This is a substudy of MARCH, in which we are exploring the changes in the vascular endothelium using pulse wave tonometry (a non invasive measure of cardiac health) to measure the changes in small and large arterial elasticity in participants of the MARCH study who switch to maraviroc-based regimens over 96 weeks of follow-up.

Cardiovascular disease is increasingly recognised as a complication of HIV +/- therapies to treat it. Blood vessel elasticity, or compliance, can be depicted as the ability of the vessels to convert intermittent blood flow (cardiac ejection during systole) to continuous blood flow throughout the cardiac cycle. The compliance, or ability of vessels to accept energy, can be subdivided into elasticity of large and small vessels. Pulse wave tonometry is a non-invasive technique performed using a hand-held tonometer that generates two indices which correspond to large artery elasticity (LAE) and small artery elasticity (SAE). LAE and SAE estimates by pulse waveform analysis have previously shown greater correlation to Framingham risk when directly compared with other techniques such as flow-mediated diltation, and both LAE and SAE are associated with traditional cardiovascular risk factors (smoking, insulin resistance, hypertension).

It is unclear what the net effect of maraviroc, a chemokine-receptor blocker is on cardiovascular function.

The aims of this substudy are:

• To compare changes in the vascular endothelium between the control arm ((N(t)RTI) plus PI/r) and each of the maraviroc switch arms over 48 weeks of follow-up.
• To compare the changes in biomarkers and selected immunological markers between the control arm ((N(t)RTI) plus PI/r) and each of the maraviroc switch arms over 48 weeks of follow-up.

Inclusion Criteria:

• Enrolled prior to treatment in the parent study;
• Provision of written, informed consent for participation in the substudy

Exclusion Criteria:

• Known supraventricular tachycardia such as atrial flutter and/or fibrillation that precludes the measurement of pulse wave using tonometry.

Participants in MARCH