Cardiac resynchronisation therapy in 2015: keeping up with the pace.

Despite improved understanding of the pathophysiology of heart failure (HF) and availability of better medical therapies, HF continues to grow as a cause of morbidity and mortality in Australia and worldwide. Over the past decade, cardiac resynchronisation therapy (CRT), or biventricular pacing, has been embraced as a powerful weapon against this growing epidemic. However, much has changed in our understanding of dyssynchrony in HF, and this has led to a change in guidelines to ensure more appropriate selection of CRT candidates to improve the 'non-response' rate. More data have also emerged about the use of CRT in atrial fibrillation and in pacemaker-dependent patients. There has also been a growing focus on multimodality imaging to guide patient selection and lead positioning. Exciting new lead technologies are also emerging, with the potential to improve CRT outcomes further.

Subspecialisation in cardiology care and outcome: should clinical services be redesigned, again?

BACKGROUND: Inpatient management of cardiac patients by cardiologists results in reduced mortality and hospitalisation. With increasing subspecialisation of the field because of growing management complexity and use of technological innovations, the impact of sub-specialisation on patient outcomes is unclear. AIM: To investigate whether management by subspecialty cardiologists impacts the outcomes of patients with subspecialty-specific diseases. METHODS: All patients admitted to a tertiary centre over nine years with a diagnosis of heart failure, acute coronary syndrome (ACS) or primary arrhythmia were reviewed. The outcomes of these patients managed by cardiologists subspecialised in their admission diagnosis (heart failure specialists, interventionalists and electrophysiologists) were compared with those treated by general cardiologists. RESULTS: Heart failure was diagnosed in 1704 patients, ACS in 7763 and arrhythmia in 4398. There was no difference in length of stay (LOS) (P = 0.26), mortality (P = 0.57) or cardiovascular readmissions (P = 0.50) in heart failure patients treated by general cardiologists compared with subspecialists. In ACS patients, subspecialty management was associated with reduced LOS, cardiovascular readmissions and mortality (all P < 0.05). This reduction in mortality was seen mainly in lower risk patients (P < 0.05). There was a reduction in LOS and cardiovascular readmissions in arrhythmia patients receiving subspecialty management (both P < 0.05) but no difference in mortality (P = 0.14). ACS patients managed by interventionalists were more likely to undergo coronary intervention (P < 0.05). Electrophysiologists more frequently referred patients for catheter ablation and pacemaker implantation than general cardiologists (P < 0.05). CONCLUSIONS: The benefits of subspecialty care seem attributable to the appropriate selection of patients who would benefit from technological innovations in care. These results suggest that the development of healthcare systems which align cardiovascular disease with the subspecialist may be more effective.

Requirement for cardiac telemetry during intravenous phenytoin infusion: guideline fact or guideline fiction?

Guidelines recommend the use of cardiac telemetry when phenytoin is administered intravenously. Clinical areas where telemetry is available may not always be the most suitable place to monitor and treat these sick patients. We sought to clarify the evidence regarding the need for cardiac telemetry during intravenous infusion of phenytoin.

Utility of atrial temporary pacing as an acute treatment for bradyarrhythmias and tachyarrhythmias in the intensive care setting with preservation of atrioventricular synchrony.

Temporary pacing is often used as an acute treatment of bradyarrhythmias and suppression of tachyarrhythmias. In patients with cardiogenic shock, loss of atrioventricular synchrony may worsen cardiovascular haemodynamics. We present a series where temporary right atrial pacing was used as an acute treatment for both bradyarrhythmias and tachyarrhythmias.

Catheter ablation for ventricular tachycardia.

Sudden cardiac death due to ventricular arrhythmias remains the most common cause of death in developed nations. Implantable cardioverter defibrillators have been shown to improve mortality in high-risk groups for ventricular tachyarrhythmias, but they are not curative, with the risk of arrhythmia recurrence remaining unaltered. It is also important to remember that ventricular tachycardia (VT) in the setting of a structurally normal heart is often not associated with an increased risk of sudden death and catheter ablation is a potentially curative procedure in this cohort. Recent advances in catheter ablation for VT have increased the efficacy in creating adequate lesions, accurate three-dimensional maps and mapping haemodynamically unstable VT, all of which have increased the utility of this modality in the treatment of ventricular arrhythmias. In this article, we review the recent advances that have fuelled renewed interest in catheter ablation of VT, its clinical utility and who should be referred.

Monomorphic ventricular tachycardia related to Wolff-Parkinson-White surgery.

Monomorphic ventricular tachycardia (MVT) is well described in patients who have had a ventricular scar due to repair of congenital heart disease. A 54-year-old woman presented with MVT 20 years after WPW surgery for a left-sided accessory pathway. The circuit was mapped to an area at the base of the left ventricle consistent with the incision described in the operation report. Entrainment confirmed the re-entrant circuit. Successful radiofrequency ablation was performed in a zone of slowed conduction consistent with the circuit isthmus. Any iatrogenic ventricular scar may form the substrate for MVT and be treated with standard electrophysiology techniques.

WITHDRAWN: Secondary Harmonic Imaging Overestimates Left Ventricular Mass Compared to Fundamental Echocardiography.

The publisher regrets that this was an accidental duplication of an article that has already been published in Eur. J. Echocardiogr., 4 (2003) 178-181, . The duplicate article has therefore been withdrawn.

Secondary harmonic imaging overestimates left ventricular mass compared to fundamental echocardiography.

AIMS: The significance of left ventricular hypertrophy in hypertension is well documented, being an independent risk factor for cardiovascular morbidity and mortality. Normal values for left ventricular mass and partition values for left ventricular hypertrophy come from measurements obtained by fundamental echocardiography. Secondary harmonic imaging improves definition of cardiac borders. We hypothesise that this overestimates left ventricular mass compared to fundamental imaging. METHODS AND RESULTS: Thirty patients had four parasternal long-axis M-modes performed, two using 1.7 mHz output frequency, receiving at two octaves higher and two using fixed frequency of 2.5 mHz (fundamental imaging). Absolute left ventricular mass and left ventricular mass index were calculated for each modality. Intra-observer variability was <7%. Range on fundamental imaging was 54-264 g/m2 compared to 80-293 g/m2 on secondary harmonic imaging. Mean left ventricular mass index for the group was 118 g/m2 (fundamental imaging) vs 147 g/m2, P<0.001. Twenty-nine of 30 patients had higher left ventricular mass index on secondary harmonic imaging compared to fundamental imaging. Left ventricular mass index was an average of 26% higher on secondary harmonic imaging, range (-7 to 65%) corresponding to average absolute left ventricular mass difference of 55 g. Eleven of 30 patients had left ventricular hypertrophy on fundamental imaging and 17/30 on secondary harmonic imaging. CONCLUSION: Secondary harmonic imaging overestimates left ventricular mass index compared to fundamental imaging. Normal left ventricular mass index range is based on equations using fundamental imaging measurements. Management decisions and prognostic implications made on the basis of raised left ventricular mass index using secondary harmonic imaging should be done so with caution.

Rapid access chest pain clinics--can they be justified?

Rapid access chest pain clinics are expanding across the country with marked resource implications despite a paucity of data regarding their efficacy. Early assessment of patients in this manner potentially delays review of patients referred via the traditional route. We conducted a prospective observational study of patients referred with chest pain to the Cardiology Outpatient Department over a four-week period in a District General Hospital to compare demographics and outcomes in patients referred to the rapid access with those referred to the general cardiology clinics. There were no significant differences in baseline demographics, exercise test result or clinic outcome. Both populations were low risk. Discussion is needed between primary and secondary care to achieve a consensus as to the purpose of a rapid access system and how best to utilise the service appropriately. Further studies are required to assess the efficacy and health economics of this system.

The influence of sex and age on response to head-up tilt-table testing in patients with recurrent syncope.

BACKGROUND: Syncope is a common problem, accounting for 6% of hospital admissions. Often a diagnosis is not established. Head-up tilt testing is a diagnostic test for neuro-cardiogenic syncope, a condition which is often thought to affect younger women and be relatively rare in older people. We examined the effect of sex and age on response to head-up tilt testing in patients with unexplained syncope. METHODS: We performed a retrospective analysis on consecutive tilt tests performed using the Westminster drug-free protocol from January 1992 to June 1998. Patients were divided into four groups on the basis of sex and age (< or = or > 65 years). Responses were classified according to the Vasovagal International Study Investigators' criteria. RESULTS: We performed 665 tests in 590 patients. Mean age was 50 years +/-17.6 (range 12-83). One hundred and fifty-three patients (23%) were > 65 years. There was an almost equal sex distribution. Two hundred and eight tests (31%) were positive, with 113 (54%) showing a mixed response (type 1), 65 (32%) a cardio-inhibitory response (type 2) and 30 (14%) a vasodepressor response (type 3). Age and sex had no effect on rates of positive tests or time to positive result. There was no gender influence with respect to response type. However, subjects aged > 65 years had a higher incidence of vasodepressor response (type 3)-29% versus 9% (P < 0.001). CONCLUSIONS: Head-up tilt testing is a useful tool in the investigation of all patients with suspected neuro-cardiogenic syncope. Age and sex do not influence the likelihood of a positive response, but older patients have an increased frequency of pure vasodepressor responses. This may have implications with respect to treatment strategies.

Coronary sinus pacing in an elderly patient with Bjork-Shiley tricuspid valve replacement.

We report the first case of permanent pacing via the coronary sinus in a patient with a Bjork-Shiley tricuspid valve replacement. This may be the route of choice in this group of patients.