Cardiac resynchronization therapy in heart failure patients: An update

Heart failure continues to be a major public health problem with high morbidity and mortality rates, despite the advances in medical treatment. Advanced heart failure patients have severe persistent symptoms and a poor quality of life. Cardiac resynchronization therapy (CRT), an invasive therapy which involves synchronized pacing of both right and left ventricles, improves ventricular conduction delay and left ventricular performance. Several clinical trials of CRT in medically refractory heart failure patients with wide QRS (> 120 ms), left ventricular ejection fraction &#163; 35% and New York Heart Association (NYHA) class III and IV have shown improved quality of life, NYHA class, left ventricular ejection fraction and reduced mortality. About 30% of heart failure patients who receive CRT do not respond to treatment. Mechanical dyssynchrony may play a role in identifying patients who may respond better to CRT treatment. However, recent large scale clinical trials PROSPECT and RethinQ have challenged this concept. The role of CRT in heart failure patients with narrow QRS (< 120 ms), NYHA class I and II, atrioventricular nodal ablation in patients with atrial fibrillation and triple site pacing are evolving. Our review discusses the current evidence, indications, upcoming trials and future directions

Predictors of coronary artery disease in patients with left bundle branch block who undergo myocardial perfusion imaging

Background: Due to difficulties in diagnosing coronary ischemia in patients with left bundle branch block (LBBB), identifying clinical characteristics that might help to predict coronary artery disease (CAD) is important. Our study aimed to identify clinical predictors of CAD among patients with and without LBBB who undergo myocardial perfusion imaging (MPI). Methods: All patients with LBBB who underwent MPI (LBBB group) from June 2005 to February 2007 were compared with patients with normal baseline electrocardiography who underwent treadmill MPI (non-LBBB group) during the same period. Results: LBBB patients with CAD were younger and had lower ejection fraction (EF) compared to LBBB patients without CAD. Similarly non-LBBB patients with CAD had lower EF, but did not differ significantly in age compared to non-LBBB patients without CAD. Regression analysis among patients with LBBB showed that EF < 55% was the most significant predictor of CAD, after controlling for other factors. A regression analysis in non-LBBB patients showed that male gender and EF &#163; 55% were significant predictors of CAD. A regression analysis conducted in the combined data of both LBBB and non-LBBB groups showed male gender, EF &#163; 55% and LBBB to be the most significant predictors of CAD. Conclusions: Patients with LBBB have a high probability of CAD based on MPI findings. Patients with LBBB and reduced EF have a much higher likelihood of CAD compared to patients without LBBB and normal EF. Further studies on early invasive approach in patients with LBBB and reduced EF seem warranted

Comparison of outcomes in patients undergoing defibrillation threshold testing at the time of implantable cardioverter-defibrillator implantation versus no defibrillation threshold testing

Background: Inability to perform defibrillation threshold (DFT) testing during implantable cardioverter defibrillator (ICD) implantation due to co-morbidities may influence long-term survival. Methods: Retrospective review at The University of Michigan (1999-2004) identified 55 patients undergoing ICD implantation without DFT testing (&#8220;No-DFT group&#8221;). A randomly selected sample of patients (n = 57) undergoing standard DFT testing (&#8220;DFT group&#8221;) was compared in terms of appropriate shocks, clinical shock efficacy and all-cause mortality. Results: DFT testing was withheld due to hypotension, atrial fibrillation with inability to exclude left atrial thrombus, left ventricular thrombus, CHF and/or ischemia. The No-DFT group had a similar appropriate shock rate, but lower total survival (69.1% vs. 91.2%, p = 0.004) than the DFT group. The No-DFT group had a higher incidence of ventricular fibrillation (VF) episodes (9.1% vs. 3.1%, p = 0.037), and deaths attributable to VF (3 of 17 deaths vs. 0 of 5 deaths) compared to the DFT group. Multivariate analysis found a trend toward increased risk of death in the No-DFT group (HR 3.18, 95% CI 0.82-12.41, p = 0.095) after adjusting for baseline differences in gender distribution, NYHA class and prior CABG. Conclusions: In summary, overall mortality was higher in the No-DFT group. More deaths attributable to VF occurred in the No-DFT group. Thus, DFT testing should therefore remain the standard of care. Nevertheless, ICD therapy should not be withheld in patients who meet appropriate implant criteria simply on the basis of clinical scenarios that preclude routine DFT testing. (Cardiol J 2007; 14: 463-469

Metaanalysis on effects of cardiac resynchronization therapy in heart failure patients with narrow QRS complex

Background: To systematically review the benefits of cardiac resynchronization therapy (CRT) in heart failure patients with narrow QRS (< 120 ms) who have baseline mechanical asynchrony. Methods: We searched the MEDLINE, Cochrane Central Register of Controlled Trials, and reference lists of retrieved articles for relevant trials through October 2007. Studies were included if they were clinical trials in heart failure patients with narrow QRS complex, had at least 3 months of duration and measured baseline mechanical dyssynchrony. Weighted mean difference (WMD) for changes in left ventricular ejection fraction (LVEF), New York Heart Association (NYHA) class and 6 minute walk distance (6MWD) at the end of follow up period were estimated using fixed effects meta-analysis. Results: Three relevant clinical trials (enrolling 98 patients) out of 80 identified studies were included in the final analysis. When compared to baseline, CRT in heart failure patients with narrow QRS complex significantly improved mean LVEF (WMD 7.98%, 95% CI 5.94, 10.03) and 6MWD (WMD 67 m, 95% CI 39.12, 94.98) at the end of follow up period with no significant heterogeneity between the included studies (I2 < 50%). Similarly, there was a significant reduction in NYHA at the end of follow-up (WMD &#8211;0.87, 95% CI &#8211;1.01, &#8211;0.74) but there was significant heterogeneity between the included studies. Conclusions: In patients with narrow QRS complex and baseline mechanical asynchrony, who underwent CRT after optimal medical management, there was a significant reduction in NYHA class, improvement in LVEF and increase in 6MWD during follow up. Further data from large randomized trials are warranted to explore the role of CRT in heart failure patients with narrow QRS complex. (Cardiol J 2008; 15: 230-236

Aging reduces left atrial performance during adrenergic stress in middle aged and older patients

Background: During adrenergic stress, the influence of age on left atrial (LA) function is unknown. We hypothesized that aging decreases LA total emptying fraction (LAEF) during maximal adrenergic stress. The aim of the study was to determine the influence of aging on LA function during adrenergic stress in middle aged and older patients. Methods: We enrolled 167 middle aged and elderly participants, and measured LA and left ventricular (LV) volumes using a multi-slice three-dimensional cine white blood cardiovascular magnetic resonance (CMR) technique before and during intravenous dobutamine infused to achieve 80% of the maximum heart rate response for age. Paired sample t-test was used to detect differences in LA and LV volumes between baseline and peak dose stage of dobutamine stress CMR, and multivariable linear regression was used to identify predictors of LA function. Results: Participants averaged 68 &#177; 8 years in age, 53% were men, 25% exhibited coronary artery disease, 35% had diabetes, 9% had a remote history of atrial fibrillation, 90% had hypertension, and 11% had inducible LV wall motion abnormalities indicative of ischemia during dobutamine CMR. Increasing age correlated with LA volumes (maximal and minimal) and inversely correlated with LAEF at rest and after peak adrenergic stress. Age was an independent predictor of LAEF during adrenergic stress, even after accounting for gender, LV volumes, and other co-morbidities including inducible ischemia. Conclusions: Age is associated with a decrease in LA function during adrenergic stress even after adjusting for co-morbidities associated with cardiovascular disease and LV function. (Cardiol J 2012; 19, 1: 45&#8211;52

Porównanie wyników leczenia u pacjentów poddawanych lub niepoddawanych ocenie progu defibrylacji w czasie wszczepienia kardiowertera-defibrylatora

Wstęp: Brak możliwości przeprowadzenia oceny progu defibrylacji (DFT) podczas implantacji kardiowertera-defibrylatora (ICD) ze względu na występowanie współistniejących chorób może wpływać na przeżywalność w obserwacji odległej. Metody: W retrospektywnym przeglądzie przeprowadzonym na University of Michigan (1999-2004) zidentyfikowano 55 pacjentów, u których przeprowadzono implantację ICD bez oceny DFT. Grupę tą porównano pod względem występowania uzasadnionych wyładowań, ich klinicznej skuteczności oraz całkowitej śmiertelności z losowo wybraną grupą osób (n = 57), u których przeprowadzono standardową ocenę DFT. Wyniki: Oceny DFT nie dokonywano z powodu niskiej wartości ciśnienia tętniczego, migotania przedsionków z niemożnością wykluczenia skrzepliny w lewym przedsionku, skrzepliny w lewej komorze, zastoinowej niewydolności serca i/lub niedokrwienia. W grupie bez oceny DFT liczba uzasadnionych wyładowań była podobna, natomiast łączne przeżycie mniejsze (69,1% vs. 91,2%; p = 0,004) niż w grupie poddawanej ocenie DFT. W grupie bez oceny DFT stwierdzono większą częstość incydentów migotania komór (VF; 9,1% vs. 3,1%; p = 0,037) i zgonów z powodu VF (3 spośród 17 zgonów vs. 0 spośród 5 zgonów) ni&#191; w grupie poddawanej ocenie DFT. W analizie wielozmiennej wykazano trend w kierunku zwiększonego ryzyka zgonów w grupie bez oceny DFT [iloraz hazardu (HR) 3,18; 95% przedział ufności (CI) 0,82&#8211;12,41; p = 0,095] po uwzględnieniu początkowych różnic rozkładu płci, klasy czynnościowej według Nowojorskiego Towarzystwa Kardiologicznego (NYHA) oraz wcześniejszego pomostowania tętnic wieńcowych. Wnioski: Całkowita śmiertelność była większa w grupie bez oceny DFT, gdzie wystąpiło więcej zgonów, które można było przypisywać VF. Ocena DFT powinna więc pozostać standardem postępowania. Mimo to nie należy rezygnować z leczenia za pomocą ICD u pacjentów, którzy spełniają kryteria implantacji, jeżeli jedynym powodem tego miałoby być występowanie sytuacji klinicznych wykluczających ocenę DFT

Implications of the 2013 ACC/AHA cholesterol guidelines on contemporary clinical practice for patients with atherosclerotic coronary and peripheral arterial disease

Background: Cholesterol management guidelines from the American College of Cardiology/American Heart Association (ACC/AHA-2013) recommend fixed statin dosing (dose depends on age ≤ or >75 years) compared to the earlier adult treatment panel III (ATPIII) guidelines which recommended specific low-density lipoprotein-cholesterol (LDL-C) targets. Clinical implications of this recommendation are not known. Methods: We retrospectively compared cholesterol levels and statin utilization across cohorts with coronary artery disease (CAD) (n = 9563), peripheral arterial disease (PAD) (n = 596) and CAD + PAD (n = 975) by applying both guidelines. The percentage of patients who achieved guideline-specific targets using 2013 ACC/AHA (use of moderate/high intensity statins) or ATPIII guidelines (LDL-C < 100 mg/dl) was compared between all groups. Results: Using both guidelines, the PAD only group demonstrated lower utilization and lower statin doses than the CAD or CAD + PAD groups. When applying the ACC/AHA guidelines, more patients in the CAD only group (age ≤75 years) were considered at goal as compared to the ATPIII guidelines (92.2% vs. 75%), primarily driven by the group placed on moderate/high intensity statins but had an LDL-C level >100 mg/dl. Conclusions: Application of the ACC/AHA guidelines results in a higher percentage of patients considered to be ‘at goal’ when compared to the ATP III guidelines without changes in clinical practice. This is due to patients ≤75 years old on adequate statin doses but still have LDL-C levels >100 mg/dl, thereby raising concerns that physicians may not pursue alternate LDL reduction strategies since they are now considered at goal despite LDL-C >100 mg/dl. Lipid management of PAD patients remains sub-optimal as compared to CAD and CAD + PAD

No consistent evidence of differential cardiovascular risk amongst proton-pump inhibitors when used with clopidogrel:meta-analysis

Data from pharmacokinetic and pharmacodynamic studies indicate that the adverse clopidogrel - proton pump inhibitor (PPI) interaction may vary between PPIs, with pantoprazole considered relatively less problematic. We aimed to evaluate systematically whether individual PPIs differ in their risk for cardiovascular events when concomitantly administered with clopidogrel