Non-Invasive Assessment of Pulmonary Vascular Resistance in Pulmonary Hypertension: Current Knowledge and Future Direction

Pulmonary Hypertension (PHT) is relatively common, dangerous and under-recognised. Pulmonary hypertension is not a diagnosis in itself; it is caused by a number of differing diseases each with different treatments and prognoses. Therefore, timely and accurate recognition of the underlying cause for PHT is essential for appropriate management. This is especially true for patients with Pulmonary Arterial Hypertension (PAH) in the current era of disease-specific drug therapy. Measurement of Pulmonary Vascular Resistance (PVR) helps separate pre-capillary from post-capillary PHT, and is measured with right heart catheterisation (RHC). Echocardiography has been used to derive a number of non-invasive surrogates for PVR, with varying accuracy. Ultimately, the goal of non-invasive assessment of PVR is to separate PHT due to left heart disease from PHT due to increased PVR, to help streamline investigation and subsequent treatment. In this review, we summarise the physiology and pathophysiology of pulmonary blood flow, the various causes of pulmonary hypertension, and non-invasive surrogates for PVR.

Heart failure with preserved ejection fraction: A growing global epidemic

BACKGROUND

Heart failure with preserved ejection fraction (HFpEF) is an emerging global health problem of which there is limited awareness. HFpEF has a prognosis similar to that of heart failure with reduced ejection fraction (HFrEF) and accounts for approximately half of all patients with heart failure.

OBJECTIVE

The aim of this article is to review HFpEF and its consequences and management, including examples of patients with HFpEF.

DISCUSSION

Patients with HFpEF may present with dyspnoea, fluid retention, lethargy and dizziness, making it difficult to differentiate clinically from HFrEF. The risk factors include increasing age, obesity, hypertension, diabetes, chronic kidney disease and obstructive sleep apnoea. The diagnosis requires good clinical acumen combined with echocardiography and elevated plasma B-type natriuretic peptide concentration. Management of HFpEF, especially in later stages, is difficult as there is no evidence-based therapy to date. Prevention is the best strategy. Early recognition and diagnosis are also very important to tackle this global epidemic.

Pulmonary Hypertension in Central Australia: A Community-Based Cohort Study

BACKGROUND

The burden of pulmonary hypertension (PHT) in Central Australia has not been previously studied. Our aim is to characterise the prevalence, clinical classification, and long-term survival of individuals with PHT in Central Australia.

METHODS

A community-based cohort study of all individuals diagnosed with PHT in Central Australia between 2005 and 2016 was undertaken. We estimated PHT prevalence using population data, describe clinical PHT classification, and characterised long-term survival using Kaplan-Meier approaches.

RESULTS

A total of 183 patients were identified (mean age 52±16years, 63% female). Of these individuals, 149 (81.4%) were of Aboriginal and Torres Strait Islander (ATSI) descent. The prevalence per 100,000 of any PHT was significantly higher In ATSI (723 [95% CI 608-839] compared to non-ATSI individuals (126 [95% CI 84-168], p<0.001). Furthermore, ATSI individuals were diagnosed at younger ages compared to non-ATSI individuals (49±15 vs 64±16years, p<0.001). Median estimated pulmonary artery systolic pressure (ePASP) was higher in patients with pulmonary arterial hypertension (PAH) compared to other causes (62 [IQR 54-69] vs 50 [IQR 44-58] mmHg, p<0.01). The median survival rate from diagnosis was 9 years (IQR 7.2-13.2). Age and ePASP were significant predictors of mortality (HR 1.05 [95% CI 1.02-1.07] and HR 1.56 [95% 1.00-2.42] respectively).

CONCLUSIONS

In this community based study, we found a high burden of PHT in Central Australia. The prevalence of PHT is greater in ATSI individuals and is diagnosed at younger ages compared to non-ATSI individuals. Together with other cardiovascular diseases, PHT may be in-part contributing to the gap in life expectancy between ATSI and non-ATSI individuals.

Top End Pulmonary Hypertension Study: Understanding Epidemiology, Therapeutic Gaps and Prognosis in Remote Australian Setting

INTRODUCTION

The Top End of Australia has a high proportion of Indigenous people with a high burden of chronic cardiac and pulmonary diseases likely to contribute to pulmonary hypertension (PH). The epidemiology of PH has not been previously studied in this region.

METHODS

Patients with PH were identified from the Northern Territory echocardiography database from January 2010 to December 2015 and followed to the end of 2019 or death. Pulmonary hypertension was defined as a tricuspid regurgitation velocity ≥2.75 m/s measured by Doppler echocardiography. The aetiology of PH, as categorised by published guidelines, was determined by reviewing electronic health records.

RESULTS

1,764 patients were identified comprising 49% males and 45% Indigenous people. The prevalence of PH was 955 per 100,000 population (with corresponding prevalence of 1,587 for Indigenous people). Hypertension, atrial fibrillation, diabetes and respiratory disease were present in 85%, 45%, 41% and 39%, respectively. Left heart disease was the leading cause for PH (58%), the majority suffering from valvular disease (predominantly rheumatic). Pulmonary arterial hypertension (PAH), respiratory disease related PH, chronic thromboembolic PH (CTEPH) and unclear multifactorial PH represented 4%, 16%, 2% and 3%, respectively. Underlying causes were not identifiable in 17% of the patients. Only 31% of potentially eligible patients were on PAH-specific therapy. At census, there was 40% mortality, with major predictors being age, estimated pulmonary artery systolic pressure (ePASP) and Indigenous ethnicity.

CONCLUSION

Pulmonary hypertension is prevalent in Northern Australia, with a high frequency of modifiable risk factors and other treatable conditions. Whether earlier diagnosis, interpretation and intervention improve outcomes merits further assessment.

Mackay Heart Failure Study: Examining the Root Causes, Compliance With Guideline-Based Therapy and Prognosis

INTRODUCTION

Heart failure patients have poor outcomes comparable to some malignancies; however, the modern guideline directed medical therapy (GDMT) has improved its outcomes. The clinical characteristics and prescribers' compliance with GDMT for heart failure patients have not been studied in the Mackay region.

METHODS

A retrospective cohort study of 115 consecutive adult heart failure patients was conducted at our institution.

RESULTS

The study cohort consisted of 80% (n=92) males. Ischaemia was the leading cause accounting for 54% (n=62) of the cohort, followed by idiopathic cardiomyopathy at 32% (n=37). Drug-induced and Takotsubo cardiomyopathies were responsible for 11% and 1% respectively. Two (2) patients (2%) had valvular heart disease. Hypertension was present in 57% while diabetes and atrial fibrillation were present in 32% and 43% of patients. Fifty-nine per cent (59%) had a smoking history. All, except four patients, had reduced left ventricular ejection fraction (LVEF <50%) at diagnosis. Among patients with coronary ischaemia, 37% and 31% were revascularised with percutaneous coronary interventions and bypass graft surgeries, respectively. Renin-angiotensin-aldosterone system inhibitors and beta blockers were prescribed in 94% and 95% of the patients, respectively. Mineralocorticoid inhibitors were used in 25% while ivabradine was given to 8% of patients. Nine per cent (9%) of patients received cardiac resynchronisation therapy. Most patients had improvement in functional class and LVEF during follow-up. There were very few mortalities at 3% (n=3) at the median follow-up of 403 (IQR 239-896) days.

CONCLUSION

Our study has shed light on heart failure epidemiology in the Mackay region. We found excellent compliance with GDMT and good prognosis for most patients in terms of both symptom and survival.

Acute Bioprosthetic Mitral Valve Failure Diagnosed Using Point-of-Care Ultrasound Leading to Prompt Treatment and Good Outcome

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Acute bioprosthetic mitral valve failure is a medical emergency.

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POCUS can confirm the diagnosis along with a good history and physical exam.

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Early diagnosis and prompt multidisciplinary treatment will deliver the best outcome.

Pulmonary hypertension in remote and disadvantaged population: overcoming unique challenges for improved outcomes

Pulmonary hypertension (PH) is a common and debilitating medical condition with high mortality. PH research has traditionally focused on pulmonary arterial hypertension and its management in expert PH centres. Other forms of PH such as PH associated with cardiac or respiratory disease are more common, less well-understood and associated with higher mortality. Epidemiology of PH in disadvantaged, remote and rural regions, remains largely undocumented. In this review, we discuss the unique challenges in identifying PH in rural and disadvantaged populations using the Top End region of the Northern Territory of Australia as an example. We propose a simple diagnostic approach, ideally suited to regions where resource allocation is scarce, using clinical skills, echocardiography, and an escalation algorithm. The brief history, epidemiology and current literature on PH are summarised to inform the busy clinicians. We highlight two case examples from the Top End to illustrate the challenges and potential solutions.