Prelude to CHD: Risk estimation of ‘kalawang’

Column-Dr Ramon Abarquez photoMedicine is Not an Exact Science

Ramon F. Abarquez, Jr., MD, EFACC, FAsCC, FPCP, FPCC, CSPSH

NEXT to endothelial dysfunction, coronary artery calcium (CAC) scoring can detect subclinical and early atherosclerotic disease based on age-related autopsy detected coronary arteries calcium deposits (which may look like intravascular “kalawang” or rust) among soldiers killed during the last two World Wars.

CAC distribution reflects the natural history of the disease, starting at the first two centimeters of the left anterior descending (LAD), followed by right coronary artery (RCA), left main, and left circumflex (LCX). (Schmermund, Am J Cardiol 2000;86:127–132). Such CAC sequential pattern confirms previous pathological anatomic studies and analysis of coronary angiography. (Halon, Am J Cardiol 1983;52:921–926)

DSCT and CAC score

A meta-analysis of 24 studies evaluated the diagnostic accuracy of the first generation dual-source computed tomography (DSCT) to detect calcium coronary artery deposits, in the diagnosis of CAD. In patient-based analysis, pooled sensitivity was 0.980, specificity 0.870, median positive predictive value (PPV) 0.876 and negative predictive value (NPV) 0.964. In vessel-based analysis pooled sensitivity was 0.957, specificity 0.930, median PPV 0.838 and NPV 0.973.

In segment-based analysis pooled sensitivity was 0.915, specificity 0.959, median PPV 0.782 and NPV 0.985. When analyzed based on segment with a cutoff calcium score of 400, the sensitivity was slightly higher in the subgroup with a score over 400 than in the subgroup with a score below 400 (94 versus 91 percent), while the specificity was much lower in the subgroup with the high calcium score than the subgroup with the low calcium score (85 versus 96 percent). Thus, DSCT is highly sensitive for patient-based analysis of CAD and has high specificity and NPV for segment-based analysis of CAD, in the evaluation of patients with chest pain, non-invasive examination to diagnose or exclude significant CAD. (Guo, Int J Cardiovasc Imaging. 2011 Jul;27(6):755- 71) Zero CAC excludes CAD.

CCTA and CAC

Among 1145 included patients, (35 percent) CCTA were normal, (40percent) had <50 percent stenosis, (25 percent) had = 50 percent stenosis, and (16 percent) had = 70 percent stenosis. Among 42 percent patients with CAC zero, 82 percent had normal CCTA, 17 percent had <50 percent stenosis, and 1.5 percent had = 50 percent stenosis. For diagnosis of = 50 percent stenosis, CAC had a sensitivity of 98 percent and specificity of 55 percent. The negative predictive value (NPV) for CAC was 99 percent for = 50 percent stenosis and 99.6 percent for = 70 percent stenosis by CCTA. Thus, among symptomatic patients with CAC zero, after two years, 1-2 percent potentially obstructive CAD occurs but without adverse prognosis. (Hulten, Atherosclerosis. 2014 Mar;233(1):190-5)

VMS with CAC and CVD

Exact etiology of hot flushes and night sweats vasomotor symptoms (VMS) as CAD markers has been evaluated in several studies. Women’s Health Initiative (WHI) observational study (60 000 women, mean age 63 years, mean follow-up period 10 years) showed that, at onset of menopause, a significant decreased risk of stroke, total cardiovascular disease events, and all cause mortality, compared with women having no VMS. Contrarily, women with late VMS (reported at enrollment to the study but not at onset of menopause) had an increased risk in the above-mentioned parameters. There was no interaction between hormone use and VMS Thus, relevant data, shows that hot flushes seem to be a marker for physiological alterations that could be associated with cardiovascular disease late after menopause. (Pines, Climacteric. 2011 Oct;14(5):535-6) VMS reflects FMD activity.

VMS and CAC

Vasomotor symptoms may be associated with coronary artery calcium (CAC) and hormone therapy (HT). This association was determined among 918 women with a mean (SD) age of 55.1 (2.8) years. CAC score higher than 0 in 46 percent, and CAC score of 10 or higher and higher than 100 was 39 percent and 19 percent, respectively. At randomization, 77 percent reported VMS at any time versus 20 percent reported any VMS present only at enrollment. History of any VMS at any time was associated with significantly reduced odds for CAC higher than 0 (odds ratio, 0.66; 95 percent CI, 0.45-0.98). Moreover, as duration of HT increased, the inverse association between any VMS and CAC moved toward the null. (Allison, Menopause. 2010 Nov-Dec;17(6):1136-45) VMS hot flushes and sweating may reflect on endothelial function.

CAC and BP in post-menopause

To determine the magnitude and significance of the associations among coronary artery calcium and SBP, DBP, PP and MAP among women (50 to 59 years) in the Women’s Health Initiative clinical trial of conjugated equine estrogen, enrolled subjects underwent computed tomography scanning of the chest at the end of the trial. The prevalence of a CAC score >0, >or=10, and >100 was 47 percent, 39 percent, and 19 percent, respectively. There was a linear association between the log-odds of any CAC and SBP. For any DBP, the probability of CAC increased with higher levels of SBP, whereas for any given value of SBP, the probability of any CAC decreased with higher levels of DBP.

Also, a pulse pressure >or=55 mm Hg was associated with a higher odds (1.95; 95 percent CI, 1.24 to 3.06) for having any CAC, whereas individuals with isolated systolic hypertension had a 73 percent higher odds for CAC >0 (95 percent CI, 1.03 to 2.90; P=0.04). In postmenopausal women, higher levels of PP and SBP were strong determinants of CAC, whereas DBP was inversely related. (Allison, Hypertension. 2008 Nov;52(5):833-40) Wide PP and high DBP can have lower or higher coronary perfusion effects respectively.

LSM and CAC

Systematic review of CAC, a subclinical marker of CAD, on behavioral or lifestyle modification, risk perception, and medication adherence yield 15 studies. CAC screening improved medication adherence and could likely motivated individuals for beneficial behavioral or lifestyle changes to improve CAD. (Mamudu, Atherosclerosis. 2014 Aug 1;236(2):338-350)

CAC may reflect on endothelial vasomotor function, lifestyle behavior, coronary perfusion, and CAD negative predictive value wherein a null CAC negates CAD “kalawang”.

Vital Signs Issue 70 Vol. 3, December 1-31 2014

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