Muhammad Asrar ul Haq

Therapeutic interventions for heart failure with preserved ejection fraction: A summary of current evidence

Heart failure with preserved ejection fraction (HFPEF) is common and represents a major challenge in cardiovascular medicine. Most of the current treatment of HFPEF is based on morbidity benefits and symptom reduction. Various pharmacological interventions available for heart failure with reduced ejection fraction have not been supported by clinical studies for HFPEF. Addressing the specific aetiology and aggressive risk factor modification remain the mainstay in the treatment of HFPEF. We present a brief overview of the currently recommended therapeutic options with available evidence.

Clinical Utility of Exercise Training in Heart Failure with Reduced and Preserved Ejection Fraction

Reduced exercise tolerance is an independent predictor of hospital readmission and mortality in patients with heart failure (HF). Exercise training for HF patients is well established as an adjunct therapy, and there is sufficient evidence to support the favorable role of exercise training programs for HF patients over and above the optimal medical therapy. Some of the documented benefits include improved functional capacity, quality of life (QoL), fatigue, and dyspnea. Major trials to assess exercise training in HF have, however, focused on heart failure with reduced ejection fraction (HFREF). At least half of the patients presenting with HF have heart failure with preserved ejection fraction (HFPEF) and experience similar symptoms of exercise intolerance, dyspnea, and early fatigue, and similar mortality risk and rehospitalization rates. The role of exercise training in the management of HFPEF remains less clear. This article provides a brief overview of pathophysiology of reduced exercise tolerance in HFREF and heart failure with preserved ejection fraction (HFPEF), and summarizes the evidence and mechanisms by which exercise training can improve symptoms and HF. Clinical and practical aspects of exercise training prescription are also discussed.

Left ventricular torsional dynamics post exercise for LV diastolic function assessment

Aims2D speckle tracking echocardiography allows for assessment of left ventricular (LV) torsional deformation as a composite function of the radial, longitudinal and circumferential fibres. We test the hypothesis that post-exercise LV torsional dynamics are more sensitive markers for myocardial dysfunction than resting measures, and better predictors for exercise capacity compared to post-exercise LV diastolic filling pressure (E/e’).MethodsWe studied 88 patients referred for stress echocardiogram. Treadmill exercise was performed using Bruce protocol, and echo images were acquired using GE Vivid 7. LV rotational dynamics were analysed by speckle tracking method using the GE ECHOPAC software. Tertiles were defined according to exercise capacity measured by the achieved metabolic equivalents (METS) adjusted for age and gender. Comparison was made between LV torsional dynamics and E/e’ to correlate with METS to predict exercise capacity.ResultsMean age of the study population was 58 years, 48% females. Patients with systolic dysfunction or evidence of ischaemia were excluded from the analysis. No significant correlation was found between METS and LV torsion measures at rest. There was statistically significant correlation between METS and post-exercise LV torsion (r=0.34, p=0.001), twist velocity increase (r=0.27, p=0.01), and incremental change in torsion (r=0.22, p<0.05). In addition, a correlation was also shown between post-exercise E/e’ and METS (r=-0.33, p=0.002).ConclusionPost-exercise LV torsional dynamics correlate with exercise capacity and may be a useful tool for assessing LV myocardial function in subjects with normal LVEF.

The invasive assessment of coronary atherosclerosis and stents using optical coherence tomography: a clinical update

Ischaemic heart disease (IHD) remains one of the leading causes of death. Atherosclerosis has been intensely researched given the IHD prevalence and the financial impacts on healthcare systems. More recently, in vivo characterisation of coronary atherosclerotic plaque and tissue responses following stent implantation in a coronary artery has been made possible by a novel technology called optical coherence tomography (OCT). OCT is a light-based, invasive, intracoronary imaging modality long applied to the field of ophthalmology and now in clinical use worldwide. It gives a unique view of within the coronary artery using near-infrared light with a resolution of 15 microns, 10 times higher than other invasive coronary imaging techniques like intravascular ultrasound. The technology is being adopted to comprehensively detect features that make plaques ‘vulnerable’ (eg, large lipid pool, thin, fibrous-cap atheroma), whether stents are implanted optimally within the artery, and visualise the small layers of tissue that form over stent metal surfaces over time, which in turn may provide surrogate markers for long-term stent safety and help guide the optimal duration of dual antiplatelet therapy, a topic of big discussion at the current point of time.

Advances in three-dimensional coronary imaging and computational fluid dynamics: is virtual fractional flow reserve more than just a pretty picture?

Percutaneous coronary intervention (PCI) has shown a high success rate in the treatment of coronary artery disease. The decision to perform PCI often relies on the cardiologist’s visual interpretation of coronary lesions during angiography. This has inherent limitations, particularly due to the low resolution and two-dimensional nature of angiography. State-of-the-art modalities such as three-dimensional quantitative coronary angiography, optical coherence tomography and invasive fractional flow reserve (FFR) may improve clinicians’ understanding of both the anatomical and physiological importance of coronary lesions. While invasive FFR is the gold standard technique for assessment of the haemodynamic significance of coronary lesions, recent studies have explored a surrogate for FFR derived solely from three-dimensional reconstruction of the invasive angiogram, and therefore eliminating need for a pressure wire. Utilizing advanced computational fluid dynamics research, this virtual fractional flow reserve (vFFR) has demonstrated reasonable correlation with invasive measurements and remains an intense area of ongoing study. However, at present, several limitations and computational fluid dynamic assumptions may preclude vFFR from widespread clinical use. This review demonstrates the tight integration of advanced three-dimensional imaging techniques and vFFR in assessing coronary artery disease, reviews the advantages and disadvantages of such techniques and attempts to provide a glimpse of how such advances may benefit future clinical decision-making during PCI.

Effects of intravenous caffeine on fractional flow reserve measurements in coronary artery disease

Background Intravenous adenosine is used to minimise the coronary micro-resistance to achieve maximal hyperaemia along with nitrates for optimal fractional flow reserve (FFR) measurements. We hypothesise that caffeine, being a competitive inhibitor of adenosine, would influence adenosine-mediated FFR readings. Methods Consecutive patients undergoing angiogram and FFR measurements were enrolled after abstaining from caffeine for 24 h. Patients with any contraindications to intravenous adenosine or caffeine were excluded. FFR measurements were taken using nitrates and adenosine pre and post 4 mg/kg intravenous caffeine administration and results were compared. Results 10 patients were analysed (80% men, age 59.9±9.4, weight 87.5±15.6). Baseline caffeine levels were undetectable in all patients and increased significantly postintravenous caffeine administration (16.4±5.5 μg/mL). Baseline preadenosine FFR values were similar before and after caffeine administration (0.91±0.06 vs 0.91±0.07; p=0.41). Postadenosine FFR readings were 0.79±0.07, which increased non-significantly to 0.82±0.11 postcaffeine (p=0.15). Two significant FFR readings (≤0.8) changed to non-significant after caffeine administration (0.77–0.93 and 0.8–0.91). Conclusions Caffeine may affect FFR results in some patients. Larger studies are warranted to clarify the extent and magnitude of caffeine/adenosine interaction particularly due to ubiquitous nature of caffeine and increasing importance of FFR in clinical practice.

A Twist in the Transradial Coronary Catheterisation

The transradial approach for coronary angiography was first described in 1989. With the advent of modern equipment and improved technology it has recently gained significant interest amongst interventional cardiologists. As compared to femoral access, the radial approach has the major advantages of lower access site complication rates, cost-effectiveness, and shorter hospital stays. Further clinical benefits of lower morbidity and cardiac mortality in patients with ST-elevation myocardial infarction have been shown recently. Rare vascular complications may include radial artery spasm, dissection, occlusion, perforation or compartment syndrome. Here, we present two unusual cases of an entrapped catheter in the radial artery and their outcomes.

Prevalence and outcomes of trans-radial access for percutaneous coronary intervention in contemporary practise

BACKGROUND Trans-radial access for percutaneous coronary intervention (PCI) has been associated with lower vascular complication rates and improved outcomes. We assessed the current uptake of trans-radial PCI in Victoria, Australia, and evaluated if patients were selected according to baseline bleeding risk in contemporary clinical practise, and compared selected clinical outcomes. METHODS PCI data of all patients between 1st January 2013 and 31st December 2014 were analysed using The Victorian Cardiac Outcomes Registry (VCOR). Propensity-matched analysis was performed to compare the clinical outcomes. RESULTS 11,711 procedures were analysed. The femoral route was the predominant access site (66%). Patients undergoing trans-radial access PCI were younger (63.9±11.6 vs. 67.2±11.8; p<0.001), had a higher BMI (28.9±5.5 vs. 28.5±5.2; p<0.001), more likely to be male (80.0 vs. 74.9%;p<0.001), less likely to have presented with cardiogenic shock (0.9 vs. 2.8%; p<0.001) or have the following comorbidities: diabetes (19.8 vs. 23.1%; p<0.001), peripheral vascular disease (2.9 vs. 4.3%; p=0.005) or renal impairment (13.6 vs. 22.1%; p<0.001). The radial group had less bleeding events (3.2 vs. 4.6%; p<0.001) and shorter hospital length of stay (3.1±4.7 vs. 3.3±3.9; p=0.006). There was no significant difference in mortality (1.0 vs. 1.4%; p=0.095). CONCLUSIONS Trans-femoral approach remains the dominant access site for PCI in Victoria. The choice of route does not appear to be selected by consideration of bleeding risk. The radial route is associated with improved clinical outcomes of reduced bleeding and length of stay consistent with previous findings, and this supports the efficacy and safety of trans-radial PCI in real-world clinical practise.

Treatment of hypertension in heart failure with preserved ejection fraction.

Prevalence of Heart Failure with Preserved Ejection (HFPEF) has been rising steadily in the recent past. Studies have shown that at least half of patients presenting with symptoms and signs of heart failure (HF) have preserved left ventricular ejection fraction, i.e. HFPEF, and that this portion of the HF population consists predominantly of women, older age group, and people with hypertension and other cardiovascular risk factors. The morbidity and mortality associated with HFPEF are much higher than the normal population. Chronic hypertension is the most common cause in addition to age, with suggestion of up to 60% of patients with HFPEF being hypertensive. Addressing the specific aetiology and aggressive risk factor modification remain the mainstay in the treatment of HFPEF. Current guidelines recommend the management should involve treatment of hypertension, control of heart rate, venous pressure reduction, and prevention of myocardial ischemia. This review aims to discuss the role of hypertension in the pathophysiology, risk stratification and prognosis of HFPEF, as well as the current available data on various antihypertensive options in this population.

Late Strut Fracture Within a Partially Resorbed Bioresorbable Vascular Scaffold: A Possible Cause of Late Scaffold Thrombosis and Acute Coronary Syndrome

The Bioresorbable Vascular Scaffold (BVS, Abbott Vascular, Santa Clara, Cal, USA) is an exciting advance in percutaneous coronary intervention providing a temporary drug eluting scaffold resorbed in two to five years. We present two cases of late scaffold thrombosis associated with strut fracture during the period of resorption, at 20 and 24 months following BVS implantation. We propose luminal migration of malapposed struts following strut fracture during resorption as a potential mechanism for late scaffold thrombosis and acute coronary syndrome.