Under-recognition of Low Blood Pressure Readings in Patients with Duchenne Muscular Dystrophy.

Duchenne muscular dystrophy (DMD), a recessive sex-linked hereditary disorder, is characterized by degeneration, atrophy, and weakness of skeletal and cardiac muscle. The purpose of this study was to document the prevalence of abnormally low resting BP recordings in patients with DMD in our outpatient clinic. The charts of 31 patients with DMD attending the cardiology clinic at Rush University Medical Center were retrospectively reviewed. Demographic data, systolic, diastolic, and mean blood pressures along with current medications, echocardiograms, and documented clinical appreciation and management of low blood pressure were recorded in the form of 104 outpatient clinical visits. Blood pressure (BP) was classified as low if the systolic and/or mean BP was less than the fifth percentile for height for patients aged ≤17 years (n = 23). For patients ≥18 years (n = 8), systolic blood pressure (SBP) <90 mmHg or a mean arterial pressure (MAP) <60 mmHg was recorded as a low reading. Patients with other forms of myopathy or unclear diagnosis were excluded. Statistical analysis was done using PASW version 18. BP was documented at 103 (99.01 %) outpatient encounters. Low systolic and mean BP were recorded in 35 (33.7 %) encounters. This represented low recordings for 19 (61.3 %) out of a total 31 patients with two or more successive low recordings for 12 (38.7 %) patients. Thirty-one low BP encounters were in patients <18 years old. Hispanic patients accounted for 74 (71.2 %) visits and had low BP recorded in 32 (43.2 %) instances. The patients were non-ambulant in 71 (68.3 %) encounters. Out of 35 encounters with low BP, 17 patients (48.6 %) were taking heart failure medication. In instances when patients had low BP, 22 (66.7 %) out of 33 echocardiography encounters had normal left ventricular ejection fraction. Clinician comments on low BP reading were present in 11 (10.6 %) encounters, and treatment modification occurred in only 1 (1 %) patient. Age in years (p = .031) and ethnicity (p = .035) were independent predictors of low BP using stepwise multiple regression analysis. Low BP was recorded in a significant number of patient encounters in patients with DMD. Age 17 years or less and Hispanic ethnicity were significant predictors associated with low BP readings in our DMD cohort. Concomitant heart failure therapy was not a statistically significant association. There is a need for enhanced awareness of low BP in DMD patients among primary care and specialty physicians. The etiology and clinical impact of these findings are unclear but may impact escalation of heart failure therapy.