Serum cardiac troponin I in canine syncope and seizures

Preliminary investigation of serum cardiac troponin I in dogs with acute ischaemic stroke

OBJECTIVES

To describe the incidence of elevated serum cardiac troponin I in dogs with acute ischaemic strokes, to evaluate its prognostic value in these patients and characterise a possible relationship between cardiac troponin I elevation in dogs with ischaemic strokes and underlying cardiac dysfunction.

MATERIALS AND METHODS

Prospective study of 18 dogs with acute ischaemic stroke diagnosed by MRI of the brain. Serum cardiac troponin I concentration, trans-thoracic echocardiography and six-lead electrocardiography were performed and findings were compared between dogs with good and poor outcome.

RESULTS

Serum cardiac troponin I was increased in 17 dogs (median 0.95 ng/mL; range 0.146 to 153). Focal hyperechoic regions of myocardium were visible in two dogs using trans-thoracic echocardiography and presumed to represent acute infarcts. A significant association was found between cardiac troponin I and creatinine concentrations. No difference in cardiac troponin I concentrations was detected between dogs that experienced good and poor outcomes. Clinically important cardiac dysfunction was identified in two dogs.

CLINICAL SIGNIFICANCE

Cardiac troponin I is commonly elevated in patients diagnosed with acute ischaemic stroke but, in this small study population, did not have prognostic value. Larger studies (recruiting a study population of 98 dogs for a power of 0.8 and a 0.05 alpha/critical value) would aid in further investigation of these preliminary results.

Analytical quality assessment and method comparison of two immunoassays for the measurement of serum cardiac Troponin I in dogs and cats

BACKGROUND

Cardiac troponin I (cTnI) is a sensitive and specific biomarker for myocardial injury. Validation of point-of-care (POC) analyzers for cTnI measurement is valuable to the critical care setting, in which rapid results can facilitate prompt diagnoses. An immunoassay for detecting cTnI is available for the POC AIA-360 analyzer (Tosoh Bioscience), but this has not been validated using canine and feline serum.

OBJECTIVES

The objectives were (a) to determine precision, accuracy, and linearity of cTnI measurement using the AIA-360 immunoassay in pooled canine and feline samples, and (b) to compare results for individual canine and feline samples with those obtained using a reference chemiluminescence method (Immulite 1000, Siemens).

METHODS

Intra- and inter-assay repeatability was determined using pooled canine and feline samples, and the coefficient of variation (CV) was calculated for each. Pooled samples were also serially diluted to assess linearity. A modified spike and recovery analysis was performed by mixing pooled samples with different concentrations. Bland-Altman and Deming regression analyses were used to determine bias for individual samples, and the total observed error (TE_obs ) was calculated.

RESULTS

Coefficient of variation values were well within the required maximum of 20%. Linearity was demonstrated over the range of samples tested, and the recovery study showed minimal proportional inaccuracies. Although the correlation between the analyzers was excellent, there was a large mean bias due to relative proportional bias. Total observed error consequently exceeded the total allowable error (TE_A ).

CONCLUSION

Although, in most respects, the analyzer demonstrated adequate performance, pronounced bias contributed to the large TE_obs , indicating a requirement for analyzer-specific reference intervals.

Indications for permanent pacing in dogs and cats

Pacemaker implantation is considered as a standard procedure for treatment of symptomatic bradycardia in both dogs and cats. Advanced second-degree and third-degree atrioventricular blocks, sick sinus syndrome, persistent atrial standstill, and vasovagal syncope are the most common rhythm disturbances that require pacing to either alleviate clinical signs or prolong survival. Most pacemakers are implanted transvenously, using endocardial leads, but rarely epicardial leads may be necessary. To decide whether a patient is a candidate for pacing, as well as which pacing modality should be used, the clinician must have a clear understanding of the etiology, the pathophysiology, and the natural history of the most common bradyarrhythmias, as well as what result can be achieved by pacing patients with different rhythm disturbances. The goal of this review was, therefore, to describe the indications for pacing by evaluating the available evidence in both human and veterinary medicine. We described the etiology of bradyarrhythmias, clinical signs and electrocardiographic abnormalities, and the choice of pacing modality, taking into account how different choices may have different physiological consequences to selected patients. It is expected that this review will assist veterinarians in recognizing arrhythmias that may require permanent pacing and the risk-benefit of each pacing modality and its impact on outcome.