Can You Use a Heart Calcium CT to Assess Therapy of an Elevated LDL-Cholesterol? Yes!

A group called SHAPE proposed in 2007 that some patients are so low risk that they do not need Rx cholesterol lowering medications like statins even if the LDL-cholesterol (LDL-C) was quite high. They suggested that a heart coronary artery calcium score (CACS) of zero bu CT was an indicator of a group that could avoid Rx medications even if the LDL-cholesterol was high.

Now, it is known more than ever more that LDL-C is an important causal risk factor for atherosclerotic cardiovascular disease (ASCVD). However, a sizable proportion of middle-aged individuals with elevated LDL-C level have not developed coronary atherosclerosis as assessed by coronary artery calcification (CAC). The hypothesis of 2007 has been tested and has held accurate but mroe data is needed to confirm this.  Now researchers in Denmark have evaluated the association of LDL-C with future ASCVD events in patients with and without CAC in a large prospective study.

METHODS:

The study included 23,132 consecutive symptomatic patients evaluated for coronary artery disease using CACS from the Western Denmark Heart Registry, a seminational, multicenter-based registry with longitudinal registration of patient and procedure data.

Researchers assessed the association of LDL-C level obtained before CT with ASCVD (myocardial infarction and ischemic stroke) events occurring during follow-up stratified by CACS>0 versus CACS=0 adjusted for baseline characteristics.

The results in the National Heart, Lung, and Blood Institute–funded Multi-Ethnic Study of Atherosclerosis (MESA).

RESULTS:

During a median follow-up of 4.3 years, 552 patients experienced a first ASCVD event.

In the overall population, LDL-C (per 38.7 mg/dL increase) was associated with ASCVD events occurring during follow-up.

When stratified by the presence or absence of baseline CAC, LDL-C was only associated with ASCVD in the 10 792/23,132 patients (47%) with CAC>0 .

No association was observed among the 12 340/23 132 patients (53%) with CAC=0.

Similarly, a very high LDL-C level (>193 mg/dL) versus LDL-C <116 mg/dL was associated with ASCVD in patients with CAC>0 but not in those without.

In patients with CAC=0, diabetes, current smoking, and low high-density lipoprotein cholesterol levels were associated with future ASCVD events. T

he principal findings were replicated in the MESA database that had follow up over 16 years.

CONCLUSIONS:

LDL-C appears to be almost exclusively associated with ASCVD events over ≈5 years of follow-up in middle-aged individuals with a CACS>0 versus without evidence of coronary atherosclerosis. The same results were found over 16 years in the MESA study group.

This information is valuable for individualized risk assessment among middle-aged people with or without coronary atherosclerosis. A CACS is essential in deciding on Rx to lower LDL-C. A CACS of 0 should be repeated perhaps every 5 years to reassess the need for Rx therapy. This is true even when the LDL-C is quite high like over 190 mg/dl.

Attempts at diet, weight loss, exercise, and supplements should be offered to lower LDL-C in those with a CACS of 0. 

Author
Dr. Joel Kahn

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