Guidelines and Expert Consensus Documents summarize and evaluate all currently available evidence on a particular issue with the aim to assist physicians in selecting the best management strategies for a typical patient, suffering from a given condition, taking into account the impact on outcome, as well as the risk/benefit ratio of particular diagnostic or therapeutic means. Guidelines are no substitutes for textbooks. The legal implications of medical guidelines have been discussed previously.

Rationale: Incident pulmonary arterial hypertension was underrepresented in most pulmonary hypertension registries and may have a different disease profile to prevalent disease. Objectives: To determine the characteristics and outcome of a purely incident, treatment-naive cohort of idiopathic, heritable, and anorexigen-associated pulmonary arterial hypertension and to determine the changes in presentations and survival over the past decade in the United Kingdom and Ireland. Methods: All consecutive newly diagnosed patients from 2001 to 2009 were identified prospectively. Measurements and Main Results: A total of 482 patients (93% idiopathic, 5% heritable, and 2% anorexigen-associated pulmonary arterial hypertension) were diagnosed, giving rise to an estimated incidence of 1.1 cases per million per year and prevalence of 6.6 cases per million in 2009. Younger patients (age ≤ 50 yrs) had shorter duration of symptoms, fewer comorbidities, better functional and exercise capacity, higher percent diffusing capacity of carbon monoxide, more severe hemodynamic impairment, but better survival compared with older patients. In comparison with the earlier cohorts, patients diagnosed in 2007–2009 were older, more obese, had lower percent diffusing capacity of carbon monoxide,_, and more comorbidities, but better survival. Registry to Evaluate Early and Long-Term Pulmonary Arterial Hypertension Disease Management (REVEAL) equation, REVEAL risk score, and Pulmonary Hypertension Connection Registry survival equation accurately predicted survival of our incident cohort at 1 year. Conclusions: This study highlights the influence of age on phenotypes of incident pulmonary arterial hypertension and has shown the changes in demographics and epidemiology over the past decade in a national setting. The results suggest that there may be two subtypes of patients: the younger subtype with more severe hemodynamic impairment but better survival, compared with the older subtype who has more comorbidities.

Troponin elevation is common in hospitalized COVID-19 patients, but underlying aetiologies are ill-defined. We used multi-parametric cardiovascular magnetic resonance (CMR) to assess myocardial injury in recovered COVID-19 patients. One hundred and forty-eight patients (64 ± 12 years, 70% male) with severe COVID-19 infection [all requiring hospital admission, 48 (32%) requiring ventilatory support] and troponin elevation discharged from six hospitals underwent convalescent CMR (including adenosine stress perfusion if indicated) at median 68 days. Left ventricular (LV) function was normal in 89% (ejection fraction 67% ± 11%). Late gadolinium enhancement and/or ischaemia was found in 54% (80/148). This comprised myocarditis-like scar in 26% (39/148), infarction and/or ischaemia in 22% (32/148) and dual pathology in 6% (9/148). Myocarditis-like injury was limited to three or less myocardial segments in 88% (35/40) of cases with no associated LV dysfunction; of these, 30% had active myocarditis. Myocardial infarction was found in 19% (28/148) and inducible ischaemia in 26% (20/76) of those undergoing stress perfusion (including 7 with both infarction and ischaemia). Of patients with ischaemic injury pattern, 66% (27/41) had no past history of coronary disease. There was no evidence of diffuse fibrosis or oedema in the remote myocardium (T1: COVID-19 patients 1033 ± 41 ms vs. matched controls 1028 ± 35 ms; T2: COVID-19 46 ± 3 ms vs. matched controls 47 ± 3 ms). During convalescence after severe COVID-19 infection with troponin elevation, myocarditis-like injury can be encountered, with limited extent and minimal functional consequence. In a proportion of patients, there is evidence of possible ongoing localized inflammation. A quarter of patients had ischaemic heart disease, of which two-thirds had no previous history. Whether these observed findings represent pre-existing clinically silent disease or de novo COVID-19-related changes remain undetermined. Diffuse oedema or fibrosis was not detected.

Pulmonary arterial hypertension (PAH) is a progressive vascular disease with a high mortality rate. It is characterized by an occlusive vascular remodeling due to a pro-proliferative and antiapoptotic environment in the wall of resistance pulmonary arteries (PAs). Proliferating cells exhibit a cancer-like metabolic switch where mitochondrial glucose oxidation is suppressed, whereas glycolysis is up-regulated as the major source of adenosine triphosphate production. This multifactorial mitochondrial suppression leads to inhibition of apoptosis and downstream signaling promoting proliferation. We report an increase in pyruvate dehydrogenase kinase (PDK), an inhibitor of the mitochondrial enzyme pyruvate dehydrogenase (PDH, the gatekeeping enzyme of glucose oxidation) in the PAs of human PAH compared to healthy lungs. Treatment of explanted human PAH lungs with the PDK inhibitor dichloroacetate (DCA) ex vivo activated PDH and increased mitochondrial respiration. In a 4-month, open-label study, DCA (3 to 6.25 mg/kg b.i.d.) administered to patients with idiopathic PAH (iPAH) already on approved iPAH therapies led to reduction in mean PA pressure and pulmonary vascular resistance and improvement in functional capacity, but with a range of individual responses. Lack of ex vivo and clinical response was associated with the presence of functional variants of SIRT3 and UCP2 that predict reduced protein function. Impaired function of these proteins causes PDK-independent mitochondrial suppression and pulmonary hypertension in mice. This first-in-human trial of a mitochondria-targeting drug in iPAH demonstrates that PDK is a druggable target and offers hemodynamic improvement in genetically susceptible patients, paving the way for novel precision medicine approaches in this disease.