the circulatory system]

Kinins play an important role in numerous of pathophysiological processes in organism. This paper encompasses mechanisms of kinins action and their role in the circulatory system. Individual components of the kallikrein-kinin system as well as their origin, structure and biodegeneration were described. Bradykinin B1 and B2 receptors along with their functions were discussed. Enzymes taking part in biodegradation of kinins were characterised. The role of the bradykinin as an inflammatory mediator as well as links between the kallikrein-kinin and renin-angiotensin systems, together with their contribution to myocardial ischaemia, were described.