K. Poon

Spontaneous Coronary Artery Dissection Utility of Intravascular Ultrasound and Optical Coherence Tomography During Percutaneous Coronary Intervention

Spontaneous coronary artery dissection (SCAD) is an infrequent cause of acute coronary syndromes but is represented disproportionately in young female patients. No specific guidelines exist concerning the appropriate treatment (medical therapy, intracoronary stents, coronary bypass surgery) or the optimal type of stents in otherwise atheroma-free vessels. The role of intracoronary imaging with intravascular ultrasound (IVUS) and optical coherence tomography (OCT) has yet to be fully established. A 39-year-old woman with no traditional risk factors for coronary artery disease presented with an anterior ST-segment elevation myocardial infarct after undergoing rigorous aerobic exercises. The patient was gravida 3 para 3, not known to be pregnant, and not postmenopausal. Her last pregnancy was 5 years earlier, and subsequent β human chorionic gonadotropin was negative. Coronary angiography suggested a long spiral dissection in the left anterior descending artery. Her other coronary arteries were smooth walled with no evidence of atherosclerosis. With ongoing symptoms and persisting ST elevation of the surface …

Impact of optimising fluoroscopic implant angles on paravalvular regurgitation in transcatheter aortic valve replacements - utility of three-dimensional rotational angiography.

AIMS The clinical value of optimising implant angles during transcatheter aortic valve replacements (TAVR) remains undefined. The Aortic Valve Guide (AVG) is a proprietary software that provides structured analysis of three-dimensional images from rotational angiography (DynaCT). This study compares AVG with preprocedural multislice computed tomography (MSCT) and DynaCT in optimal implant angle prediction for TAVR, and evaluates if an optimised implant angle is associated with reduced paravalvular regurgitation (PVR). METHODS AND RESULTS One hundred and six consecutive patients were included, comprising three groups. Group 1 (n=19) underwent no preprocedural MSCT or DynaCT (or AVG); Group 2 (n=44) underwent periprocedural DynaCT, without AVG; Group 3 (n=43) had DynaCT with AVG. Implant angles yielded were graded as excellent, satisfactory or poor. Group 3 were more likely than Groups 2 and 1 to have excellent implant angles (83.7% vs. 52.3% vs. 42.1%, respectively, p=0.001). In 100 patients who had 30-day transthoracic echocardiogram follow-up, an excellent implant angle was significantly more likely to be associated with no PVR than a non-excellent angle (41.3% vs. 21.6%, respectively, p=0.045), independent of operator experience and THV used. CONCLUSIONS Optimising implant angles may be important in reducing PVR. This is significantly more likely to be achieved with AVG rotational angiography.

Early experience of transaortic TAVI--the future of surgical TAVI?

BACKGROUND Trans-catheter aortic valve implantation (TAVI) is now a well recognised procedure for the high risk surgical patient with native or bioprosthetic aortic valve stenosis. Transfemoral and transapical implantation techniques are well described. With increasing referral of more marginal transapical patients, we describe our experience of a transaortic TAVI approach which we believe reduces the postoperative wound pain, respiratory complications, operative risk and hospital stay. METHODS Patients referred for surgical TAVI underwent trans-catheter aortic valve implantation via an upper sternotomy and direct cannulation of the ascending aorta. RESULTS Thirteen patients with a mean age of 81 years underwent transaortic Edwards SAPIEN valve implantation. There was no in hospital mortality in our series. One patient required insertion of a permanent pacemaker for complete heart block. There were no aortic cannulation complications. CONCLUSION The transaortic TAVI approach provides good exposure of the distal ascending aorta, a familiar cannulation site for cardiac surgeons. Our initial experience demonstrates the approach to be a safe technique with the potential for faster and less complicated recovery in patients undergoing surgical TAVI procedures. With further experience and greater acceptance, the transaortic approach may ultimately become the procedure of choice for patients unsuitable for a transfemoral approach.

Pre-Hospital Ambulance Notification and Initiation of Treatment of ST Elevation Myocardial Infarction is Associated with Significant Reduction in Door-to-Balloon Time for Primary PCI

BACKGROUND Mortality in ST elevation myocardial infarction (STEMI) is strongly predicted by the time from first medical contact to reperfusion. The aim of this study was to examine the impact of pre-hospital diagnosis by paramedics in the field on the door-to-balloon (DTB) times of patients with ST elevation myocardial infarction undergoing primary percutaneous intervention. METHODS Paramedics in the field identified patients with ST elevation myocardial infarction on a 12-lead electrocardiograph, activated the cardiac catheter laboratory team from the field and initiated therapy with anticoagulants and antiplatelet agents in the pre-hospital setting. This cohort of patients was compared to a similar group of patients without pre-hospital diagnosis and notification. The primary outcome measure was DTB times. A secondary end point was mortality at 30 days and mortality at six months. RESULTS A total of 281 patients, mean age of 61.1±12.9 years underwent primary percutaneous intervention with pre-hospital notification occurring in 63 cases. DTB times were lower in those with pre notification than in those without pre-hospital notification (40.4 vs. 75.6 minutes, p<0.001). This represented a 47.6% shorter DTB time. A non-statistically significant mortality reduction at one month and six months was observed in the pre-hospital notification group (1.6 versus 4.3%, p= 0.307 and 1.6 versus 6.4%, p= 0.203, respectively). CONCLUSION Pre-hospital intervention at our centre had a powerful effect in reducing the time to reperfusion in patients with STEMI undergoing primary percutaneous intervention.

Massive Left Atrial Thrombus in a Patient With Rheumatic Mitral Stenosis and Atrial Fibrillation While Anticoagulated With Dabigatran

Dabigatran is an oral direct thrombin inhibitor licensed for use by the Food and Drug Administration.1,2 This novel anticoagulant is effective and approved for prevention of stroke and systemic embolism in nonvalvular atrial fibrillation (AF) and prevention of venous thromboembolism in adults receiving elective total hip or knee replacement surgery.1,2 These images present a cautionary account of failed dabigatran anticoagulation in a patient with valvular AF: an indication for which its use has not been approved. A 50-year-old female with severe rheumatic mitral stenosis underwent open mitral valvotomy under cardiopulmonary bypass 25 years prior. On subsequent annual surveillance, she remained asymptomatic and her mitral stenosis remained moderate on echocardiography with a mean transmitral gradient of 8 mm Hg. Permanent AF was previously diagnosed 12 months earlier, and she was commenced on warfarin and metoprolol. She had stable anticoagulation monitoring, no bleeding complications, and normal renal function, but was needle-phobic with psychological …

Transcatheter valve-in-valve replacement of degenerated bioprosthetic aortic valves: a single Australian Centre experience.

BACKGROUND Patients with degenerated surgical bioprosthetic valves may be at high risk for further surgery because of age, comorbidities and the difficulties of repeat procedures. Percutaneous valve-in-valve implantation offers what may be a simpler and safer procedure. METHODS From May 2009 to March 2014 at the Prince Charles Hospital 1625 patients underwent surgical aortic valve replacement while 262 underwent transcatheter aortic valve implantation. Twelve patients had valve-in-valve implants for degenerated bioprosthetic aortic valves. RESULTS These implants were deployed successfully without major valvular or paravalvular regurgitation. There were no periprocedural deaths, myocardial infarcts, neurological events or major vascular complications. Two patients died after 1624 and 1319days. Median survival for the remainder is 581days; they are stable with New York Heart Association class I/II functional status although 4 have a degree of patient-prosthesis mismatch, one has moderate aortic regurgitation and one required surgery for a late aortic dissection. CONCLUSION Transcatheter valve-in-valve implantation is safe and effective treatment for patients with failed bioprosthetic aortic valves for whom reoperation is considered to be hazardous.

Non-Pharmacological Therapy for Atrial Fibrillation: Managing the Left Atrial Appendage

The prevalence of atrial fibrillation (AF) is increasing in parallel with an ageing population leading to increased morbidity and mortality. The most feared complication of AF is stroke, with the arrhythmia being responsible for up to 20% of all ischemic strokes. An important contributor to this increased risk of stroke is the left atrial appendage (LAA). A combination of the LAAs unique geometry and atrial fibrillation leads to low blood flow velocity and stasis, which are precursors to thrombus formation. It has been hypothesized for over half a century that excision of the LAA would lead to a reduction in the incidence of stroke. It has only been in the last 20–25 years that the knowledge and technology has been available to safely carry out such a procedure. We now have a number of viable techniques, both surgical and percutaneous, which will be covered in this paper.

Factors Contributing to Acute Kidney Injury and the Impact on Mortality in Patients Undergoing Transcatheter Aortic Valve Replacement

BACKGROUND Transcatheter aortic valve replacement (TAVR) patients are at a high risk of acute kidney injury (AKI). This study aimed to investigate AKI and the relationship with iodinated contrast media (ICM), whether there are significant pre- or peri- procedural variables predicting AKI, and whether AKI impacts on hospital length of stay and mortality. METHODS Serum creatinine (SC) levels pre- and post- (peak) TAVR were recorded in 209 consecutive TAVR patients. AKI was defined by the Valve Academic Research Consortium 2 (VARC2) criteria. Baseline characteristics, procedural variables, hospital length of stay (LOS) and mortality at 72hours, 30 days and one year were analysed. RESULTS Eighty-two of 209 (39%) patients suffered AKI. Mean ICM volume was 228cc, with no difference between patients with AKI and those with no AKI (227cc (213-240(95%CI)) vs 231cc (212-250) p=0.700)). Univariate and multivariate analysis demonstrated that chronic kidney disease, respiratory failure, previous stroke, the need for blood transfusion and valve repositioning were all predictors of AKI. Acute kidney injury increased LOS (5.6 days (3.8 - 7.5) vs 3.2 days (2.6 - 3.9) no AKI (P=0.004)) but was not linked to increased mortality. Mortality rates did increase with AKI severity. CONCLUSION Acute kidney injury is a common complication of TAVR. The severity of AKI is important in determining mortality. Acute kidney injury appears to be independent of ICM use but pre-existing renal impairment and respiratory failure were predictors for AKI. Transcatheter aortic valve replacement device repositioning or retrieval was identified as a new risk factor impacting on AKI.

The demographic profile of young patients (<45 years-old) with acute coronary syndromes in Queensland.

BACKGROUND There is little data regarding the demographic profile of young (<45 years) Australian acute coronary syndrome patients. The aim of this study was to compare baseline characteristics, risk factor profile and outcomes of young patients compared with their older counterparts referred to two metropolitan Queensland hospitals. METHODS Over a four-year period, data on acute coronary syndrome patients referred to The Prince Charles and Royal Brisbane Hospitals were retrospectively analysed. Three major groups were identified: <45 years, 45-60 years and those >60 years. Age, sex, body mass index, risk factor profile, degree of coronary disease, left ventricular dysfunction, mode of presentation, initial pharmacological therapy and mortality data were compared between the three groups. RESULTS 4549 patients were analysed of whom, 277 were less than 45 years old. Younger patients tended to be male, more overweight and present more commonly with ST segment elevation myocardial infarction compared to their older counterparts. Smoking, family history and dyslipidaemia tended to occur more frequently in younger patients as compared to those >45 years. Those patients >45 years tended to present with non-ST segment elevation myocardial infarction and have a higher degree of ischaemic burden and left ventricular dysfunction. No patients <45 years died in their index admission at 30 days or at one year. CONCLUSIONS Although young patients <45 years make up the minority (6.1%) of patients presenting with acute coronary syndrome and generally have a favourable prognosis, this paper highlights the need for aggressive risk factor modification, with particular attention to smoking and dyslipidaemia, before the onset of overt clinical disease.

Focused clinical review: periprocedural management of antiplatelet therapy in patients with coronary stents.

Coronary stent implantation, particularly drug eluting stents, is now the major method of coronary revascularisation. Following drug-eluting stent implantation dual antiplatelet therapy with aspirin and thienopyridine is recommended for at least 12 months. Premature discontinuation, often at the time of noncardiac surgery, has been associated with stent thrombosis which has a significant risk of death and myocardial infarction. Late (>30 days) and very late (>365 days) stent thrombosis appears to more common with DES and poses the questions of when is it safe to stop antiplatelet therapy post coronary stenting and how to manage patients who need non-cardiac surgery. This article reviews the evidence for stent thrombosis and the peri-operative management of patients with coronary stents and provides an algorithm for patient management based on multidisciplinary assessment of bleeding risk, perioperative cardiac event and stent thrombosis risk.