Paola Capozza

Obstructive coronary atherosclerosis and ischemic heart disease: An elusive link!

In the current pathophysiological model of chronic ischemic heart disease (IHD), myocardial ischemia and exertional angina are caused by obstructive atherosclerotic plaque, and the clinical management of IHD is centered on the identification and removal of the stenosis. Although this approach has been in place for years, several lines of evidence, including poor prognostic impact, suggest that this direct relationship may present an oversimplified view of IHD. Indeed, a large number of studies have found that IHD can occur in the presence or absence of obstructive coronary artery disease and that atherosclerosis is just 1 element in a complex multifactorial pathophysiological process that includes inflammation, microvascular coronary dysfunction, endothelial dysfunction, thrombosis, and angiogenesis. Furthermore, the high recurrence rates underscore the fact that removing stenosis in patients with stable IHD does not address the underlying pathological mechanisms that lead to the progression of nonculprit lesions. The model proposed herein shifts the focus away from obstructive epicardial coronary atherosclerosis and centers it on the microvasculature and myocardial cell where the ischemia is taking place. If the myocardial cell is placed at the center of the model, all the potential pathological inputs can be considered, and strategies that protect the cardiomyocytes from ischemic damage, regardless of the causative mechanism, can be developed.

Patterns of left ventricular remodeling in chronic heart failure: prevalence and prognostic implications.

BACKGROUND AND AIM Many descriptors of left ventricular (LV) remodeling have important prognostic implications in patients with chronic systolic heart failure (HF). We sought to assess the prognostic value of the combination of increased LV mass with a disproportion between wall thickness and internal diameter. METHODS AND PATIENTS Patients (n = 536) with chronic HF, ejection fraction <50% and LV end-diastolic volume index >91 mL/m(2), classified according to LV mass index and relative wall thickness (RWT), were followed up for 33 ± 21 months. Ventricular mass was determined using a standard M-mode echocardiographic method. Relative wall thickness was defined as the ratio of (sum of interventricular septum thickness in diastole + posterior wall thickness in diastole)/LV end-diastolic diameter. RESULTS Prevalence of the pattern of increased LV mass index, defined as LV mass index >148 g/m(2) in men and >122 g/m(2) in women, and decreased RWT (<0.34) was 29%. Multivariable predictors of all-cause mortality were age >70 years (P < .0001), New York Heart Association class >2 (P < .0001), increased LV mass index, and decreased RWT (P = .003), E wave deceleration time ≤140 ms (P = .005), and male gender (P = .025). Patients with increased LV mass index and decreased RWT had a worse survival (33%) than patients with less LV mass index and normal to reduced RWT (log-rank 23.92; P < .0001). Comparisons of Cox models showed that the combination of increased mass index and decreased RWT added prognostic value to a model that included ejection fraction and end-systolic volume index. CONCLUSION In patients with systolic HF, an independent and incremental risk of adverse outcome was associated with increased mass index and decreased RWT.

Right ventricular remodelling in systemic hypertension: a cardiac MRI study

Background Consistent evidence shows an impact of systemic haemodynamic overload on the right ventricle, but its functional and structural consequences have received scarce attention for several reasons including the difficult application of conventional imaging techniques due to the complex shape and orientation of that cardiac chamber. Aims To evaluate whether mild to moderate, uncomplicated hypertension associates with abnormal right ventricular structure and function and how those changes relate to homologous changes in the left ventricle. Data were acquired by steady-state free-precession cardiac MRI, the state of the art tool for the morphological and functional evaluation of the right ventricle. Materials and methods Twenty-five (12 women) uncomplicated, untreated, essential hypertensive patients were compared with 24 (13 women) sedentary normotensive controls of comparable age. Wall thickness, indexed ventricular mass, end-diastolic volumes, early peak filling rate, a correlate of diastolic relaxation, and ejection fraction were measured at both ventricles. Remodelling index, the ratio of ventricular mass to end-diastolic volume, was used as an index of concentricity. Results Right ventricular mass index, ventricular wall thickness and remodelling index were greater in hypertensive subjects and associated with reduced peak filling rate, a pattern consistent with concentric right ventricular remodelling. In the hypertensive group, positive, highly significant biventricular correlations existed between indexed mass, early peak filling rate and ejection fraction. Conclusions Systemic hypertension associates with concentric right ventricular remodelling and impaired diastolic function, confirming that the unstressed ventricle is not immune to the effects of systemic hypertension. Structural and functional right ventricular adaptation to systemic hypertension tends to parallel the homologous modifications induced by systemic haemodynamic overload on the left ventricle.

Pharmacological approaches to coronary microvascular dysfunction

In recent decades coronary microvascular dysfunction has been increasingly identified as a relevant contributor to several cardiovascular conditions. Indeed, coronary microvascular abnormalities have been recognized in patients suffering acute myocardial infarction, chronic stable angina and cardiomyopathies, and also in patients with hypertension, obesity and diabetes. In this review, we will examine pathophysiological information needed to understand pharmacological approaches to coronary microvascular dysfunction in these different clinical contexts. Well-established drugs and new pharmacological agents, including those for which only preclinical data are available, will be covered in detail.

Microvascular Function/Dysfunction Downstream a Coronary Stenosis

For decades coronary macrovascular atherosclerosis has been considered the principal manifestation of coronary heart disease, with most of our effort dedicated to identifying and removal of coronary stenosis. However, growing body of literature indicates that coronary microcirculation also contributes substantially to the pathophysiology of cardiovascular disease. An understanding of mechanisms regulating microvascular function is of critical importance in understanding its role in disease, especially because these regulatory mechanisms vary substantially across species, vascular bed and due to comorbidities. Indeed, the most obvious consequence of coronary stenosis is that it may limit blood supply to the dependent myocardium to the point of causing ischaemia during exercise or even at rest. However, this flow limiting effect is not only due to the passive hydraulic effect of a narrowed conduit, but also to active responses in the coronary microcirculation triggered by the presence of an epicardial stenosis. To understand this problem it is important to review the inter-related mechanisms that regulate flow to the left ventricular wall and modulate transmural distribution of flow. These regulatory mechanisms operate hierarchically and are heterogeneously distributed along the coronary vascular tree. It is also important to discuss the effect of myocardial performance in modulating both blood flow demands and coronary resistance. Some of the interactions between coronary stenosis and microcirculation are transient, like those documented in acute coronary syndromes or during percutaneous interventions. However, microcirculatory remodeling may be triggered by a chronic coronary stenosis, leading to a sustained impairment of blood supply even after successful removal of the epicardial stenosis. A deeper understanding of these phenomena may explain paradoxical findings in patients undergoing coronary revascularization, particularly when functional tests are used in their assessment. These aspects are discussed in detail in this review.

Therapy Against Ischemic Injury

The advent of reperfusion therapy constituted a historical change for the management of myocardial infarction (MI) patients. However, shortly after, experimental models recognized an intrinsic damage, related to reperfusion itself, which was termed as ischemiareperfusion injury (IRI). Clinical studies attribute IRI a significant burden of morbidity and mortality observed in patients undergoing successful epicardial reperfusion. Several mechanisms have been identified and, as many strategies, have been investigated to address the phenomenon. In this review we will discuss the current evidence for IRI, pharmacological and non-pharmacological preventive strategies adopted both in experimental models and in clinical practice. Finally, we will try to provide a critical appraisal to the lack of consistent benefit observed in translational medicine.

Stress Testing After Complete and Successful Coronary Revascularization

BACKGROUND Noninvasive stress tests play a determinant role in the initial management of patients with chronic angina. Nonetheless, their use in the same patient population is considered inappropriate within 2 years after percutaneous coronary intervention (PCI). Indeed, early abnormal results correlate less well with angiographic control and are attributed to a number of confounding factors. We prospectively assessed prevalence and impact on the quality of life of abnormal stress test results in a highly selected patient population. METHODS Patients with no cardiac comorbidities who underwent successful and complete PCI with stenting for typical angina and had an abnormal exercise stress test (EST) under guideline-directed medical treatment were administered the Seattle Angina Questionnaire (SAQ). Clinical evaluation, EST, and the SAQ were repeated at 1, 6, and 12 months after the index PCI. RESULTS One hundred ninety-eight patients qualified and were included in the study (mean age, 64 years; 79% men). Although the majority had normal EST results or an increased threshold to angina, at 1 month after the index PCI, 29% of patients still had an abnormal result. At 6 and 12 months, 31% and 29% of patients had abnormal results, respectively. Quality-of-life assessment by the SAQ showed consistent results, with persistent angina in one third of patients. Control angiography documented a critical lesion, attributable to in-stent coronary restenosis, in only 8% of patients. CONCLUSIONS When stress testing is systematically performed after PCI, the prevalence of abnormal results is high and is associated with impaired quality of life. Prognostic significance along with the underlying pathophysiological mechanisms of such findings should be investigated.

OBSTRUCTIVE CORONARY ATHEROSCLEROSIS AND ISCHEMIC HEART DISEASE: AN ELUSIVE LINK!

In the current pathophysiological model of chronic ischemic heart disease (IHD), myocardial ischemia and exertional angina are caused by obstructive atherosclerotic plaque, and the clinical management of IHD is centered on the identification and removal of the stenosis. Although this approach has been in place for years, several lines of evidence, including poor prognostic impact, suggest that this direct relationship may present an oversimplified view of IHD. Indeed, a large number of studies have found that IHD can occur in the presence or absence of obstructive coronary artery disease and that atherosclerosis is just 1 element in a complex multifactorial pathophysiological process that includes inflammation, microvascular coronary dysfunction, endothelial dysfunction, thrombosis, and angiogenesis. Furthermore, the high recurrence rates underscore the fact that removing stenosis in patients with stable IHD does not address the underlying pathological mechanisms that lead to the progression of nonculprit lesions. The model proposed herein shifts the focus away from obstructive epicardial coronary atherosclerosis and centers it on the microvasculature and myocardial cell where the ischemia is taking place. If the myocardial cell is placed at the center of the model, all the potential pathological inputs can be considered, and strategies that protect the cardiomyocytes from ischemic damage, regardless of the causative mechanism, can be developed. (J Am Coll Cardiol 2012;60:951–6)

Progression of myocardial fibrosis and functional clinical status in Hypertrophic Cardiomyopathy: a study with cardiac magnetic resonance

In 29 patients with HCM (20 males; mean age 42 ± 19 years) we repeated two cardiac magnetic resonance examinations, using a 1.5 Tesla scanner (GE Healthcare, Milwaukee, USA). We evaluated LV mass and volumes and LVEF by the acquisition of conventional SSFP cine short axis images. DE was detected using T1 GRE IR acquired 10 minutes following contrast injection. Quantification of DE was performed as previously described (1). Results At the first CMR DE was detected in 21 subjects (72%), with an average extent of 8.1 ± 8 % of LV mass. CMR was repeated after an average of 772 ± 300 days. At the second CMR exam DE was found in 28 patients (97%). Among them, 16 subjects showed a significant increase of extent of DE (mean augment of 6.9 ± 5.5%, p< 0.0001). During the time interval between the 2 examination, NYHA class worsened in 10 patients who presented higher increase of DE extent than those with preserved functional status (8.3 ± 6.8 vs 3.4 ± 3.1, p < 0.04). Conclusions From these data we conclude that the progression of fibrosis in HCM is fast. The increase of extent of fibrosis in these patients is related to a worse clinical status. Therefore MRI can be applied as an useful safe tool, for longitudinal follow up evaluation of progression of the disease.