Causes of death in Irish Wolfhounds with atrial fibrillation and/or dilated cardiomyopathy

Causes of death in Irish Wolfhounds with atrial fibrillation and/or dilated cardiomyopathy
Atrial fibrillation
The objective of the study was to evaluate the frequency of dilated cardiomyopathy (DCM) and cardiac death (CD) in Irish Wolfhounds (IW) with subclinical atrial fibrillation (AF). Cardiac and all-cause mortality was compared to a contemporaneous control group of apparently healthy IW with sinus rhythm.
Included were 52 IW with AF, but without echocardiographic evidence of DCM or other cardiac disease, and an age- and gender- matched control cohort of 52 apparently healthy IW. Data from 1552 IW were retrospectively evaluated. Fifty-two dogs with subclinical AF were compared to 52 IW controls. Time from initial diagnosis to development of DCM was recorded, and survival data were analyzed using cumulative incidence functions. Twenty-six out of 52 AF dogs developed DCM. At the end of the study, in the AF and control group each, 49/52 AF dogs had died, 3 were still alive. Death in the AF cohort was attributed to CD in 22/49 dogs (12 CHF, 10 sudden cardiac deaths, SCD), while 27 dogs died from non-CD. In the control group significantly fewer dogs developed DCM (11/52 dogs, p=0.004), even fewer died from CD (5/49; 3 CHF, 2 SCD; p=0.001). The odd-ratios (95% CI) for dogs with AF versus controls to develop DCM was 3.7 (1.6, 8.8) and to die from CD was 7.2 (2.4, 21.2). Median all-cause survival for AF IWs (CD, 36.3 months; non-CD, 33.2 months) did not differ significantly from the control group (CD, 28.6 months, p=0.377; non-CD, 45.3 months, p=0.631). In conclusion, IW with subclinical AF commonly develop DCM and die from cardiac death, however life expectancy of IW is significantly shortened by a number of other than cardiac disease predispositions causing death in relatively young dogs.
Dilated cardiomyopathy
Dilated cardiomyopathy (DCM) is an important cause of morbidity in Irish Wolfhounds (IW), a breed also predisposed to neoplastic, medical and orthopaedic diseases that shorten life expectancy. The objective of this study was to investigate survival and causes of death in IW with DCM and to characterize the clinical findings of DCM over time. Data from cardiovascular examinations performed in 1591 IW, including echocardiography and electrocardiography, were retrospectively evaluated. One-hundred-and-fifty-one IW with DCM (95males, 56 females) on medical therapy with long term longitudinal follow-up were included in this study. Based on their clinical status at initial diagnosis, IW were classified into 1 of 3 groups: preclinical DCM with sinus rhythm (PC-DCM-SR, n= 35), preclinical DCM with atrial fibrillation (PC-DCM-AF, n=87), and congestive heart failure with DCM and AF (CHF-DCM-AF, n=29). Survival data were analyzed using cumulative incidence functions, Kaplan-Meier and Cox regression.
CHF was predominantly characterized by chylous pleural and mild pericardial effusions. Causes of death were cardiac (CD) in 73/151 and non-cardiac (non-CD) in 62/151; 16 dogs remained alive at study end. The majority of deaths in both preclinical DCM groups were non-CD (PC-DCM-AF = 46% non-CD, 42.5% CD; PC-DCM-SR, 54.3% non-CD, 28.5% CD). In the CHF-DCM-AF group most dogs (89.6%) experienced a CD. Median survival of the CHF-DCM-AF group (7.3 months) was significantly shorter than in the PC-DCM-AF group (21.9 months) or PC-DCM-SR group (29.1 months, P=0.001). In conclusion CHF-DCM-AF in IW is associated with reduced life expectancy and CD, while most IW with preclinical DCM die from non-cardiac causes due to predispositions of the breed to other severe diseases causing death in relatively young dogs.