Emily Honeycutt

Modifiable risk factors associated with sudden cardiac arrest within hemodialysis clinics

Sudden cardiac arrest is the most common cause of death among patients with end-stage kidney disease (ESKD) maintained on hemodialysis. Here we sought to identify dialysis-related factors associated with this increased risk in a case-control study encompassing 43,200 patients dialyzed in outpatient clinics of a large organization. Within this group, we compared the clinical and dialysis-specific data of 502 patients who experienced a sudden cardiac arrest with 1632 age- and dialysis-vintage-matched controls. There were 4.5 sudden cardiac arrest events per 100,000 dialysis treatments during the 3-year study period. These patients were significantly more likely to have been exposed to low potassium dialysate of less than 2 meq/l. These differences could not be explained by predialysis serum potassium levels. There was no evidence for a beneficial effect of low potassium dialysate even among those with higher predialysis serum potassium levels. Other factors strongly associated with sudden cardiac arrest by multivariable analysis included increased ultrafiltration volumes, exposure to low calcium dialysate, and predialysis serum creatinine levels. These relationships persisted after adjustment for covariates, but traditional risk factors such as history of coronary heart disease and congestive heart failure were not significantly influential. Hence, our study suggests that modifications of the hemodialysis prescription may improve the risk of sudden cardiac arrest in patients with ESKD.

Chronic kidney disease is associated with increased risk of sudden cardiac death among patients with coronary artery disease

Sudden cardiac death is the most common cause of mortality among patients with end-stage kidney disease maintained on hemodialysis. To examine whether this increased risk is also seen with less advanced kidney disease, we studied the relationship between glomerular filtration rate and risk of sudden cardiac death in patients with moderate kidney disease and known coronary artery disease. This retrospective longitudinal study encompassed 19,440 consecutive patients who underwent cardiac catheterization at a single academic institution. There were 522 adjudicated sudden cardiac death events, yielding an overall rate of 4.6 events per 1000 patient years. This figure reflected rates of 3.8 events in 14,652 patients with estimated glomerular filtration rates (eGFR) > or =60 (stage 2 CKD or better) and 7.9 events in 4788 patients with glomerular filtration rates <60 (stage 3-5 CKD), all normalized to 1000 patient-years. After adjusting for differences in known cardiac risk factors and other covariates in a multivariate Cox proportional hazards model, the eGFR was independently associated with sudden cardiac death (hazard ratio (HR)=1.11 per 10 ml/min decline in the eGFR). Our analysis found that reductions in the eGFR in CKD stages 3-5 are associated with a progressive increase in risk of sudden cardiac death in patients with coronary artery disease. Additional studies are needed to better characterize the mechanisms by which reduced kidney function increases this risk.

Repeatability and reproducibility of phase analysis of gated single-photon emission computed tomography myocardial perfusion imaging used to quantify cardiac dyssynchrony.

BackgroundA novel method to quantify dyssynchrony has been developed using phase analysis of gated single-photon emission computed tomography perfusion imaging. We report on the effect of variability in image reconstruction on the phase analysis results (repeatability) and on the interobserver and intraobserver reproducibility of the technique. MethodsPhase standard deviation (SD) and bandwidth are phase indices that quantify dyssynchrony. To evaluate repeatability, raw data sets were processed twice in 50 patients with left ventricular dysfunction and 50 normal controls. To determine the optimal processing method, two replicated phase analysis results were obtained using automated and manual base parameter placement. Reproducibility of the phase analysis was determined using the data from 20 patients. ResultsIn normal controls, manual base parameter placement improves repeatability of the phase analysis as measured by the mean absolute difference between two reads for phase SD (12.0° vs. 1.2°, P<0.0001) and bandwidth (33.7° vs. 3.6°, P<0.0001). Repeatability is better for normal controls than for patients with left ventricular dysfunction for phase SD (1.2° vs. 6.0°, P<0.0001) and bandwidth (3.6° vs. 26.5°, P<0.0001). Reproducibility of the phase analysis is high as measured by the intraclass correlation coefficients for phase SD and bandwidth of 0.99 and 0.99 for the interobserver comparisons and 1.00 and 1.00 for the intraobserver comparisons. ConclusionA novel method to quantify dyssynchrony has been developed using gated single-photon emission computed tomography perfusion imaging. Manual base parameter placement reduces the effect that variability in image reconstruction has on phase analysis. A high degree of reproducibility of phase analysis is observed.

Contemporary patterns of fractional flow reserve and intravascular ultrasound use among patients undergoing percutaneous coronary intervention in the United States: insights from the National Cardiovascular Data Registry.

To the Editor: The use of fractional flow reserve (FFR) and intravascular ultrasound (IVUS) to assess intermediate coronary stenoses (defined as 40% to 70% stenosis) has been associated with improved procedural and clinical outcomes ([1,2][1]) in patients undergoing percutaneous coronary

Survival Prognosis and Surgical Management of Ischemic Mitral Regurgitation

BACKGROUND Ischemic mitral regurgitation (IMR) has an adverse prognosis, but survival characteristics and management are controversial. This study reviewed a 20-year series of IMR patients managed with multiple approaches to assess and refine surgical strategies. METHODS Patients having surgery for primary coronary disease from 1986 to 2006 were divided into group 1 (no IMR; bypass grafting only; n = 16,209), group 2a (IMR; bypass only; n = 3,181), group 2b (IMR; mitral repair; n = 416), and group 2c (IMR; mitral replacement; n = 106). Cox proportional hazards modeling adjusted for baseline differences, and therapeutic adequacy was quantified by area under each survival curve expressed as a percentage of group 1. RESULTS Group 2 patients were older than group 1 patients and had worse baseline characteristics. Group 2a had less severe MR and group 2b had the most comorbidity. Assuming group 1 provided the best adjusted outcome at a given baseline risk, group 2a achieved 97.7%, 2b achieved 93.7%, and 2c achieved 79.1% of potential survival (hazard ratio 1.1, 1.4, and 1.6, respectively; p < 0.003). Most of the survival difference was perioperative. CONCLUSIONS Worse baseline risk is a major factor reducing long-term survival in IMR. Current algorithms in which mild to moderate IMR is managed with bypass only (group 2a) generally produced good late results. In patients with moderate and severe IMR, repair achieved 93.7% of full survival potential; valve replacement was less satisfactory, primarily owing to higher operative mortality. Future therapeutic refinement, emphasizing reparative procedures and better perioperative care, could enhance the surgical prognosis of IMR.

Percutaneous Coronary Intervention in Native Arteries Versus Bypass Grafts in Prior Coronary Artery Bypass Grafting Patients: A Report From the National Cardiovascular Data Registry

OBJECTIVES This study examined a large registry to determine the frequency, predictors, and outcomes of native coronary artery versus bypass graft percutaneous coronary intervention (PCI) in patients with prior coronary artery bypass graft surgery (CABG). BACKGROUND The PCI target vessel and corresponding outcomes in prior CABG patients are poorly studied. METHODS We analyzed the frequency and factors associated with native versus bypass graft PCI in prior CABG patients undergoing PCI between January 1, 2004, and June 30, 2009, in the National Cardiovascular Data Registry (NCDR) CathPCI Registry. Generalized estimating equations logistic regression modeling was used to generate independent variables associated with native versus bypass graft PCI and in-hospital mortality. RESULTS During the study period, PCI in prior CABG patients represented 17.5% of the total PCI volume (300,902 of 1,721,046). The PCI target was a native coronary artery in 62.5% and a bypass graft in 37.5%: saphenous vein graft (SVG) (104,678 [34.9%]), arterial graft (7,517 [2.5%]), or both arterial graft and SVG (718 [0.2%]). Compared with patients undergoing native coronary artery PCI, those undergoing bypass graft PCI had higher-risk characteristics and more procedural complications. On multivariable analysis, several parameters (including graft stenosis and longer interval from CABG) were associated with performing native coronary PCI, and bypass graft PCI was associated with higher in-hospital mortality (adjusted odds ratio: 1.22, 95% confidence interval: 1.12 to 1.32). CONCLUSIONS Most PCIs performed in prior CABG patients are done in native coronary artery lesions. Compared with native coronary PCI, bypass graft PCI is independently associated with higher in-hospital mortality.

Evaluation of mechanical dyssynchrony and myocardial perfusion using phase analysis of gated SPECT imaging in patients with left ventricular dysfunction

AbstractBackground. Using phase analysis of gated single photon emission computed tomography (SPECT) imaging, we examined the relation between myocardial perfusion, degree of electrical dyssynchrony, and degree of SPECT-derived mechanical dyssynchrony in patients with left ventricular (LV) dysfunction. Methods and Results. We retrospectively examined 125 patients with LV dysfunction and ejection fraction of 35% or lower. Fourier analysis converts regional myocardial counts into a continuous thickening function, allowing resolution of phase of onset of myocardial thickening. The SD of LV phase distribution (phase SD) and histogram bandwidth describe LV phase dispersion as a measure of dyssynchrony. Heart failure (HF) patients with perfusion abnormalities have higher degrees of dyssynchrony measured by median phase SD (45.5° vs 27.7°, P<.0001) and bandwidth (117.0° vs 73.0°, P=.0006). HF patients with prolonged QRS durations have higher degrees of dyssynchrony measured by median phase SD (54.1° vs 34.7°, P<.0001) and bandwidth (136.5° vs 99.0°, P=.0005). Mild to moderate correlations exist between QRS duration and phase analysis indices of phase SD (r=0.50) and bandwidth (r=0.40). Mechanical dyssynchrony (phase SD >43°) was 43.2%. Conclusions. HF patients with perfusion abnormalities or prolonged QRS durations have higher degrees of mechanical dyssynchrony. Gated SPECT myocardial perfusion imaging can quantify myocardial function, perfusion, and dyssynchrony and may help in evaluating patients for cardiac resynchronization therapy. (J Nucl Cardiol 2008;15:663-70.)

Impact of Recovery of Renal Function on Long-Term Mortality After Coronary Artery Bypass Grafting

Whether prognosis differs in acute renal failure (ARF) after coronary artery bypass grafting (CABG) in patients with and without recovery of renal function is not known. We studied patients who had CABG at Duke University Medical Center (1995 to 2008). ARF was defined as an increase in peak creatinine ≥50% after CABG or ≥0.7 mg/dl above baseline or need for new dialysis. Patients were categorized into 3 groups: (1) no ARF after CABG, (2) ARF after CABG and completely recovered renal function at day 7 (return of creatinine to no higher than baseline and no dialysis), or (3) ARF after CABG with no recovery of renal function at day 7 (creatinine no higher than baseline or new dialysis). Main outcome measurement was risk-adjusted long-term mortality (excluding death ≤7 days). ARF after CABG occurred in 2,083 of 10,415 patients (20%) and completely recovered in 703 (33.7%). Risk-adjusted mortality was highest in patients with ARF without recovery of renal function (hazard ratios 1.47, 95% confidence interval 1.34 to 1.62) and intermediate in those with ARF but completely recovered renal function (hazard ratios 1.21, 95% confidence interval 1.07 to 1.37, referent no-ARF group). Mortality was lower in patients with ARF compared to those without complete recovery of renal function (p = 0.0083). In conclusion, in patients with ARF after CABG, complete recovery of renal function was associated with significantly lower long-term mortality compared to those without such recovery, although this was significantly higher than in those without ARF. Thus, major emphasis should be on prevention of ARF in patients undergoing CABG.

Mitral Valve Repair for Degenerative Disease: A 20-Year Experience

BACKGROUND Recent advances in surgical technique allow repair of most mitral valves with degenerative disease. However, few long-term data exist to support the superiority of repair versus prosthetic valve replacement, and repair could be limited by late durability or other problems. This study was designed to compare survival characteristics of mitral valve repair versus prosthetic replacement for degenerative disorders during a 20-year period. METHODS From 1986 to 2006, 2,580 patients underwent isolated mitral valve procedures (with or without coronary artery bypass grafting), with 989 classified as having degenerative origin. Of these, 705 received valve repair, and 284 had prosthetic valve replacement. Differences in baseline characteristics between groups were assessed, and unadjusted survival estimates were generated using Kaplan-Meier methods. Survival curves were examined after adjustment for differences in baseline profiles using a Cox model, and average adjusted survival differences were quantified by area under the curve methodology. Survival differences during 15 years of follow-up also were assessed with propensity matching. RESULTS Baseline characteristics were similar, except for (variable: repair, replacement) age: 62 years, 68 years; concomitant coronary artery bypass grafting: 24%, 32%; ejection fraction: 0.51, 0.55; congestive heart failure: 68%, 43%; and preoperative arrhythmia: 11%, 7% (all p < 0.05). Long-term survival was significantly better in the repair group, both for unadjusted data (p < 0.001) and for risk-adjusted results (p = 0.040). Patient survival in the course of 15 years averaged 7.3% better with repair, and increased with time of follow-up: 0.7% better for 0 to 5 years, 4.9% better for 5 to 10 years, and 21.3% better for 10 to 15 years. Treatment interaction between repair or replacement and age was negative (p = 0.66). In the propensity analysis, survival advantages of repair versus replacement were similar in magnitude with a p value of 0.046. CONCLUSIONS As compared with prosthetic valve replacement, mitral repair is associated with better survival in patients with degenerative disease, especially after 10 to 15 years. This finding supports the current trend of increasing repair rates for degenerative disorders of the mitral valve.

In-hospital switching between adenosine diphosphate receptor inhibitors in patients with acute myocardial infarction treated with percutaneous coronary intervention: Insights into contemporary practice from the TRANSLATE-ACS study:

Aims: While randomized clinical trials have compared clopidogrel with higher potency adenosine diphosphate (ADP) receptor inhibitors among patients with acute myocardial infarction, little is known about the frequency, effectiveness and safety of switching between ADP receptor inhibitors in routine clinical practice. Methods and results: We studied 11,999 myocardial infarction patients treated with percutaneous coronary intervention at 230 hospitals from April 2010 to October 2012 in the TRANSLATE-ACS study. Multivariable Cox regression was used to compare six-month post-discharge risks of major adverse cardiovascular events (MACE: death, myocardial infarction, stroke, or unplanned revascularization) and Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries (GUSTO)-defined bleeding between in-hospital ADP receptor inhibitor switching versus continuation of the initially selected therapy. Among 8715 patients treated initially with clopidogrel, 994 (11.4%) were switched to prasugrel or ticagrelor; switching occurred primarily after percutaneous coronary intervention (60.9%) and at the time of hospital discharge (26.7%). Among 3284 patients treated initially with prasugrel or ticagrelor, 448 (13.6%) were switched to clopidogrel; 48.2% of switches occurred after percutaneous coronary intervention and 48.0% at hospital discharge. Switching to prasugrel or ticagrelor was not associated with increased bleeding when compared with continuation on clopidogrel (2.7% vs. 3.3%, adjusted hazard ratio 0.96, 95% confidence interval 0.64–1.42, p=0.82). Switching from prasugrel or ticagrelor to clopidogrel was not associated with increased MACE (8.9% vs. 7.7%, adjusted hazard ratio 1.06, 95% confidence interval 0.75–1.49, p=0.76) when compared with continuation on the higher potency agent. Conclusions: In-hospital ADP receptor inhibitor switching occurs in more than one in 10 myocardial infarction patients in contemporary practice. In this observational study, ADP receptor inhibitor switching does not appear to be significantly associated with increased hazard of MACE or bleeding.