Table 2—

Studies of CAN and silent myocardial ischemia

Tests of autonomic functionDefinition of CAN% SMI+/CAN+% SMI+/CANNotes
Reference
 Niakan et al. (63)1. Valsalva maneuverAbnormal Valsalva ratio20% (5/25)4% (2/48)*All subjects had symptomatic peripheral neuropathy. Outcome was silent myocardial infarction
 Hume et al. (64)
  1. HRV during deep breathing

  2. Valsalva maneuver

  3. 30:15 ratio

At least two of three were abnormal36% (5/14)20% (9/46)Asymptomatic middle-aged men, no symptoms or signs of heart disease
 Murray et al. (65)
  1. HRV during deep breathing

  2. Valsalva maneuver

  3. 30:15 ratio

  4. BP response to standing

  5. BP response to handgrip

At least two of the first three tests = mild CAN72% (13/18)42% (5/12)Patients with known or suspect CAD
 Langer et al. (66)
  1. HRV during deep breathing

  2. Valsalva maneuver

  3. 30:15 ratio

  4. sBP response to standing

  5. dBP response to handgrip

At least two of the tests were abnormal38% (8/21)5% (2/37)Men only, no clinical evidence of CAD
 O’Sullivan et al. (67)
  1. HRV during deep breathing

  2. Valsalva maneuver

  3. 30:15 ratio

  4. sBP response to standing

  5. dBP response to handgrip

At least two abnormal parasympathetic function tests65% (11/17)4% (1/24)‡Men >40 years old. One-half of patients with known or suspected CAD
 Koistinen et al. (68)
  1. HRV during deep breathing

  2. 30:15 ratio

  3. BP response to standing

Both HRV during deep breathing and 30:15 ratio were abnormal38% (3/8)38% (11/29)Patients with known CAD
 Hartmann et al. (69)
  1. HRV at rest over 5 min

  2. HRV during deep breathing

Authors did not indicate whether only one or both tests were abnormal82% (9/11)40% (4/10)CAD confirmed by coronary angiography
 Jermendy et al. (70)
  1. HRV during deep breathing

  2. Valsalva maneuver

  3. 30:15 ratio

  4. BP response to standing

Results of parasympathetic tests (1,2,3) were scored 0 = normal, 1 = borderline, 2 = abnormal. Those with a score of 0–1 = without CAN, score of 2–3 = early CAN, and score of 4–6 = definitive CAN.30% (11/37)0% (0/26)Diabetic subjects with lack of symptoms of angina pectoris and ≥1 additional CVD risk factor
 Zarich et al. (71)
  1. HRV during deep breathing

  2. Valsalva maneuver

  3. sBP response to standing

  4. dBP response to handgrip

Two or more abnormal test results were classified as moderate to severe100% (10/10)67% (10/15)Subjects with known CAD
 MiSAD Group (72)
  1. HRV during deep breathing

  2. HRV from lying to standing

  3. Orthostatic hypotension

Autonomic neuropathy score ≥37% (13/175)6% (46/750)Asymptomatic men and women aged 40–65 years with no prior history of CAD
 Jalal et al. (73)
  1. HRV during deep breathing

  2. Valsalva maneuver

  3. 30:15 ratio

  4. BP response to standing

  5. BP response to handgrip

Normal = all tests normal or one borderline; Early = one of the three heart rate tests abnormal or two borderline; Definite = ≥two heart rate tests abnormal; severe = ≥two heart rate tests abnormal plus one or both BP tests abnormal40% (12/30)10% (3/30)Subjects with history of CAD were excluded. CAN subjects age- and sex-matched to CAN+ subjects
 Valensi et al. (74)
  1. HRV during deep breathing

  2. Valsalva maneuver

  3. 30:15 ratio

Not indicated30% (10/33)36% (15/42)Subjects asymptomatic for CAD, but had diabetes and ≥2 additional CVD risk factors
Total§110/399108/1,069
  • BP, blood pressure; CAD, coronary artery disease; dBP, diastolic blood pressure; sBP, systolic blood pressure; SMI, silent myocardial ischemia.

  • *

    * P < 0.05;

  • P < 0.001;

  • §

    § Mantel-Haenszel estimate for the pooled rate ratio for silent myocardial ischemia = 1.96 (95% CI: 1.53–2.51, P < 0.001).