Abstract 1861: Low Dose Transdermal Nitroglycerin Therapy Improves Quality of Life and Exercise Capacity in Patients with Systolic Dysfunction
Introduction: While nitroglycerin (NTG) is often used in the treatment of CHF it is not formally approved for that purpose. Whether addition of low dose NTG is of value in patients already on guideline-based therapy (ACE inhibitors, beta-blockers, diuretics) is not known, nor is it known whether response to NTG added to these medicines varies with severity of left ventricular dysfunction.
Methods: Exercise capacity by six-minute walk test (6MWT), quality of life by the Minnesota Living with Heart Failure Questionnaire (HFQ), and ejection duration (ED) by Sphygmocor© were measured at baseline and after a 4 week course of transdermal NTG, given at 0.2 mg/hr for 12 hours daily. We studied 45 NYHA Class II and III patients (84% male, 53.4 ± 9.1 yrs, 42% with CAD, CHF duration 3 ± 2.6 yrs, LVEF ≤40%) on stable, standard, guideline-based CHF therapy. ED was defined in msec from the foot to the incisura of the applanation tonometry derived radial artery pressure waveform.
Results: Subjects were divided by tertiles: Group I - LVEF <20% (n=13), Group II - LVEF 20 – 29% (n=19), and Group III -LVEF 30 – 40% (n=13). Results are mean ± SE. After 4 wks the 6MWT distance improved by 242 ± 57 ft in Group I (p=0.001), 103 ± 25 ft in Group II (p=0.0006), and 183 ± 34 ft in Group III (p=0.0002). Repeated measures ANOVA showed that improvement in distance with time was different across groups (p=0.037), with the largest improvement occurring in the low EF group. Group I also had significant improvement in ED at 4 weeks (286 ± 7 to 301 ± 7 ms, p=0.030), while there was no change in ED in Group II (285 ± 6 to 281 ± 6 p=0.48) or Group III (314 ± 9 to 307 ± 6 p=0.27). HFQ scores improved by 16 ± 6 points in Group I (p = 0.016), 13 ± 4 points in Group II (p = 0.003) and 10 ± 4 points in Group III (p = 0.029).
Conclusions: Low dose transdermal NTG improved exercise capacity and quality of life in patients with chronic CHF already on guideline-based cardiac medications. These findings support the role of organic nitrates as an adjunctive therapy to standard cardiac medications, more so in those with a severely depressed LV function. Noninvasive assessment of ED provides useful information about potential response to nitrates and may allow better identification of patients most likely to benefit from NTG treatment.