Nis Høst

Collagen : scaffold for repair or execution

The shape, cellular arrangement and the tensile strength of organs are determined by their extracellular matrix (ECM) [l]. This consists of a variety of molecules, among which fibrillar collagens and proteoglycans quantitatively predominate. The cells of the connective tissue were formerly considered to be almost metabolically inactive, but are now recognised as being an active participant in the initiation and modulation of tissue growth and repair [l-4]. Under normal physiological conditions, the ECM undergoes constant maintenance, with a relatively low basic turnover. Damage to tissue, largely independent of aetiology and target organ, produces a uniform response resulting in repair, which dramatically increases the activity of connective tissue cells [5-71. Fundamentally, the process of repair serves to minimise the extent of initial damage and to preserve organ function. Increased collagen synthesis is an important part of this process. Despite the intention to save organ function, the outcome may be a twoedged sword: in an effort to save the organ, re-establishment of normal function is impaired by increased amounts of collagen. In cardiovascular diseases, the reduced contractility in the zone adjacent to a myocardial infarct [8,9], the stiffness of the myocardium in hypertrophied cardiomyopathies, and the reduced compliance of the arteries in hypertension, are all examples of impaired function brought about by the increased amounts of deposited collagen. Therefore, a better understanding of the role played by the connective tissue cells in cardiovascular diseases is essential if further diagnostic and therapeutic improvements are to be achieved. The promising reports on the collagen modulating effect of ACE inhibition and specific angiotensin II antagonists, clearly prompts this. Furthermore, thrombolytic therapy of acute myocardial infarction represent a clinical situation with pronounced influence on collagen metabolism. The first step towards management of unwanted fibrosis, without interfering with necessary repair is the development and validation of non-invasive methods for sequential measurement of extracellular activity, i.e. deposition and degradation of collagen. Serological markers of the collagen metabolism seems to constitute a good tool for forthcoming clinical research in the field. The current knowledge of serological markers of the collagen metabolism in cardiovascular diseases, is reviewed in the present article.

Coronary Microvascular Function and Cardiovascular Risk Factors in Women With Angina Pectoris and No Obstructive Coronary Artery Disease: The iPOWER Study

Background The majority of women with angina‐like chest pain have no obstructive coronary artery disease when evaluated with coronary angiography. Coronary microvascular dysfunction is a possible explanation and associated with a poor prognosis. This study evaluated the prevalence of coronary microvascular dysfunction and the association with symptoms, cardiovascular risk factors, psychosocial factors, and results from diagnostic stress testing. Methods and Results After screening 3568 women, 963 women with angina‐like chest pain and a diagnostic coronary angiogram without significant coronary artery stenosis (<50%) were consecutively included. Mean age (SD) was 62.1 (9.7). Assessment included demographic and clinical data, blood samples, questionnaires, and transthoracic echocardiography during rest and high‐dose dipyridamole (0.84 mg/kg) with measurement of coronary flow velocity reserve (CFVR) by Doppler examination of the left anterior descending coronary artery. CFVR was successfully measured in 919 (95%) women. Median (IQR) CFVR was 2.33 (1.98–2.76), and 241 (26%) had markedly impaired CFVR (<2). In multivariable regression analysis, predictors of impaired CFVR were age (P<0.01), hypertension (P=0.02), current smoking (P<0.01), elevated heart rate (P<0.01), and low high‐density lipoprotein cholesterol (P=0.02), but these variables explained only a little of the CFVR variation (r 2=0.09). CFVR was not associated with chest pain characteristics or results from diagnostic stress testing. Conclusion Impaired CFVR was detected in a substantial proportion, which suggests that coronary microvascular dysfunction plays a role in the development of angina pectoris. CFVR was associated with few cardiovascular risk factors, suggesting that CFVR is an independent parameter in the risk evaluation of these women. Symptom characteristics and results from stress testing did not identify individuals with impaired CFVR.

Thrombolytic Therapy of Acute Myocardial Infarction Alters Collagen Metabolism

The objective of the study was to monitor collagen metabolism after thrombolytic therapy. Sequential measurements of serum aminoterminal type-III procollagen propeptide (S-PIIINP) and carboxyterminal type-I procollagen propeptide (S-PICP) were made in 62 patients suspected of acute myocardial infarction and receiving thrombolytic therapy. Regardless of whether acute myocardial infarction was confirmed or not, S-PIIINP increased (94-120%) 4 h after streptokinase therapy (p < or = 0.02), and decreased during the next 20 h with median values at 24 h still above the baseline (p < 0.02). With confirmed acute myocardial infarction, S-PIIINP increased from 24 h towards a plateau reached at day 2-3 (p < 0.01), with values still elevated at 6 months. No similar biphasic pattern was found for S-PICP, but patients with acute myocardial infarction had S-PICP above baseline at 1, 2, and 6 months (p < 0.05). A less pronounced S-PIIINP increase was noted with tissue-plasminogen activator than with streptokinase. Thrombolytic therapy induces collagen breakdown regardless of whether acute myocardial infarction is confirmed or not. With confirmed acute myocardial infarction collagen metabolism is altered for at least 6 months. Furthermore, fibrin-specific and nonspecific thrombolytic agents appear to affect collagen metabolism differently.

LA emptying fraction improves diagnosis of paroxysmal AF after cryptogenic ischemic stroke: results from the SURPRISE study.

In 25% of patients with ischemic stroke, no etiologic factor is identified: so-called cryptogenic strokes (CS) [(1)][1]. Asymptomatic paroxysmal atrial fibrillation (PAF) is often suspected to be the cause of stroke in these patients. Echocardiographic estimates of left atrial (LA) function, such

Cardiac remodelling and function with primary mitral valve insufficiency studied by magnetic resonance imaging

AIMS Evaluation of patients with primary mitral valve insufficiency (MI) is best supported by quantitative measures. Cardiovascular magnetic resonance imaging (CMR) offers flow and cardiac chamber volume quantification. We studied cardiac remodelling with CMR to determine MI regurgitation volumes (MIVol) related to severe MI. METHODS AND RESULTS In total, 24, 20, and 28 patients determined to have mild, moderate, and severe primary MI, respectively, were studied. Combining cine stacks with phase-contrast velocity mapping across the ascending aorta, CMR-determined MIVol was reproducibly obtained as the difference between left ventricular (LV) stroke volume and aortic forward flow (Aoflow). With increasing MI severity, MIVol, left heart volumes, and pulmonary venous diameters increased (P < 0.01). Severe MI with LV end-systolic diameter of 40 mm was signified by MIVol >40 mL, MI regurgitant fraction >0.30, LV end-diastolic volume (LVEDV(i)) >108 mL m(-2), and a total left heart volume >188 mL m(-2) with dilated pulmonary veins and a LVEDV/right ventricular EDV ratio >1.2. In severe MI, LV ejection fraction was unaffected, but the Aoflow and the peak ejection rate indexed to LVEDV were lowered (P < 0.05). In surgical patients, the MIVol correlated to the decrease in LV dimension after valve surgery (P < 0.02). CONCLUSION CMR provides a reproducible quantitative technique for evaluation of MI, as MIVol and cardiac chamber volumes can be held against diagnostic cut-off values. The Aoflow and peak ejection rate indexed to LVEDV may reveal early LV systolic dysfunction in patients with severe MI. Severe MI is related to lower MI regurgitation volume and fraction than previously believed.

Transthoracic Doppler echocardiography compared with positron emission tomography for assessment of coronary microvascular dysfunction: The iPOWER study

BACKGROUND Coronary microvascular function can be assessed by transthoracic Doppler echocardiography as a coronary flow velocity reserve (TTDE CFVR) and by positron emission tomography as a myocardial blood flow reserve (PET MBFR). PET MBFR is regarded the noninvasive reference standard for measuring coronary microvascular function but has limited availability. We compared TTDE CFVR with PET MBFR in women with angina pectoris and no obstructive coronary artery disease and assessed repeatability of TTDE CFVR. METHODS From a cohort of women with angina and no obstructive coronary artery stenosis at invasive coronary angiography, TTDE CFVR by dipyridamole induced stress and MBFR by rubidium-82 PET with adenosine was successfully measured in 107 subjects. Repeatability of TTDE CFVR was assessed in 10 symptomatic women and in 10 healthy individuals. RESULTS MBFR was systematically higher than CFVR. Median MBFR (interquartile range, IQR) was 2.68 (2.29-3.10) and CFVR (IQR) was 2.31 (1.89-2.72). Pearsons correlation coefficient was 0.36 (p<0.01). Limits of agreement (2·standard deviation) assessed by the Bland-Altman (confidence interval, CI) method was 1.49 (1.29;1.69) and unaffected by time-interval between examinations. Results were similar when adjusting for rate pressure product or focusing on perfusion of the left anterior descending artery region. Limits of agreement (CI) for repeated CFVR in 10 healthy individuals and in 10 women with angina was 0.44 (0.21;0.68) and 0.48 (0.22; 0.74), respectively. CONCLUSION CFVR had a good repeatability, but the agreement between CFVR and MBFR was modest. Divergence could be due to methodology differences; TTDE estimates flow velocities whereas PET estimates myocardial blood flow.

Diagnosing Paroxysmal Atrial Fibrillation in Patients With Ischemic Strokes and Transient Ischemic Attacks Using Echocardiographic Measurements of Left Atrium Function.

Twenty-five to 35 percentage of stroke cases are cryptogenic, and it has been demonstrated that paroxysmal atrial fibrillation (AF) is the causal agent in up to 25% of these incidents. The purpose of this study was to investigate if left atrial (LA) parameters have value for diagnosing paroxysmal AF in patients with ischemic stroke (IS) and transient ischemic attack (TIA). We retrospectively analyzed 219 patients who after acute IS or TIA underwent a transthoracic echocardiographic examination. Patients were designated as patients with paroxysmal AF if they had one or more reported incidents of AF before or after their echocardiographic examination. Patients in the paroxysmal AF group were significantly older and had higher CHA2DS2-VASc score than patients without paroxysmal AF (p <0.05 for both). None of the conventional echocardiographic parameters were significantly associated with paroxysmal AF. However, the atrial measurements evaluating LA function (min LA volume and LA emptying fraction) were significantly different (LA emptying fraction: 45% ± 10% vs 50% ± 10%, p = 0.004; minimal LA volume: 30.2 ml ± 17.3 ml vs 24 ml ± 10 ml, p = 0.035 in patients with paroxysmal AF, even after adjustment for age, gender, CHA2DS2-VASc score, and stroke severity [p <0.05 for both]). By combining the cut-off values of age, LA emptying fraction, and minimal LA volume the diagnostic accuracy of paroxysmal AF was improved, resulting in a sensitivity of 95% and negative predictive value of 97%. In conclusion, in patients with IS and TIA, LA function measurements (minimal LA volume and LA emptying fraction) are independently associated with paroxysmal AF and may improve risk stratification for paroxysmal AF presence after IS or TIA.

Results of voluntary cardiovascular examination of elite athletes in Denmark: Proposal for Nordic collaboration.

We investigated the cardiovascular status of elite athletes in Denmark, the extent of abnormal cardiac findings – both training related and pathologic – and how participating in cardiac examination was perceived by the athletes. A standardized protocol of questionnaires, physical examination, resting electrocardiogram, and 2D echocardiography was used. In total 1347 elite athletes were invited; 516 athletes (38%) from 30 different sports participated. Results were stored in a web‐based database for future research and long‐term follow‐up. Cardiac pathology was infrequent; eight athletes (1.6%) received a cardiac diagnosis; one athlete (0.2%) diagnosed with long QT syndrome was advised against competition level sports. In total, 60 athletes (11.6%) were referred for additional testing. The athletes presented a very low level of psychological stress before and a slight decrease immediately after the examination as measured by the REST‐Q 76 Sport questionnaire. Athletes needing further examinations did not present a higher level of stress after the initial examination compared with athletes with normal test results. Overall, very few athletes were diagnosed with a cardiac condition that increased risk of sudden cardiac death. Less than half of the invited athletes volunteered, but participation was not perceived stressful by the enrolled athletes, not even when additional testing was needed.

Age-related decline in mitral peak diastolic velocities is unaffected in well-trained runners

Abstract Objectives. We examined whether diastolic left ventricular function in young and senior lifelong endurance runners was significantly different from that in sedentary age-matched controls, and whether lifelong endurance running appears to modify the age-related decline in diastolic left ventricular function. Design. The study comprised 17 senior athletes (age: 59–75 years, running distance: 30–70 km/week), 10 young athletes (age: 20–36 years, matched for running distance), and 11 senior and 12 young weight-matched sedentary controls. Peak early (E) and late (A) mitral inflow and early (e’) and late (a’) diastolic and systolic (s’) annular longitudinal tissue Doppler velocities were measured by echocardiography during four stages (rest, supine bike exercise at 30% and 60% of maximal workload, and recovery). Results. The athletes had marked cardiac remodeling, while overall differences in mitral inflow and annular tissue Doppler velocities during rest and exercise were more associated with age than with training status. The senior participants had lower E/A at rest, overall lower E, e’ and s’, and greater E/e’ compared to the young participants (all values of P < 0.05). The athletes had greater E/A (P = 0.004), but tissue Doppler velocities were not different from those of the controls. Conclusions. Lifelong endurance running was not found to be associated with major attenuation of the age-related decline in diastolic function at rest or during exercise.

Effect of ACE-inhibition on coronary microvascular function and symptoms in normotensive women with microvascular angina: A randomized placebo-controlled trial

Objective Studies have suggested a beneficial effect of angiotensin-converting enzyme (ACE) inhibition. To explore whether the ACE inhibitor ramipril has a direct effect on the microvasculature beyond the blood pressure (BP) lowering effect, we investigated whether ramipril improved coronary microvascular function in normotensive women with coronary microvascular dysfunction (CMD). Methods We included 63 normotensive women with angina, no epicardial stenosis>50% and CMD defined as a coronary flow velocity reserve (CFVR)<2.2 assessed by adenosine stress-echocardiography in a randomized double-blinded, superiority trial with 1:1 allocation to placebo or ramipril (maximum dose 10 mg depending on blood pressure) for 24±6 weeks. Primary outcome was CFVR. Secondary outcomes were left ventricular systolic and diastolic function and symptoms evaluated by Seattle Angina Questionnaire (clinicaltrials.gov, NCT02525081). Results Follow-up was available on 55 patients. BP remained unchanged during treatment in both groups. CFVR improved in both the ramipril (p = 0.004) and placebo group (p = 0.026) with no difference between groups (p = 0.63). Symptoms improved in both groups with no significant between-group differences. No changes were detected in parameters of systolic and diastolic function. No serious adverse reactions were reported. Conclusions In normotensive women with angina and CMD, treatment with ramipril had no significant effect on CFVR or symptoms compared with placebo. The effect of ACE inhibition previously reported may be mediated by blood pressure reduction.