Optimizing exercise testing‐based risk stratification to predict poor prognosis after acute heart failure

AIMS

The timely selection of severe heart failure (HF) patients for cardiac transplantation and advanced HF therapy is challenging. Peak oxygen consumption (VO₂ ) values obtained by the cardiopulmonary exercise testing are used to determine the transplant recipient list. This study reassessed the prognostic predictability of peak VO₂ and compared it with the Heart Failure Survival Score (HFSS) in the modern optimized guideline-directed medical therapy (GDMT) era.

METHODS AND RESULTS

We retrospectively selected 377 acute HF patients discharged from the hospital. The primary outcome was a composite of all-cause mortality, or urgent cardiac transplantation. We divided these patients into the more GDMT (two or more types of GDMT) and less GDMT groups (fewer than two types of GDMT) and compared the performance of their peak VO₂ and HFSS in predicting primary outcomes. The median follow-up period was 3.3 years. The primary outcome occurred in 57 participants. Peak VO₂ outperformed HFSS when predicting 1 year (0.81 vs. 0.61; P = 0.017) and 2 year (0.78 vs. 0.58; P < 0.001) major outcomes. The cutoff peak VO₂ for predicting a 20% risk of a major outcome within 2 years was 10.2 (11.8-7.0) for the total cohort. Multivariate Cox regression analyses showed that peak VO₂ , sodium, previous implantable cardioverter defibrillator (ICD) implantation, and estimated glomerular filtration rate were significant predictors of major outcomes.

CONCLUSIONS

Optimizing the cutoff value of peak VO₂ is required in the current GDMT era for advanced HF therapy. Other clinical factors such as ICD use, hyponatraemia, and chronic kidney disease could also be used to predict poor prognosis. The improvement of resource allocation and patient outcomes could be achieved by careful selection of appropriate patients for advanced HF therapies, such as cardiac transplantation.

Long-term prognostic value of myocardin expression levels in non-ischemic dilated cardiomyopathy

The mortality of patients with non-ischemic dilated cardiomyopathy (NIDCM) remains substantial. We evaluated gene expression levels of myocardin, an early cardiac gene, in the peripheral blood cells of NIDCM patients as a prognostic biomarker in their long-term outcome and mortality from congestive HF (CHF). We retrospectively analyzed 101 consecutives optimally treated NIDCM patients of Cretan origin who were enrolled from the HF clinic of our hospital from November 2005 to December 2008. Our patient data were either taken from their medical files or recorded during visits to the HF unit or hospitalizations. Follow-up was carried out by telephone interview and by accessing information from general practitioners and cardiologists in private practice. The median follow-up period was 8 years (mean follow-up 7 ± 3.4 years). The overall mortality during follow-up was 61.4%, while mortality due to congestive heart failure (CHF) was 49.5%. Higher CHF and all-cause mortality were observed in patients with myocardin levels < 14.26 (p < 0.001 for both CHF and all-cause mortality). A multivariate Cox regression analysis showed that myocardin level of expression had independent significant prognostic value for the risk of death from CHF (HR 14.5, 95% confidence interval (CI) 5.3-39) in those patients. Peripheral blood cells gene expression of myocardin, an early myocardial marker, may serve as prognostic biomarkers of the long-term outcome of patients with NIDCM. Our findings open new prospects in the risk stratification of these patients.

Atrial Fibrillation Is Associated With Higher Overall Mortality in Patients With Implantable Cardioverter-Defibrillator: A Systematic Review and Meta-Analysis

Background Implantable cardioverter-defibrillator ( ICD ) improves survival when used for primary or secondary prevention of sudden cardiac death. Whether the benefits of ICD in patients with atrial fibrillation ( AF) are similar to those with normal sinus rhythm ( NSR ) is not well established. The aim of this study is to investigate whether ICD patients with AF are at higher risk of mortality and appropriate shock therapy compared with patients with NSR . Methods and Results Literature was searched and 25 observational studies with 63 283 patients were included in this meta-analysis. We compared the outcomes of (1) all-cause mortality and appropriate shock therapy among AF and NSR patients who received ICD for either primary or secondary prevention and (2) all-cause mortality among AF patients with ICD versus guideline directed medical therapy. All-cause mortality (odds ratio, 2.11; 95% confidence interval, 1.73-2.56; P<0.001) and incidence of appropriate shock therapy (odds ratio, 1.77; 95% confidence interval, 1.47-2.13; P<0.001) were significantly higher in ICD patients with AF as compared to NSR . There was no statistically significant mortality benefit from ICD compared with medical therapy in AF patients (odds ratio, 0.69; 95% confidence interval, 0.42-1.11; P=0.12) based on a separate meta-analysis of 3 studies with 387 patients. Conclusions Overall mortality and appropriate shock therapy are higher in ICD patients with AF as compared with NSR . The impact of ICD on all-cause mortality in AF patients when compared to goal-directed medical therapy is unclear, and randomized controlled trials are needed comparing AF patients with ICD and those who have indications for ICD, but are only on medical therapy.

The impact of uric acid on long-term mortality in patients with asymptomatic carotid atherosclerotic disease

BACKGROUND

Serum uric acid (SUA) has been discussed to be related to cardiovascular (CV) disease and outcome. We investigated whether levels of SUA predict long-term mortality in neurologically asymptomatic patients with carotid atherosclerotic disease.

METHODS

We prospectively studied 959 consecutive patients with carotid atherosclerosis as evaluated by duplex Doppler sonography for all-cause and CV death, respectively.

RESULTS

During a median follow-up time of 6.3 years (interquartile range [IQR], 5.4-7.1 years), 246 deaths (25.7%), including 160 CV deaths (16.7%), were recorded. Median baseline SUA levels were 5.9 mg/dL (IQR, 5.0-7.0 mg/dL). SUA was significantly associated with all-cause death and CV death. Adjusted hazard ratios (HRs) for an increase of 1 mg/dL of SUA levels were 1.12 (95% confidence interval [CI], 1.04-1.21; P = .003) and 1.20 (95% CI, 1.11-1.30; P < .001) for all-cause and CV death, respectively. Quartiles of SUA levels showed a significant association with CV mortality (log-rank P = .002). For CV death, adjusted HRs for quartiles of increasing SUA levels were 1.45 (95% CI, .87-2.43), 1.44 (95% CI, .85-2.46), and 2.26 (95% CI, 1.36-3.76; P < .01), compared with the lowest quartile, respectively. Patients with baseline carotid stenosis of more than 50% and/or increased levels of SUA (≥median) had an approximately 2-fold increase in risk of (CV) death, compared with patients with carotid narrowing of less than 50% and/or SUA levels less than the median (P < .001).

CONCLUSIONS

Levels of SUA represent independent predictors for CV mortality in a cohort of patients with asymptomatic carotid atherosclerosis.

Do implantable cardioverter defibrillators improve survival in patients with chronic kidney disease at high risk of sudden cardiac death? A meta-analysis of observational studies

AIMS

Prospective randomized clinical trials show that implantable cardioverter defibrillators (ICDs) can reduce the risk of total mortality in select populations. However, data regarding patients with chronic kidney disease (CKD) are inconclusive. The aim of this study was to evaluate if ICDs affect total mortality in CKD patients at high risk of sudden cardiac death.

METHODS AND RESULTS

Two separate meta-analyses were performed to (i) assess the effect of ICD on all-cause mortality in CKD patients at high risk of sudden cardiac death and (ii) assess the effect of CKD on all-cause mortality in patients who already had an ICD for primary or secondary prevention purposes. Medline and EMBASE were searched from 1966 to 2013. A manual search by cross-referencing was performed. Five observational studies with 17 460 CKD patients considered at high risk of sudden cardiac death were included to evaluate the effect of ICDs on patients with severe CKD. Patients with ICD implants had a reduction in all-cause mortality (adjusted hazard ratio (HR) = 0.65, 95% confidence interval (CI) = 0.47-0.91, P < 0.05) compared with a matched control group. Based on 15 observational studies with 5233 patients as part of our second comparison that evaluated the effect of CKD on patients who received an ICD, CKD was associated with higher mortality risk (HR = 2.86, 95% CI = 1.91-4.27, P < 0.05) despite an ICD.

CONCLUSION

The meta-analysis indicates that for patients undergoing ICD implant, CKD is associated with greater risk of dying. However, ICD placement reduces mortality in CKD patients at high risk of sudden cardiac death.

Comparison of benefit and mortality of implantable cardioverter-defibrillator therapy in patients aged ≥75 years versus those <75 years

Implantable cardioverter-defibrillator (ICD) therapy decreases arrhythmic and all-cause mortality in patients at high risk of sudden death. However, its clinical benefit in elderly patients is uncertain. The aim of this study was to assess the long-term efficacy of ICD treatment in elderly patients and to identify markers of successful ICD therapy and risk factors of mortality. We performed multivariate analysis of a prospective long-term database from 2 tertiary care centers including 936 consecutive patients with an ICD. Predictors of ICD therapy and risk factors for mortality were assessed in patients ≥75 years old at ICD implantation compared to younger patients. Mean follow-up time was 43 ± 40 months. Rates of ICD therapy were similar in the 2 age groups. No significant predictors of ICD therapy could be identified in older patients. Median estimated survival was 132 months in patients <75 years and 81 months in those ≥75 years old (p = 0.006). Decreased ejection fraction (hazard ratio 1.62 per 10% decrease, p = 0.03) and impaired renal function (hazard ratio 1.57 per 10 ml/kg/m(2) decrease in estimated glomerular filtration rate, p = 0.02) were independent risk factors of mortality in patients ≥75 years old. However, mortality of older patients was similar to that of the age-matched general population irrespective of delivery of ICD therapy. In conclusion, ICD therapy is effective for treatment of life-threatening arrhythmias in all age groups. However, prevention of sudden cardiac death may have limited impact on overall mortality in older patients. Despite a similar rate of appropriate ICD therapies, risk of death is increased 1.6-fold in ICD recipients ≥75 years old compared to younger patients. Patients with decreased ejection fraction and impaired renal function are at highest risk.

Elevated γ-glutamyltransferase in implantable cardioverter defibrillator patients

BACKGROUND

Elevated γ-glutamyltransferase (GGT) is a new risk factor for cardiovascular diseases, but its impact on ventricular tachyarrhythmia occurrence and survival in patients with an implantable cardioverter defibrillator (ICD) is unknown.

METHODS AND RESULTS

Considering that GGT levels are gender-dependent, female ICD recipients were excluded from our database because of the low incidence of events. In a retrospective analysis, appropriate ICD therapy (both shocks and antitachycardia pacing due to ventricular tachyarrhythmias) occurred in 31.9% of 320 male patients who had received an ICD for primary prevention (median follow-up of 2.3 years), and in 55.1% of 423 male patients who had received an ICD for secondary prevention (median follow-up of 3.9 years). Compared to normal low GGT plasma levels (below 28 U/L), total mortality but not risk for appropriate ICD therapy was elevated for higher GGT categories (p for trend = 0.004 in primary prevention and p for trend = 0.002 in secondary prevention, respectively). In Cox regression analysis, elevated GGT (>56 U/L) remained an independent predictor of death both in primary (p = 0.011) and in secondary prevention (p = 0.006). Patients with elevated GGT and renal insufficiency defined by an estimated glomerular filtration rate <60 ml/min/1.73 m(2) suffered from excess total mortality jeopardizing the benefit of ICD therapy.

CONCLUSION

Elevation of GGT is an important adverse prognostic parameter in ICD patients. A possible role of GGT for improved patient selection for ICD therapy deserves further investigation.

Effect of implantable cardioverter-defibrillator on left ventricular ejection fraction in patients with idiopathic dilated cardiomyopathy

Current guidelines have indicated an implantable cardioverter-defibrillator (ICD) for patients with severe idiopathic dilated cardiomyopathy, for both primary and secondary prevention. Compared to coronary artery disease, the overall benefit has been smaller. A more refined risk assessment, using the left ventricular ejection fraction (LVEF) and prevention mode (primary/secondary), is still needed to guide ICD implantation. Patients included in 2 large ICD registers were analyzed regarding the appropriate therapies and improvement of LVEF, overall and in subgroups of prevention mode and LVEF < 20% versus > 20%. Overall, 349 patients were included; 70% were men, the mean age was 54 years, and the mean follow-up was 33 months. Cardiac resynchronization therapy (CRT) was used in 57%, and secondary prevention was present in 30%. ICD therapies were delivered to 33% of the patients, in most for ventricular tachycardia. Patients receiving an ICD for secondary prevention and non-CRT were more likely to have arrhythmic events (both p < 0.05). The cumulative event rates at 5 years were 53% for secondary and 33% for primary prevention (p < 0.001). Depending on the prevention mode and LVEF status (< 20% vs > 20%), the event rates ranged from 30% to 76%. The mean LVEF improved by 10%, independently of the stimulation mode (CRT 22% to 31%, non-CRT 26% to 35%; p < 0.0001). A persistent improvement to > 35% was seen in only 25% of CRT patients but in 45% of non-CRT patients (p = 0.004). In conclusion, the results from the present study have demonstrated that in patients with idiopathic dilated cardiomyopathy, the potential for LVEF improvement is considerable and that the rate of ICD interventions strongly depends on the prevention mode and LVEF. These findings could be the basis for additional risk stratification tools.

The prognosis of implantable defibrillator patients treated with cardiac resynchronization therapy: comorbidity burden as predictor of mortality

Aims

Comorbidity, such as myocardial infarction, diabetes, and renal failure, plays a pivotal role in the prognosis of a patient with arrhythmias. However, data on the prognostic impact of comorbiditiy in heart failure patients with cardiac resynchronization therapy and defibrillation (CRT-D) are scarce. The purpose of this study was to determine the impact of comorbidity on survival in CRT-D patients.

Methods and results

The study population consisted of 463 heart failure patients who received a CRT-D between 1999 and 2008 in Rotterdam and Basel. The Charlson comorbidity index (CCI) is often used as an adjusting variable in prognostic models. The Cox proportional hazards analysis was performed to determine the independent effect of comorbidity on survival. During a median follow-up of 30.5 months, 85 patients died. Mortality rates at 1 and 7 years were 6.3 and 32.3%. Cumulative incidence of implantable cardioverter defibrillator (ICD) therapy at 7 years was 50%, and death without ICD therapy was observed in 9% of patients. At least three comorbid conditions were observed in 81% of patients. Patients who died had a higher CCI score compared with those who survived (3.9 ± 1.5 vs. 2.9 ± 1.5; P < 0.001). An age-adjusted CCI score ≥5 was a predictor of mortality (hazard ratio 3.69, 95% CI 2.06–6.60; P < 0.001) independent from indication for ICD therapy, and from ICD interventions during the clinical course.

Conclusion

Comorbidity is often present in heart failure patients, and a high comorbidity burden was a significant predictor of mortality in CRT-D recipients. Comorbidity cannot predict appropriate ICD therapy. Death without prior ICD therapy occurs in a minor proportion of patients.

Mortality risk score in primary prevention implantable cardioverter defibrillator recipients with non-ischaemic or ischaemic heart disease

AIMS

To assess survival and to construct a baseline mortality risk score in primary prevention implantable cardioverter defibrillator (ICD) patients with non-ischaemic or ischaemic heart disease.

METHODS AND RESULTS

Since 1996, data of all consecutive patients who received an ICD system in the Leiden University Medical Center were collected and assessed at implantation. For the current study, all 1036 patients [age 63 (SD 11) years, 81% male] with a primary indication for defibrillator implantation were evaluated and followed for 873 (SD 677) days. During follow-up, 138 patients (13%) died. Non-ischaemic and ischaemic patients demonstrated similar survival but exhibited different factors that influence risk for mortality. A risk score, consisting of simple baseline variables could stratify patients in low, intermediate, and high risk for mortality. In non-ischaemic patients, annual mortality was 0.4% (95% CI 0.0-2.2%) in low risk and 9.4% (95% CI 6.6-13.1%) in high risk patients. In ischaemic patients, mortality was 1.0% (95% CI 0.2-3.0%) in low risk and 17.8% (95% CI 13.6-22.9%) in high risk patients.

CONCLUSION

Utilization of an easily applicable baseline risk score can create an individual patient-tailored estimation on mortality risk to aid clinicians in daily practice.

Transient local injury current in right ventricular electrogram after implantable cardioverter-defibrillator shock predicts heart failure progression

OBJECTIVES

This study aimed to identify an early marker of functional impairment after an implantable cardioverter-defibrillator (ICD) shock as a predictor of heart failure progression.

BACKGROUND

The ICD population has substantial risk of death due to progressive pump failure.

METHODS

Near-field (NF) bipolar right ventricular (RV) electrograms (EGMs) during induced ventricular fibrillation (VF) and 10 s after rescue ICD shock were analyzed in 310 patients (mean age 59 +/- 14.5 years, 219 men [71%]) with structural heart disease, New York Heart Association functional class I to III, and implanted with a single- or dual-chamber Medtronic (Minneapolis, Minnesota) ICD for primary (245 patients, 79%) or secondary prevention of sudden cardiac arrest. A local injury current (LIC) on NF RV EGM was defined as a deviation of EGM potential > or =1 mV or > or =15% of the preceding R-wave peak-to-peak amplitude.

RESULTS

During mean follow-up of 29.3 +/- 15.0 months, the combined end point of death or hospitalization due to congestive heart failure (CHF) exacerbation was documented in 40 patients (12.9%, or 5.3% per person-year of follow-up). LIC was observed in 106 patients. In multivariate risk analysis, after adjustment for baseline prognostic factors (ejection fraction, history of atrial fibrillation, diabetes mellitus) and appropriate ICD shocks during follow-up, patients with observed LIC after induced VF rescue ICD shock at ICD implantation were more likely to die or to be hospitalized (hazard ratio: 2.69; 95% confidence interval: 1.41 to 5.14; p = 0.003).

CONCLUSIONS

Transient LIC on bipolar NF RV EGM after induced VF rescue ICD shock is associated with increased risk of CHF progression, future hospitalizations due to CHF exacerbation, and subsequent heart failure death.

Implantable cardioverter defibrillator therapy in chronic kidney disease: a meta-analysis

AIMS

Recent observational studies have shown that implantable cardioverter defibrillator (ICD) patients with chronic kidney disease (CKD) have increased mortality and therefore the value of device therapy in this group has been questioned. The purpose of this meta-analysis was to systematically analyse the effect of renal dysfunction on mortality of ICD patients.

METHODS AND RESULTS

Pubmed, Cochrane clinical trials database, and EMBASE were searched until December 2008. In addition, a manual search was performed using review articles, reference lists of papers, and abstracts from conference reports. Of the 90 initially identified studies, 11 observational studies with 3010 patients were analysed. The meta-analysis of these studies showed that CKD was associated with higher mortality risk (HR = 3.44, 95% CI 2.82-4.21, Z = 12.09, P < 0.001) while there were no significant differences between individual trials (P = 0.09, I(2) = 37.8%). A subgroup analysis which included the four studies that used estimated glomerular filtration rate (GFR) <60 mL/min/1.73 m(2) to define CKD showed a higher mortality in the CKD group as well (HR = 3.06, 95% CI 2.31-4.04, Z = 7.84, P < 0.001) without significant heterogeneity (P = 0.38, I(2) = 5.2%).

CONCLUSION

Our meta-analysis suggests that CKD is associated with increased mortality in patients who receive ICD therapy. Undoubtedly, prospective studies are needed in order to elucidate the impact of different stages of CKD in this setting. Given that the CKD prevalence is rapidly increasing, there is an imperative need for better risk stratification of ICD therapy candidates.