Allopurinol and the risk of ventricular arrhythmias in the elderly: a study using US Medicare data

Serum uric acid and the risk of ventricular arrhythmias: a systematic review

Uric acid (UA) is the end product of purine degradation in humans. It promotes inflammation via activation of pro-inflammatory cytokines and increases oxidative stress. The serum uric acid level has emerged as an independent risk factor of cardiovascular disease such as ventricular arrhythmias (VA). Here we had done a systematic review to assess the association between serum UA levels and the occurrence of VA. This systematic review included a total of four clinical studies with 99.383 patients for analysis. The scientific quality of all four studies was good. Three studies showed that serum uric acid levels were associated with VA in many populations. In contrast, one study with a large sample size evaluated that serum uric acid increases premature ventricle contraction prevalence. A significant association between serum uric acid level and VA was found in four studies (p<0.01; p<0.101; p=0.002; p=0.008). In conclusion, this systematic review shows an association between serum UA levels and VA.

Hyperuricemia is associated with an increased prevalence of ventricular tachycardia and fibrillation in patients with ST-elevation myocardial infarction after primary percutaneous coronary intervention

Background

Little is known about the association between hyperuricemia and ventricular tachycardia and fibrillation (VT/VF) in patients with ST-segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI).

Methods

The data from a cohort of STEMI patients undergoing PPCI at our center from January 2013 to December 2018 were retrospectively analyzed. The endpoint of the study was the occurrence of VT/VF, including (1) non-sustained ventricular tachycardia (nsVT) on Holter monitoring; (2) sustained ventricular tachycardia (SVT)/VF on cardiac monitoring.

Results

Of the 634 patients included in the study, 147 (23.2%) of them had hyperuricemia. The occurrence of VT/VF after PPCI was significantly higher in patients with hyperuricemia (19.0 vs. 9.4%, p = 0.001) compared with those without hyperuricemia. Hyperuricemia was associated with a significantly higher risk of VF/VT (odds ratio (OR) 2.11; 95% CI 1.11–4.03; p = 0.024). The strength of this association remained statistically after adjustments for age, sex, history of hypertension, estimated glomerular filtration rate, hypersensitive C reactive protein, plasma natrium, peak troponin I, fasting glucose, B-type natriuretic peptides and VT/VF in PPCI (adjusted odds ratio 2.73; 95% CI 1.19–6.27; p = 0.018).

Conclusions

There is a significant association between hyperuricemia and increased prevalence of VT/VF in STEMI patients after PPCI, independently of multiple risk factors and potential confounders.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02635-4.

Comparative cardiovascular risk in users versus non-users of xanthine oxidase inhibitors and febuxostat versus allopurinol users

OBJECTIVES

The aim of this study is to determine major adverse cardiovascular events (MACE) and all-cause mortality comparing between xanthine oxidase inhibitors (XOIs) and non-XOI users, and between allopurinol and febuxostat.

METHODS

This is a retrospective cohort study of gout patients prescribed anti-hyperuricemic medications between 2013 and 2017 using a territory-wide administrative database. XOI users were matched 1:1 to XOI non-users using propensity scores. Febuxostat users were matched 1:3 to allopurinol users. Subgroup analyses were conducted based on colchicine use.

RESULTS

Of the 13 997 eligible participants, 3607 (25.8%) were XOI users and 10 390 (74.2%) were XOI non-users. After propensity score matching, compared with non-users (n = 3607), XOI users (n = 3607) showed similar incidence of MACE (hazard ratio [HR]: 0.997, 95% CI, 0.879, 1.131; P>0.05) and all-cause mortality (HR = 0.972, 95% CI 0.886, 1.065, P=0.539). Febuxostat (n = 276) users showed a similar risk of MACE compared with allopurinol users (n = 828; HR: 0.672, 95% CI, 0.416, 1.085; P=0.104) with a tendency towards a lower risk of heart failure-related hospitalizations (HR = 0.529, 95% CI 0.272, 1.029; P=0.061). Concurrent colchicine use reduced the risk for all-cause mortality amongst XOI users (HR = 0.671, 95% 0.586, 0.768; P<0.001).

CONCLUSION

In gout patients, XOI users showed similar risk of MACE and all-cause mortality compared with non-users. Compared with allopurinol users, febuxostat users showed similar MACE and all-cause mortality risks but lower heart failure-related hospitalizations.

Cardiovascular safety risks associated with gout treatments

INTRODUCTION

Uric acid is the final byproduct of purine metabolism. The loss of the enzyme that hydrolyzes uric acid to allantoin was lost, leading to a decrease in uric acid excretion and its further accumulation. The buildup of uric acid leads to damage in different organ systems, including the cardiovascular system. With the increasing burden of cardiovascular disease worldwide, a growing body of evidence has addressed the relationship between urate, cardiovascular outcomes, and gout medication cardiovascular safety. Areas covered: We discuss the most common gout therapies used for the reduction of serum urate and management of gout flares in different observational and clinical trials and their effects on different aspects of cardiovascular disease. We selected the most representative clinical studies that evaluated cardiovascular outcomes with each gout therapy as well as recommendation given by the most representative guidelines from Rheumatology societies for the management of gout.

EXPERT OPINION

The treatment of gout reduces joint damage and it can also lessen CV morbidity. Allopurinol shows CV safety profile when compared to other ULTs. Evidence supporting CV safety with the use of colchicine and IL-1 agents is promising and research needs to be conducted to further assess this outcome.

Assessment of Cardiovascular Risk in Older Patients With Gout Initiating Febuxostat Versus Allopurinol: Population-Based Cohort Study

BACKGROUND

Hyperuricemia and gout are associated with an increased risk of cardiovascular disease. Xanthine oxidase inhibitors, allopurinol and febuxostat, are the mainstay of urate-lowering treatment for gout and may have different effects on cardiovascular risk in patients with gout.

METHODS

Using US Medicare claims data (2008-2013), we conducted a cohort study for comparative cardiovascular safety of initiating febuxostat versus allopurinol among patients with gout ≥65 years of age. The primary outcome was a composite end point of hospitalization for myocardial infarction or stroke. Secondary outcomes were individual end points of hospitalization for myocardial infarction, stroke, coronary revascularization, new and recurrent heart failure, and all-cause mortality. We used propensity score matching with a ratio of 1:3 to control for confounding. We estimated incidence rates and hazard ratios for primary and secondary outcomes in the propensity score-matched cohorts of febuxostat and allopurinol initiators.

RESULTS

We included 24 936 febuxostat initiators propensity score-matched to 74 808 allopurinol initiators. The median age was 76 years, 52% were male, and 12% had cardiovascular disease at baseline. The incidence rate per 100 person-years for the primary outcome was 3.43 in febuxostat and 3.36 in allopurinol initiators. The hazard ratio for the primary outcome was 1.01 (95% CI, 0.94-1.08) in the febuxostat group compared with the allopurinol group. Risk of secondary outcomes including all-cause mortality was similar in both groups, except for a modestly decreased risk of heart failure exacerbation (hazard ratio, 0.94; 95% CI, 0.91-0.99) in febuxostat initiators. The hazard ratio for all-cause mortality associated with long-term use of febuxostat (>3 years) was 1.25 (95% CI, 0.56-2.80) versus allopurinol. Subgroup and sensitivity analyses consistently showed similar cardiovascular risk in both groups.

CONCLUSIONS

Among a cohort of 99 744 older Medicare patients with gout, overall there was no difference in the risk of myocardial infarction, stroke, new-onset heart failure, coronary revascularization, or all-cause mortality between patients initiating febuxostat compared with allopurinol. However, there seemed to be a trend toward an increased, albeit not statistically significant, risk for all-cause mortality in patients who used febuxostat for >3 years versus allopurinol for >3 years. The risk of heart failure exacerbation was slightly lower in febuxostat initiators.

New Perspectives in Rheumatology: Implications of the Cardiovascular Safety of Febuxostat and Allopurinol in Patients With Gout and Cardiovascular Morbidities Trial and the Associated Food and Drug Administration Public Safety Alert

Recently, the US Food and Drug Administration (FDA) issued a public safety alert, responding to the results of the now-published Cardiovascular Safety of Febuxostat and Allopurinol in Patients With Gout and Cardiovascular Morbidities (CARES) trial. The CARES trial showed no significant difference between allopurinol and febuxostat in the primary composite end point of cardiovascular (CV) events in subjects with gout and established CV comorbidities at baseline. However, there was a significantly increased risk of CV and all-cause mortality with febuxostat. Urate-lowering therapy (ULT) is central to the long-term management of gout, and xanthine oxidoreductase inhibitor (XOI) therapy is the consensus first-line approach. Allopurinol is generally the first XOI used, but febuxostat is an effective XOI option, and is commonly used when allopurinol is not tolerated. These data are further relevant since CV comorbidities are common in gout. Here, we examine why the CARES trial was done, and discuss other, ongoing comparative studies of febuxostat and allopurinol whose results are awaited. We assess the strengths and limitations of the CARES trial, and appraise the robustness and biologic plausibility of the results. The CARES trial does not prove that febuxostat raises CV mortality risk, but suggests greater risk with febuxostat than allopurinol. The CARES trial results do not support first-line use of febuxostat ULT, and raise questions about febuxostat placement at various pharmacologic ULT decision tree branches. Alternatives to febuxostat that are frequently effective include allopurinol dose escalation and uricosuric therapy alone or combined with allopurinol. The FDA safety alert highlights the need for shared ULT medical decision-making with gout patients, including discussion of the CV safety of febuxostat.

Gout and arrhythmias: In search for causation beyond association

Gout is a systemic disease, characterized by the formation and deposition of crystals in tissues (mainly in and around the joints) of individuals with elevated serum uric acid levels. Lately, a considerable number of reports relating elevated uric acid and/or gout with rhythm disorders, such as atrial fibrillation, have been published. This review summarizes evidence linking common arrhythmias and hyperuricemia/gout and discusses questions or controversies that surround it. Overall, existing evidence may not be overwhelming, but strongly suggests a positive correlation between uric acid levels and common rhythm disorders. Needless to say that such a link - as a univariate association between the two - is to be expected, given the extensive overlap of risk factors and comorbidities of hyperuricemia/gout and arrhythmias. However, the observed associations seem to persist - in most studies - after extensive adjustment for potential confounders. Still, multivariable analyses of epidemiologically collected data cannot substitute for proof coming from basic and clinical studies. There is obviously a need for further basic research to establish a causal relationship between uric acid effects and arrhythmias, as well as translational studies and clinical trials to investigate the therapeutic implications of such a relationship. Simply put, we are fairly certain that there is association, but proof of causation is what we are still in want of.

Promising effects of xanthine oxidase inhibition by allopurinol on autonomic heart regulation estimated by heart rate variability (HRV) analysis in rats exposed to hypoxia and hyperoxia

Background

It has long been suggested that reactive oxygen species (ROS) play a role in oxygen sensing via peripheral chemoreceptors, which would imply their involvement in chemoreflex activation and autonomic regulation of heart rate. We hypothesize that antioxidant affect neurogenic cardiovascular regulation through activation of chemoreflex which results in increased control of sympathetic mechanism regulating heart rhythm. Activity of xanthine oxidase (XO), which is among the major endogenous sources of ROS in the rat has been shown to increase during hypoxia promote oxidative stress. However, the mechanism of how XO inhibition affects neurogenic regulation of heart rhythm is still unclear.

Aim

The study aimed to evaluate effects of allopurinol-driven inhibition of XO on autonomic heart regulation in rats exposed to hypoxia followed by hyperoxia, using heart rate variability (HRV) analysis.

Material and methods

16 conscious male Wistar rats (350 g): control-untreated (N = 8) and pretreated with Allopurinol-XO inhibitor (5 mg/kg, followed by 50 mg/kg), administered intraperitoneally (N = 8), were exposed to controlled hypobaric hypoxia (1h) in order to activate chemoreflex. The treatment was followed by 1h hyperoxia (chemoreflex suppression). Time-series of 1024 RR-intervals were extracted from 4kHz ECG recording for heart rate variability (HRV) analysis in order to calculate the following time-domain parameters: mean RR interval (RRi), SDNN (standard deviation of all normal NN intervals), rMSSD (square root of the mean of the squares of differences between adjacent NN intervals), frequency-domain parameters (FFT method): TSP (total spectral power) as well as low and high frequency band powers (LF and HF). At the end of experiment we used rat plasma to evaluate enzymatic activity of XO and markers of oxidative stress: protein carbonyl group and 8-isoprostane concentrations. Enzymatic activity of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) were measures in erythrocyte lysates.

Results

Allopurinol reduced oxidative stress which was the result of hypoxia/hyperoxia, as shown by decreased 8-isoprostane plasma concentration. XO inhibition did not markedly influence HRV parameters in standard normoxia. However, during hypoxia, as well as hyperoxia, allopurinol administration resulted in a significant increase of autonomic control upon the heart as shown by increased SDNN and TSP, with an increased vagal contribution (increased rMSSD and HF), whereas sympathovagal indexes (LF/HF, SDNN/rMSSD) remained unchanged.

Conclusions

Observed regulatory effects of XO inhibition did not confirm preliminary hypothesis which suggested that an antioxidant such as allopurinol might activate chemoreflex resulting in augmented sympathetic discharge to the heart. The HRV regulatory profile of XO inhibition observed during hypoxia as well as post-hypoxic hyperoxia corresponds to reported reduced risk of sudden cardiovascular events. Therefore our data provide a new argument for therapeutical use of allopurinol in hypoxic conditions.