Retrospective evaluation of notched and fragmented QRS complex in dogs with naturally occurring myxomatous mitral valve disease

Figures & data

Figure 1. Electrocardiographic tracing of a dog with fQRS: left – figure of the 6-lead electrocardiographic tracing calibrated at 10 mm/mV and 50 mm/sec; right – selected captions during interpretation of fragmented QRS calibrated at 200 mm/sec and 20 mm/mV – note the slurring in the peak of the R-wave characterized as a double-peaked R-wave (red arrows) in all six limb leads (leads I, II and III in the upper-right corner and aVR, aVL and aVF in the lower-right corner).

Table 1. Characteristics of the total study population and groups divided by ACVIM classes.

	Total (n = 189)	N (n = 34)	B1 (n = 65)	B2 (n = 36)	C (n = 54)
Age (years)	11.6 ± 2.8	11 ± 2.8	11.5 ± 2.8	11.6 ± 2.8	12.3 ± 2.6
Gender (M/F)	103/86	22/12	29/36	23/13	29/25
BW (kg)	8.45 ± 4.6	8 ± 4.6	8.7 ± 4.9	7.4 ± 2.6^a	7.4 ± 4.9^b

M – male, F – female; BW – body-weight.

^a Statistical difference between N and B2.

^b Statistical difference between N and C.

Figure 2. Bar-graphic representing the percentage of healthy dogs and dogs diagnosed with MMVD in different ACVIM classes according to the prevalence of notched QRS (nQRS) and fragmented QRS (fQRS); * – statistically significant difference between control group (N) and all groups of dogs diagnosed with MMVD.

Table 2. The number of dogs on the entire population and divided by ACVIM classes with a nQRS in specific leads.

Lead	Total (n/%)	N (n/%)	Class B1 (n/%)	Class B2 (n/%)	Class C (n/%)
Lead I	25/13.2%	0/0%	14/21.5	7/19.4%	4/7.4%
Lead II	18/9.5%	2/5.9%	8/12.3%	2/5.6%	6 /11.1%
Lead III	56/29.6%	2/5.9%	25/38.5%	12/33.3%	17/31.5%
Lead aVL	72/38.1%	5/14.7%	27/41.5%	17/47.2%	23/42.6%
Lead aVR	10/5.3%	2/5.9%	3/4.6%	3/8.3%	2/3.7%
Lead aVF	26/13.8%	2/5.9%	11/16.9%	2/5.6%	11/20.4%