Heart Failure

HF: CoEnzyme Q10 (2007)


Langsjoen H, Langsjoen P, Langsjoen P, Willis R, Folkers K. Usefulness of coenzyme Q10 in clinical cardiology: a long-term study. Molec Aspects Med. 1994; 15 (Suppl): s165-s175.

Study Design:
Non-Randomized Controlled Trial
D - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

To determine if treatment with CoQ10 is effective in treating different diseases of the cardiovascular system in their production of myocardial failure.

Inclusion Criteria:

Patients presented for cardiology consultation and care from 1985 to 1993 at two clinics in Texas.

Exclusion Criteria:

None listed.

Description of Study Protocol:
  • Recruitment:Patients who presented for cardiology consultation and care from 1985 to 1993 at two clinics in Texas
  • Design: Single group before-after.


  • Daily dose of 242mg (range 75mg to 600mg) CoQ10 taken twice daily
  • The starting dose varied according to severity of illness, financial considerations, concomitant medications and author's experience. 

Statistical Analysis

Not described: Only P-values were given in the figures.

Data Collection Summary:

Timing of Measurements

  • Baseline and an average of 17.8 months later
  • 213 patients were measured at 12 months
  • 107 patients were measured at between 13 and 24 months
  • 66 patients were measured at 25 to 36 months
  • 38 patients were measured more than 36 months after baseline.

Dependent Variables

  • Variable One: Functional class, according to the New York Heart Association scale
  • Variable Two
    • The same technician performed echocardiograms using a Toshiba 140A echocardiogram
    • Left ventricular size was measured by M-mode in the parasternal window as left ventricular end diastolic dimension (LVEDD) and left ventricular end systolic dimension (LVESD)
    • Fractional shortening (FS) was recorded as a percentage [(LVEDD- LVESD)/LVEDD]
    • Diastolic function was measured by pulsed wave doppler of the mitral valve inflow, with recording of the EF slope in m/s2
    • Left ventricular wall thickness was measured by M-mode from parasternal window and recorded as the sum of the septum and posterior wall in centimeters.
  • Variable Three: Detailed histories of activity tolerance and medication usage were recorded
  • Variable Four: Vital signs, weight and a directed cardiopulmonary examination.

Independent Variables


Description of Actual Data Sample:

Initial N

  • 424 patients
  • 66 (39% female, 61% male) with idiopathic dilated cardiomyopathy (DCM)
  • 58 (73% female, 27% male) with primary diastolic dysfunction (PDD)
  • 109 (54% female, 46% male) with hypertensive heart disease (HTN)
  • 131 (31% female, 69% male) with ischemic cardiomyopathy (ICM)
  • 12 (65% female, 35% male) with valvular heart disease (VHD)
  • 48 (83% female, 17% male) with mitral valve prolapse (MVP).

Attrition (Final N)

  • 394 for NYHA functional class
  • 210 for echocardiogram comparison.


Average for all of the groups ranged from 56 to 70 years.


Not provided.

Other Relevant Demographics

All patients who presented for cardiology consultation and care in Temple and Tyler, Texas.


Groups were the same when comparing the results of echocardiograms. However, the groups were not in the same diagnostic group when comparing functional status and change in number of drugs.


Temple and Tyler, Texas.

Summary of Results:


Treatment Group
Measures and Confidence Intervals

Control Group
Measures and Confidence Intervals

Statistical Significance of Group Difference

Dependent Variable One Mean, CI Mean, CI Statistically significant difference between groups

NYHA class

  • Class I: 3
  • Class II: 146
  • Class III: 213
  • Class IV: 62.
  • Class I: 212
  • Class II: 173
  • Class III: 33
  • Class IV: 6.

Not given

Dependent Variable Two DCM, PDD, ICM, VHD groups   NS


  • HTN group
  • MVP group.
  • Increase towards normal
  • Increase towards normal.
  • P<0.02
  • P<0.06.
Dependent Variable Three DCM group Improvement P<0.002


All other groups



Other Findings


VHD group   NS

DCM group                                           

Improvement P<0.001


Improvement P<0.03

HTN group                                        

Improvement P<0.001

ICM group                                        

Improvement P<0.001
MVP group                         Improvement                 P<0.01


VHD group   NS
DCM group Improvement p<0.001
PDD Improvement P<0.03
HTN group Improvement P<0.001
ICM group Improvement P<0.001
MVP group Improvement P<0.01

Diastolic Function

VHD group Improvement P<0.002
Remaining groups Improvement P<0.001

Cardiovascular drugs

80 on no drugs 120+ on no drugs Not given
~90 on 1 drug ~130, 1 drug Not given
~13 on 2 drugs ~110, 2 drugs Not given
~80 on 3 drugs ~40, 3 drugs Not given
~30 on 4 drugs ~5, 4 drugs Not given

Specific drugs

Digoxin 19% decrease Not given
Beta-blockers 51% decrease Not given
Other antiarrhythmic drugs 61% decrease Not given
Long-acting nitrates 27% decrease Not given
Calcium channel blockers 24% decrease Not given
ACE inhibitors 32% decrease Not given
Other HTN drugs 37% decrease Not given
Affect of fat on absorption of CoQ10 Increases P<0.001

Only one patient experienced any side effects and that was documented as a single case of transient nausea.

Author Conclusion:

Patients with a wide range of cardiac diseases, a common capacity to produce symptomatic myocardial failure and responding favorably to treatment with oral CoQ10 administered to maintain whole blood levels of 2.0µg per ml or greater.

Funding Source:
DFG, sudzucker/wirtschaftliche vereinigung zucker
Commodity Group:
Reviewer Comments:
  • Nice description of the subgroups of etiologies for CHF
  • No exclusion criteria
  • Statistics description lacking
  • Finding that peanut butter and possibly other fats affects the absorption of CoQ10 may have affected the results.
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? Yes
3. Were study groups comparable? No
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? No
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) No
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? Yes
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? Yes
5. Was blinding used to prevent introduction of bias? No
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? No
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) No
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? Yes
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? N/A
  6.6. Were extra or unplanned treatments described? No
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? N/A
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? Yes
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? ???
  8.1. Were statistical analyses adequately described and the results reported appropriately? No
  8.2. Were correct statistical tests used and assumptions of test not violated? ???
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? Yes
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? No
  8.6. Was clinical significance as well as statistical significance reported? No
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? N/A
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? No
10. Is bias due to study's funding or sponsorship unlikely? ???
  10.1. Were sources of funding and investigators' affiliations described? No
  10.2. Was the study free from apparent conflict of interest? ???