Can a "Loud" Right-Apical Systolic Murmur Predict the Diagnosis of Canine Pulmonary Hypertension?
The index of clinical suspicion of pulmonary hypertension (PHT) is typically low. We tested whether selected findings predict the diagnosis of PHT, as confirmed by a Doppler-derived systolic pressure gradient >35 mmHg between the right ventricle and atrium.
Data from 312 consecutive dogs were retrospectively analyzed to calculate the correspondence ratio between pairs of non-quantitative (historical and/or physical) versus quantitative (Doppler) variables. Sensitivity, specificity and predictive value indices were computed. The McNemar test was used to seek a trend among cases of disagreement.
The following (in a descending order) variables were more prevalent in PHT (n=96) than in non-PHT (n=216) patients: left apical murmur, cough, right apical murmur, syncope, ascites, dyspnea, a stronger right than left apical murmur, hepatomegaly, and orthopnea. Both left and right apical murmurs were louder in PHT than in non-PHT patients.
A "loud" right apical murmur, whether isolated or combined with non-quantitative variables as ascites or syncope, had a low sensitivity of <44% and a high specificity of >94% as a predictor of PHT. While an isolated stronger right than left apical murmur had a positive predictive value (PPV) of 82% and was 98% specific for PHT, when combined with syncope it had a PPV of 91%, and was 96% specific for PHT. The combination of ascites with a Grade >IV/VI right apical murmur had a PPV of 100% and a specificity of 100% for PHT.
A louder-than-expected right apical systolic murmur combined with ascites and/or syncope should highly increase the index of suspicion for PHT.