K. Peck

Medical therapy versus implantable cardioverter -defibrillator in preventing sudden cardiac death in patients with left ventricular systolic dysfunction and heart failure: A meta-analysis of > 35,000 patients

BACKGROUNDnPatients with left ventricular systolic dysfunction (LVSD) are at high risk of sudden cardiac death (SCD). Implantable cardioverter defibrillators (ICDs) have an important role in preventing SCD in selected patients with LVSD and chronic heart failure (CHF). Drug therapies for LVSD and CHF also appear to also be useful in reducing SCD. However, the magnitude of benefit of these approaches on SCD is uncertain. We therefore conducted a meta-analysis comparing the effect on SCD achieved by ICDs versus medical therapies, additional to standard background medical therapies including ACE inhibitors and/or beta-blockers (BBs).nnnMETHODSnOur meta-analysis included trials of >100 patients with reduced left ventricular ejection fraction (LVEF), i.e.,<40%. Fourteen randomized controlled trials met the criteria for meta-analysis, 10 involving medical therapies (angiotensin receptor blockers [ARBs], mineralocorticoid receptor antagonists [MRAs], ivabradine, n3-polyunsaturated fatty acid [PUFA], ferric carboxymaltose and aliskiren) and four involving ICDs. Results were pooled using the Mantel-Haenszel random effects method.nnnRESULTSnDrug therapy (n=36,172) reduced the risk of SCD overall (risk ratio (RR)=0.89, 95% confidence interval (CI)=0.82-0.98, p=0.02) when compared to placebo. MRAs alone were most effective in reducing SCD (n=11,032, RR=0.79 [0.68-0.91], p=0.001). ICD insertion greatly reduced SCD (n=4,269, RR=0.39 [0.30-0.51], p<0.00001) compared with placebo. The difference in treatment effect between the ICD and drug therapy was significant (p<0.002), and between ICD and MRAs (p<0.002).nnnCONCLUSIONSnDrug therapies when added to a standard background regimen comprising ACE inhibitor and/or BB reduced SCD overall and MRAs alone were most effective in this regard. ICDs were more effective than drugs in SCD abrogation. However, the added procedural morbidity and the cost of ICD need to be considered in decision-making re-approach to SCD reduction in the individual patient.

Determining the Optimal Dose of Adenosine for Unmasking Dormant Pulmonary Vein Conduction Following Atrial Fibrillation Ablation: Electrophysiological and Hemodynamic Assessment. DORMANT-AF Study

The significance of adenosine induced dormant pulmonary vein (PV) conduction in atrial fibrillation (AF) ablation remains controversial. The optimal dose of adenosine to determine dormant PV conduction is yet to be systematically explored.

Biatrial Electrical and Structural Atrial Changes in Heart Failure: Electroanatomic Mapping in Persistent Atrial Fibrillation in Humans

OBJECTIVESnThis study sought to characterize the biatrial substrate in heart failure (HF) and persistent atrial fibrillationxa0(PeAF).nnnBACKGROUNDnAtrial fibrillation (AF) and HF frequently coexist; however, the contribution of HF to the biatrial substratexa0in PeAF is unclear.nnnMETHODSnConsecutive patients with PeAF and normal left ventricular (NLV) systolic function (left ventricular ejection fraction [LVEF] >55%) or idiopathic cardiomyopathy (LVEFxa0≤45%) undergoing AF ablation were enrolled. In AF, pulmonaryxa0vein (PV) cycle length (PVCL) was recorded via a multipolar catheter in each PV and in the left atrial appendage for 100 consecutive cycles. After electrical cardioversion, biatrial electroanatomic mapping was performed. Complex electrograms, voltage, scarring, and conduction velocity were assessed.nnnRESULTSnForty patients, 20 patients with HF (mean age: 62 ± 8.9 years; AF duration: 15 ± 11 months; LVEF: 33 ± 8.4%) and 20 with NLV (mean age: 59 ± 6.7 years; AF duration: 14 ± 9.1 months; pxa0= 0.69; mean LVEF: 61 ± 3.6%; pxa0<xa00.001), were enrolled. HF reduced biatrial tissue voltage (pxa0< 0.001) with greater voltage heterogeneity (pxa0< 0.001). HF was associated with significantly more biatrial fractionation (left atrium [LA]: 30% vs. 9%; pxa0< 0.001; right atrium [RA]: 28% vs. 11%; pxa0< 0.001), low voltage (<0.5 mV) (LA: 23% vs. 6%; pxa0= 0.002; RA: 20% vs 11%; pxa0= 0.006), and scarring (<0.05xa0mV) in the LA (pxa0= 0.005). HF was associated with a slower average PVCL (185 vs. 164 ms; pxa0= 0.016), which correlated significantly with PV antral bipolar voltage (Rxa0=xa0-0.62; pxa0< 0.001) and fractionation (Rxa0= 0.46; pxa0=xa00.001).nnnCONCLUSIONSnHF is associated with significantly reduced biatrial tissue voltage, fractionation, and prolongation of PVCL. Advanced biatrial remodeling may have implications for invasive and noninvasive rhythm control strategies in patients with AF and HF.

Pulmonary vein activity does not predict the outcome of catheter ablation for persistent atrial fibrillation: A long-term multicenter prospective study

BACKGROUNDnPulmonary vein (PV) isolation (PVI) remains the cornerstone of catheter ablation (CA) in persistent atrial fibrillation (AF) (PeAF), although less successful than for paroxysmal AF. Whether rapid or fibrillatory (PV AF) PV firing may identify patients with PeAF more likely to benefit from a PV-based ablation approach is unclear.nnnOBJECTIVEnThe purpose of this study was to determine the relationship between the PV cycle length (PVCL) and the PV AF outcome after CA.nnnMETHODSnBefore ablation, the multipolar catheter was placed in each PV and the left atrial appendage (LAA) for 100 consecutive cycles. Thexa0presence of PV AF, the average PVCL of all 4 veins (PV4VAverage), the fastest vein average (PVFVAverage), the fastest cycle length (PVFast) both individually and relative to the average LAA cycle length were calculated. The ablation strategy included PVI and posterior wall isolation with a minimum of 12 months follow-up.nnnRESULTSnA total of 123 patients underwent CA (age 62 ± 9.1 years; CHA2DS2-VASC score 1.6 ± 1.1; left ventricular ejection fraction 48% ± 13%; left atrial area 31 ± 8.7 cm2; AF duration 16 ± 17 months). PVI was achieved in 100% of patients. Multiprocedure success (MPS; freedom from AF/atrial tachycardia episodes lasting >30 seconds) was achieved in 76% of patients at 24 ± 8.1 months of follow-up after 1.2 ± 0.4 procedures. PV activity was not associated with MPS either absolutely (PV4VAverage [MPS no vs yes: 178 ± 27 ms vs 177 ± 24 ms; P = .92], PVFVAverage [P = .69], or PVFast [P = .82]) or as a ratio relative to the LAA cycle length (PV4VAverage/LAA 1.05 ± 0.11 vs 1.06 ± 0.21; P = .87). The presence of PV AF (31% vs 47%; P = .13) did not predict MPS.nnnCONCLUSIONnThe rapidity of PV firing or presence of fibrillation within the PV was not predictive of outcome of CA for PeAF. PV activity does not identify patients most likely to benefit from a PV-based ablation strategy.

A comparison of the electrophysiologic and electroanatomic characteristics between the right and left atrium in persistent atrial fibrillation: Is the right atrium a window into the left?

The right atrium (RA) is readily accessible; however, it is unclear whether changes in the RA are representative of the LA. We performed detailed biatrial electroanatomic mapping to determine the electrophysiological relationship between the atria.

The Effect of Treatment Delays Associated with Inpatient Inter-hospital Transfer from Peripheral to Tertiary Hospitals for the Surgical Treatment of Cardiology Patients

BACKGROUNDnNearly 100,000 presentations to non-tertiary hospitals per year result in an inpatient transfer [1]. The timely inter-hospital transfer of patients for cardiothoracic surgery is significant to their overall outcomes. We hypothesised that patients with a prolonged pre-operative admission were at risk of nosocomial infection, leading to prolonged hospitalisation, morbidity and mortality.nnnMETHODSnPatients admitted to a non-tertiary centre (Frankston Hospital, Group 1) and requiring transfer to tertiary centres for cardiac surgery were compared to patients presenting directly to tertiary centres (Alfred Hospital, Group 2; St Vincents Hospital, Group 3) from June 2011-July 2012. Data was obtained from medical records and the National Cardiac Surgery Database.nnnRESULTSnEighty-seven patients in Group 1, 78 patients in Group 2 and 65 patients in Group 3 were identified. A higher proportion of total admission time was spent awaiting surgery in Group 1 compared to Group 2 (52.8% vs. 38.3%, p≤0.001) and Group 3 (52.8% vs. 26.3%, p≤0.001). Nosocomial infections occurred more frequently in Group 1 compared to Group 2 (20.7% vs. 5.1%, p=0.04) and Group 3 (20.7% vs. 6%, p<0.001).nnnCONCLUSIONnPresentation to a non-tertiary centre requiring inpatient cardiothoracic surgery is associated with longer pre-operative waiting time and higher rates of hospital-acquired infections.

Regression of Diffuse Ventricular Fibrosis Following Restoration of Sinus Rhythm With Catheter Ablation in Patients With Atrial Fibrillation and Systolic Dysfunction: A Substudy of the CAMERA MRI Trial

OBJECTIVESnThis study sought to determine if diffuse ventricular fibrosis improves in patients with atrial fibrillation (AF)-mediated cardiomyopathy following the restoration of sinus rhythm.nnnBACKGROUNDnAF coexists in 30% of heart failure (HF) patients and may be an underrecognized reversible cause of left ventricular systolic dysfunction. Myocardial fibrosis is the hallmark of adverse cardiac remodeling in HF, yet its reversibility is unclear.nnnMETHODSnPatients with persistent AF and an idiopathic cardiomyopathy (left ventricular ejection fraction [LVEF]xa0≤45%) were randomized to catheter ablation (CA) or ongoing medical rate control as a pre-specified substudy of the CAMERA-MRI (Catheter Ablation versus Medical Rate Control in Atrial Fibrillation and Systolic Dysfunction-an MRI-Guided Multi-centre Randomised Controlled Trial) trial. All patients had cardiac magnetic resonance imaging scans (including myocardial T1 time), serum B-type natriuretic peptide, 6-min walk tests, and Short Form-36 questionnaires performed at baseline and 6 months. Sixteen patients with no history of AF or left ventricular systolic dysfunction were enrolled as normal controls for T1 time.nnnRESULTSnThirty-six patients (18 in each treatment arm) were included in this substudy. Demographics, comorbidities, and myocardial T1 times were well matched at baseline. At 6 months, patients in the CA groupxa0had a significant reduction in myocardial T1 time from baseline compared with the medical rate control group (-124 ms; 95% confidence interval [CI]:xa0-23 toxa0-225 ms; pxa0= 0.0176), although it remained higher than that of normal controls at 6 months (pxa0= 0.0017). Improvements in myocardial T1 time with CA were associatedxa0with significant improvements in absolute LVEF (+12.5%; 95% CI: 5.9% to 19.0%; pxa0= 0.0004), left ventricular end-systolic volume (pxa0= 0.0019), and serum B-type natriuretic peptide (-216 ng/l; 95% CI:xa0-23 toxa0-225 ng/l; pxa0= 0.0125).nnnCONCLUSIONSnThe improvement in LVEF and reverse ventricular remodeling following successful CA ofxa0AF-mediated cardiomyopathy is accompanied by a regression of diffuse fibrosis. This suggests timely treatmentxa0of arrhythmia-mediated cardiomyopathy may minimize irreversible ventricular remodeling.

Acute Anteroseptal Myocardial Infarction after a Negative Exercise Stress Test.

A myocardial infarction is a rare complication which can occur after an exercise stress test. We report a 48-year-old male who was referred to the Mildura Cardiology Practice, Victoria, Australia, in August 2014 with left-sided chest pain. He underwent an exercise stress test which was negative for myocardial ischaemia. However, the patient presented to the Emergency Department of the Mildura Base Hospital 30 minutes after the test with severe retrosternal chest pain. An acute anteroseptal ST segment elevation myocardial infarction was observed on electrocardiography. After thrombolysis, he was transferred to a tertiary hospital where coronary angiography subsequently revealed significant left anterior descending coronary artery stenosis. Thrombus aspiration and a balloon angioplasty were performed. The patient was discharged three days after the surgical procedure in good health.