Case Presentation:
A 33-year-old patient with a history of ST-elevation myocardial infarction (STEMI) requiring 2 cardiac stents at the age of 30, presented with intermittent substernal chest pressure. He denied a previous history of nicotine, alcohol, or recreational drug use, and related having an uncle with premature coronary arterial disease (CAD). His physical exam was benign with non-palpable chest pain, absence of cardiac murmurs or rubs, and normal vital signs. Chest XRAY as well as serum lab work with CBC, CMP, serum troponins, and lipid panel were all unrevealing. An EKG demonstrated no ischemic pattern, but an echocardiogram was obtained showing multiple wall motion abnormalities and a 0.8 X 1.1 cm thrombus in his left ventricular (LV) apex. A secondary workup for hypercoagulable disorders demonstrated a heterozygous MTHFR c677T gene mutation. Given his young age and a lipid panel uncharacteristic of familial hypercholesterolemia, he was worked up for less conventional risk factors for CAD, and was found to have elevated levels of lipoprotein(a) (Lp(a)). Currently, he remains on coumadin as well as daily statin and aspirin for the treatment of his intra-ventricular thrombus and existing CAD.
Discussion:
The influence of MTHFR heterozygosity on LV thrombus formation, as well as the relative contribution of the intracardiac thrombus towards his chest discomfort are both unclear at this point. However, elevated levels of Lp(a) have been associated with CAD, especially in patients with premature CAD without other dyslipidemias. Screening for Lp(a) is recommended for patients with premature CAD, familial hypercholesterolemia, family history of premature CAD or elevated Lp(a), or recurrent cardiovascular disease (CVD) despite statin treatment. Several studies have identified increased levels of Lp(a) as an independent risk factor that remains constant over time as well as having a causal relationship for CAD. Lifestyle modifications do not alter serum Lp(a) levels significantly because Lp(a) is a genetically determined dyslipidemia. Although the most pragmatic and available treatment for Lp(a) dyslipidemia is the use of daily extended-release (ER) niacin, its efficacy in lowering CVD incidence presently remains unclear.
Conclusions:
In patients with premature CVD, Lp(a) dyslipidemia should be high on one’s differential, meriting additional workup and possible treatment. Elevated levels of Lp(a) are independently and causally associated with an increased risk for CVD, and cannot be significantly improved with lifestyle modifications. Use of daily high dose niacin (ER) remains the most pragmatic therapy available to lower serum Lp(a) levels and to potentially reduce the incidence of CVD events.