It's one thing for investors to get upset because a company's clinical trial is taking too long, but it's a whole other ballgame when Congress gets involved.

Yesterday, the House Committee on Energy and Commerce demanded more information about why Merck (NYSE:MRK) and Schering-Plough (NYSE:SGP) are taking so long to release results from their ENHANCE clinical trial.

The goal was to see if the duo's VYTORIN, a combination of their ZETIA drug and Merck's ZOCOR, was better at preventing heart attacks than ZOCOR alone. All the patients completed dosing in April of last year, but there's still no data to be seen.

Last month, the companies announced that releasing the data is taking so long because of different interpretations of the ultrasound images of the arteries. The trial aims to measure the amount of plaque in the arteries, which leads to heart attacks.

The companies haven't seen the data yet, so they're certainly not dragging their feet because they know the results. On the other hand, because the Food and Drug Administration has already approved VYTORIN and ZETIA, the companies are obviously in no rush to get the trial completed. Given the double-digit increases in sales of late, it's unlikely that a positive result would help sales much. But if the trial shows that ZETIA doesn't decrease the risk of heart attacks more than ZOCOR alone, patients would likely switch over to generic versions of ZOCOR or other statins such as Pfizer's (NYSE:PFE) Lipitor and AstraZeneca's (NYSE:AZN) Crestor.

While investors certainly don't want the CEOs to get letters from Congress, I doubt much will come from its investigation. The trial data will eventually come out, and investors should cross their fingers that the lower cholesterol levels ZETIA produces translates into less plaque in the arteries.

More Foolishness on trial delays:

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Fool contributor Brian Orelli, Ph.D., doesn't own shares of any company mentioned in this article. The Fool has a disclosure policy.