Cardiac Dysfunction in Heart Failure: The Cardiologist's Love Affair with Time

Phenotyping heart failure by cardiac magnetic resonance imaging of cardiac macro- and microscopic structure: state of the art review

Heart failure demographics have evolved in past decades with the development of improved diagnostics, therapies, and prevention. Cardiac magnetic resonance (CMR) has developed in a similar timeframe to become the gold-standard non-invasive imaging modality for characterizing diseases causing heart failure. CMR techniques to assess cardiac morphology and function have progressed since their first use in the 1980s. Increasingly efficient acquisition protocols generate high spatial and temporal resolution images in less time. This has enabled new methods of characterizing cardiac systolic and diastolic function such as strain analysis, exercise real-time cine imaging and four-dimensional flow. A key strength of CMR is its ability to non-invasively interrogate the myocardial tissue composition. Gadolinium contrast agents revolutionized non-invasive cardiac imaging with the late gadolinium enhancement technique. Further advances enabled quantitative parametric mapping to increase sensitivity at detecting diffuse pathology. Novel methods such as diffusion tensor imaging and artificial intelligence-enhanced image generation are on the horizon. Magnetic resonance spectroscopy (MRS) provides a window into the molecular environment of the myocardium. Phosphorus (31P) spectroscopy can inform the status of cardiac energetics in health and disease. Proton (1H) spectroscopy complements this by measuring creatine and intramyocardial lipids. Hyperpolarized carbon (13C) spectroscopy is a novel method that could further our understanding of dynamic cardiac metabolism. CMR of other organs such as the lungs may add further depth into phenotypes of heart failure. The vast capabilities of CMR should be deployed and interpreted in context of current heart failure challenges.

Mythical metrics and methods: Needed paradigm shift in disease recognition and therapy

Current medicine is practiced in an organ-based, function-appraised manner with less attention paid to the tissue characteristics of the appraised organs. The fundamentals of this paradigm have been the product of an oversimplified and often layman-based perceptions of the studied organ over the years. These perceptions drove the current definitions of normality and abnormality, parameters used in the diagnosis of the disease, goals of treatment and studied outcomes. Despite the explosive advancement in technology that could have potentially changed our 'upstream' thinking, practitioners remain captives of these old beliefs and have streamlined current technology in a 'downstream' fashion; in the form of goal-directed protocols, and engineering systems that would study their implementations. As a result, diseases continue to evolve, become more resistant to therapy, late to diagnose, and with a persistent worsening of outcomes. With a primarily focus on the heart and from an anesthesiologist prospective, we challenge the fundamentals of the current paradigm from an 'upstream' prospective. We challenge the current 'territorial' definitions of the organs studied, the current terminology of some diseases, the parameters used in their diagnosis, the diagnostic modalities used and their goals of treatment. We illustrate some examples when the current collective 'myth' meets the 'reality' in an acute care setting, further clarifying the limitations of the current paradigm. We also, provide a theoretical hypothesis of what we believe to be a potential substitute of the current paradigm. Our theory redefines disease from an organ-based functional phenomenon to a structural-based tissue phenomenon, calling for an integrative and holistic approach of tissue assessment rather than a discrete approach that may potentially obscure the interaction of non-appraised organs. We also believe in redirecting technology in an upstream direction to better redefine and early detect diseases rather than submitting to generationally inherited beliefs. Whereas we have started some of our research on our proposed paradigm, our theoretical framework remains to be thought-provoking, and hypothesis-generating at the present time.

Association between serum N-terminal pro-B-type natriuretic peptide levels and characteristics of coronary atherosclerotic plaque detected by coronary computed tomography angiography

The aim of the present study was to explore the association between the levels of serum N-terminal pro-B-type natriuretic peptide (NT-pro BNP) and the characteristics of coronary atherosclerotic plaque detected by coronary computed tomography angiography (CCTA), in patients with unstable angina (UA). A total of 202 patients (age range, 47-82 years) were divided into the following three groups: Non-cardiac disease group (57 patients); stable angina pectoris (SAP) group (62 patients); and UA group (83 patients). There were significant differences between the serum NT-pro BNP levels among the three groups (P=0.007). However, in multivariant diagnoses, NT-pro BNP level was not an independent risk factor for UA. The levels of serum NT-pro BNP were observed to be positively correlated with the number of vessels involved (r=0.462; P<0.001), SIS (r=0.475; P<0.001), segment-stenosis score (r=0.453; P<0.001), coronary calcification score (r=0.412; P=0.001), number of obstructive diseases (r=0.346; P<0.001), and the number of segments with non-calcified plaque (r=0.235; P=0.017), mixed plaque (r=0.234; P=0.017) and calcified plaque (r=0.431; P<0.001). The levels of serum NT-pro BNP were significantly higher in patients with UA and left main-left anterior descending (LM-LAD) disease, compared with UA patients without LM-LAD disease (P<0.001). In addition, serum NT-pro BNP was significantly higher in patients with obstructive disease and UA than in those without obstructive disease (P<0.001). The area under the curve of log(NT-pro BNP) was 0.656 (P=0.006; optimal cut-off value, 1.74; sensitivity, 77.6%; specificity, 51.9%). In conclusion, the levels of serum NT-pro BNP are associated with the burden and severity of coronary artery atherosclerotic disease in patients with UA, and may be helpful in risk stratification of patients with UA.

Improvement of left ventricular filling by ivabradine during chronic hypertension: involvement of contraction-relaxation coupling

Chronic hypertension is associated with left ventricular (LV) hypertrophy and LV diastolic dysfunction with impaired isovolumic relaxation and abnormal LV filling. Increased heart rate (HR) worsens these alterations. We investigated whether the I f channel blocker ivabradine exerts beneficial effects on LV filling dynamic. In this setting, we also evaluated the relationship between LV filling and isovolumic contraction as a consequence of contraction-relaxation coupling. Therefore, hypertension was induced by a continuous infusion of angiotensin II during 28 days in 10 chronically instrumented pigs. LV function was investigated after stopping angiotensin II infusion to offset the changes in loading conditions. In the normal heart, LV relaxation filling, LV early filling, LV peak early filling rate were positively correlated to HR. In contrast, these parameters were significantly reduced at day 28 vs. day 0 (18, 42, and 26 %, respectively) despite the increase in HR (108 ± 6 beats/min vs. 73 ± 2 beats/min, respectively). These abnormalities were corrected by acute administration of ivabradine (1 mg/kg, iv). Ivabradine still exerted these effects when HR was controlled at 150 beats/min by atrial pacing. Interestingly, LV relaxation filling, LV early filling and LV peak early filling were strongly correlated with both isovolumic contraction and relaxation. In conclusion, ivabradine improves LV filling during chronic hypertension. The mechanism involves LV contraction-relaxation coupling through normalization of isovolumic contraction and relaxation as well as HR-independent mechanisms.

Cardiac endothelium-myocyte interaction: clinical opportunities for new heart failure therapies regardless of ejection fraction

Heart failure (HF) is an important global health problem with great socioeconomic burden. Outcomes remain sub-optimal. Endothelium-cardiomyocyte interactions play essential roles in cardiovascular homeostasis, and deranged endothelium-related signalling pathways have been implicated in the pathophysiology of HF. In particular, disturbances in nitric oxide (NO)-mediated pathway and neuregulin-mediated pathway have been shown to contribute to the development of HF. These signalling pathways hold the potential as pathophysiological targets for new HF therapies, and may aid in patient selection for future HF trials.

Mild hypothermia induces incomplete left ventricular relaxation despite spontaneous bradycardia in pigs

AIM

Mild hypothermia (MH) decreases left ventricular (LV) end-diastolic capacitance. We sought to clarify whether this results from incomplete relaxation.

METHODS

Ten anaesthetized pigs were cooled from normothermia (NT, 38 °C) to MH (33 °C). LV end-diastolic pressure (LVPed), volume (LVVed) and pressure-volume relationships (EDPVRs) were determined during stepwise right atrial pacing. LV capacitance (i.e. LVVed at LVPed of 10 mmHg, LV VPed10) was derived from the EDPVR. Pacing-induced changes of diastolic indices (LVPed, LVVed and LV VPed10) were analysed as a function of (i) heart rate and (ii) the ratio between diastolic time interval (t-dia) and LV isovolumic relaxation constant τ, which was calculated using a logistic fit (τL ) and monoexponential fit with zero asymptote (τZ ) and nonzero asymptote (τNZ ).

RESULTS

Mild hypothermia decreased heart rate (85 ± 4 to 68 ± 3 bpm), increased τL (22 ± 1 to 57 ± 4 ms), τZ (26 ± 2 to 56 ± 5 ms) and τNZ (41 ± 1 to 96 ± 5 ms), decreased t-dia/τ ratios, and shifted the EDPVR leftwards compared to NT (all P < 0.05). During NT, pacing at ≥140 bpm shifted the EDPVR progressively leftwards. During MH, relationships between diastolic indices and heart rate were shifted towards lower heart rates compared to NT. However, relationships between diastolic indices and t-dia/τ during NT and MH were superimposable.

CONCLUSION

We conclude that the loss of LV end-diastolic capacitance during MH can be explained at least in part by slowed LV relaxation. MH thereby is an example of incomplete LV relaxation at a spontaneous low heart rate. Caution may be advised, when heart rate is increased in patients treated with MH.

Impaired myocardial oxygen availability contributes to abnormal exercise hemodynamics in heart failure with preserved ejection fraction

BACKGROUND

Hypertension is a frequent risk factor for the development of heart failure with preserved ejection fraction (HFPEF). Progressive extracellular matrix accumulation has been presumed to be the fundamental pathophysiologic mechanism that leads to the transition to impaired diastolic reserve. However, the contribution of other mechanisms affecting active and passive components of diastolic function has not been comprehensively assessed. In this study, we investigated the potential role of impaired myocardial oxygen delivery in the pathophysiology of HFPEF.

METHODS AND RESULTS

Patients with HFPEF, those with controlled hypertension, and healthy controls underwent simultaneous right-heart catheterization, echocardiography, and paired arterial and coronary sinus blood gas sampling at rest and during supine-cycle ergometry. Despite a lower workload (HFPEF vs control, hypertension: 43±8 versus 114±12, 87±14 W; P<0.001 and P<0.05, respectively), peak exercise pulmonary capillary wedge pressure was markedly higher in HFPEF patients compared with healthy and hypertensive controls (32±2 versus 16±1 and 17±1 mm Hg, both P<0.001). During exercise, the transcardiac oxygen gradient increased significantly in all groups; however, the peak transcardiac oxygen gradient was significantly lower in HFPEF patients (P<0.05). In addition, the left ventricular-work corrected transcardiac oxygen gradient remained significantly lower in HFPEF patients compared with controls (P<0.001).

CONCLUSION

The current study provides unique data suggesting that the abnormal diastolic reserve observed during exertion in HFPEF patients may, in part, be explained by impaired myocardial oxygen delivery due possibly to microvascular dysfunction. Further studies are required to confirm the structural and functional basis of these findings and to investigate the influence of potential therapies on this abnormality.

Ivabradine improves left ventricular function during chronic hypertension in conscious pigs

During chronic hypertension, increases in heart rate (HR) or adrenergic stimulation are associated with maladaptive left ventricular responses as isovolumic contraction and relaxation durations failed to reduce, impeding filling. We, therefore, investigated the effects of acute selective HR reduction with ivabradine on left ventricular dysfunction during chronic hypertension. Accordingly, chronically instrumented pigs received angiotensin II infusion during 4 weeks to induce chronic hypertension. Left ventricular function was investigated while angiotensin II infusion was stopped. A single intravenous dose of ivabradine was administered at days 0 and 28. Dobutamine infusion was also performed. HR was increased at day 28 versus day 0. Paradoxically, both isovolumic contraction and relaxation times failed to reduce and remained unchanged (57±3 versus 58±3 ms and 74±3 versus 70±3 at day 28 versus day 0, respectively). At day 28, ivabradine significantly reduced HR by 27%. Concomitantly, abnormal ventricular responses were corrected because both isovolumic contraction and relaxation times were significantly reduced while filling time was improved. Similarly at day 28, maladaptive responses of isovolumic contraction and relaxation to dobutamine were no longer observed during HR reduction with ivabradine. Correction of HR reduction with pacing showed that non-HR-related mechanisms also participated to these beneficial effects. In this model of chronic hypertension and left ventricular hypertrophy, acute HR reduction with ivabradine corrects the maladaptive responses of cardiac cycle phases by restoring a normal profile for isovolumic contraction and relaxation both at rest and under adrenergic stimuli, ultimately favoring filling.

Systems biology applied to heart failure with normal ejection fraction

Heart failure with normal ejection fraction (HFNEF) is currently the most prevalent clinical phenotype of heart failure. However, the treatments available have shown no reduction in mortality so far. Advances in the omics sciences and techniques of high data processing used in molecular biology have enabled the development of an integrating approach to HFNEF based on systems biology.

This study aimed at presenting a systems-biology-based HFNEF model using the bottom-up and top-down approaches.

A literature search was conducted for studies published between 1991 and 2013 regarding HFNEF pathophysiology, its biomarkers and systems biology. A conceptual model was developed using bottom-up and top-down approaches of systems biology.

The use of systems-biology approaches for HFNEF, a complex clinical syndrome, can be useful to better understand its pathophysiology and to discover new therapeutic targets.

Pathophysiology of diastolic dysfunction in chronic heart failure

Chronic heart failure is a disease with high morbidity and mortality, and its incidence is increasing rapidly worldwide. New therapies are needed that can halt or even reverse the progression of heart failure, but little progress has been made in the last 20 years. This is partly due to the fact that chronic heart failure is a heterogeneous disease with many different etiologies and clinical phenotypes. At present, a pathophysiological concept to unify these different phenotypes is missing. A prominent pathophysiological feature of chronic heart failure is diastolic dysfunction, which is almost universally present in heart failure patients. This review will examine the role and mechanisms of diastolic dysfunction in heart failure. We will study diastolic dysfunction at different levels of complexity of organization: the cardiovascular system, the heart as an organ, the myocardium as a tissue, the myocyte as a cell and the molecular aspects of diastolic dysfunction.

Ruling out cardiac failure: cost-benefit analysis of a sequential testing strategy with NT-proBNP before echocardiography

OBJECTIVES

To estimate the possible economic benefit of a sequential testing strategy with NT-proBNP to reduce the number of echocardiographies.

METHODS

Retrospective study in a third-party payer perspective. The costs were calculated from three Swedish counties: Blekinge, Östergötland, and Uppland. Two cut-off levels of NT-proBNP were used: 400 and 300 pg/mL. The cost-effectiveness of the testing strategy was estimated through the short-term cost avoidance and reduction in demand for echocardiographies.

RESULTS

The estimated costs for NT-proBNP tests and echocardiographies per county were reduced by 33%-36% with the 400 pg/mL cut-off and by 28%-29% with the 300 pg/mL cut-off. This corresponded to a yearly cost reduction of approximately €2-5 million per million inhabitants in these counties.

CONCLUSION

The use of NT-proBNP as a screening test could substantially reduce the number of echocardiographies in the diagnostic work-up of patients with suspected cardiac failure, as well as the associated costs.

Role of preeclampsia-related angiogenic factors in sunitinib cardiotoxicity: two cases and review of the literature

Sunitinib is a multi-targeted tyrosine kinase inhibitor widely used in clear cell renal carcinoma and in imatinib-resistant gastrointestinal stromal tumors. Sunitinib-associated cardiotoxicity has been recognized and includes hypertension, left ventricular dysfunction and congestive heart failure; nevertheless, few data exist in the literature regarding the role of preeclampsia-related angiogenic factors in sunitinib cardiotoxicity. We report a case of sunitinib-induced severe left ventricular dysfunction that occurred in a hypertensive woman with metastatic renal carcinoma and a history of preeclampsia, and a case of sunitinib-induced preeclampsia-like syndrome in a normotensive patient with an imatinib-resistant gastrointestinal stromal tumor. Our experience confirms that inhibition of angiogenic factors to treat cancer is a novel challenge for the oncologist and requires the cardiologist's support.

Impaired left ventricular function in the presence of preserved ejection in chronic hypertensive conscious pigs

Systolic function is often evaluated by measuring ejection fraction and its preservation is often assimilated with the lack of impairment of systolic left ventricular (LV) function. Considering the left ventricle as a muscular pump, we explored LV function during chronic hypertension independently of increased afterload conditions. Fourteen conscious and chronically instrumented pigs received continuous infusion of either angiotensin II (n = 8) or saline (n = 6) during 28 days. Hemodynamic recordings were regularly performed in the presence and 1 h after stopping angiotensin II infusion to evaluate intrinsic LV function. Throughout the protocol, the mean arterial pressure steadily increased by 55 ± 4 mmHg in angiotensin II-treated animals. There were no significant changes in stroke volume, LV fractional shortening or LV wall thickening, indicating the lack of alterations in LV ejection. In contrast, we observed maladaptive changes with (1) the lack of reduction in isovolumic contraction and relaxation durations with heart rate increases, (2) abnormally blunted isovolumic contraction and relaxation responses to dobutamine and (3) a linear correlation between isovolumic contraction and relaxation durations. None of these changes were observed in saline-infused animals. In conclusion, we provide evidence of impaired LV function with concomitant isovolumic contraction and relaxation abnormalities during chronic hypertension while ejection remains preserved and no sign of heart failure is present. The evaluation under unloaded conditions shows intrinsic LV abnormalities.

Pulmonary hypertension and right heart failure in heart failure with preserved left ventricular ejection fraction: pathophysiology and natural history

PURPOSE OF REVIEW

Pulmonary hypertension and right heart failure are common findings in patients suffering from heart failure with preserved ejection fraction (HFpEF). In this review, we summarize our current understanding of the pathophysiology of pulmonary hypertension related to heart failure.

RECENT FINDINGS

HFpEF is a clinical syndrome with increasing prevalence and a mortality rate similar to heart failure with reduced ejection fraction. Because the pathophysiology and even the definition of this disease are still controversial, we will first outline the current conceptual framework around heart failure with preserved ejection fraction. Next, we will outline our current knowledge on the pathophysiology of pulmonary hypertension related to left ventricular failure and diastolic dysfunction. Diastolic dysfunction induces pulmonary hypertension through passive transmission of elevated end diastolic pressures, reactive pulmonary vasoconstriction, and vascular remodeling. Eventually, right ventricular failure develops that can further potentiate left ventricular failure because of their close mechanical, cellular, and biochemical integration.

SUMMARY

Exciting new studies have led to an increased understanding of the underlying pathophysiology and indicate that pulmonary hypertension in heart failure may be treatable.

Pressure overload

This review discusses cardiac consequences of pressure overload. In response to elevated pressure, the ventricular hypertrophy compensates for the increased wall stress. However, the ventricular hypertrophy involves numerous structural adaptations that may lead to ventricular dysfunction and, eventually, heart failure. Particular emphasis is placed on molecular mechanisms that govern the development of hypertrophy and that may lead to maladaptive structural changes resulting in adverse cardiac events.

Quantifying cardiac functions in embryonic and adult zebrafish

Zebrafish embryos have been extensively used to study heart development and cardiac function, mainly due to the unique embryology and genetics of this model organism. Since most human heart disease occurs during adulthood, adult zebrafish models of heart disease are being created to dissect mechanisms of the disease and discover novel therapies. However, due to its small heart size, the use of cardiac functional assays in the adult zebrafish has been limited. To address this bottleneck, the transparent fish line casper;Tg(cmlc2:nuDsRed) that has a red fluorescent heart can be used to document beating hearts in vivo and to quantify cardiac functions in adult zebrafish. Here, we describe our methods for quantifying shortening fraction and heart rate in embryonic zebrafish, as well as in the juvenile and adult casper;Tg(cmlc2:nuDsRed) fish. In addition, we describe the red blood cell flow rate assay that can be used to reflect cardiac function indirectly in zebrafish at any stage.

Assessment of myocardial mechanics using speckle tracking echocardiography: fundamentals and clinical applications

The authors summarize the recent developments in speckle-tracking echocardiography (STE), a relatively new technique that can be used in conjunction with two-dimensional or three-dimensional echocardiography for resolving the multidirectional components of left ventricular (LV) deformation. The tracking system is based on grayscale B-mode images and is obtained by automatic measurement of the distance between 2 pixels of an LV segment during the cardiac cycle, independent of the angle of insonation. The integration of STE with real-time cardiac ultrasound imaging overcomes some of the limitations of previous work in the field and has the potential to provide a unified framework to more accurately quantify the regional and global function of the left ventricle. STE holds promise to reduce interobserver and intraobserver variability in assessing regional LV function and to improve patient care while reducing health care costs through the early identification of subclinical disease. Following a brief overview of the approach, the authors pool the initial observations from clinical studies on the development, validation, merits, and limitations of STE.

The vulnerability of the heart as a pluricellular paracrine organ: lessons from unexpected triggers of heart failure in targeted ErbB2 anticancer therapy

In this review, we address clinical aspects and mechanisms of ventricular dysfunction induced by anticancer drugs targeted to the ErbB2 receptor. ErbB2 antagonists prolong survival in cancer, but also interfere with homeostatic processes in the heart. ErbB2 is a coreceptor for ErbB4, which is activated by neuregulin-1. This epidermal growth factor-like growth factor is released from endothelial cells in the endocardium and in the myocardial microcirculation, hence contributing to intercellular crosstalk in the ventricle. We look at the physiological aspects of neuregulin-1/ErbB signaling in the ventricle, and review its (mal)adaptive responses in chronic heart failure. We also compare structural aspects of ErbB receptor activation in cancer and cardiac cells, and analyze the mode of action of current ErbB2 antagonists. This allows us to predict how these drugs interfere with paracrine processes in the ventricle. Differences in the mode of action of individual ErbB2 antagonists affect their impact on the function of the ventricle, considered to be "on-target" or "off-target." Establishing the relation between the cardiac side effects of ErbB2 antagonists and their impact on paracrine ventricular control mechanisms may direct the design of a next generation of ErbB2 inhibitors. For cardiologists, there are lessons to be learned from the unexpected side effects of ErbB2-targeted cancer therapy. The vulnerability of the heart as a pluricellular paracrine system appears greater than anticipated and intercellular crosstalk an essential component of its functional and structural integrity.

Current controversies in heart failure with a preserved ejection fraction

Heart failure with a preserved ejection fraction is a fascinating and multifaceted condition that has provoked enormous debate and a wealth of mechanistic studies. Controversies exist with regard to its nomenclature. If its nomenclature is questioned, one can be certain the pathogenesis is ill understood. If the pathogenesis is disputed, the diagnosis becomes difficult and inconsistent. These diagnostic challenges result in inappropriate recruitment to clinical trials. Therefore, the trials may be underpowered and difficult to interpret. This paper examines contemporary theories of heart failure with a preserved ejection fraction, clarifies the controversies and attempts to resolve the divergences of opinion.

The challenges associated with current clinical trials for diastolic heart failure

PURPOSE OF REVIEW

Diastolic heart failure (DHF) is the culmination of various cardiovascular insults, producing a proportionally greater alteration of diastolic performance, subtle reductions of systolic function and the clinical syndrome of heart failure. Over half of heart failure patients aged 65 years or older have DHF, which carries similar morbidity and mortality to systolic heart failure (SHF). The aging population and increased prevalence of hypertension, diabetes mellitus and obesity will result in disproportionately higher incidence of DHF.

RECENT FINDINGS

To date, seven large placebo-controlled trials have been conducted in DHF and none have convincingly demonstrated substantial morbidity or mortality reductions. This review will highlight DHF clinical trial efforts and provide explanations for the discordance between clinical trial patients and clinical practice patients.

SUMMARY

Greater parity between clinical trial and clinical practice can be achieved by selecting DHF patients in the context of a few general principles: trials should enroll patients on the basis of the diagnostic criteria set forth by the European Study Group on Diastolic Heart Failure. A history of (<6 months) or current hospitalization for heart failure along with prespecified higher grades of diastolic dysfunction insures that a sufficiently at-risk population is studied. Patients with DHF are older, with multiple noncardiovascular comorbidities, and longer trial duration (>3 years) may be plagued with competing risks.

Hypertension and heart failure: a dysfunction of systole, diastole or both?

The pathological myocardial hypertrophy associated with hypertension contains the seed for further maladaptive development. Increased myocardial oxygen consumption, impaired epicardial coronary perfusion, ventricular fibrosis and remodelling, abnormalities in long-axis function and torsion, cause, to a varying degree, a mixture of systolic and diastolic abnormalities. In addition, chronotropic incompetence and peripheral factors such as lack of vasodilator reserve and reduced arterial compliance further affect cardiac output particularly on exercise. Many of these factors are common to hypertensive heart failure with a normal ejection fraction as well as systolic heart failure. There is increasing evidence that these apparently separate phenotypes are part of a spectrum of heart failure differing only in the degree of ventricular remodelling and volume changes. Furthermore, dichotomizing heart failure into systolic and diastolic clinical entities has led to a paucity of clinical trials of therapies for heart failure with a normal ejection fraction. Therapies aimed at reversing myocardial fibrosis, and targets outside the heart such as enhancing vasodilator reserve and improving chronotropic incompetence deserve further study and may improve the exercise capacity of hypertensive heart failure patients. Hypertension heart disease with heart failure is simply not a dysfunction of systole and diastole. Other peripheral factors including heart rate and vasodilator response with exercise may deserve equal attention in an attempt to develop more effective treatments for this disorder.

Diastolic heart failure: a separate disease or selection bias?

Chronic heart failure (CHF) is often subdivided based on left ventricular ejection fraction (LVEF) in 2 distinct forms, usually specified as "diastolic heart failure" and "systolic heart failure." In this review, arguments are provided against an LVEF-based bimodal view, and CHF is presented as one pathophysiological identity encompassing a continuous spectrum of closely related phenotypes. Most importantly, there is currently no pathophysiological basis to support a bimodal view. As a result, conceptual presentations of CHF, such as the vicious circle paradigm of CHF, become obsolete. Furthermore, the binary view of CHF is the unfortunate result of selection biases that has confounded practically all clinical trials of CHF. Unfortunately, current investigations still introduce selection bias when studying heart failure at preserved or reduced LVEF. Future investigations should analyze CHF as one disease and focus on the mechanisms through which disease modifiers such as sex, diabetes, and hypertension induce phenotypic diversity.