Rhododendron and their kin (azalea, mountain-laurel) can struggle when planted close to a foundation, due in part to the reduced airflow from the crowding and nearby wall, compacted soil, potentially higher pH (they require acidic soil to thrive, and leaching from the concrete might alter pH over time), and a possible rain shadow from a roof of the wall, or root zone flooding if a downspout outlet is nearby or uphill of the shrubs.

In this case, we suspect Botryosphaeria canker was at least partially responsible for dieback. There is no set lifespan for Rhododendron (they can live for decades), but stress can predispose plants to conditions that can cause dieback or root loss. That particular fungal canker tends to impact Rhododendrons that are stressed by drought, and unless you happened to be watering regularly last year, the 2024 drought was significant across much of the state, weakening even well-established plants. Stress can also make Rhododendrons a more vulnerable to borers, as mentioned in our azalea/rhododendron diagnostic web page.

The foliage pictured looks healthy and isn't showing signs of nutrient deficiency that can result from soil pH changes. It doesn't look wilted in the way that root rot can cause, which also suggests that cumulative stress from summer heat and drought might have played a role in canker development and dieback. You can prune off any branches or branch stubs that do not leaf-out next spring. Sometimes, a severe pruning to cut back a mature Rhododendron can result in renewed growth that can refresh the plant's appearance after it takes a couple years to fill in.

If you prefer to replace the plants, assuming the site conditions are partial shade (given the Eastern exposure) with acidic soil that doesn't get too wet, plus the deer browsing risk you mentioned, below are some ideas. Botanical names are in italics. To narrow options down, consider mature size and how much room you have in that planting bed, since not all shrubs are conducive to being pruned to restrain their growth.

• Leucothoe (either Leucothoe axillaris or L. fontanesiana, they look nearly identical) -- some varieties have colorful foliage; these are native to the southeast, though not within MD
• Illicium (Illicium; various species and cultivars, some more cold-hardy than others) -- harder to find locally as they are more marginally hardy in central MD, but usually they handle our average winters fine; they do bloom, but they're not nearly as showy as Rhododendron flowers, though the foliage does look very similar; mature size varies depending on cultivar, with the shortest being only about 3 feet tall and the largest over 10 feet; a couple species are native to the southeast
• Japanese Plum Yew (Cephalotaxus harringtonia) -- unlike "true" yews (Taxus), these relatives are much less palatable to deer; there are several cultivars that grow wider than tall, and a couple that grow more upright and slender, though each can be pruned lightly for slight size adjustments
• False Holly (Osmanthus heterophyllus) -- holly-shaped foliage with fragrant white flowers in mid- to late autumn; dwarf cultivars exist (which will be slow-growing), and the taller growers tolerate pruning well; as the shrubs age, some leaves may become less spiny, as can happen with some hollies (though it's probably variety-dependent); some cultivars have colorful foliage
• American Holly (Ilex opaca), specifically a dwarf cultivar like 'Maryland Dwarf' or 'Clarendon Spreading' because the others get much too large -- locally native species; the dwarf cultivars don't produce nearly as many berries as non-dwarf forms do, so they may not be as showy, but the low, broad growth habit requires little to no pruning; be advised, though, that the growth rate is slow, and while 'Maryland Dwarf' has become a bit more widely available at area nurseries in recent years, it will cost more than the average shrub in the same pot size due to that slower growth
• if Rhododendrons have otherwise been doing fairly well in this location for those decades, then perhaps you could use a dwarf Rhododendron cultivar, of which there are dozens on the market; while Rhododendron is generally not considered deer-resistant, those with indumentum (fuzz, basically) on the undersides of their leaves are less palatable to them, though flower buds would always be at risk; cultivars in the Rhododendron yakushimanum group tend to have cinnamon-brown, golden-tan, or grayish indumentum on young leaves; Rhododendron cultivars in the 'PJM' group (they have R. carolinianum parentage and smaller leaves, more like an azalea's in size) have very fragrant foliage when the leaves are crushed, a trait deer might find unappealing; those cultivars tend to stay around 5 feet tall or less, depending on variety

Miri