Alan Robert Denniss

Early exercise stress testing is safe after primary percutaneous coronary intervention.

Background: The optimal timing of exercise stress testing post primary percutaneous coronary intervention is uncertain with anecdotal evidence suggesting an increased risk of acute myocardial infarction and/or death if performed too early. This has translated into a delayed return to normal life activities following an acute myocardial infarction resulting in an increase in socio-economic burden. Aims: We hypothesize that early (within 7 days of primary percutaneous coronary intervention) exercise stress testing is safe. Methods: A prospective study of consecutive patients enrolled into the Cardiac Rehabilitation Program at a tertiary referral centre that underwent primary percutaneous coronary intervention, and who were able to perform a treadmill stress test were recruited. Timing of exercise stress testing was within 7 days post primary percutaneous coronary intervention and outcomes of death, acute myocardial infarction and other major adverse cardiac event were assessed 24 hours post exercise stress testing. Results: Recruited patients (n=230) aged between 29 and 78 (mean age 56 ± 10 years) with 191 being males (83%) and 39 being females (17%). While 28 patients had a positive stress test (12.2%), there were no deaths, acute myocardial infarction or any other major adverse cardiac event within 24 hours of performing the exercise stress testing. Mean METS achieved were 8.1 ± 2.3. Conclusions: Early exercise stress testing after primary percutaneous coronary intervention appears safe.

Myocardial Viability: From Proof of Concept to Clinical Practice

Ischaemic left ventricular (LV) dysfunction can arise from myocardial stunning, hibernation, or necrosis. Imaging modalities have become front-line methods in the assessment of viable myocardial tissue, with the aim to stratify patients into optimal treatment pathways. Initial studies, although favorable, lacked sufficient power and sample size to provide conclusive outcomes of viability assessment. Recent trials, including the STICH and HEART studies, have failed to confer prognostic benefits of revascularisation therapy over standard medical management in ischaemic cardiomyopathy. In lieu of these recent findings, assessment of myocardial viability therefore should not be the sole factor for therapy choice. Optimization of medical therapy is paramount, and physicians should feel comfortable in deferring coronary revascularisation in patients with coronary artery disease with reduced LV systolic function. Newer trials are currently underway and will hopefully provide a more complete understanding of the pathos and management of ischaemic cardiomyopathy.

An Update on Renal Artery Denervation and Its Clinical Impact on Hypertensive Disease

Hypertension is a globally prevalent condition, with a heavy clinical and economic burden. It is the predominant risk factor for premature cardiovascular and cerebrovascular disease, and is associated with a variety of clinical disorders including stroke, congestive cardiac failure, ischaemic heart disease, chronic renal failure, and peripheral arterial disease. A significant subset of hypertensive patients have resistant hypertensive disease. In this group of patients, catheter-based renal artery denervation has emerged as a potential therapy, with favourable clinical efficacy and safety in early trials. Additional benefits of this therapy are also being identified and include effects on left ventricular remodeling, cardiac performance, and symptom status in congestive cardiac failure. Utility of renal denervation for the management of resistant hypertension, however, has become controversial since the release of the Symplicity HTN-3 trial, the first large-scale blinded randomised study investigating the efficacy and safety of renal artery denervation. The aim of this paper is to evaluate the history, utility, and clinical efficacy of renal artery denervation technology, including an in-depth appraisal of the current literature and principal trials.

Cardiac Rehabilitation for Patients with an Implantable Cardioverter Defibrillator

Patients with an implantable cardioverter defibrillator (ICD) are not routinely referred to Cardiac Rehabilitation (CR) due to fears that exercise may induce ventricular tachyarrhythmias. Meta analyses and systematic reviews have shown that a CR program with an exercise component can improve survival, as well as non-fatal disease manifestations, functional capacity and quality of life (QOL) in patients with previous myocardial infarction or cardiac surgery (Ades 2001; Lewin et al., 2001; Wenger 2008). Whether the same is true for patients with an ICD is not clear, especially as these patients may have ischaemic or non-ischaemic causes for their propensity for ventricular tachyarrhythmias, and are more likely to need treatment for heart failure. There is evidence that exercise programs can improve functional status and counter deconditioning in cardiac patients with heart failure ( Smart and Marwick 2004 ). Most previous studies which have examined the safety of exercising ICD patients have been small, with less than 100 patients in their studies ( Belardinelli et al., 2006; Chinnaiyan et al., 2007; Dougherty et al., 2008; Fan et al., 2009; Fitchet et al., 2003; Vanhees et al., 2004 ) . A notable exception was the HF-ACTION cohort, in which 1285 patients had an ICD implanted before or during the trial and had at least one exercise test performed after ICD implantation ( Keteylan et al., 2009 ). This large study clearly demonstrated the safety of exercise testing in ICD patients, but did not show the changes in workloads achievable during the course of a CR program, or examine QOL issues. Exercise capacity at treadmill testing, expressed as peak metabolic equivalents ( METS ), has been shown to be of prognostic significance ( Kokkinos et al., 2007 ), with each 1 MET increase in exercise capacity being associated with a 13% decrease in mortality (mean follow-up 7.5 years). This data suggests that exercise programs should aim to improve functional capacity in cardiac patients, and endeavour to help sustain this level of functional improvement over time.