title: Lack of effect of nitrates on exercise stress test results in patients with microvascular angina.
abstract: OBJECTIVE
  To assess the effects of short-acting nitrates on exercise stress test (EST) results and the relation between EST results and coronary blood flow (CBF) response to nitrates in patients with microvascular angina (MVA).
  
  
  METHODS
  We completed 2 symptom/sign limited ESTs on 2 separate days, in a random sequence and in pharmacological washout, in 29 MVA patients and in 24 patients with obstructive coronary artery disease (CAD): one EST was performed without any intervention (control EST, C-EST), and the other after sublingual isosorbide dinitrate, 5 mg (nitrate EST, N-EST). CBF response to nitroglycerin (25 μg) was assessed in the left anterior descending coronary artery by transthoracic Doppler-echocardiography.
  
  
  RESULTS
  At C-EST. ST-segment depression ≥1 mm (STD) was induced in 26 (90 %) and 23 (96 %) MVA and CAD patients, respectively (p=0.42), whereas at N-EST, STD was induced in 25 (86 %) and 14 (56 %) MVA and CAD patients, respectively (p=0.01). Time and rate pressure product at 1 mm STD increased during N-EST, compared to C-EST, in CAD patients (475±115 vs. 365±146 s, p<0.001; and 23511±4352 vs. 20583±6234 bpm∙mmHg, respectively, p=0.01), but not in MVA patients (308±160 vs. 284±136 s; p=0.19; and 21290±5438 vs. 20818±4286 bpm∙mmHg, respectively, p=0.35). In MVA patients, a significant correlation was found between heart rate at STD during N-EST and CBF response to nitroglycerin (r=0.40, p=0.04).
  
  
  CONCLUSIONS
  Short-acting nitrates improve EST results in CAD, but not in MVA patients. In MVA patients a lower nitrate-dependent coronary microvascular dilation may contribute to the lack of effects of nitrates on EST results.
authors: Istituto di Cardiologia, Università Cattolica del Sacro Cuore, Largo A. Gemelli, 8, 00168 Rome, Italy.
authors: Giulio
authors: G
authors: Russo
authors: Antonino
authors: A
authors: Di Franco
authors: Priscilla
authors: P
authors: Lamendola
authors: Pierpaolo
authors: P
authors: Tarzia
authors: Roberto
authors: R
authors: Nerla
authors: Alessandra
authors: A
authors: Stazi
authors: Angelo
authors: A
authors: Villano
authors: Alfonso
authors: A
authors: Sestito
authors: Gaetano A
authors: GA
authors: Lanza
authors: Filippo
authors: F
authors: Crea
mesh_terms: D000368:Aged; D001157:Arterial Occlusive Diseases / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D001783:Blood Flow Velocity / Q000187:drug effects; D017023:Coronary Angiography; D003326:Coronary Circulation / Q000187:drug effects; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000187:drug effects / Q000503:physiopathology; D018592:Cross-Over Studies; D015150:Echocardiography, Doppler; D005080:Exercise Test / Q000187:drug effects*; D005260:Female; D006801:Humans; D007548:Isosorbide Dinitrate / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008833:Microcirculation / Q000187:drug effects; D017566:Microvascular Angina / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology; D008875:Middle Aged; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000494:pharmacology*
chemical_list: D014665:Vasodilator Agents; D007548:Isosorbide Dinitrate