A New Guideline on Treatment of Hypertension in Those with Coronary Artery Disease

Hypertension is a major risk factor for coronary artery disease (CAD) and the two frequently coexist. The peak cardiology and hypertension societies of the United States recently published new guidelines on the treatment of hypertension in people with CAD. The guidelines update those previously issued eight years previously in the light of new trial data. However, for the most part they will validate what cardiologists are already doing in these patients. The major change is resetting of the blood pressure general treatment target for most people with hypertension and CAD from 130/80 mm Hg to 140/90 mm Hg. It is arguable that the evidence supporting the new target is any stronger than that supporting the old. While this will remain controversial in the absence of good data on the relative benefits of different treatment targets in hypertension it is in line with trends from a number of other general hypertension guidelines.

Introduction

A new scientific statement on the treatment of hypertension in people with coronary artery disease was recently issued jointly by the American Heart Association, the American College of Cardiology and the American Society of Hypertension [1]. This is an update of a 2007 statement. It tackles four main questions in the light of recent evidence. These are:

• What are the appropriate blood pressure targets in people with coronary artery disease (CAD)?

• Are there effects of particular classes of anti-hypertensive drugs beyond their effects on blood pressure?

• Are certain drugs preferred in secondary prevention?

• Which anti-hypertensive drugs should be used in particular patient groups including stable angina, acute coronary syndromes (ACS), non–ST-segment elevation myocardial infarction (NSTEMI), ST-elevation myocardial infarction (STEMI), or heart failure with underlying CAD?

The main recommendations regarding choice of drugs in particular circumstances are shown in Figure 1. The recommended blood pressure goals are shown in Table 1. The drug choices are more firmly evidence based and are classified by the writing group as having a good size and a reasonable level of a certainty and precision of the treatment effect (class IA evidence). Of the blood pressure goals only a level less than 140/90mml in people with coronary disease in general is classified as IA evidence. The other targets listed in Table 1 have lower classification of evidence, reflecting the lack of trials specifically designed to determine blood pressure targets in hypertension.

The first question that can be asked is - do we need statements and/or guidelines for the management of the individual risk factors for CAD? [2]. Should we not consider all risk factors together as they commonly coexist in people with CAD and their effects on the likelihood of future major clinical events are additive or even multiplicative? There has been a move amongst guideline committees in recent years to lump conventional risk factors together using algorithms to calculate absolute risk and provide advice on how elevated risk should be reduced. In Australia, we have a national guideline on absolute risk calculated using a Framingham-like algorithm [3], [4]. The European hypertension guidelines emphasise risk but high risk is defined by the presence of clinically derived factors such as evidence of target organ damage or associated clinical conditions. Recently in the US, lipid guidelines have taken an absolute risk based approach but this has been less evident in recent statements on the management of hypertension [5], [6].

An absolute risk based approach does address one problem in the field. There are too many guidelines and statements in circulation that mostly say the same things albeit in different ways. It does have its problems though. Absolute risk equations are generally derived in specific populations across an age range that excludes the very young and the elderly. Extrapolation beyond the age range where the data was obtained is problematic, particularly as age is a major variable in the calculation itself. Standard equations do not apply well to special populations including Aboriginal and Torres Strait Islanders, or people with co-existing diseases including renal impairment, psychiatric disorders and inflammatory diseases.

In people with hypertension and CAD, the questions are very different, as their risk has been clearly established, is very high and proper management is essential.