Titin cardiomyopathy leads to altered mitochondrial energetics, increased fibrosis and long-term life-threatening arrhythmias.

Aims: Truncating titin variants (TTNtv) are the most prevalent genetic cause of dilated cardiomyopathy (DCM). We aim to study clinical parameters and long-term outcomes related to the TTNtv genotype and determine the related molecular changes at tissue level in TTNtv DCM patients. Methods and results: A total of 303 consecutive and extensively phenotyped DCM patients (including cardiac imaging, Holter monitoring, and endomyocardial biopsy) underwent DNA sequencing of 47 cardiomyopathy-associated genes including TTN, yielding 38 TTNtv positive (13%) patients. At long-term follow-up (median of 45 months, up to 12 years), TTNtv DCM patients had increased ventricular arrhythmias compared to other DCM, but a similar survival. Arrhythmias are especially prominent in TTNtv patients with an additional environmental trigger (i.e. virus infection, cardiac inflammation, systemic disease, toxic exposure). Importantly, cardiac mass is reduced in TTNtv patients, despite similar cardiac function and dimensions at cardiac magnetic resonance. These enhanced life-threatening arrhythmias and decreased cardiac mass in TTNtv DCM patients go along with significant cardiac energetic and matrix alterations. All components of the mitochondrial electron transport chain are significantly upregulated in TTNtv hearts at RNA-sequencing. Also, interstitial fibrosis was augmented in TTNtv patients at histological and transcript level. Conclusion: Truncating titin variants lead to pronounced cardiac alterations in mitochondrial function, with increased interstitial fibrosis and reduced hypertrophy. Those structural and metabolic alterations in TTNtv hearts go along with increased ventricular arrhythmias at long-term follow-up, with a similar survival and overall cardiac function.

Targeted HFpEF therapy based on matchmaking of human and animal models.

The diversity in clinical phenotypes and poor understanding of the underlying pathophysiology of heart failure with preserved ejection fraction (HFpEF) is the main reason why no effective treatments have been found yet. Targeted, instead of one size fits all, treatment seems the only promising approach for treating HFpEF. To be able to design a targeted, phenotype-specific HFpEF treatment, the matrix relating clinical phenotypes and underlying pathophysiological mechanisms has to be clarified. This review discusses the opportunities for additional evaluation of the underlying pathophysiological processes, e.g., to evaluate biological phenotypes on top of clinical routine, to guide us toward a phenotype-specific HFpEF treatment. Moreover, a translational approach with matchmaking of animal models to biological HFpEF phenotypes will be a valuable step to test the effectiveness of novel, targeted interventions in HFpEF. Listen to this article's corresponding podcast at https://ajpheart.podbean.com/e/personalized-medicine-in-hfpef/ .

Webtool to enhance the accuracy of diagnostic algorithms for HFpEF: a prospective cross-over study.

AIMS: Diagnosis of heart failure with preserved ejection fraction (HFpEF) can be challenging. This study aimed to evaluate the potential of a webtool to enhance the scoring accuracy when applying the complex HFA-PEFF and H2 FPEF algorithms, which are commonly used for diagnosing HFpEF. METHODS AND RESULTS: We developed an online tool, the HFpEF calculator, that enables the automatic calculation of current HFpEF algorithms. We assessed the accuracy of manual vs. automatic scoring, defined as the percentage of correct scores, in a cohort of cardiologists with varying clinical experience. Cardiologists scored eight online clinical cases using a triple cross-over design (i.e. two manual-two automatic-two manual-two automatic). Data were analysed in study completers (n = 55, 29% heart failure specialists, 42% general cardiologists, and 29% cardiology residents). Manually calculated scores were correct in 50% (HFA-PEFF: 50% [50-75]; H2 FPEF: 50% [38-50]). Correct scoring improved to 100% using the HFpEF calculator (HFA-PEFF: 100% [88-100], P < 0.001; H2 FPEF: 100% [75-100], P < 0.001). Time spent on clinical cases was similar between scoring methods (±4 min). When corrections for faulty algorithm scores were displayed, cardiologists changed their diagnostic decision in up to 67% of cases. At least 67% of cardiologists preferred using the online tool for future cases in clinical practice. CONCLUSIONS: Manual calculation of HFpEF diagnostic algorithms is often inaccurate. Using an automated webtool to calculate HFpEF algorithms significantly improved correct scoring. This new approach may impact the eventual diagnostic decision in up to two-thirds of cases, supporting its routine use in clinical practice.

The Role of Systemic Microvascular Dysfunction in Heart Failure with Preserved Ejection Fraction.

Heart failure with preserved ejection fraction (HFpEF) is a condition with increasing incidence, leading to a health care problem of epidemic proportions for which no curative treatments exist. Consequently, an urge exists to better understand the pathophysiology of HFpEF. Accumulating evidence suggests a key pathophysiological role for coronary microvascular dysfunction (MVD), with an underlying mechanism of low-grade pro-inflammatory state caused by systemic comorbidities. The systemic entity of comorbidities and inflammation in HFpEF imply that patients develop HFpEF due to systemic mechanisms causing coronary MVD, or systemic MVD. The absence or presence of peripheral MVD in HFpEF would reflect HFpEF being predominantly a cardiac or a systemic disease. Here, we will review the current state of the art of cardiac and systemic microvascular dysfunction in HFpEF (Graphical Abstract), resulting in future perspectives on new diagnostic modalities and therapeutic strategies.

Improving diagnosis and risk stratification across the ejection fraction spectrum: the Maastricht Cardiomyopathy registry.

AIMS: Heart failure (HF) represents a clinical syndrome resulting from different aetiologies and degrees of heart diseases. Among these, a key role is played by primary heart muscle disease (cardiomyopathies), which are the combination of multifactorial environmental insults in the presence or absence of a known genetic predisposition. The aim of the Maastricht Cardiomyopathy registry (mCMP-registry; NCT04976348) is to improve (early) diagnosis, risk stratification, and management of cardiomyopathy phenotypes beyond the limits of left ventricular ejection fraction (LVEF). METHODS AND RESULTS: The mCMP-registry is an investigator-initiated prospective registry including patient characteristics, diagnostic measurements performed as part of routine clinical care, treatment information, sequential biobanking, quality of life and economic impact assessment, and regular follow-up. All subjects aged ≥16 years referred to the cardiology department of the Maastricht University Medical Center (MUMC+) for HF-like symptoms or cardiac screening for cardiomyopathies are eligible for inclusion, irrespective of phenotype or underlying causes. Informed consented subjects will be followed up for 15 years. Two central approaches will be used to answer the research questions related to the aims of this registry: (i) a data-driven approach to predict clinical outcome and response to therapy and to identify clusters of patients who share underlying pathophysiological processes; and (ii) a hypothesis-driven approach in which clinical parameters are tested for their (incremental) diagnostic, prognostic, or therapeutic value. The study allows other centres to easily join this initiative, which will further boost research within this field. CONCLUSIONS: The broad inclusion criteria, systematic routine clinical care data-collection, extensive study-related data-collection, sequential biobanking, and multi-disciplinary approach gives the mCMP-registry a unique opportunity to improve diagnosis, risk stratification, and management of HF and (early) cardiomyopathy phenotypes beyond the LVEF limits.

Iron deficiency impacts prognosis but less exercise capacity in heart failure with preserved ejection fraction.

AIMS: Whether and how iron deficiency (ID) impacts patients with heart failure (HF) with preserved ejection fraction (HFpEF) remain unclear. The aim of our study was to investigate the impact of ID on functional status, exercise capacity, and prognosis in HFpEF. METHODS AND RESULTS: The study population consisted of 300 HFpEF patients. ID was defined as serum ferritin <100 µg/L or 100-300 µg/L and transferrin-saturation <20%. Baseline functional status, quality of life (HADS score and EQ 5D index), 6 min walking test, echocardiography, and outcome (all-cause mortality and combined all cause-mortality and HF hospitalization) were evaluated. ID was found in 159 (53%) patients. Patients with ID had a worse prognosis with a higher combined endpoint of all-cause mortality and HF hospitalization after 4 years of follow-up (log rank = 0.008). Pulmonary hypertension, depression, and thyroid disease were more prevalent in the ID group. Multivariable analysis showed that ID was independently associated with body mass index (P = 0.003), pulmonary hypertension (P = 0.008), and thyroid disease (P = 0.01). Although patients with ID had a lower exercise capacity compared with patients without ID (393 m [294-455] vs. 344 m [260-441], P = 0.008), there was no significant correlation after multivariable correction for age, BMI, NT-proBNP, DM, and depression. CONCLUSIONS: Heart failure with preserved ejection fraction patients with ID have a worse prognosis and impaired exercise capacity compared with those without ID. However, although a trend was observed, after multivariable correction ID was no longer significantly associated with a reduced exercise capacity. This reflects that impaired exercise capacity in HFpEF is complex and seems multifactorial. Interestingly, pulmonary hypertension was an independent predictor of both ID and exercise capacity.

The prognostic impact of mechanical atrial dysfunction and atrial fibrillation in heart failure with preserved ejection fraction.

AIMS: This study assessed the prognostic implications of mechanical atrial dysfunction in heart failure with preserved ejection fraction (HFpEF) patients with different stages of atrial fibrillation (AF) in detail. METHODS AND RESULTS: HFpEF patients (n = 258) systemically underwent an extensive clinical characterization, including 24-h Holter monitoring and speckle-tracking echocardiography. Patients were categorized according to rhythm and stages of AF: 112 with no history of AF (no AF), 56 with paroxysmal AF (PAF), and 90 with sustained (persistent/permanent) AF (SAF). A progressive decrease in mechanical atrial function was seen: left atrial reservoir strain (LASr) 30.5 ± 10.5% (no AF), 22.3 ± 10.5% (PAF), and 13.9 ± 7.8% (SAF), P < 0.001. Independent predictors for lower LASr values were AF, absence of chronic obstructive pulmonary disease, higher N-terminal-pro hormone B-type natriuretic peptide, left atrial volume index, and relative wall thickness, lower left ventricular global longitudinal strain, and echocardiographic signs of elevated left ventricular filling pressure. LASr was an independent predictor of adverse outcome (hazard ratio per 1% decrease =1.049, 95% confidence interval 1.014-1.085, P = 0.006), whereas AF was not when the multivariable model included LASr. Moreover, LASr mediated the adverse outcome associated with AF in HFpEF (P = 0.008). CONCLUSION: Mechanical atrial dysfunction has a possible greater prognostic role in HFpEF compared to AF status alone. Mechanical atrial dysfunction is a predictor of adverse outcome independently of AF presence or stage, and may be an underlying mechanism (mediator) for the worse outcome associated with AF in HFpEF. This may suggest mechanical atrial dysfunction plays a crucial role in disease progression in HFpEF patients with AF, and possibly also in HFpEF patients without AF.

Validation of the HFA-PEFF score for the diagnosis of heart failure with preserved ejection fraction.

AIMS: Diagnosing heart failure with preserved ejection fraction (HFpEF) is challenging. The newly proposed HFA-PEFF algorithm entails a stepwise approach. Step 1, typically performed in the ambulatory setting, establishes a pre-test likelihood. The second step calculates a score based on echocardiography and natriuretic peptides. The aim of this study is to validate the diagnostic value and establish the clinical impact of the second step of the HFA-PEFF score. METHODS AND RESULTS: The second step of the HFA-PEFF score was evaluated in two independent, prospective cohorts, i.e. the Maastricht cohort (228 HFpEF patients and 42 controls) and the Northwestern Chicago cohort (459 HFpEF patients). In Maastricht, the HFA-PEFF score categorizes 11 (4%) of the total cohort with suspected HFpEF in the low-likelihood (0-1 points) and 161 (60%) in the high-likelihood category (5-6 points). A high HFA-PEFF score can rule in HFpEF with high specificity (93%) and positive predictive value (98%). A low score can rule out HFpEF with a sensitivity of 99% and a negative predictive value of 73%. The diagnostic accuracy of the score is 0.90 (0.84-0.96), by the area under the curve of the receiver operating characteristic curve. However, 98 (36%) are classified in the intermediate-likelihood category, where additional testing is advised. The distribution of the score shows a similar pattern in the Northwestern (Chicago) and Maastricht HFpEF patients (53% vs. 65% high, 43% vs. 34% intermediate, 4.8% vs. 1.3% low). CONCLUSION: This study validates and characterizes the HFA-PEFF score in two independent, well phenotyped cohorts. We demonstrate that the HFA-PEFF score is helpful in clinical practice for the diagnosis of HFpEF.

Risk of bias in studies investigating novel diagnostic biomarkers for heart failure with preserved ejection fraction. A systematic review.

AIM: Diagnosing heart failure with preserved ejection fraction (HFpEF) in the non-acute setting remains challenging. Natriuretic peptides have limited value for this purpose, and a multitude of studies investigating novel diagnostic circulating biomarkers have not resulted in their implementation. This review aims to provide an overview of studies investigating novel circulating biomarkers for the diagnosis of HFpEF and determine their risk of bias (ROB). METHODS AND RESULTS: A systematic literature search for studies investigating novel diagnostic HFpEF circulating biomarkers in humans was performed up until 21 April 2020. Those without diagnostic performance measures reported, or performed in an acute heart failure population were excluded, leading to a total of 28 studies. For each study, four reviewers determined the ROB within the QUADAS-2 domains: patient selection, index test, reference standard, and flow and timing. At least one domain with a high ROB was present in all studies. Use of case-control/two-gated designs, exclusion of difficult-to-diagnose patients, absence of a pre-specified cut-off value for the index test without the performance of external validation, the use of inappropriate reference standards and unclear timing of the index test and/or reference standard were the main bias determinants. Due to the high ROB and different patient populations, no meta-analysis was performed. CONCLUSION: The majority of current diagnostic HFpEF biomarker studies have a high ROB, reducing the reproducibility and the potential for clinical care. Methodological well-designed studies with a uniform reference diagnosis are urgently needed to determine the incremental value of circulating biomarkers for the diagnosis of HFpEF.

Pathophysiological understanding of HFpEF: microRNAs as part of the puzzle.

Half of all heart failure patients have preserved ejection fraction (HFpEF). Comorbidities associated with and contributing to HFpEF include obesity, diabetes and hypertension. Still, the underlying pathophysiological mechanisms of HFpEF are unknown. A preliminary consensus proposes that the multi-morbidity triggers a state of systemic, chronic low-grade inflammation, and microvascular dysfunction, causing reduced nitric oxide bioavailability to adjacent cardiomyocytes. As a result, the cardiomyocyte remodels its contractile elements and fails to relax properly, causing diastolic dysfunction, and eventually HFpEF. HFpEF is a complex syndrome for which currently no efficient therapies exist. This is notably due to the current one-size-fits-all therapy approach that ignores individual patient differences. MicroRNAs have been studied in relation to pathophysiological mechanisms and comorbidities underlying and contributing to HFpEF. As regulators of gene expression, microRNAs may contribute to the pathophysiology of HFpEF. In addition, secreted circulating microRNAs are potential biomarkers and as such, they could help stratify the HFpEF population and open new ways for individualized therapies. In this review, we provide an overview of the ever-expanding world of non-coding RNAs and their contribution to the molecular mechanisms underlying HFpEF. We propose prospects for microRNAs in stratifying the HFpEF population. MicroRNAs add a new level of complexity to the regulatory network controlling cardiac function and hence the understanding of gene regulation becomes a fundamental piece in solving the HFpEF puzzle.